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    Wenjiao Xu, Huaigang Cheng, Enze Li, Zihe Pan, Fangqin Cheng
    Frontiers of Chemical Science and Engineering, 2022, 16(11): 1659-1671.

    For decades, distiller waste and CO2 were not the first choice for production of high valued products. Here, CaCO3 hollow microspheres, a high-value product was synthesized from such a reaction system. The synthetic methods, the formation mechanism and operational cost were discussed. When 2.5 L·min–1·L–1 CO2 was flowed into distiller waste (pH = 11.4), spheres with 4–13 μm diameters and about 2 μm shell thickness were obtained. It is found that there is a transformation of CaCO3 particles from solid-cubic nuclei to hollow spheres. Firstly, the Ca(OH)2 in the distiller waste stimulated the nucleation of calcite with a non-template effect and further maintained the calcite form and prevented the formation of vaterite. Therefore, in absence of auxiliaries, the formation of hollow structures mainly depended on the growth and aging of CaCO3. Studies on the crystal morphology and its changes during the growth process point to the inside–out Ostwald effect in the formation of hollow spheres. Change in chemical properties of the bulk solution caused changes in interfacial tension and interfacial energy, which promoted the morphological transformation of CaCO3 particles from cubic calcite to spherical clusters. Finally, the flow process for absorption of CO2 by distiller waste was designed and found profitable.

    Dongyang Liu, Yibo Zhi, Yuen Bai, Liang Zhao, Jinsen Gao, Chunming Xu
    Frontiers of Chemical Science and Engineering, 2022, 16(12): 1700-1712.

    The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.

    Chenxi Xu, Shunli Li, Zhaohui Hou, Liming Yang, Wenbin Fu, Fujia Wang, Yafei Kuang, Haihui Zhou, Liang Chen
    Frontiers of Chemical Science and Engineering, 2023, 17(6): 679-690.

    The massive conversion of resourceful biomass to carbon nanomaterials not only opens a new avenue to effective and economical disposal of biomass, but provides a possibility to produce highly valued functionalized carbon-based electrodes for energy storage and conversion systems. In this work, biomass is applied to a facile and scalable one-step pyrolysis method to prepare three-dimensional (3D) carbon nanotubes/mesoporous carbon architecture, which uses transition metal inorganic salts and melamine as initial precursors. The role of each employed component is investigated, and the electrochemical performance of the attained product is explored. Each component and precise regulation of their dosage is proven to be the key to successful conversion of biomass to the desired carbon nanomaterials. Owing to the unique 3D architecture and integration of individual merits of carbon nanotubes and mesoporous carbon, the as-synthesized carbon nanotubes/mesoporous carbon hybrid exhibits versatile application toward lithium-ion batteries and Zn-air batteries. Apparently, a significant guidance on effective conversion of biomass to functionalized carbon nanomaterials can be shown by this work.

    Lixin Xing, Jiaming Wang, Xuehua Ruan, Gaohong He
    Frontiers of Chemical Science and Engineering, 2022, 16(11): 1536-1559.

    Poly(ether−ether ketone) (PEEK) is a linear aromatic macromolecule, which can form semi-crystalline aggregative status, allowing PEEK materials to have strong environment tolerance and excellent physicochemical properties. PEEK materials have become a promising alternative to fabricate particular membranes used in extreme conditions. In the past few decades, many researches and evolutions have emerged in membrane fabrication with PEEK materials and its applications for treating organic solvents and their mixtures; however, there are little systematic and comprehensive literature to summarize fabrication approaches, compile applications, and elaborate PEEK property-structure relationship. In this review, the main approaches to fabricate PEEK-based membranes are illustrated concretely, including conventional thermal-induced and non-solvent-induced phase separation, and novel chemical-induced crystallization; the representative applications in ultrafiltration, nanofiltration and membrane contactor containing organic solvents are demonstrated systematically. Meanwhile, the mechanism to tune PEEK solubility in solvents, which can be achieved by altering monomers in synthesis processes or changing membrane preparation routes, is deeply analyzed. Moreover, the existing problems and the future prospects are also discussed. This review provides positive guidance for designing and fabricating membranes using PEEK and its derivative materials for task-specific applications in harsh conditions.

    Yixuan Chang, Fanwei Kong, Zihao Zhu, Ziai Wang, Chunxia Chen, Xiaobai Li, Hongwei Ma
    Frontiers of Chemical Science and Engineering, 2023, 17(7): 966-975.

    The efficient utilization of natural lignin, which is the main by-product of the cellulose industry, is crucial for enhancing its economic value, alleviating the environmental burden, and improving ecological security. By taking advantage of the large sp2 hybrid domain of lignin and introducing amino functional groups, new lignin-derived carbon dots (SPN-CDs) with red fluorescence were successfully synthesized. Compared with green and blue fluorescent materials, red SPN-CDs have desirable anti-interference properties of short-wave background and exhibit superior luminescence stability. The SPN-CDs obtained exhibited sensitive and distinctive visible color with fluorescence-dual responses toward hypochlorite. Considering this feature, a portable, low-cost, and sensitive fluorescence sensing paper with a low limit of detection of 0.249 μmol∙L–1 was fabricated using the SPN-CDs for hypochlorite detection. Furthermore, a new type of visible-light and fluorescence dual-channel information encryption platform was constructed. Low-concentration hypochlorite can be employed as an accessible and efficient information encryption/decryption stimulus, as well as an information “eraser”, facilitating a safe and diversified transmission and convenient decryption of information. This work opens new avenues for high-value-added applications of lignin-based fluorescent materials.

    Wang Li, Wen-Ying Li, Xing-Bao Wang, Jie Feng
    Frontiers of Chemical Science and Engineering, 2022, 16(12): 1689-1699.

    Radicals are important intermediates in direct coal liquefaction. Certain radicals can cause the cleavage of chemical bonds. At high temperatures, radical fragments can be produced by the splitting of large organic molecules, which can break strong chemical bonds through the induction pyrolysis of radicals. The reaction between the formation and annihilation of coal radical fragments and the effect of hydrogen-donor solvents on the radical fragments are discussed in lignite hydrogenolysis. Using the hydroxyl and ether bonds as indicators, the effects of different radicals on the cleavage of chemical bond were investigated employing density functional theory calculations and lignite hydrogenolysis experiments. Results showed that the adjustment of the coal radical fragments could be made by the addition of hydrogen-donor solvents. Results showed that the transition from coal radical fragment to H radical leads to the variation of product distribution. The synergistic mechanism of hydrogen supply and hydrogenolysis of hydrogen-donor solvent was proposed.

    Linghong Yin, Zizhu Zhao, Meng Han, Wangda Qu
    Frontiers of Chemical Science and Engineering, 2023, 17(8): 1051-1064.

    This research is a follow-up to our recent discovery of a facile strategy for directly converting lignin powder into carbon foam. In this work, we report that the thermal pretreatment parameters in air can remarkably influence the formation and properties of the derived carbon foam. Thermal pretreatment parameters (heating rate, temperature, and residence time) were systematically investigated and a conversion mechanism into carbon foam was proposed. During the thermal pretreatment, relatively low temperatures, low heating rates, and short residence time hindered the formation of smooth and well-connected structures in the carbon foam. The overall product yields were similar regardless of the thermal pretreatment conditions. The densities of the different carbon foams ranged 0.27–0.83 g∙cm−3. The carbon foams with the highest compressive strengths (> 10 MPa) were KLPC280-2-5, KLPC300-0-5, and KLPC300-2-2.5. KLPC280-2-5 exhibited a high iodine sorption value (182 mg∙g−1). KLPC300-2-5 exhibited a specific capacitance of 158 F∙g−1 at a current density of 0.05 A∙g−1. The maximum evaporation rates in the solar vapor generation experiments were 1.05 and 1.38 kg∙m−2∙h−1 under 100 and 150 mW∙cm−2 irradiation, respectively. The good performances are attributed to the robust, porous, and continuous structure.

    Chaoqun Yao, Shuainan Zhao, Lixue Liu, Zhikai Liu, Guangwen Chen
    Frontiers of Chemical Science and Engineering, 2022, 16(11): 1560-1583.

    Emulsion systems are widely applied in agriculture, food, cosmetic, pharmaceutical and biomedical industries. Ultrasound has attracted much attention in emulsion preparation, especially for nanoemulsion, due to its advantages of being eco-friendly, cost-effective and energy-efficient. This review provides an overview for readers to the area of ultrasonic emulsification technology. It briefly introduces and summarizes knowledge of ultrasonic emulsification, including emulsion characteristics, acoustic cavitation, emulsification mechanism, ultrasonic devices and applications. The combination of microfluidics and ultrasound is highlighted with huge advantages in controlling cavitation phenomena and emulsification intensification. A novel scale of C0.6/μD0.33EV is proposed to be able to compare the energy efficiency of emulsion preparation in different devices.

    Wenquan Xie, Xianhui Zhang, Dengke Xi, Rusen Zhou, Size Yang, Patrick Cullen, Renwu Zhou
    Frontiers of Chemical Science and Engineering, 2023, 17(5): 594-605.

    The increasing amount of food waste from various industrial, agricultural, and household sources is an environmental burden if managed inappropriately. Numerous waste management approaches have been developed for the disposal of food waste, but still suffer from either high cost, production of toxic by-products, or secondary environmental pollutions. Herein, we report a new and sustainable plasma electrolysis biorefinery route for the rapid and efficient liquefaction of food waste. During the plasma electrolysis process, only the solvent is added to liquefy the waste, and anions in the waste can contribute to catalyzing the biowaste conversion. While liquefying the waste, the highly reactive species produced in the plasma electrolysis process can efficiently reduce the content of O, N, and Cl in the liquefied products and oxidize most of the metals into solid residues. Especially, the removal rate of Na and K elements was greater than 81%, which is significantly higher than using the traditional oil bath liquefaction, resulting in a relatively high-quality biocrude oil with a high heating value of 25.86 MJ·kg–1. Overall, this proposed strategy may provide a new sustainable and eco-friendly avenue for the power-to-chemicals valorization of food waste under benign conditions.

    Wanli Wang, Dongfang Yang, Xiaoran Yan, Licheng Wang, Han Hu, Kai Wang
    Frontiers of Chemical Science and Engineering, 2023, 17(6): 635-678.

    Wave energy is inexhaustible renewable energy. Making full use of the huge ocean wave energy resources is the dream of mankind for hundreds of years. Nowadays, the utilization of water wave energy is mainly absorbed and transformed by electromagnetic generators (EMGs) in the form of mechanical energy. However, waves usually have low frequency and uncertainty, which means low power generation efficiency for EMGs. Fortunately, in this slow current and random direction wave case, the triboelectric nanogenerator (TENG) has a relatively stable output power, which is suitable for collecting blue energy. This article summarizes the main research results of TENG in harvesting blue energy. Firstly, based on Maxwell’s displacement current, the basic principle of the nanogenerator is expounded. Then, four working modes and three applications of TENG are introduced, especially the application of TENG in blue energy. TENG currently used in blue energy harvesting is divided into four categories and discussed in detail. After TENG harvests water wave energy, it is meaningless if it cannot be used. Therefore, the modular storage of TENG energy is discussed. The output power of a single TENG unit is relatively low, which cannot meet the demand for high power. Thus, the networking strategy of large-scale TENG is further introduced. TENG’s energy comes from water waves, and each TENG’s output has great randomness, which is very unfavorable for the energy storage after large-scale TENG integration. On this basis, this paper discusses the power management methods of TENG. In addition, in order to further prove its economic and environmental advantages, the economic benefits of TENG are also evaluated. Finally, the development potential of TENG in the field of blue energy and some problems that need to be solved urgently are briefly summarized.

    Xinhe Wang, Liuqing Yang, Xiaolin Ji, Yunfei Gao, Fanxing Li, Junshe Zhang, Jinjia Wei
    Frontiers of Chemical Science and Engineering, 2022, 16(12): 1726-1734.

    Chemical looping reforming of methane is a novel and effective approach to convert methane to syngas, in which oxygen transfer is achieved by a redox material. Although lots of efforts have been made to develop high-performance redox materials, a few studies have focused on the redox kinetics. In this work, the kinetics of SrFeO3−δ–CaO∙MnO nanocomposite reduction by methane was investigated both on a thermo-gravimetric analyzer and in a packed-bed microreactor. During the methane reduction, combustion occurs before the partial oxidation and there exists a transition between them. The weight loss due to combustion increases, but the transition region becomes less inconspicuous as the reduction temperature increased. The weight loss associated with the partial oxidation is much larger than that with combustion. The rate of weight loss related to the partial oxidation is well fitted by the Avrami–Erofeyev equation with n = 3 (A3 model) with an activation energy of 59.8 kJ∙mol‒1. The rate law for the partial oxidation includes a solid conversion term whose expression is given by the A3 model and a methane pressure-dependent term represented by a power law. The partial oxidation is half order with respect to methane pressure. The proposed rate law could well predict the reduction kinetics; thus, it may be used to design and/or analyze a chemical looping reforming reactor.

    Jiawei Wang, Jie Hu, Junjie Cheng, Zefei Huang, Baoqian Ye
    Frontiers of Chemical Science and Engineering, 2023, 17(1): 46-55.

    Because of the increasing amount of oily wastewater produced each day, it is important to develop superhydrophilic/underwater superoleophobic oil/water separation membranes with ultrahigh flux and high separation efficiency. In this paper, a superhydrophilic/underwater superoleophobic N-isopropylacrylamide-coated stainless steel mesh was prepared through a simple and convenient graft polymerization approach. The obtained mesh was able to separate oil/water mixtures only by gravity. In addition, the mesh showed high-efficiency separation ability (99.2%) and ultrahigh flux (235239 L∙m–2∙h–1). Importantly, due to the complex cross-linked bilayer structure, the prepared mesh exhibited good recycling performance and chemical stability in highly saline, alkaline and acidic environments.

    Yana Li, Zenghui Li, Yuwen Wang, Liangbo Sun, Houchang Pei
    Frontiers of Chemical Science and Engineering, 2023, 17(6): 704-715.

    The multifunctional films was prepared by blending chitosan and nano-ZnO with purple tomato anthocyanins or black wolfberry anthocyanins. The properties of films functioned by anthocyanins source and nano-ZnO content were studied. It was found purple tomato anthocyanins showed more significant color change against pH than black wolfberry anthocyanins. The nano-ZnO were widely dispersed in matrix and enhanced the compatibility of anthocyanins with chitosan. However, the anthocyanins source influenced the properties of the films more slightly than nano-ZnO addition. The tensile strength, antioxidant and antibacterial effects of the chitosan films dramatically increased after cooperated by nano-ZnO and anthocyanins, which also enhanced with increase of nano-ZnO content, whereas the elongation at break of the composite films decreased. Especially, the anthocyanin and nano-ZnO promoted the antibacterial activity of films synergistically. Composite films made from black wolfberry anthocyanins exhibited higher mechanical performance than those made from purple tomato anthocyanins but weaker antibacterial effects. The purple tomato anthocyanins/chitosan and nano-ZnO/purple tomato anthocyanins/chitosan films effectively reflected pork spoilage, changing their colors from dark green to brown, indicating the potential for applications in active and intelligent food packaging.

    Benjing Xu, Jinhang Dai, Ziting Du, Fukun Li, Huan Liu, Xingxing Gu, Xingmin Wang, Ning Li, Jun Zhao
    Frontiers of Chemical Science and Engineering, 2023, 17(7): 817-829.

    Amino acids are important nitrogen-containing chemicals that have a variety of applications. Currently, fermentation is the widely employed method to produce amino acids; however, the products are mostly limited to natural amino acids in the L-configuration. Catalytic synthesis is an alternative approach for the synthesis of amino acids with different types and configurations, where the use of renewable biomass-based feedstocks is highly attractive. To date, several lignocellulose and triacylglycerol-derived intermediates, typically α-keto acids and α-hydroxyl acids, have been transformed into amino acids via the amination reaction in the presence of additional nitrogen sources (i.e., NH3·H2O). Making full use of inherent nitrogen in biomass (i.e., chitin and protein) to produce amino acids avoids the use of extra nitrogen sources and meets the requirements of green chemistry, which is attracting increasing attention. In this review, we summarize different chemical-catalytic systems for the transformation of biomass to amino acids. An outlook on the challenges and opportunities for more effective production of amino acids from biomass by catalytic methods is provided.

    Guojia Yu, Dongyu Jin, Xinyu Li, Fan Zhang, Shichao Tian, Yixin Qu, Zhiyong Zhou, Zhongqi Ren
    Frontiers of Chemical Science and Engineering, 2022, 16(12): 1735-1742.

    A nitrogen-containing ionic liquid was synthesized using an aromatic nitrogen-containing heterocyclic and an amino acid, and applied to the extractive desulfurization process to remove benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiphene from a model fuel oil. Chemical characterizations and simulation using Gaussian 09 software confirmed the rationality of an ionic liquid structure. Classification of non-covalent interactions between the ionic liquid and the three sulfur-containing contaminants was studied by reduced density gradient analysis. The viscosity of the ionic liquid was adjusted by addition of polyethylene glycol. Under extraction conditions of the volume of ionic liquid to oil as 1:1 and temperature as room temperature, the desulfurization selectivity of ionic liquid followed the order of 4,6-dimethyldibenzothiphene (15 min) < benzothiophene (15 min) ≈ dibenzothiophene (10 min). Addition of p-xylene and cyclohexene to the fuel oil had little effect. The extractant remained stable and effective after multiple regeneration cycles.

    Melvin X. J. Wee, Bridgid L. F. Chin, Agus Saptoro, Chung L. Yiin, Jiuan J. Chew, Jaka Sunarso, Suzana Yusup, Abhishek Sharma
    Frontiers of Chemical Science and Engineering, 2023, 17(9): 1141-1161.

    The Association of Southeast Asian Nations is blessed with agricultural resources, and with the growing population, it will continue to prosper, which follows the abundance of agricultural biomass. Lignocellulosic biomass attracted researchers’ interest in extracting bio-oil from these wastes. However, the resulting bio-oil has low heating values and undesirable physical properties. Hence, co-pyrolysis with plastic or polymer wastes is adopted to improve the yield and quality of the bio-oil. Furthermore, with the spread of the novel coronavirus, the surge of single-use plastic waste such as disposable medical face mask, can potentially set back the previous plastic waste reduction measures. Therefore, studies of existing technologies and techniques are referred in exploring the potential of disposable medical face mask waste as a candidate for co-pyrolysis with biomass. Process parameters, utilisation of catalysts and technologies are key factors in improving and optimising the process to achieve commercial standard of liquid fuel. Catalytic co-pyrolysis involves a series of complex mechanisms, which cannot be explained using simple iso-conversional models. Hence, advanced conversional models are introduced, followed by the evolutionary models and predictive models, which can solve the non-linear catalytic co-pyrolysis reaction kinetics. The outlook and challenges for the topic are discussed in detail.

    Huabin Wang, Dingxiang Chen, Yi Wen, Ting Cui, Ying Liu, Yong Zhang, Rui Xu
    Frontiers of Chemical Science and Engineering, 2023, 17(7): 880-892.

    The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization. However, these materials would be inevitably aged by natural forces after entering into the environment, while there are seldom studies reported the aging effects of zero-valent iron modified biochar. In this work, the hydrogen peroxide and hydrochloric acid solution were applied to simulate aging conditions of zero-valent iron modified biochar. According to the results, the adsorption capacity of copper(II) contaminants on biochar, zero-valent iron modified biochar-1, and zero-valent iron modified biochar-2 after aging was decreased by 15.36%, 22.65% and 23.26%, respectively. The surface interactions were assigned with chemisorption occurred on multi-molecular layers, which were proved by the pseudo-second-order and Langmuir models. After aging, the decreasing of capacity could be mainly attributed to the inhibition of ion-exchange and zero-valent iron oxidation. Moreover, the plant growth and soil leaching experiments also proved the effects of aging treatment, the zero-valent iron modified biochar reduced the inhibition of copper(II) bioavailability and increased the mobility of copper(II) after aging. All these results bridged the gaps between bio-adsorbents customization and their environmental behaviors during practical agro-industrial application.

    Nanlong Hong, Jiahui Wang, Jinhua You
    Frontiers of Chemical Science and Engineering, 2023, 17(8): 1075-1084.

    Inspired by the importance of the phenolic group to the electron transporting property of hole transport materials, phenolic hydroxyl groups were introduced in lignosulfonate (LS) via the alkyl chain bridging method to prepare phenolated-lignosulfonate (PLS). The results showed that the phenolic group was boosted from 0.81 mmol∙g–1 of LS to 1.19 mmol∙g–1 of PLS. The electrochemical property results showed two oxidation peaks in the cyclic voltammogram (CV) curve of PLS, and the oxidation potential of the PLS-modified electrode decreased by 0.5 eV compared with that of LS. This result indicates that PLS is more easily oxidized than LS. Based on the excellent electron transporting property of PLS, PLS was applied as a dopant in poly(3,4-ethylenedioxythiophene) (PEDOT, called PEDOT:PLSs). PLS showed excellent dispersion properties for PEDOT. Moreover, the transmittance measurement results showed that the transmittance of PEDOT:PLSs exceeded 85% in the range of 300–800 nm. The CV results showed that the energy levels of PEDOT:PLSs could be flexibly adjusted by PLS amounts. The results indicate that the phenolic hydroxyl group of lignin can be easily boosted by the alkyl chain bridging method, and phenolated lignin-based polymers may have promising potential as dopants of PEDOT to produce hole transporting materials for different organic photovoltaic devices.

    Jiangwei Li, Lina Meng, Jiaxuan Chen, Xu Chen, Yonggui Wang, Zefang Xiao, Haigang Wang, Daxin Liang, Yanjun Xie
    Frontiers of Chemical Science and Engineering, 2023, 17(8): 1038-1050.

    Phase change materials are potential candidates for the application of latent heat storage. Herein, we fabricated porous capsules as shape-stable materials from cellulose-based polyelectrolyte complex, which were first prepared using cellulose 6-(N-pyridinium)hexanoyl ester as the cationic polyelectrolyte and carboxymethyl cellulose as the anionic polyelectrolyte to encapsulate polyethylene glycol by the vacuum impregnation method. Furthermore, the multi-walled carbon nanotube or graphene oxide, which were separately composited into the polyelectrolytes complex capsules to enhance thermal conductivity and light-to-thermal conversion efficiency. These capsules owned a typical core–shell structure, with an extremely high polyethylene glycol loading up to 34.33 g∙g‒1. After loading of polyethylene glycol, the resulted cellulose-based composite phase change materials exhibited high thermal energy storage ability with the latent heat up to 142.2 J∙g‒1, which was 98.5% of pure polyethylene glycol. Further results showed that the composite phase change materials demonstrated good form-stable property and thermal stability. Moreover, studies involving light-to-thermal conversion determined that composite phase change materials exhibited outstanding light-to-thermal conversion performance. Considering their exceptional comprehensive features, innovative composite phase change materials generated from cellulose presented a highly interesting choice for thermal management and renewable thermal energy storage.

    Jiwei Xie, Guijing Liu, Kaikai Wang, Xueming Li, Yusen Bai, Shanmin Gao, Leqing Fan, Rundou Zheng
    Frontiers of Chemical Science and Engineering, 2023, 17(2): 217-225.

    Aqueous zinc-ion batteries are attracting considerable attention because of their high safety compared with conventional lithium-ion batteries. Manganese-based materials have been widely developed for zinc-ion batteries cathode owning to their low cost, high security and simple preparation. However, the severe volume expansion and poor stability during charging and discharging limit the further development of manganese-based cathodes. Herein, superior α-MnO2@g-C3N4 was successfully prepared for stable zinc-ion batteries (ZIBs) cathode by introducing g-C3N4 nanosheets. Compared with pure α-MnO2, α-MnO2@g-C3N4 has a specific capacity of 298 mAh·g–1 at 0.1 A·g–1. Even at 1 A·g–1, the α-MnO2@g-C3N4 still retains 100 mAh·g–1 (83.4% retention after 5000 cycles), implying its excellent cycling stability. The α-MnO2@g-C3N4-based cathode has the highest energy density (563 Wh·kg–1) and power energy density (2170 W·kg–1). This work provides new avenues for the development of a wider range of cathode materials for ZIBs.

    Xuepeng Ni, Kunming Li, Changlei Li, Qianqian Wu, Chenglin Liu, Huifang Chen, Qilin Wu, Anqi Ju
    Frontiers of Chemical Science and Engineering, 2023, 17(6): 691-703.

    Cellulose has a wide range of applications in many fields due to their naturally degradable and low-cost characteristics, but few studies can achieve cellulose-nanofibers by conventional electrospinning. Herein, we demonstrate that the freestanding cellulose-based carbon nanofibers are successfully obtained by a special design of electrospinning firstly, pre-oxidation and high-temperature carbonization (1600 °C), which display a superior electrical conductivity of 31.2 S·cm–1 and larger specific surface area of 35.61 m2·g–1 than that of the polyacrylonitrile-based carbon nanofibers (electrical conductivity of 18.5 S·cm–1, specific surface area of 12 m2·g–1). The NiCo2O4 nanoflake arrays are grown uniformly on the cellulose-based carbon nanofibers successfully by a facile one-step solvothermal and calcination method. The as-prepared cellulose-based carbon nanofibers/NiCo2O4 nanoflake arrays are directly used as electrodes to achieve a high specific capacitance of 1010 F·g–1 at 1 A·g–1 and a good cycling stability with 90.84% capacitance retention after 3000 times at 10 A·g–1. Furthermore, the all-solid-state symmetric supercapacitors assembled from the cellulose-based carbon nanofibers/NiCo2O4 deliver a high energy density of 62 W·h·kg–1 at a power density of 1200 W·kg–1. Six all-solid-state symmetric supercapacitors in series can also power a ‘DHU’ logo consisted of 36 light emitting diodes, confirming that the cellulose-based carbon nanofiber is a promising carbon matrix material for energy storage devices.

    Jiannan Zhu, Vladimir Mahalec, Chen Fan, Minglei Yang, Feng Qian
    Frontiers of Chemical Science and Engineering, 2023, 17(6): 759-771.

    This work introduces a deep-learning network, i.e., multi-input self-organizing-map ResNet (MISR), for modeling refining units comprised of two reactors and a separation train. The model is comprised of self-organizing-map and the neural network parts. The self-organizing-map part maps the input data into multiple two-dimensional planes and sends them to the neural network part. In the neural network part, residual blocks enhance the convergence and accuracy, ensuring that the structure will not be overfitted easily. Development of the MISR model of hydrocracking unit also benefits from the utilization of prior knowledge of the importance of the input variables for predicting properties of the products. The results show that the proposed MISR structure predicts more accurately the product yields and properties than the previously introduced self-organizing-map convolutional neural network model, thus leading to more accurate optimization of the hydrocracker operation. Moreover, the MISR model has smoother error convergence than the previous model. Optimal operating conditions have been determined via multi-round-particle-swarm and differential evolution algorithms. Numerical experiments show that the MISR model is suitable for modeling nonlinear conversion units which are often encountered in refining and petrochemical plants.

    Yunpeng Shen, Weishan Tang, Jinyang Li, Zhijun Ke, Lirong Liao, Peng Yang, Yuntao Lu, Xiaoping Rao
    Frontiers of Chemical Science and Engineering, 2023, 17(9): 1267-1279.

    The emergence of vitrimer, a new class of polymer materials can address the problem of recyclability, reprocess ability and recyclability of thermosetting plastics. Rosin, a natural product, is an ideal raw material for the preparation of polymers in a more sustainable way. Nevertheless, due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure, the cross-link density of materials is frequently lowered. In this study, hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids, which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers. It was completely characterized by differential scanning calorimetry test, thermogravimetric analysis, shape memory test and self-healing test. The prepared vitrimers exhibited good self-healing properties, excellent heat resistance (Td = 352 °C) as well as high mechanical properties (tensile strength of 46.75 MPa). The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton. Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy. Moreover, our work expanded the application field of rosin, increased the added value of rosin, and provided a novel method for preparing rosin-based vitrimers with ideal properties.

    Zihan Xu, Huajie Xu, Lu Liu, Rongpei Jiang, Haisheng Ren, Xiangyuan Li
    Frontiers of Chemical Science and Engineering, 2022, 16(12): 1743-1750.

    The standard enthalpy of formation is an important predictor of the reaction heat of a chemical reaction. In this work, a high-precision method was developed to calculate accurate standard enthalpies of formation for polycyclic aromatic hydrocarbons based on the general connectivity based hierarchy (CBH) with the discrete correction of atomization energy. Through a comparison with available experimental findings and other high-precision computational results, it was found that the present method can give a good description of enthalpy of formation for polycyclic aromatic hydrocarbons. Since CBH schemes can broaden the scope of application, this method can be used to investigate the energetic properties of larger polycyclic aromatic hydrocarbons to achieve a high-precision calculation at the CCSD(T)/CBS level. In addition, the energetic properties of CBH fragments can be accurately calculated and integrated into a database for future use, which will increase computational efficiency. We hope this work can give new insights into the energetic properties of larger systems.

    Shiqing Ma, Chundong Peng, Zeyu Jia, Yanmei Feng, Kai Chen, Hao Ding, Daimei Chen, Zhong-Yong Yuan
    Frontiers of Chemical Science and Engineering, 2023, 17(11): 1718-1727.

    In recent years, organic photocatalyst under visible-light absorption has shown significant potential for solving environmental problems. However, it is still a great challenge for constructing a highly active organic photocatalyst due to the low separation efficiency of photogenerated carriers. Herein, an effective and robust photocatalyst perylene-3,4,9,10-tetracarboxylic diamide/boron nitride quantum dots (PDI/BNQDs), consisting of self-assemble PDI with π–π stacking structure and BNQDs, has been constructed and researched under visible light irradiation. The PDI/BNQDs composite gradually increases organic pollutant photodegradation with the loading amount of BNQDs. With 10 mL of BNQDs solution added (PDI/BNQDs-10), the organic pollutant photodegradation performance reaches a maximum, about 6.16 times higher with methylene blue and 1.68 times higher with ciprofloxacin than that of pure PDI supramolecular. The enhancement is attributed to improved separation of photogenerated carriers from self-assembled PDI by BNQDs due to their preeminent ability to extract holes. This work is significant for the supplement of PDI supramolecular composite materials. We believe that this photocatalytic design is capable of expanding organic semiconductors’ potential for their applications in photocatalysis.

    De Fang, Guanlin Huang, Jingyi Yang, Shengxing Pan, Caihong Lv, Da Li
    Frontiers of Chemical Science and Engineering, 2023, 17(10): 1399-1411.

    Three kinds of Ce-based catalysts (CePO4, CeVO4, Ce2(SO4)3) were synthesized and used for the selective catalytic reduction (SCR) of NO by NH3. NH3-SCR performances were conducted in the temperature range of 80 to 400 °C. The catalytic efficiencies of the three catalysts are as follow: CePO4 > CeVO4 > Ce2(SO4)3, which is in agreement with their abilities of NH3 adsorption capacities. The highest NO conversion rate of CePO4 could reach about 95%, and the catalyst had more than 90% NO conversion rate between 260 and 320 °C. The effect of PO43–, VO43– and SO42– on NH3-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis, NH3 temperature programmed desorption, H2 temperature programmed reduction and field emission scanning electron microscopy tests. The key factors that can enhance the SCR are the existence of Ce4+, large NH3 adsorption capacity, high and early H2 consumptions, and suitable microstructures for gas adsorption. Finally, CePO4 and CeVO4 catalysts also exhibited relatively strong tolerance of SO2, and the upward trend about 8% was detected due to the sulfation enhancement by SO2 for Ce2(SO4)3.

    You Han, Xiang Ma, Lin-Bing Sun, Jianhong Xu
    Frontiers of Chemical Science and Engineering, 2022, 16(11): 1533-1535.
    Pengfei Li, Huijiang Huang, Zheng Wang, Ziying Hong, Yan Xu, Yujun Zhao
    Frontiers of Chemical Science and Engineering, 2023, 17(1): 82-92.

    The amination of alkyl alcohols is one of the most promising paths in synthesis of aliphatic amines. Herein, cerium doped nickel-based catalysts were synthesized and tested in a gas-phase amination of n-hexanol to n-hexylamine. It was found that the activity of the Ni/γ-Al2O3 catalyst is significantly improved by doping an appropriate amount of cerium. The presence of cerium effectively inhibits the agglomeration of nickel particle, resulting in better Ni dispersion. As Ni particle size plays critical role on the catalytic activity, higher turnover frequency of n-hexanol amination was achieved. Cerium doping also improves the reduction ability of nickel and enhances the interactions between Ni and the catalyst support. More weak acid sites were also found in those cerium doped catalysts, which promote another key step—ammonia dissociative adsorption in this reaction system. The overall synergy of Ni nanoparticles and acid sites of this Ni–Ce/γ-Al2O3 catalyst boosts its superior catalytic performance in the amination of n-hexanol.

    Xinyi Yang, Xiaolu Liu, Yanfang Liu, Xiao-Feng Wang, Zhongshan Chen, Xiangke Wang
    Frontiers of Chemical Science and Engineering, 2023, 17(4): 395-403.

    Radioactive iodine exhibits medical values in radiology, but its excessive emissions can cause environmental pollution. Thus, the capture of radioiodine poses significant engineering for the environment and medical radiology. The adsorptive capture of radioactive iodine by metal–organic frameworks (MOFs) has risen to prominence. In this work, a Th-based MOF (denoted as Th-BPYDC) was structurally designed and synthesized, consisting of [Th63-O)43-OH)4(H2O)6]12+ clusters, abundant bipyridine units, and large cavities that allowed guest molecules diffusion and transmission. Th-BPYDC exhibited the uptake capacities of 2.23 g·g−1 and 312.18 mg·g−1 towards I2 vapor and I2 dissolved in cyclohexane, respectively, surpassing its corresponding analogue Th-UiO-67. The bipyridine units boosted the adsorption performance, and Th-BPYDC showed good reusability with high stability. Our work thus opened a new way for the synthesis of MOFs to capture radioactive iodine.

    Xuxin Zhao, Kunling Yang, Zhou Liu, Ho Cheung Shum, Tiantian Kong
    Frontiers of Chemical Science and Engineering, 2022, 16(11): 1681-1687.

    Bubbles and foams are ubiquitous in daily life and industrial processes. Studying their dynamic behaviors is of key importance for foam manufacturing processes in food packaging, cosmetics and pharmaceuticals. Bare bubbles are inherently fragile and transient; enhancing their robustness and shelf lives is an ongoing challenge. Their rupture can be attributed to liquid evaporation, thin film drainage and the nuclei of environmental dust. Inspired by particle-stabilized interfaces in Pickering emulsions, armored bubbles and liquid marble, bubbles are protected by an enclosed particle-entrapping liquid thin film, and the resultant soft object is termed gas marble. The gas marble exhibits mechanical strength orders of magnitude higher than that of soap bubbles when subjected to overpressure and underpressure, owing to the compact particle monolayer straddling the surface liquid film. By using a water-absorbent glycerol solution, the resulting gas marble can persist for 465 d in normal atmospheric settings. This particle-stabilizing approach not only has practical implications for foam manufacturing processes but also can inspire the new design and fabrication of functional biomaterials and biomedicines.