2023 Vol. 8, No. 6

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Short communication
Temperature-regulation liquid gating membrane with controllable gas/liquid separation
Baiyi Chen, Huimeng Wang, Jiadai Xu, Liting Pan, Yuan Jing, Xu Hou
2023, 8(6): 1501-1508. doi: 10.1016/j.gee.2023.04.002
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Membrane separation technology with the ability to regulate gas/liquid transport and separation is critical for environmental fields, such as sewerage treatment, multiphase separation, and desalination. Although numerous membranes can dynamically control liquid-phase fluids transport via external stimuli, the transport and separation of gas-phase fluids remains a challenge. Here, we show a temperature-regulation liquid gating membrane that allows in-situ dynamically controllable gas/liquid transfer and multiphase separation by integrating a thermo-wettability responsive porous membrane with functional gating liquid. Experiments and theoretical analysis have demonstrated the temperature-regulation mechanism of this liquid gating system, which is based on thermo-responsive changes of porous membrane surface polarity, leading to changes in affinity between the porous membrane and the gating liquid. In addition, the sandwich configuration with dense Au-coated surfaces and heterogeneous internal components by a bistable interface design enables the liquid gating system to enhance response sensitivity and maintain working stability. This temperature-regulation gas/liquid transfer strategy expands the application range of liquid gating membranes, which are promising in environmental governance, water treatment and multiphase separation.
Review articles
Review on lithium metal anodes towards high energy density batteries
Jun-Fan Ding, Yu-Tong Zhang, Rui Xu, Rui Zhang, Ye Xiao, Shuo Zhang, Chen-Xi Bi, Cheng Tang, Rong Xiang, Ho Seok Park, Qiang Zhang, Jia-Qi Huang
2023, 8(6): 1509-1530. doi: 10.1016/j.gee.2022.08.002
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Lithium metal anode (LMA) is a promising candidate for achieving next-generation high-energy-density batteries due to its ultrahigh theoretical capacity and most negative electrochemical potential. However, the practical application of lithium metal battery (LMB) is largely retarded by the instable interfaces, uncontrolled dendrites, and rapid capacity deterioration. Herein, we present a comprehensive overview towards the working principles and inherent challenges of LMAs. Firstly, we diligently summarize the intrinsic mechanism of Li stripping and plating process. The recent advances in atomic and mesoscale simulations which are crucial in guiding mechanism study and material design are also summarized. Furthermore, the advanced engineering strategies which have been proved effective in protecting LMAs are systematically reviewed, including electrolyte optimization, artificial interface, composite/alloy anodes and so on. Finally, we highlight the current limitations and promising research directions of LMAs. This review sheds new lights on deeply understanding the intrinsic mechanism of LMAs, and calls for more endeavors to realize practical Li metal batteries.
Advances in the structure design of substrate materials for zinc anode of aqueous zinc ion batteries
Sinian Yang, Hongxia Du, Yuting Li, Xiangsi Wu, Bensheng Xiao, Zhangxing He, Qiaobao Zhang, Xianwen Wu
2023, 8(6): 1531-1552. doi: 10.1016/j.gee.2022.08.009
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Aqueous zinc ion batteries (AZIBs) demonstrate tremendous competitiveness and application prospects because of their abundant resources, low cost, high safety, and environmental friendliness. Although the advanced electrochemical energy storage systems based on zinc ion batteries have been greatly developed, many severe problems associated with Zn anode impede its practical application, such as the dendrite formation, hydrogen evolution, corrosion and passivation phenomenon. To address these drawbacks, electrolytes, separators, zinc alloys, interfacial modification and structural design of Zn anode have been employed at present by scientists. Among them, the structural design for zinc anode is relatively mature, which is generally believed to enhance the electroactive surface area of zinc anode, reduce local current density, and promote the uniform distribution of zinc ions on the surface of anode. In order to explore new research directions, it is crucial to systematically summarize the structural design of anode materials. Herein, this review focuses on the challenges in Zn anode, modification strategies and the three-dimensional (3D) structure design of substrate materials for Zn anode including carbon substrate materials, metal substrate materials and other substrate materials. Finally, future directions and perspectives about the Zn anode are presented for developing high-performance AZIBs.
The case-dependent lignin role in lignocellulose nanofibers preparation and functional application-A review
Xiya Zhang, Lili Zhang, Yimin Fan, Zhiguo Wang
2023, 8(6): 1553-1566. doi: 10.1016/j.gee.2022.09.008
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Lignocellulose nanofibers (LCNFs) as a new material is attracting extensive attention. The pretreatment and mechanical fibrillation are the two main stages involved in the preparation of LCNFs, and lignin plays the important role of these two stages. This review discussed the interaction between lignin and chemicals in the pretreatment stage, and discovered the general law of the effect of lignin in the mechanical fibrillation stage. Lignin exhibits both promotion and inhibition effects on mechanical fibrillation, and the mutual competition between the two effects ultimately affects the energy consumption, morphology and yield of LCNFs. Furthermore, the recent research progress related to the contributions of lignin on the functional application of LCNFs was summarized, aiming to provide profound guidance for the preparation and application of LCNFs.
Rational catalyst design and mechanistic evaluation for electrochemical nitrogen reduction at ambient conditions
Muhammad Ibrar Ahmed, David Brynn Hibbert, Chuan Zhao
2023, 8(6): 1567-1595. doi: 10.1016/j.gee.2022.10.001
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Ammonia (NH3), a carbon-free hydrogen carrier, is an important commodity for the food supply chain owing to its high energy capacity and ease of storage and transport. The Haber–Bosch process is currently the favored industrial method for large-scale ammonia production but requires energy-intensive and sophisticated infrastructure which hampers its utilization in a sustainable and decentralized system of manufacture. The electrochemical nitrogen reduction reaction (eNRR) at ambient conditions holds great potential for sustainable production of ammonia using electricity generated from renewable energy sources such as solar and wind. However, this approach is limited by a low rate of ammonia production with high overpotential and the competing hydrogen evolution reaction (HER). For a better understanding and utilization of eNRR as a sustainable process, insight into rational catalyst design and mechanistic evaluations by a theoretically-directed experimental approach is imperative. Herein, recent insights into rational catalyst design and mechanisms, based on intrinsic and extrinsic catalytic activity are articulated. Following the elucidation of basic principles and mechanisms, a framework supplied by theoretical studies that lead to the optimal selection and development of eNRR catalysts is presented. Following a discussion of recently developed electrocatalysts for eNRR, we outline various recently-used theoretical and experimental methodologies to improve the intrinsic and extrinsic catalytic activity of advanced electrocatalysts. This review is anticipated to contribute to the development of active, selective, and efficient catalysts for nitrogen reduction.
Synthesis strategies of covalent organic frameworks: An overview from nonconventional heating methods and reaction media
Jing Xiao, Jia Chen, Juewen Liu, Hirotaka Ihara, Hongdeng Qiu
2023, 8(6): 1596-1618. doi: 10.1016/j.gee.2022.05.003
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Covalent organic frameworks (COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have made rapid progress and substantial development in the chemistry and materials fields. However, the synthesis of COFs has been dominated by solvothermal methods for a long time and it usually involves high temperature, high pressure and toxic organic solvents, which created many challenges for environmental considerations. Recently, the exploration of new approaches for facile fabrication of COFs has aroused extensive interest. Hence, in this review, we comprehensively describe the synthetic strategies of COFs from the aspects of nonconventional heating methods and reaction media. In addition, the advantages, limitations and properties of the preparation methods are compared. Finally, we outline the main challenges and development prospects of the synthesis of COFs in the future and propose some possible solutions.
Research papers
A core-shell copper oxides-cobalt oxides heterostructure nanowire arrays for nitrate reduction to ammonia with high yield rate
Hui Liu, Jingsha Li, Feng Du, Luyun Yang, Shunyuan Huang, Jingfeng Gao, Changming Li, Chunxian Guo
2023, 8(6): 1619-1629. doi: 10.1016/j.gee.2022.03.003
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Electrochemical nitrate reduction to ammonia (NRA) can realize the green synthesis of ammonia (NH3) at ambient conditions, and also remove nitrate contamination in water. However, the current catalysts for NRA still face relatively low NH3 yield rate and poor stability. We present here a core-shell heterostructure comprising cobalt oxide anchored on copper oxide nanowire arrays (CuO NWAs@Co3O4) for efficient NRA. The CuO NWAs@Co3O4 demonstrates significantly enhanced NRA performance in alkaline media in comparison with plain CuO NWAs and Co3O4 flocs. Especially, at -0.23 V vs. RHE, NH3 yield rate of the CuO NWAs@Co3O4 reaches 1.915 mmol h-1 cm-2, much higher than those of CuO NWAs (1.472 mmol h-1 cm-2), Co3O4 flocs (1.222 mmol h-1 cm-2) and recent reported Cu-based catalysts. It is proposed that the synergetic effects of the heterostructure combing atom hydrogen adsorption and nitrate reduction lead to the enhanced NRA performance.
Facile preparation of Ag2S/KTa0.5Nb0.5O3 heterojunction for enhanced performance in catalytic nitrogen fixation via photocatalysis and piezo-photocatalysis
Lu Chen, Junfeng Wang, Xiaojing Li, Jiayu Zhang, Chunran Zhao, Xin Hu, Hongjun Lin, Leihong Zhao, Ying Wu, Yiming He
2023, 8(6): 1630-1643. doi: 10.1016/j.gee.2022.03.007
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In this work, a novel heterojunction composite Ag2S/KTaxNb1-xO3 was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTaxNb1-xO3 and the Ag2S content were optimized. The best 0.5% Ag2S/KTa0.5Nb0.5O3 (KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag2S. Under simulated sunlight, the NH3 generation rate of 0.5% Ag2S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0. XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag2S/KTN heterojunction established a type-II band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag2S/KTN composite exhibited higher NH3 generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.
Self-supported metal (Fe, Co, Ni)-embedded nitrogen-doping carbon nanorod framework as trifunctional electrode for flexible Zn-air batteries and switchable water electrolysis
Qiuyan Jin, Liping Xiao, Weidong He, Hao Cui, Chengxin Wang
2023, 8(6): 1644-1653. doi: 10.1016/j.gee.2022.03.008
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To meet the practical demand of wearable/portable electronics, developing high-efficiency and durable multifunctional catalyst and in-situ assembling catalysts into electrodes with flexible features are urgently needed but challenging. Herein, we report a simple route to fabricate bendable multifunctional electrodes by in-situ carbonization of metal ion absorbed polyaniline precursor. Alloy nanoparticles encapsulated in graphite layer are uniformly distributed in the N-doping carbon nanorod skeleton. Profiting from the favorable free-standing structure and the cooperative effect of metallic nanoparticles, graphitic layer and N doped-carbon architecture, the trifunctional electrodes exhibit prominent activities and stability toward HER, OER and ORR. Notably, due to the protection of carbon layer, the electrocatalysts show the reversible catalytic HER/OER properties. The overall water splitting device can continuously work for 12 h under frequent exchanges of cathode and anode. Importantly, the bendable metal air batteries fabricated by self-supported electrode not only displays the outstanding battery performance, achieving a decent peak power density (125 mW cm-2) and exhibiting favorable charge-discharge durability of 22 h, but also holds superb flexible stability. Specially, a lightweight self-driven water splitting unit is demonstrated with stable hydrogen production.
New insight into the design of highly dispersed Pt supported CeO2-TiO2 catalysts with superior activity for VOCs low-temperature removal
Yijun Shi, Xiaolin Guo, Yiyan Wang, Fanzhe Kong, Renxian Zhou
2023, 8(6): 1654-1663. doi: 10.1016/j.gee.2022.03.009
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A series of CeO2-TiO2 mixed oxides supports with various Ce/Ti molar ratio were synthesized by modified coprecipitation method. The corresponding Pt loaded (0.5 wt% Pt) catalysts were prepared by electronless deposition method and evaluated for the deep oxidation of n-hexane as a model VOCs. The results show that the CeO2 and TiOx nanoparticles can highly disperse into each other and form Ce2Ti2O7 solid solution with appropriate Ce/Ti molar ratio, which significantly improves their redox ability by enhancing the interaction between CeO2 and TiOx. The dispersibility of Pt species can also be adjusted by altering the Ce/Ti molar ratio, and Pt/CeTi-2/1 catalyst with Ce/Ti molar ratio of 2:1 exhibits the best Pt dispersibility that Pt species mainly exist as Pt single atoms. The high dispersion of Pt species in the Pt/CeO2-TiO2 catalysts would promote the catalytic activity of VOCs oxidation with low T90% values (1000 ppm, GHSV = 15,000 h-1), such as for n-hexane degradation with T90% of 139 ℃. The characterizations reveal that the superior activity is mainly related to possessing the more Pt2+ species, adsorbed oxygen species and higher low-temperature reducibility owing to the strong interaction between highly dispersed Pt species and CeO2-TiO2 as well as the promoted migration of lattice oxygen by the formation of more Ce2Ti2O7 species. Furthermore, the Pt/CeTi-2/1 catalyst also exhibits excellent stability for chlorinated and other non-chlorinated VOCs oxidation, making it very promising for real application under various operating conditions.
Inverse-opal structured TiO2 regulating electrodeposition behavior to enable stable lithium metal electrodes
Xuewen Wu, Shaolun Cui, Minfei Fei, Sheng Liu, Xueping Gao, Guoran Li
2023, 8(6): 1664-1672. doi: 10.1016/j.gee.2022.03.010
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Lithium metal anode is almost the ultimate choice for high-energy density rechargeable batteries, but its uneven electrochemical dissolution-deposition characteristics lead to poor cycle stability and lithium dendrites safety problems. The fundamental solution to the problems is to interfere electrodeposition process of lithium metal so that it can be carried out reversibly and stably. In this work, an inverse-opal structured TiO2 membrane with a thickness of only ~1 μm is designed to regulate the electrodeposition behavior of lithium metal, in which the ordered channels homogenize mass transfer process, the anatase TiO2 walls of the ion channels reduce desolvation barrier of solvated lithium-ions, and the spherical cavities with a diameter of ~300 nm confine migration of the adsorbed lithium atoms during electrocrystallization to diminish overpotential of lithium. These systematic effects cover and essentially change the whole process of electrodeposition of lithium metal and eliminate the possibility of lithium dendrite formation. The as-obtained lithium metal electrode delivers a Coulombic efficiency of 99.86% in the 100th cycle, and maintains a low deposition overpotential of 0.01 V for 800 h.
Efficient oil-water separation by novel biodegradable all cellulose composite filter paper
Chizhou Wang, Shaodi Wu, Ning Zhang, Zhaoli Jiang, Xianglin Hou, Long Huang, Tiansheng Deng
2023, 8(6): 1673-1682. doi: 10.1016/j.gee.2022.03.013
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Industrial production and domestic discharge produce a large amount of oily wastewater, which seriously affects the stability of the ecological environment. Membrane separation technology provides another path to treating oily wastewater. And appropriate surface modification of the membrane helps to achieve high efficiency of treating oily wastewater. With green, economy and stability been more concerned. The focal research reports a completely biodegradable all cellulose composite filter paper (ACCFP) composed of I-cellulose macrofibers and II-cellulose matrix. It is a simple one-step impregnation method to adjust the surface microstructure of the pristine filter paper (PFP), and it does not involve with chemical reaction. The pre-wetted ACCFP consist of II-cellulose hydrogel and I-cellulose reinforcement in the process of oil-water separation. This layer of hydrogel is the fundamental to underwater superoleophobicity, which determines their eligibility for applications of efficient oil-water mixture or oil-in-water (oil/water) emulsion separation. The separation efficiency of oil-water mixture and oil/water emulsion exceed 95% and 99.9%, respectively. In addition, excellent mechanical properties of ACCFP in dry and wet conditions ensure its stability in service and prolong service life in applications. The focal study provides a new method for high-performance oil-water separation and it is more in line with sustainable chemistry.
Heterogeneously-catalyzed aerobic oxidation of furfural to furancarboxylic acid with CuO-Promoted MnO2
Xin Yu, Tingke Jin, Huiqiang Wang, Guoqing Zhang, Wenlong Jia, Lincai Peng, Yong Sun, Xing Tang, Xianhai Zeng, Shuliang Yang, Zheng Li, Feng Xu, Lu Lin
2023, 8(6): 1683-1692. doi: 10.1016/j.gee.2022.03.016
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A cost-effective and sustainable noble-metal free catalyst system based on ubiquitously available Mn-Cu bimetallic oxides was served as efficient catalysts for furfural selective oxidation to furancarboxylic acid (FA). Interestingly, Mn2Cu1Ox exhibited an excellent furfural conversion of 99% with quantitative selectivity toward FA. Especially, we demonstrate the significant weakening of the Mn-O bonds with the incorporation of CuO into the Mn-Cu oxides, resulting in an improved OL reactivity of Mn2Cu1Ox, which brings about a higher catalytic activity for furfural oxidation. More importantly, Mn2Cu1Ox could exhibit YFA>90% over 5 cycles of reusability test. Through this study, the relationship between the morphology, surface chemistry, and catalytic activity of Mn-Cu bimetallic oxides are elucidated, providing a simple and environmentally friendly catalytic strategy and scientific basis for the development of Mn-Cu bimetallic oxides bioderived molecular aerobic oxidation materials.
Hierarchically porous Fe/N/S/C nanospheres with high-content of Fe-Nx for enhanced ORR and Zn-air battery performance
Luming Wu, Ruge Zhao, Guo Du, Huan Wang, Machuan Hou, Wei Zhang, Pingchuan Sun, Tiehong Chen
2023, 8(6): 1693-1702. doi: 10.1016/j.gee.2022.03.014
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Heteroatom-doped carbon-based transition-metal single-atom catalysts (SACs) are promising electrocatalysts for oxygen reduction reaction (ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N-S-doped carbon catalyst (FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential (E1/2) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm-2 for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites (up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres (NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2 charge-discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.
Ethylene purification in a metal-organic framework over a wide temperature range via pore confinement
Xue-Qian Wu, Peng-Dan Zhang, Xin Zhang, Jing-Hao Liu, Tao He, Jiamei Yu, Jian-Rong Li
2023, 8(6): 1703-1710. doi: 10.1016/j.gee.2022.03.015
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The separation of C2H4 from C2H6/C2H4 mixture is of great importance but difficult and energy intensive. Adsorptive separation provides an alternative approach to ameliorate this situation. Here, we report a microporous metal-organic framework (MOF) BUT-315-a as a C2H6-selective adsorbent for the separation of C2H6/C2H4 gas mixture. BUT-315-a combines good IAST selectivity of 2.35 with high C2H6 uptake of 97.5 cm3 g-1, giving superior high separation potential ΔQ (2226 mmol L-1) for equimolar C2H6/C2H4 at 298 K. Impressively, such excellent performance can be preserved at higher temperatures of 313 and 323 K to accommodate industrial conditions. Efficient dynamic separation performance of BUT-315-a has been demonstrated by column breakthrough experiments under varied temperatures and gas ratios. Theoretical calculations further reveal multiple synergistic interactions between C2H6 and the framework. This work highlights a new benchmark material for C2H6/C2H4 separation and provides guidance for designing adsorbent for separation applications.
One-step floating conversion of biomass into highly graphitized and continuous carbon nanotube yarns
Gongxun Zhai, Qianqian Wang, Fuyao Liu, Zexu Hu, Chao Jia, Dengxin Li, Hengxue Xiang, Meifang Zhu
2023, 8(6): 1711-1718. doi: 10.1016/j.gee.2022.04.002
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The rapid growth of the demand for carbon nanotubes (CNTs) has greatly promoted their large-scale synthesis and development. However, the continuous production of CNT fibers by floating catalyst chemical vapor deposition (FCCVD) requires a large amount of non-renewable carbon sources. Here, the continuous production of highly graphitized CNT yarns from biomass tannic acid (TA) is reported. The chelation of TA and catalyst promotes the rapid cracking of biomass into carbon source gas, and the pyrolysis cracking produces the reducing gas, which solves the problems of the continuous production of CNT yarns using biomass. Through simple twisting, the mechanical strength of CNT yarn can reach 886 ±46 MPa, and the electrical conductivity and graphitization (IG/ID) can reach 2×105 S m-1 and 6.3, respectively. This work presents a promising solution for the continuous preparation of CNT yarns based on green raw material.
Selective hydrogenation of glucose to sorbitol with tannic acid-based porous carbon sphere supported Ni-Ru bimetallic catalysts
Ran Xi, Yiwei Tang, Richard Lee Smith, Xiaoning Liu, Le Liu, Xinhua Qi
2023, 8(6): 1719-1727. doi: 10.1016/j.gee.2022.04.003
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Ni-Ru bimetallic porous carbon sphere (Ni-Ru@PCS) catalysts were synthesized via formaldehyde-assisted, metal-coordinated crosslinking sol-gel chemistry, in which biomass-derived tannic acid and F127 surfactant were used as carbon precursor and soft template, respectively, and Ni2+ and Ru3+ were used as cross-linkers. In the developed method, Ni-Ru particles became uniformly dispersed in the carbon skeleton due to strong coordination bonds between metal ions (Ni2+ and Ru3+) and tannic acid molecules and bimetal interactions. The as-synthesized Ni-Ru10:1@PCS catalyst with a loading Ni:Ru mole ratio of 10:1 was applied for the selective hydrogenation of glucose to sorbitol, and provided 99% glucose conversion with a sorbitol selectivity of 100% at 140 ℃ in 150 min reaction time and exhibited good stability and recyclability in which sorbitol yield remained at 98% after 4 cycles with little or no metal agglomeration. The catalyst was applied to glucose solutions as high as 20 wt% with 97% sorbitol yields being obtained at 140 ℃ in 20 h. The developed bimetallic porous carbon sphere catalysts take advantage of sustainably-derived materials in their structure and are applicable to related biomass conversion reactions.
MoNi4-NiO heterojunction encapsulated in lignin-derived carbon for efficient hydrogen evolution reaction
Yanlin Qin, Yunzhen Chen, Xuezhi Zeng, Yingchun Liu, Xuliang Lin, Wenli Zhang, Xueqing Qiu
2023, 8(6): 1728-1736. doi: 10.1016/j.gee.2022.04.005
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Molybdenum nickel alloy has been proved to be an efficient noble-metal-free catalyst for hydrogen evolution reaction (HER) in alkaline medium, but its electrocatalytic activity and stability need to be further improved to meet industrial requirements. In this study, carboxymethylated enzymatic hydrolysis lignin (EHL) was used as a biomacromolecule frame to coordinate with transition metal ions and reduced by pyrolysis to obtain the MoNi4-NiO heterojunction (MoNi4-NiO/C). The oblate sphere structure of MoNi4-NiO/C exposed a large catalytic active surface to the electrolyte. As a result, the hydrogen evolution reaction of MoNi4-NiO/C displayed a low overpotentials of 41 mV to achieve 10 mA cm-2 and excellent stability of 100 h at 100 mA cm-2 in 1 mol L-1 KOH, which was superior to that of commercial Pt/C. Lignin assisted the formation of NiO to construct the MoNi4-NiO interface and MoNi4-NiO heterojunction structure, which reduced the energy barrier by forming a more favorable transition states and then promoted the formation of adsorbed hydrogen at the heterojunction interface through water dissociation in alkaline media, leading to the rapid reaction kinetics. This work provided an effective strategy for improving the electrocatalytic performance of noble-metal-free electrocatalysts encapsulated by lignin-derived carbon.
Rare earth metal based DES assisted the VPO synthesis for n-butane selective oxidation toward maleic anhydride
Muhammad Faizan, Yingwei Li, Xingsheng Wang, Piao Song, Ruirui Zhang, Ruixia Liu
2023, 8(6): 1737-1752. doi: 10.1016/j.gee.2022.04.007
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Deep eutectic solvents (DESs) are now considered a new class of ionic liquid analogs that have been generously used in various fields. Herein, vanadium phosphorus oxide (VPO) catalysts are synthesized in combination with a deep eutectic solvent containing rare earth metal (rE-DES), and their catalytic performance in n-butane selective oxidation to produce maleic anhydride (MA) is evaluated. The rE-DES is produced from the interaction of choline chloride (ChCl) and rare earth metal salts (Cerium, Europium, Lanthanum, and Samarium metal salt) (ChCl:rE=1:0.5-1:3) under mild conditions. It was found that DESs served as structural modifiers and electronic promoters during VPO synthesis. It regulated the chemical state of the catalyst surface, such as the vanadium valence state, acid-base properties, and ratios of V4+/V5+, Lat-O/Sur-O and P/V. Various characterization techniques, such as FT-IR, DSC, XRD, SEM, EDS, TEM, Raman, TGA, NH3-TPD, and XPS, were used to examine its physical and chemical characteristics. These characteristics were correlated with the catalytic performance. The VPO catalyst modified by rE-DES showed a significant enhancement of n-butane conversion and MA selectivity while suppressing the selectivity of CO and CO2 as well as the CO/CO2 ratio compared to the unpromoted VPO catalyst. Especially for Ce-DES-VPO, it increased the n-butane conversion and MA mass yield up to approximately 11% and 10%, respectively. In addition, we evaluated the catalytic performance under different activation atmospheres.
1+1>2: Learning from the interfacial modulation on single-atom electrocatalysts to design dual-atom electrocatalysts for dinitrogen reduction
Qiang Zhou, Feng Gong, Yunlong Xie, Rui Xiao
2023, 8(6): 1753-1763. doi: 10.1016/j.gee.2022.06.005
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Developing efficient electrocatalysts for converting dinitrogen to ammonia through electrocatalysis is of significance to the decentralized ammonia production. Here, through high-throughput density functional theory calculations, we demonstrated that the interfacial modulation of hexagonal boron nitride/graphene (hBN-graphene) could sufficiently improve the catalytic activity of the single transition metal atom catalysts for nitrogen reduction reaction (NRR). It was revealed that Re@hBN-graphene and Os@hBN-graphene possessed remarkable NRR catalytic activity with low limiting potentials of 0.29 V and 0.33 V, respectively. Furthermore, the mechanism of the enhanced catalytic activity was investigated based on various descriptors of the adsorption energies of intermediates, where the synergistic effect of hBN and graphene in the hybrid substrate was found to play a key role. Motivated by the synergistic effect of hybrid substrate in single-atom catalysts, a novel strategy was proposed to efficiently design dual-atom catalysts by integrating the merits of both metal components. The as-designed dual-atom catalyst Fe-Mo@hBN exhibited more excellent NRR catalytic performance with a limiting potential of 0.17 V, manifesting the solidity of the design strategy. Our findings open new avenues for the search of heterostructure substrates for single-atom catalysts and the efficient design of dual-atom catalysts for NRR.

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