### Oct 2022, Volume 16 Issue 10

Cover illustration

• Epoxy resin products exhibit some intrinsic limitations of poor fire resistance and low tribology features under dry sliding, making them not suitable for many professional applications. Thus, the comprehensive properties of EP composites must be boosted to meet the needs when served as engineering parts and broaden their application field in high-demanding circumstances. Nie and his co-workers utilized the metal–organic framework as the hard template and nickel source to syn [Detail] ...

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• REVIEW ARTICLE
Xi-Le Hu, Hui-Qi Gan, Fan-De Meng, Hai-Hao Han, De-Tai Shi, Shu Zhang, Lei Zou, Xiao-Peng He, Tony D. James

Due to their simplicity in preparation, sensitivity and selectivity, fluorescent probes have become the analytical tool of choice in a wide range of research and industrial fields, facilitating the rapid detection of chemical substances of interest as well as the study of important physiological and pathological processes at the cellular level. In addition, many long-wavelength fluorescent probes developed have also proven applicable for in vivo biomedical applications including fluorescence-guided disease diagnosis and theranostics (e.g., fluorogenic prodrugs). Impressive progresses have been made in the development of sensing agents and materials for the detection of ions, organic small molecules, and biomacromolecules including enzymes, DNAs/RNAs, lipids, and carbohydrates that play crucial roles in biological and disease-relevant events. Here, we highlight examples of fluorescent probes and functional materials for biological applications selected from the special issues “Fluorescent Probes” and “Molecular Sensors and Logic Gates” recently published in this journal, offering insights into the future development of powerful fluorescence-based chemical tools for basic biological studies and clinical translation.

• RESEARCH ARTICLE
Zambaga Otgonbayar, Kwang Youn Cho, Chong-Hun Jung, Won-Chun Oh

The development of CO2 into hydrocarbon fuels has emerged as a green method that could help mitigate global warning. The novel structured photocatalyst is a promising material for use in a photocatalytic and magneto-electrochemical method that fosters the reduction of CO2 by suppressing the recombination of electron−hole pairs and effectively transferring the electrons to the surface for the chemical reaction of CO2 reduction. In our study, we have developed a novel-structured AgCuZnS2–graphene–TiO2 to analyze its catalytic activity toward the selective evolution of CO2. The selectivity of each nanocomposite substantially enhanced the activity of the AgCuZnS2–graphene–TiO2 ternary nanocomposite due to the successful interaction, and the selectivity of the final product was improved to a value 3 times higher than that of the pure AgCuZnS2 and 2 times higher than those of AgCuZnS2–graphene and AgCuZnS2–TiO2 under ultra-violet (UV)-light (λ = 254 nm) irradiation in the photocatalytic process. The electrochemical CO2 reduction test was also conducted to analyze the efficacy of the AgCuZnS2–graphene–TiO2 when used as a working electrode in laboratory electrochemical cells. The electrochemical process was conducted under different experimental conditions, such as various scan rates (mV·s–1), under UV-light and with a 0.07 T magnetic-core. The evolution of CO2 substantially improved under UV-light (λ = 254 nm) and with 0.07 T magnetic-core treatment; these improvements were attributed to the facts that the UV-light activated the electron-transfer pathway and the magnetic core controlled the pathway of electron-transmission/prevention to protect it from chaotic electron movement. Among all tested nanocomposites, AgCuZnS2–graphene–TiO2 absorbed the CO2 most strongly and showed the best ability to transfer the electron to reduce the CO2 to methanol. We believe that our newly-modeled ternary nanocomposite opens up new opportunities for the evolution of CO2 to methanol through an electrochemical and photocatalytic process.

• RESEARCH ARTICLE

Carbon nanotubes-based materials have been identified as promising sorbents for efficient CO2 capture in fluidized beds, suffering from insufficient contact with CO2 for the high-level CO2 capture capacity. This study focuses on promoting the fluidizability of hard-to-fluidize pure and synthesized silica-coated amine-functionalized carbon nanotubes. The novel synthesized sorbent presents a superior sorption capacity of about 25 times higher than pure carbon nanotubes during 5 consecutive adsorption/regeneration cycles. The low-cost fluidizable-SiO2 nanoparticles are used as assistant material to improve the fluidity of carbon nanotubes-based sorbents. Results reveal that a minimum amount of 7.5 and 5 wt% SiO2 nanoparticles are required to achieve an agglomerate particulate fluidization behavior for pure and synthesized carbon nanotubes, respectively. Pure carbon nanotubes + 7.5 wt% SiO2 and synthesized carbon nanotubes + 5 wt% SiO2 indicates an agglomerate particulate fluidization characteristic, including the high-level bed expansion ratio, low minimum fluidization velocity (1.5 and 1.6 cm·s–1), high Richardson−Zakin index (5.2 and 5.3 > 5), and low Π value (83.2 and 84.8 < 100, respectively). Chemical modification of carbon nanotubes causes not only enhanced CO 2 uptake capacity but also decreases the required amount of silica additive to reach a homogeneous fluidization behavior for synthesized carbon nanotubes sorbent.

• RESEARCH ARTICLE
Yue Liu, Ji-Wei Wang, Jian Zhang, Ting-Ting Qi, Guang-Wen Chu, Hai-Kui Zou, Bao-Chang Sun

Green and efficient $NOx$ removal at low temperature is still desired. $NOx$ removal via non-thermal plasma (NTP) reduction is one of such technique. This work presents the experimental and theoretical study on the $NOx$ removal via NTP reduction (NTPRD) in dielectric barrier discharge reactor (DBD). The effect of $O2$ molar fraction on $NOx$ species in the outlet of DBD, and effects of $NH3$/NO molar ratio and discharge power of DBD on $NOx$ removal efficiency are investigated. Results indicate that anaerobic condition and higher discharge power is beneficial to direct removal of $NOx$, and the $NOx$ removal efficiency can be up to 98.5% under the optimal operating conditions. It is also found that adding $NH3$ is favorable for the reduction of $NOx$ to $N2$ at lower discharge power. In addition, the $NOx$ removal mechanism and energy consumption analysis for the NTPRD process are also studied. It is found that the reduced active species ( $N∗$, $N−$, N+, $N2∗$, $N H2+$, etc.) generated in the NTPRD process play important roles for the reduction of $NOx$ to $N2$. Our work paves a novel pathway for $NOx$ removal from anaerobic gas in industrial application.

• RESEARCH ARTICLE
Juntian Niu, Haiyu Liu, Yan Jin, Baoguo Fan, Wenjie Qi, Jingyu Ran

Methane activation is a pivotal step in the application of natural gas converting into high-value added chemicals via methane steam/dry reforming reactions. Ni element was found to be the most widely used catalyst. In present work, methane activation on MgO supported Ni–M (M = Fe, Co, Cu, Pd, Pt) cluster was explored through detailed density functional theory calculations, compared to pure Ni cluster. CH4 adsorption on Cu promoted Ni cluster requires overcoming an energy of 0.07 eV, indicating that it is slightly endothermic and unfavored to occur, while the adsorption energies of other promoters M (M = Fe, Co, Pd and Pt) are all higher than that of pure Ni cluster. The role of M on the first C–H bond cleavage of CH4 was investigated. Doping elements of the same period in Ni cluster, such as Fe, Co and Cu, for C–H bond activation follows the trend of the decrease of metal atom radius. As a result, Ni–Fe shows the best ability for C–H bond cleavage. In addition, doping the elements of the same family, like Pd and Pt, for CH4 activation is according to the increase of metal atom radius. Consequently, C–H bond activation demands a lower energy barrier on Ni–Pt cluster. To illustrate the adsorptive dissociation behaviors of CH4 at different Ni–M clusters, the Mulliken atomic charge was analyzed. In general, the electron gain of CH4 binding at different Ni–M clusters follows the sequence of Ni–Cu (–0.02 e) < Ni (–0.04 e) < Ni–Pd (–0.08 e) < Ni–Pt (–0.09 e) < Ni–Co (–0.10 e) < Ni–Fe (–0.12 e), and the binding strength between catalysts and CH 4 raises with the CH4 electron gain increasing. This work provides insights into understanding the role of promoter metal M on thermal-catalytic activation of CH4 over Ni/MgO catalysts, and is useful to interpret the reaction at an atomic scale.

• RESEARCH ARTICLE
Yuxuan Xu, Guanglong Dai, Shibin Nie, Jinian Yang, Song Liu, Hong Zhang, Xiang Dong

Metal−organic framework-derived materials have attracted significant attention in the applications of functional materials. In this work, the rod-like nickel-based metal−organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology. Then, the nickel phyllosilicate whiskers were evaluated to enhance the mechanical, thermal, flammable, and tribological properties of epoxy resin. The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix, improving the tensile strength and elastic modulus by 13.6% and 56.4%, respectively. Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings, it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities. Additionally, it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature. Moreover, the wear rate of epoxy resin nanocomposites was reduced significantly by 80% for pure epoxy resin by adding 1 phr whiskers. The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites.

• RESEARCH ARTICLE
Reyila Abuduwayiti, Feng-Yun Ma, Xing Fan

Four supported catalysts, nickel and ruthenium on a HZSM-5 support, were prepared by equal volume impregnation and in-situ decomposition of carbonyl nickel. The properties of catalysts were investigated by catalytic hydro-conversion of 2,2′-dinaphthyl ether as the model compound and extraction residue of Naomaohu lignite as the sample under an initial H2 pressure of 5 MPa and temperature at 150 °C. According to the catalytic hydro-conversion results of the model compound, Ni−Ru/HZSM-5 exhibited the best catalytic performance. It not only activated H2 into H···H, but also further heterolytically split H···H into immobile H attached on the acidic centers of Ni−Ru/HZSM-5 and relatively mobile H+. Catalytic hydro-conversion of the extraction residue from Naomaohu lignite was further examined over the optimized catalyst, Ni−Ru/HZSM-5. Detailed molecular compositions of products from the extraction residue with and without hydrogenation were characterized by Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry. The analytical results showed that the oxygen-containing functional groups in products of hydrogenated extraction residue were obviously reduced after the catalytic treatment. The relative content of oxygenates in the product with catalytic treatment was 18.57% lower than that in the product without catalytic treatment.

• RESEARCH ARTICLE
Vishal Kandathil, Akshay Moolakkil, Pranav Kulkarni, Alaap Kumizhi Veetil, Manjunatha Kempasiddaiah, Sasidhar Balappa Somappa, R. Geetha Balakrishna, Siddappa A. Patil

The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supported-palladium nanoparticles enriched magnetic nanocatalyst (Pd/Fe3O4@C) using a simple multi-step process under aerobic conditions. Under mild reaction conditions, the Pd/Fe3O4@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates. Also, the Pd/Fe3O4@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction. Also, we explored the use of Pd/Fe3O4@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction. Interestingly, the Pd/Fe3O4@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite (Fe3O4 nanoparticles) with an overpotential of 293 mV at a current density of 10 mA·cm–2.