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  • RESEARCH ARTICLE
    Seungbae Oh, Xue Dong, Chaeheon Woo, Xiaojie Zhang, Yeongjin Kim, Kyung Hwan Choi, Bom Lee, Ji-Hee Kim, Jinsu Kang, Hyeon-Seok Bang, Jiho Jeon, Hyung-Suk Oh, Hak Ki Yu, Junyoung Mun, Jae-Young Choi
    EcoMat, 2024, 6(6): e12469. https://doi.org/10.1002/eom2.12469
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    The development of advanced anode materials for lithium-ion batteries that can provide high specific capacity and stable cycle performance is of paramount importance. This study presents a novel approach for synthesizing molecular-level homogeneous carbon integration to porous SiO2 nanoparticles (SiO2@C NPs) tailored to enhance their electrochemical activities for lithium-ion battery anode. By varying the ratio of the precursors for sol–gel reaction of (phenyltrimethoxysilane (PTMS) and tetraethoxysilane (TEOS)), the carbon content and porosity within SiO2@C NPs is precisely controlled. With a 4:6 PTMS and TEOS ratio, the SiO2@C NPs exhibit a highly mesoporous structure with thin carbon and the partially reduced SiOx phases, which balances ion and charge transfer for electrochemical activation of SiO2@C NPs resulting remarkable capacity and cycle performance. This study offers a novel strategy for preparing affordable high capacity SiO2-based advanced anode materials with enhanced electrochemical performances.

  • RESEARCH ARTICLE
    Yulin Liu, Sumin Bae, Seongha Lee, Anqi Wang, Youngsoo Jung, Doh-Kwon Lee, Jung-Kun Lee
    EcoMat, 2024, 6(6): e12456. https://doi.org/10.1002/eom2.12456
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    Formamidinium lead iodide (FAPbI3) and SnO2 are a promising pair of halide perovskite and electron transport layer (ETL). However, FAPbI3 and SnO2 have inherent problems such as high crystallization temperature of FAPbI3 and surface defects of SnO2 like oxygen vacancies. They cause low crystallinity, non-uniform grain growth, and more interface defects, leading to carrier recombination and leakage current. The passivation of the interface between FAPbI3 and SnO2 is an effective process to address these materials issues. Herein, a dual role of lead sulfide (PbS) quantum dots (QDs) in the interface passivation is explored. PbS QDs which are introduced to the interface between FAPbI3 and ETL, link to Sn-dangling bonds of SnO2 ETLs and anchor the iodine atoms of FAPbI3. This changes considerably lower nonradiative recombination, achieve a better energetic alignment between ETL and PbI3, and facilitate electron extraction, leading to a power conversion efficiency of 21.66%.

  • RESEARCH ARTICLE
    Gyeong G. Jeon, Da Seul Lee, Min Jun Choi, You-Hyun Seo, Shujuan Huang, Jong H. Kim, Seong Sik Shin, Jincheol Kim
    EcoMat, 2024, 6(6): e12455. https://doi.org/10.1002/eom2.12455
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    Indoor photovoltaics are limited by their inherently low-photogenerated carrier density, leading to heightened carrier recombination and adverse leakage currents compared with conventional solar cells operating under 1 sun condition. To address these problems, this work incorporates a porous insulating interlayer (Al2O3) in perovskite devices, which effectively mitigates recombination and parasitic leakage current. A systematic investigation of the relationship between shunt resistance, photocarrier generation, and recombination at different light intensities demonstrates the effectiveness of the alumina interlayer in perovskite solar cells under low-light conditions. Moreover, the practicability of the alumina interlayer was demonstrated through its successful implementation in a large-area perovskite solar module (PSM). With bandgap engineering, the optimized PSM achieves a remarkable power conversion efficiency of 33.5% and a record-breaking power density of 107.3 μW cm−2 under 1000 lux illumination. These results underscore the potential of alumina interlayers in improving energy harvesting performance, particularly in low-light indoor environments.

  • RESEARCH ARTICLE
    Jinlin Chang, Weiling Wang, Zhaoxin Li, Yujiao Wang, Yacong Hou, Zhiyuan Cao, Zhenwei Liang, Yuan Ma, Ding Weng, Jun Song, Yadong Yu, Lei Chen, Jiadao Wang
    EcoMat, 2024, 6(6): e12454. https://doi.org/10.1002/eom2.12454
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    Wearable photothermal materials can capture light energy in nature and convert it into heat energy, which is critical for flexible outdoor sports. However, the conventional flexible photothermal membranes with low specific surface area restrict the maximum photothermal capability, and loose structure of electrospun membrane limits durability of wearable materials. Here, an ultrathin nanostructure candle soot/multi-walled carbon nanotubes/poly (L-lactic acid) (CS/MWCNTs/PLLA) photothermal membrane is first prepared via solvent-induced recrystallization. The white blood cell membrane-like nanowrinkles with high specific surface area are achieved for the first time and exhibit optimal light absorption. The solvent-induced recrystallization also enables the membrane to realize large strength and durability. Meanwhile, the membranes also show two-sided heterochromatic features and transparency in thick and thin situations, respectively, suggesting outstanding fashionability. The nano-wrinkled photothermal membranes by novel solvent-induced recrystallization show high flexibility, fashionability, strength, and photothermal characteristics, which have huge potential for outdoor warmth and winter sportswear.

  • RESEARCH ARTICLE
    I Ketut Gary Devara, Mi Ji Kwon, Su-Yeon Cho, Dong-Jun Kwon, Jun Hong Park
    EcoMat, 2024, 6(6): e12453. https://doi.org/10.1002/eom2.12453
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    As global urbanization intensifies, there is an increasing need for highly sensitive and accurate environmental monitoring devices that can meet the demands of specific gas sensing applications with low power consumption. This study focuses on enhancing the sensitivity of MXene-based chemiresistive sensors for detecting CO2(g) and NO2(g) under zero-bias operation. This study shows that lignin hybridization effectively improves the sensitivity of a Ti3C2Tx MXene-based chemiresistive sensor; under zero-bias operation, lignin hybridization increases the sensitivity to 15 ppm NO2(g) and CO2(g) by 157.38% and 297.95%, respectively. When deposited on a flexible substrate, the MXene/lignin flexible sensor shows a similar response and sensitivity to 15 ppm NO2(g) and CO2(g) under 38° curvature compared to the planar sensor. Consequently, the MXene/lignin hybrid sensor is attractive for room temperature and zero-bias NO2(g) and CO2(g) detection. The MXene/lignin flexible sensor serves as a model system for advanced solid-state sensory platforms suitable for curved structures.

  • REVIEW
    Xuexia Lan, Zhen Li, Yi Zeng, Cuiping Han, Jing Peng, Hui-Ming Cheng
    EcoMat, 2024, 6(5): e12452. https://doi.org/10.1002/eom2.12452
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    Advancing fast-charging technology is an important strategy for the development of alkali metal ion batteries (AMIBs). The exploitation of a new generation of anode material system with high-rate performance, high capacity, and low risk of lithium/sodium/potassium plating is critical to realize fast-charging capability of AMIBs while maintaining high energy density and safety. Among them, phosphorus-based anodes including phosphorus anodes and metal phosphide anodes have attracted wide attention, due to their high theoretical capacities, safe reaction voltages, and natural abundance. In this review, we summarize the research progress of different phosphorus-based anodes for fast-charging AMIBs, including material properties, mechanisms for storing alkali metal ions, key challenges and solution strategies for achieving fast-charging capability. Moreover, the future development directions of phosphorus-based anodes in fast-charging AMIBs are highlighted.

  • REVIEW
    Muhammad U. Zia, Prabhakaran Thanjavur Sambasivam, Dechao Chen, Shamsul A. Bhuiyan, Rebecca Ford, Qin Li
    EcoMat, 2024, 6(5): e12451. https://doi.org/10.1002/eom2.12451
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    The productivity of global crop production is under threat caused by various biotic and abiotic adverse conditions, such as plant diseases and pests, which are responsible for 20%–40% of global crop losses estimated at a value of USD 220 billion, and can be further exacerbated by climate change. Agricultural industries are calling for game-changer technologies to enable productive and sustainable farming. Carbon dots (C-dots) are carbon-based nanoparticles, smaller than 50 nm, exhibiting unique opto-electro-properties. They have been shown to have positive impact on managing diverse biotic and abiotic stresses faced by the crops. Owing to their versatile carbon chemistry, the surface functionalities of C-dots can be readily tuned to regulate plant physiological processes. This review is focussed on establishing the correlations between the physiochemical properties of C-dots and their impacts on plants growth and health. The summary of the literature demonstrates that C-dots hold great promise in improving plant tolerance to heat, drought, toxic chemicals, and invading pathogens.

  • RESEARCH ARTICLE
    Yanqi Wu, Pak-Sheng Soon, Jing-Tong Lu, Jinling Zhou, Yi-Xuan Liu, Zhaohui Guo, Ke Wang, Wen Gong
    EcoMat, 2024, 6(5): e12450. https://doi.org/10.1002/eom2.12450
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    Over the years, lead-based piezoelectric ceramics found extensive use in vital fields such as sensors and actuators. Despite their exceptional electromechanical properties, lead-containing materials pose severe environmental risks and foster a new era of lead-free piezoelectric materials after decades of research. However, recent comparative assessments of potassium sodium niobate (KNN) versus lead zirconate titanate (PZT) piezoelectric materials proposed that the environmental damage already presented before use due to raw material extraction and processing, invoking concerns on the true greenness of the lead-free alternatives. Nevertheless, many other factors deserve further consideration, for example, reference geometry and life cycle stage. Herein, the comprehensive life cycle assessment is undertaken on PZT and KNN-based ceramics with a unit volume of 0.001 m3 from cradle to gate. Results show that PZT exhibits higher negative impacts than KNN-based counterparts, attributed to lead extraction, processing, and associated environmental emissions. Across primary quantitative impact indicators from toxicity, environmental, and resource aspects, KNN-based ceramics impose fewer risks on the environment and human health, with the overall impact being only 28% of PZT ceramics. Still, more efficient methods are required for KNN-based ceramics to reduce the high energy consumption and emission during extraction and purification of raw material Nb2O5. This work not only offers critical insights for material development but also serves as a multifaceted reference for advanced fabrication technologies.

  • RESEARCH ARTICLE
    Rui Mao, Yingqi Liu, Pengfei Shu, Bingyi Lu, Biao Chen, Yanli Chen, Yanze Song, Yeyang Jia, Zhiyang Zheng, Qiong Peng, Guangmin Zhou
    EcoMat, 2024, 6(5): e12449. https://doi.org/10.1002/eom2.12449
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    The sluggish reaction kinetics has greatly hampered the development of reversible Li-CO2 batteries. Especially during charge, high charge voltage and possible side reactions during Li2CO3 decomposition require both high activity and strong durability of catalysts. Herein, a strategy of introducing rich sulfur vacancies is proposed, which tailors the configuration of Li2CO3 and the orbital structure of CoS to realize the dual enhancement. The calculation results show that charge redistribution by sulfur vacancies on the catalyst stretches the adsorbed Li2CO3 and consequently facilitates its decomposition. Moreover, the induced vacancies lower the S 2p band center, promoting the electrochemical stability of sulfides. Therefore, Li-CO2 batteries with sulfur vacancy-rich CoS exhibit a low overpotential of 1.07 V after 400 h cycling, while batteries with pristine CoS have a short lifespan that the overpotential exceeds 1.75 V after cycling for 200 h. This study not only proposes a strategy to improve both catalytic activity and stability but also paves new avenues for designing advanced catalysts for Li-CO2 batteries and beyond.

  • RESEARCH ARTICLE
    Liang Xu, Songyi Zhong, Tao Yue, Zixuan Zhang, Xiao Lu, Yangqiao Lin, Long Li, Yingzhong Tian, Tao Jin, Quan Zhang, Chengkuo Lee
    EcoMat, 2024, 6(5): e12448. https://doi.org/10.1002/eom2.12448
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    Sedentary, inadequate sleep and exercise can affect human health. Artificial intelligence (AI) and Internet of Things (IoT) create the Artificial Intelligence of Things (AIoT), providing the possibility to solve these problems. This paper presents a novel approach to monitor various human behaviors for AIoT-based health management using triboelectric nanogenerator (TENG) sensors. The insole with solely one TENG sensor, creating a most simplified system that utilizes machine learning (ML) for personalized motion monitoring, encompassing identity recognition and gait classification. A cushion with 12 TENG sensors achieves real-time identity and sitting posture recognition with accuracy rates of 98.86% and 98.40%, respectively, effectively correcting sedentary behavior. Similarly, a smart pillow, equipped with 15 sensory channels, detects head movements during sleep, identifying 8 sleep patterns with 96.25% accuracy. Ultimately, constructing an AIoT-based health management system to analyze these data, displaying health status through human-machine interfaces, offers the potential to help individuals maintain good health.

  • RESEARCH ARTICLE
    Han Ku Nam, Jungrak Choi, Tongmei Jing, Dongwook Yang, Younggeun Lee, Young-Ryeul Kim, Truong-Son Dinh Le, Byunggi Kim, Liandong Yu, Seung-Woo Kim, Inkyu Park, Young-Jin Kim
    EcoMat, 2024, 6(4): e12447. https://doi.org/10.1002/eom2.12447
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    In the pursuit of carbon neutrality policies, the development of eco-friendly and intelligent furniture commands a significant role. However, the integration of non-biodegradable electronic components in smart furniture fabrication has led to substantial electronic waste. Here, we report a straightforward approach, the rapid production of Laser-Induced Graphene (LIG) on medium-density fiberboard (MDF), a prevalent recycled wood in furniture production. This LIG electrode is crafted with negligible material ablation in ambient air with the aid of femtosecond laser pulses, without requiring any additional materials, showcasing the highest electrical conductivity (2.781 Ω sq−1) among previously reported lignocellulosic materials-based LIG. The application of this LIG electrode for lighting, heating, and touch sensors displays sufficient performance for smart furniture implementation. For eco-conscious furniture, LIG-based human-machine interfaces are demonstrated on recycled woods for the facile control of smart devices, which will readily enable IoT-oriented smart sustainable furniture.

  • RESEARCH ARTICLE
    Yeeun Kim, Hyunjun Lee, Cheongbeom Lee, Beomjin Kim, Nayoon Kwon, Taewoong Son, Jaehee Lee, Jaegwan Sin, Taejoo Shin, Jungyup Yang, Kyeounghak Kim, Jangwon Seo
    EcoMat, 2024, 6(4): e12446. https://doi.org/10.1002/eom2.12446
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    We incorporated triphenylsulfonium triflate (TPST), a sulfonium-based additive consisting of polar triflate and bulky hydrophobic phenyl rings, to the PbI2 precursor solution for preparation of less-defect perovskite film via two-step fabrication. TPST induced localized alterations in the array of the PbI2 structure due to its large size, thereby forming a more discontinuous and coarser surface with a greater number of pinholes and subsequently facilitating more efficient organic–inorganic reactions. As a result, we achieved the production of thick perovskite films with enlarged granules and decreased PbI2 residuals in the two-step fabrication process. Furthermore, TPST facilitated the passivation of bulk film defects by increasing the binding energy with the defects. Consequently, the ITO/SnO2 np-based device and the FTO/CBD SnO2-based device obtained the best PCEs of 23.88% and 24.30%, respectively. Furthermore, the moisture stability of the perovskite was improved by the hydrophobic character of the TPST additive.

  • RESEARCH ARTICLE
    Sung Hyuk Park, Yong Woon Lee, Da Eun Kim, Kyung Gook Cho, Min Su Kim, Dong Hyun Park, Junyoung Mun, Keun Hyung Lee
    EcoMat, 2024, 6(4): e12443. https://doi.org/10.1002/eom2.12443
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    Deformable lithium-ion batteries (LIBs) can serve as the main power sources for flexible and wearable electronics owing to their high energy capacity, reliability, and durability. The pivotal role of cathodes in LIB performance necessitates the development of mechanically free-standing and stretchable cathodes. This study demonstrates a promising strategy to generate deformable cathodes with electrical conductivity by forming 3D interconnected elastomeric networks. Beginning with a physically crosslinked polymer network using poly(vinylidene fluoride-co-hexafluoropropylene) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]), subsequent exchange with a 1 M LiPF6 electrolyte imparts elastic characteristics to the cathodes. The resulting LiFePO4 composite electrodes maintained their resistance under 500 consecutive bending cycles at an extremely small bending radius of 1.8 mm and showed high discharge capacity of 158 mAh g−1 with stable potential plateaus in charging and discharging curves. Moreover, flexible cells utilizing the composite electrodes exhibited superior operational stability under rolling, bending, and folding deformations.

  • RESEARCH ARTICLE
    Hansol Lee, Landep Ayuningtias, Hoimin Kim, Jaehoon Lee, Jiyun Lee, Min-Jae Kim, Dongki Lee, Byung Mook Weon, Dong-Am Park, Nam-Gyu Park, Sung Yun Son, Junki Kim, Yun-Hi Kim, Boseok Kang
    EcoMat, 2024, 6(4): e12442. https://doi.org/10.1002/eom2.12442
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    The introduction of alkoxy side chains into the backbone of conjugated polymers is an effective way to change their properties. While the impact on the structure and optoelectronic properties of polymer thin films was well-studied in organic solar cells and transistors, limited research has been conducted on their effects on doping and thermoelectric properties. In this study, the effects of methoxy functionalization of conjugated backbones on the doping and thermoelectric properties are investigated through a comparative study of diketopyrrolopyrrole-based conjugated polymers with and without methoxy groups (P29DPP-BTOM and P29DPP-BT, respectively). Methoxy-functionalization significantly enhances doping efficiency, converting undopable pairs to dopable ones. This dramatic change is attributed to the structural changes in the polymer film caused by the methoxy groups, which increases the lamellar spacing and facilitates the incorporation of dopants within the polymer crystals. Moreover, methoxy-functionalization is advantageous in improving the Seebeck coefficient and power factor of the doped polymers, because it induces a bimodal orientational distribution in the polymer, which contributes to the increased splitting of Fermi and charge transport levels. This study demonstrates the impact of methoxy-functionalization of a conjugated polymer on doping behavior and thermoelectric properties, providing a guideline for designing high-performance conjugated polymers for thermoelectric applications.

  • RESEARCH ARTICLE
    Junming Shi, Guoyang Gao, Can Jin, Hongqing Wu, Weizhen Wang, Yulong An, Zhen Zhou, Zhanhua Huang, Wenshuai Chen
    EcoMat, 2024, 6(4): e12441. https://doi.org/10.1002/eom2.12441
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    Value-added conversion of lignocellulose is a sustainable approach. Photo-refining biomass is in line with current environmental protection strategies. However, photo-reforming biomass suffers from poor catalyst stability and low conversion efficiency. Here, we designed fructose as a lignocellulosic model. The heterogeneous structure of Prussian blue coating was constructed with a special covalent bond structure of Co—CN—Zn. This structure has a catalytic conversion mechanism that can accelerate electron transfer. Fructose was simultaneously converted to value-added platform compounds (5-HMF and formic acid) and gaseous fuels (CO, CH4) with a conversion rate of up to 92.5%, which is more than 1.7 times than that of catalysts without adding Prussian blue. Hydrogen transfer and carbon transfer on the carbon atoms of fructose facilitates the production and accelerates the spillover of CO from formic acid. This work provides new ideas for the development of Prussian blue catalysts and the conversion of pentose.