2022 Vol. 7, No. 5

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Research highlight
Exclusive CO2-to-formate conversion over single-atom alloyed Cu-based catalysts
Junjun Li, Zhicheng Zhang, Wenping Hu
2022, 7(5): 855-857. doi: 10.1016/j.gee.2021.11.004
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Electrochemical CO2 reduction reaction (CO2RR), powered by renewable energy sources, provides an appealing approach to convert emitted CO2 to value-added chemicals and fuels and achieve a carbon-neutral cycle. Among various carbon-based products, formic acid (HCOOH) has been considered as a promising liquid hydrogen storage material due to its high energy density and hydrogen content. However, so far, the reported HCOOH-selective catalysts (e.g., Bi, Sn, In, Pb and Pd) have failed in either activity (< 500 mA cm-2) or stability (< 20 h), which significantly inhibits the industrialized feasibility of CO2RR. In contrast, Cu takes the advantages of excellent activity and low cost, making it more commercially viable. To date, one of the most challenging issues of Cu-based catalysts lies in unsatisfactory selectivity, that is, tending to produce mixed products rather than specific one, due to the complicated reaction paths involved. Very recently, Zheng et al. have developed a single-atom alloy (SAAs) strategy for the exclusive CO2-to-formate conversion over Cu-based catalysts. The as-prepared Pb single-atom alloyed Cu catalyst (Pb1Cu) (Fig. 1a) exhibited near unity selectivity towards HCOOH and impressive stability, providing the prospect of industrial production of HCOOH from CO2.
Review articles
Understanding of the electrochemical behaviors of aqueous zinc–manganese batteries: Reaction processes and failure mechanisms
Xinyu Luo, Wenchao Peng, Yang Li, Fengbao Zhang, Xiaobin Fan
2022, 7(5): 858-899. doi: 10.1016/j.gee.2021.08.006
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As one of the most common cathode materials for aqueous zinc-ion batteries (AZIBs), manganese oxides have the advantages of abundant reserves, low cost, and low toxicity. However, the electrochemical mechanism at the cathode of aqueous zinc–manganese batteries (AZMBs) is complicated due to different electrode materials, electrolytes and working conditions. These complicated mechanisms severely limit the research progress of AZMBs system and the design of cells with better performance. Hence, the mechanism of AZMBs currently recognized by most researchers according to the classification of the main ions involved in the faradaic reaction is introduced in the review. Then a series of reasons that affect the electrochemical behavior of the battery are summarized. Finally, the failure mechanisms of AZMBs over prolonged cycling are discussed, and the current insufficient research areas of the system are explained, along with the direction of further research being prospected.
Catalyst design strategy toward the efficient heterogeneously-catalyzed selective oxidation of 5-hydroxymethylfurfural
Huai Liu, Xing Tang, Xianhai Zeng, Yong Sun, Xixian Ke, Tianyuan Li, Jiaren Zhang, Lu Lin
2022, 7(5): 900-932. doi: 10.1016/j.gee.2021.10.004
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The selective oxidation of 5-hydroxymethylfurfural (HMF), a versatile bio-based platform molecule, leads to the formation of several intriguing and useful downstream chemicals, such as 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), formyl 2-furancarboxylic acid (FFCA), 2,5-furandicarboxylic acid (FDCA) and furan-2,5-dimethylcarboxylate (FDMC). These products have been extensively employed to fabricate novel polymers, pharmaceuticals, sustainable dyes and many other value-added fine chemicals. The heart of the developed HMF oxidation processes is always the catalyst. In this regard, this review comprehensively summarized the established heterogeneous catalyst design strategy for the selective oxidation of HMF via thermo-catalysis. Particular attention has been focused on the reaction mechanism of HMF oxidation over different catalysts as well as enhancing the catalytic performance of the catalyst through manipulating the properties of the support and fabricating of multi-component metal nano-particles and oxides. The current challenges and possible research directions for the catalytic oxidation of HMF in the future are also discussed.
Research papers
Pd nanocluster-decorated CoFe composite supported on nitrogen carbon nanotubes as a high-performance trifunctional electrocatalyst
Revanasiddappa Manjunatha, Li Dong, Zibo Zhai, Jianyi Wang, Qianru Fu, Wei Yan, Jiujun Zhang
2022, 7(5): 933-947. doi: 10.1016/j.gee.2020.12.005
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Rational design and synthesis of low-cost trifunctional electrocatalysts with improved stability and superior electrocatalytic activity for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are highly desirable but remain as the bottlenecks at the current state of technology. In this paper, the cobalt-iron (Co–Fe) composite supported on nitrogen-doped carbon nanotubes (CoFe composite/NCNTs) is synthesized. The intrinsic OER and HER catalytic activities of this CoFe composite/NCNTs composite are significantly improved with palladium (Pd) nanocluster decoration [Pd-coated (CoFe composite/NCNTs)]. The as-prepared Pd-coated (CoFe composite/NCNTs) catalyst exhibits excellent trifunctional electrocatalytic activity and stability due to the interfacial coupling between Pd and (CoFe composite/NCNTs). This catalyst is successfully employed in the water electrolysis cell as both OER and HER electrode catalysts, flexible rechargeable Zn-air battery as the bifunctional ORR and OER electrode catalyst. The cell voltage of this catalyst-coated electrodes requires only 1.60 V to achieve 10 mA cm-2 current density for water electrolysis cell, which is comparable to and even better than that of Pt/C and Ir/C based cell. The primary Zn-air battery using this catalyst shows a constant high open-circuit voltage (OCV) of 1.47 V and a maximum power density of 261 mW cm-2 in the flooded mode configuration. Most importantly, a flexible Zn-air battery with this catalyst runs very smoothly without a change in voltage gap during flat, bending, and twisting positions.
High retention volume covalent organic polymer for xenon capture: Dynamic separation of Xe and Kr
Qian Wang, Zhu Meng, Juntao Li, Shuming Peng, Zhonghua Xiang
2022, 7(5): 948-956. doi: 10.1016/j.gee.2020.12.010
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Xenon capture and Xe/Kr separation are important processes in industry. For instance, Xe/Kr separation is an indispensable step in recycle and treatment of nuclear fuel emission. Among different separation methods, selectively adsorb gas molecules using porous materials is a promising way to reduce the high energy consumption in traditional cryogenic distillation. However, many reported adsorbents still face the challenges of: i) poor separation property at low Xe/Kr concentrations; ii) insufficient retention volumes, which influence the viability of whole process. In this work, we present a stable covalent organic polymer, i.e., COP-14, showing promising potential for Xe/Kr separiton. In dynamic breakthrough experiments, COP-14 successfully separates low concentration Xe (350 ppm) and Kr (35 ppm) from target gas mixtures. Meanwhile, the xenon retention volume per gram (1700 mL g-1 at 298 K) of COP-14 in dynamics absorption process achieves 3.8 times of benchmark active carbon. The good performance of the newly devloped COP-14 mainly from its rich nitrogen sites and suitable pore size with xenon molecues. The promising results of COP-14 on Xe/Kr separation in this work provide a promising way for designing efficient Xe/Kr separation mateirals.
Na-MnOx catalyzed aerobic oxidative cleavage of biomass-derived 1,2-diols to synthesis medium-chain furanic chemicals
Qing-Shan Kong, Xing-Long Li, Hong-Bo Shen, Hua-Jian Xu, Yao Fu
2022, 7(5): 957-964. doi: 10.1016/j.gee.2020.12.007
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Medium-chain furanic chemicals have outstanding practical potential, especially in the application of pharmaceuticals and polymers. Herein, we describe an eco-friendly and efficient heterogeneous sodium-doped porous sodium manganese oxide catalyst (Na-MnOx) for oxidative cleavage of furanic 1,2-diols into medium-chain furanic aldehyde compounds. Subsequently, various high value-added chemicals (diacids and esters, diols, hydroxy acids, acrylics) were synthesized based on the widely applicable and highly selective catalytic approaches. The Na-MnOx was prepared by the coprecipitation method and characterized by XRD, SEM, XPS and FT-IR, and TGA. XPS revealed that Mn species existed in the mixed oxidation states MnII, MnIII and MnIV. When NaOH concentration up to 1.8 mol L-1 during the preparation process of the catalyst, the ratio of Mn4+ in the catalyst was the highest, and the yield of product (Furan-2-acrolein) in the model reaction is also optimal. Overall, this protocol developed a novel and general route for the preparation of medium-chain furanic compounds utilizing cellulose-derived platform molecules.
Magnetically enhancing diffusion for dendrite-free and long-term stable lithium metal anodes
Yongxiu Chen, Xiangyu Dou, Kai Wang, Yongsheng Han
2022, 7(5): 965-974. doi: 10.1016/j.gee.2020.12.014
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Lithium metal batteries are promising devices for the next-generation energy storage due to their ultrahigh theoretical specific capacity and extremely low electrochemical potential. Their inherent problem is the formation of lithium dendrites in cycling, which has induced safety concerns for almost half a century. After understanding the formation mechanism of branching structures, we propose to suppress lithium dendrites by adopting external magnetic fields to induce diffusion enhancement at the interface of the anode, thus attenuating concentration gradient there and reducing the driving force for the formation of dendritic structures. The diffusion coefficient of lithium ions is dependent on the strength of magnetic fields, confirming the effectiveness of magnetic fields in improving Li+ diffusion. After employing the magnetic field of 0.8 T, the concentration gradients at the growth front becomes nearly half of the control case, which leads to a dendrite-free lithium deposition up to the high current density of 10 mA cm-2. Both the Cu|LiCoO2 batteries and the symmetric Li|Li coin cells show a long-term stable cycling at high current densities under the assistance of magnetic field. This diffusion enhanced technique promises a facile and general approach to suppress dendritic structures in secondary batteries, which may help to develop quick charging strategies.
Scaled-up synthesis of defect-rich layered double hydroxide monolayers without organic species for efficient oxygen evolution reaction
Haoyuan Chi, Jingwen Dong, Tian Li, Sha Bai, Ling Tan, Jikang Wang, Tianyang Shen, Guihao Liu, Lihong Liu, Luyi Sun, Yufei Zhao, Yu-Fei Song
2022, 7(5): 975-982. doi: 10.1016/j.gee.2020.12.013
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The scaled-up synthesis of organic-free monolayer nanomaterials is highly desirable, especially in obtaining green energy by electrocatalysis. In this study, a method for the scaled-up synthesis of the series of monolayer layered double hydroxides (LDHs) without the addition of organic solvents is reported via the separate nucleation and aging steps process. The resulting monolayer LDHs with the thicknesses of less than 1 nm showed a narrow thickness distribution. X-ray absorption fine-structure revealed that monolayer NiFe-LDH nanosheets have a number of oxygen and metal vacancies defects. As a practical application, monolayer NiFe-LDH nanosheets containing defects showed an enhanced electrocatalytic water oxidation activity compared with that of bulk NiFe-LDH. Density functional theory calculations uncovered that excellent catalytic activity is attributed to vacancies defects. The proposed method is an economical and universally applicable strategy for the scaled-up production of monolayer LDHs.
Efficient catalytic removal of COS and H2S over graphitized 2D micro-meso-macroporous carbons endowed with ample nitrogen sites synthesized via mechanochemical carbonization
Xun Kan, Guanqing Zhang, Yingying Luo, Fujian Liu, Yong Zheng, Yihong Xiao, Yanning Cao, Chak-tong Au, Shijing Liang, Lilong Jiang
2022, 7(5): 983-995. doi: 10.1016/j.gee.2020.12.016
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Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide (COS) and hydrogen sulfide (H2S) is of great significance in terms of industrial safety and environmental protection. We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900 ℃. The as-synthesized graphitized catalysts, designated as 2D-NHPC-x (x = urea/glucose mass ratio), are endowed with an ultra-high concentration (12.9–20.2 wt%) of stable and versatile nitrogen sites (e.g. pyrrole and pyridine) which are anchored on the surface via stable covalent bonding. As a result, the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H2S, and the H2S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials. Among the prepared catalysts, 2D-NHPC-x can catalytically hydrolysize 91% of COS to H2S at 30 ℃, whereas the conversion ratio over the common catalysts g-C3N4 and Fe2O3 are below 6.0%. Furthermore, these catalysts also exhibit H2S conversion and sulfur selectivity of nearly 100% at 180 ℃ with long-time durability, which is higher than those of the most reported carbon-based catalysts. In contrast, the H2S capacities of activated carbon, ordered mesoporous carbons (OMC) and N-doped OMC are 3.9, 1.5 and 2.39 mmol g-1, respectively. Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H2S.
Synthesis and fluorescent properties of quinoxaline derived ionic liquids
Jiaqi Wu, Lei Zhang, Jinxing Long, Qiang Zeng, Biaolin Yin, Xuehui Li
2022, 7(5): 996-1005. doi: 10.1016/j.gee.2020.12.018
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Ionic liquids (ILs) have attracted increasing attention since last few decades due to their high molecular design abilities and wide applications in different fields. In this study, four novel fluorescent isoquinolino [2,1-a]quinoxalin-5-ium ILs were designed and synthesized via a two-step process including a simple dual Schiff's base formation and a subsequent [RhCp*Cl2]2-catalyzed oxidative C–H activation/annulation reaction. The as-synthesized ILs were extensively characterized using FT-IR, 1H-NMR, 13C-NMR, 19F-NMR, HSQC-NMR, HMBC-NMR and HR-MS. Their photophysical properties were determined by steady-state fluorescence spectroscopy. The results demonstrate that all these ILs showed dual or triple emissions, large stokes shift (90 nm) and mechanochromic behaviors. Basing on solvatochromism and titration experiments, it is thought that the emission bands of the ILs are raised from their local excited states, charge transfer states or excited state proton transfer of cations, while the substitute effect of these quinoxaline derived ILs on their stokes shifts is negligible.
Building of multifunctional and hierarchical HxMoO3/PNIPAM hydrogel for high-efficiency solar vapor generation
Shuai Cao, Jingyun Jiang, Qingyong Tian, Cang Guo, Xuzhe Wang, Kun Dai, Qun Xu
2022, 7(5): 1006-1013. doi: 10.1016/j.gee.2020.12.012
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Solar distillation is a sustainable and promising technique to generate fresh water. However, the solar vapor generation is a high energy consumption process, resulting in a low water yield under natural sunlight. Hence, developing of advanced evaporators that can simultaneously reduce the energy requirement of water vaporization and accelerate solar water evaporation remains a great challenge. In this study, we report the fabrication of a multifunctional hydrogel of HxMoO3/PNIPAM with PNIPAM as hydratable skeleton and HxMoO3 as the light-absorbing unit for solar water evaporation. The experimental results demonstrate that the as-prepared hydrogel owns excellent photothermal activity. Accurately, the fabricated hydrogel -based solar evaporators achieved high water evaporation rate of 1.65 kg m-2 h-1 with the energy conversion efficiency of 85.87% under 1 kW m-2 irradiation. The enhanced photothermal activity of HxMoO3/PNIPAM hydrogel can be attributed to the synergistic effects of the components composed in this hierarchical architecture that change the water state and further speed up water evaporation. The HxMoO3/PNIPAM evaporators indicate its great potential for practical implementation of solar water evaporation.
The influence of pore structures and Lewis acid sites on selective hydrogenolysis of guaiacol to benzene over Ru/TS-1
Yingying Xin, Zhaoxia Zheng, Zhicheng Luo, Chengzhen Jiang, Shaofeng Gao, Zhihao Wang, Chen Zhao
2022, 7(5): 1014-1023. doi: 10.1016/j.gee.2020.12.024
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Here, we report a Ru/TS-1 catalyst for selective hydrogenolysis of guaiacol to benzene in the aqueous phase at conditions of 240 ℃ and 0.2 MPa H2, achieving a benzene yield of 86% with a hydrogenolysis rate of 103.1 mmol g-1 h-1. It was found that Silicalite-1 (MFI type) with suitable pore sizes supported Ru nanoparticles (NPs) favored for hydrogenolysis of guaiacol, whereas de-aluminated Ru/HBEA, Ru/HY and Ru/MWW (without acidic sites) accelerated the parallel reactions of hydrogenation of aromatics. In addition, Ru NPs located at the orifice of Silicalite-1 was proved to be more electron-deficient and active than Ru NPs on the outer surface, as evidenced by CO-IR characterization and activity tests on Ru/Silicalite-1 (with and without templates). Moreover, Brønsted acid sites (BAS) on Ru/MFI highly promoted the hydrogenation rates of aromatics, while Lewis acid sites (LAS) on Ru/TS-1 and Ru/MFI led to a linear increase of guaiacol hydrogenolysis rate to benzene, probably due to the enhanced absorbance capability of guaiacol and phenol on the LAS of MFI. Thus, pore structure properties of MFI coupled with abundant LAS (TS-1) as well as Ru NPs on the orifice of pores of TS-1 construct a promising catalyst for achieving efficient aromatic hydrocarbons from selective hydrogenolysis of lignin.
Engineering heterostructured Ni@Ni(OH)2 core-shell nanomaterials for synergistically enhanced water electrolysis
Jun-Wei Zhang, Xian-Wei Lv, Tie-Zhen Ren, Zheng Wang, Teresa J. Bandosz, Zhong-Yong Yuan
2022, 7(5): 1024-1032. doi: 10.1016/j.gee.2020.12.009
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Heterostructure engineering of electrocatalysts provides a fascinating platform to reasonably manipulate the physicochemical properties of nanomaterials and further improve their catalytic efficiency for water electrolysis. However, it still remains a huge challenge to construct well-designed core-shell heterostructured catalysts and identify the key role of components for synergistic catalysis. Herein, a melted polymeric salt tactics was innovatively developed to synthesize heterostructured Ni@Ni(OH)2 core-shell nanomaterials supported on porous carbon (named Ni@Ni(OH)2/PC), wherein well-defined Ni(OH)2-Ni heterostructure plays a pivotal role in improving electrocatalytic activity for water reduction and oxidation. Besides, the stable porous carbon support functions as a highway for continuous electron transfer between Ni and Ni(OH)2, and simultaneously enables the full exposure of accessible active sites. The fabricated Ni@Ni(OH)2/PC exhibits outstanding bifunctional electrocatalytic performance for overall water splitting (η10 = 1.55 V) with a good long-time stability. This work sheds new light on the design of engineering heterostructure of active bifunctional electrocatalysts for efficient energy conversion system.
Synthesis of ordered hierarchically mesoporous/microporous carbon materials via compressed CO2 for fructose-to-HMF transformation
Sen Luan, Wei Li, Zanwu Guo, Wenxiu Li, Xiaojian Hou, Yi Song, Ran Wang, Qian Wang
2022, 7(5): 1033-1044. doi: 10.1016/j.gee.2021.01.005
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Well-ordered hierarchically mesoporous/microporous carbon materials have been successfully fabricated by using dual soft-templating approach through compressed CO2. Pluronic F127 and different type of surfactants, including nonionic, cationic, and anionic surfactants, were used as dual templates to investigate the influence on the morphology and nanostructure of the as-prepared carbon samples. TEM, SEM, N2 sorption, wide-angle and small-angle XRD analysis were employed to reveal the well-ordered hierarchically micro-mesoporous structure with 2D hexagonal symmetry by using compressed CO2. The prepared HPC samples with different pressures as the catalyst carriers have been functioned by chlorosulfonic acid for the fructose conversion into HMF. Chlorosulfonic acid concentration, catalyst dosage and reaction temperature have been optimized for fructose-to-HMF transformation with the obtained catalyst. The performances of as-made HPC–SO3H samples in HMF yield and reaction rate of fructose-to-HMF transformation have been investigated. The stability of the samples was also conducted in the dehydration of fructose to HMF for five cycles. The possible catalytic mechanism by using hierarchically porous carbon materials as catalyst support for fructose-to-HMF transformation was proposed.
Ga2OSe monolayer: A promising hydrogen evolution photocatalyst screened from two-dimensional gallium chalcogenides and the derived janus
Yu Cui, Mengyuan Li, Xiaoli Zhang, Sufan Wang, Yucheng Huang
2022, 7(5): 1045-1052. doi: 10.1016/j.gee.2021.01.002
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Using first-principles calculations, hydrogen evolution reaction (HER) activity on two-dimensional (2D) gallium chalcogenides monolayers GaX (X = O, S, Se, and Te) as well as the derived Janus monolayers Ga2XY (X≠Y, X/Y = O, S, Se, and Te) were systematically examined. It was found that Ga2OSe Janus monolayer with a 0.3% strain has the lowest ΔGH* of 0.19 eV (modified to -0.01 eV including the solvation effect) because (i) O is the most electronegative among X/Y atoms, (ii) the Ga2OSe monolayer has a larger lattice parameter with respect to GaO monolayer, and (iii) the built-in electric field is enhanced after H adsorption. The enhanced H adsorption with the lattice stretching is a result of the weaker Ga–O bond strength before H adsorption and the reduced electron fillings of anti-bonding molecular orbital formed by H 1s and O 2p orbitals after H adsorption. The O-pz band center can be served as a descriptor to describe the HER activity trend for these p-block materials. Moreover, Ga2OSe monolayer has appropriate band alignment, distinguished optical absorption coefficient (105 cm-1), low exciton binding energy (0.71 eV), and the spontaneous HER process, indicating that it is a highly potential candidate for near-infrared photocatalyst for hydrogen production. Our research provides a novel paradigm that forming Janus structure can effectively tune the HER activity, which would guide the searching for excellent HER photocatalysts for clean hydrogen production.
Green fabrication of nickel-iron layered double hydroxides nanosheets efficient for the enhanced capacitive performance
Yuchen Wang, Zuo Chen, Man Zhang, Yaoyu Liu, Huixia Luo, Kai Yan
2022, 7(5): 1053-1061. doi: 10.1016/j.gee.2021.01.019
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Rational synthesis of robust layered double hydroxides (LDHs) nanosheets for high-energy supercapacitors is full of challenges. Herein, we reported an ultrasonication-assisted strategy to eco-friendly fabricate NiFe-LDHs nanosheets for the enhanced capacitive behavior. The experimental results combined with different advanced characterization tools document that the utilization of ultrasonication has a profound effect on the morphology and thickness of the as-obtained NiFe-LDHs, alternatively affecting the capacitive behavior. It shows that NiFe-LDHs nanosheets prepared with 2-h ultrasonic treatments display the exceptional capacitive performance because of the synergetic effect of ultrathin thickness, large specific surface area, and high mesoporous volume. The maximum specific capacitance of Ni3Fe1-LDHs nanosheets with the thickness of 7.39 nm and the specific surface area of 77.16 m2 g-1 reached 1923 F g-1, which is competitive with most previously reported values. In addition, the maximum specific energy of the assembled NiFe-LDHs//AC asymmetric supercapacitor achieved 49.13 Wh kg-1 at 400 W kg-1. This work provides a green technology to fabricate LDHs nanosheets, and offers deep insights for understanding the relationship between the morphology/structure and capacitive behavior of LDHs nanosheets, which is helpful for achieving high-performance LDHs-based electrode materials.
Analyzing acetylene adsorption of metal–organic frameworks based on machine learning
Peisong Yang, Gang Lu, Qingyuan Yang, Lei Liu, Xin Lai, Duli Yu
2022, 7(5): 1062-1070. doi: 10.1016/j.gee.2021.01.006
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Metal–organic frameworks (MOFs) containing open metal sites are important materials for acetylene (C2H2) adsorption. However, it is inefficient or even impossible to search suitable MOFs by molecular simulation method in nearly infinite MOFs space. Therefore, machine learning (ML) methods are adopted in the material screening and prediction of high-performance MOFs. In this paper, architecture, chemical and structural features are used to analyze the C2H2 adsorption performance of the MOFs. Different ML algorithms are applied to perform classification and regression analysis to the factors affecting material adsorption. By decision tree (DT) algorithm, it is found that only PV, GSA, and Cu-OMS are sufficient to determine the high adsorption of the MOFs. Furthermore, the influence of topology on the performance of MOFs is obtained. Gradient Boosting Decision Tree (GBDT), Support Vector Machine (SVM), and Back Propagation Neural Network (BPNN), are introduced to analyze the quantitative structure–property relationship (QSPR) between C2H2 adsorption and the features of MOFs. The prediction of the GBDT model is found to have the highest accuracy, with R2 as 0.93 and RMSE as 11.58. In addition, the GBDT model is used for feature analysis, and the contribution of each feature to the performance is obtained, which is of great significance for the design and analysis of MOFs. The successful application of ML to MOFs screening greatly reduce the calculation time and provides important reference for the design and synthesis of new MOFs.
Carbonized waste milk powders as cathodes for stable lithium–sulfur batteries with ultra-large capacity and high initial coulombic efficiency
Rabia Khatoon, Sanam Attique, Rumin Liu, Sajid Rauf, Nasir Ali, Luhong Zhang, Yu-Jia Zeng, Yichuan Guo, Yusuf Valentino Kaneti, Jongbeom Na, Haichao Tang, Hongwen Chen, Yang Tian, Jianguo Lu
2022, 7(5): 1071-1083. doi: 10.1016/j.gee.2021.01.007
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To explore the natural resources as sustainable precursors offers a family of green materials. The use of bio-waste precursors especially the remaining from food processing is a scalable, highly abundant, and cost-effective strategy. Exploring waste materials is highly important especially for new materials discovery in emerging energy storage technologies such as lithium sulfur batteries (LSBs). Herein, waste milk powder is carbonized and constructed as the sulfur host with the hollow micro-/mesoporous framework, and the resulting carbonized milk powder and sulfur (CMP/S) composites are employed as cathodes for LSBs. It is revealed that the hollow micro-/mesoporous CMP/S framework can not only accommodate the volume expansion but also endow smooth pathways for the fast diffusion of electrons and Li-ions, leading to both high capacity and long cycling stability. The CMP/S composite electrode with 56 wt% loaded sulfur exhibits a remarkable initial capacity of 1596 mAh g-1 at 0.1 C, corresponding to 95% of the theoretical capacity. Even at a rate of 1 C, it maintains a high capacity of 730 mAh g-1 with a capacity retention of 72.6% after 500 cycles, demonstrating a very low capacity fading of only 0.05% per cycle. Importantly, the Coulombic efficiency is always higher than 96% during all the cycles. The only used source material is expired waste milk powders in our proposal. We believe that this “trash to treasure” approach will open up a new way for the utilization of waste material as environmentally safe and high performance electrodes for advanced LSBs.
Vitamin B9 derived nitrogen-doped graphene for metal-free aerobic oxidation of biomass-derived chemicals
Duan-Jian Tao, Xin Zhao, Yanxin Wang, Xixi Liu, Hong-Ping Li, Zhang-Min Li, Yan Zhou, Ziliang Yuan, Zehui Zhang
2022, 7(5): 1084-1092. doi: 10.1016/j.gee.2021.01.008
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A superior carbocatalyst ultrahigh N-doped graphene (NG) was prepared by a novel self-sacrificial templating method of one-step annealing vitamin B9. The NG catalyst with pyrolysis temperature of 800 ℃ (abbreviated VB9-NG-800) has an ultrahigh nitrogen content of 13.5 wt% and demonstrated the highest activity for the oxidation of bio-based alcohols and terpenes with molecular oxygen without any additives. Systematic characterizations and quantum-chemical calculations further manifested that high contents of graphitic N and pyridinic N species in VB9-NG-800 promoted the generation of ·O2- active species from molecular oxygen effortlessly, resulting in excellent catalytic performance for aerobic oxidation.
A succinct enhanced luminescence strategy for fluorescent ionic liquids and the application for detecting CO2
Siying Che, Jiachen Guo, Lu Gan, Qiaoxin Xiao, Haoran Li, Yuanbin She, Congmin Wang
2022, 7(5): 1093-1101. doi: 10.1016/j.gee.2021.01.010
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An interesting phenomenon was found that fluorophore was introduced into ionic liquid (IL) to magnify fluorescence signal via the thermally activated delayed fluorescence process; thus up to 15 fold enhancements were achieved. Hence, we reported a succinct enhanced luminescence strategy to reduce single-triplet energy split by the tunability of ILs. This strategy could be extended to more kinds of ILs by the virtue of a preliminary DFT calculation screening. Moreover, the optical feature of IL sensor made it a promising candidate as a gas fluorescence sensor.
Versatile control of concentration gradients in non-fullerene acceptor-based bulk heterojunction films using solvent rinse treatments
Chang-Mok Oh, Soyeong Jang, Jihoon Lee, Sung Heum Park, In-Wook Hwang
2022, 7(5): 1102-1110. doi: 10.1016/j.gee.2021.01.009
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Solvent rinse treatments using polar methanol (MeOH) and nonpolar n-hexane have been developed for controlling material concentration gradients along the longitudinal direction of non-fullerene acceptor-based bulk heterojunction (BHJ) films comprised of electron donor polymer, PBDB-T and acceptor, ITIC-m. Before the used solvents (chlorobenzene with 1 vol% DIO) were completely evaporated, ITIC-m rich domains were formed at the top surface of the BHJ films after they were rinsed with MeOH, as evidenced by water contact angle, atomic force microscopy, time-of-flight secondary ion mass spectroscopy, which led to enhanced electron transport in the conventional structure of organic solar cells (OSCs). In contrast, after rinsing with n-hexane, ITIC-m rich domains were formed at the bottom surface of the films, which improved electron transport in the inverted structure OSCs. The enhanced carrier transports increased the PCEs (11.80% and 11.15%) in both conventional and inverted OSCs by 10.29% and 10.35% compared with control devices. The versatile control of material concentration gradients is determined to be feasible owing to the chemical interaction of the used substrates (glass, PEDOT:PSS, and ZnO) and rinsing solvents.
N-doped graphene anchored ultrasmall Ir nanoparticles as bifunctional electrocatalyst for overall water splitting
Wenqing Yao, Xian Jiang, Yulian Li, Cuiting Zhao, Linfei Ding, Dongmei Sun, Yawen Tang
2022, 7(5): 1111-1118. doi: 10.1016/j.gee.2021.01.011
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Abstract:
Seeking for extremely active and durable bifunctional electrocatalysts towards the overall water splitting possesses a strategic significance on the development of sustainable and clean energy for the replacement of fossil fuels. Ir-based nanomaterials are deemed as one of the most high-efficiency oxygen evolution reaction electrocatalysts while the hydrogen evolution reaction performance is unfavorable. In this work, we report a one-pot hydrothermal synthesis of N-doped graphene anchored Ir nanoparticles (Ir/N-rGO) with ultrasmall particle size (~2.0 nm). Apart from the predictably superior OER performance, the resultant Ir/N-rGO also displays excellent hydrogen evolution reaction (HER) performance, requiring merely 76 and 260 mV overpotentials to achieve the current density of 10 mA cm-2 towards HER and OER, respectively. When applied as the bifunctional electrodes for overall water splitting, Ir/N-rGO needs a lower overpotential (1.74 V) to achieve a current density of 50 mA cm-2 in alkaline solution, exceeding that of Pt/C and RuO2 couple (1.85 V). Thus, the as-fabricated Ir/N-rGO has a commendable prospect in the practical application of alkaline water electrocatalysis.
Homodispersed B–CN/P–CN S-scheme homojunction for enhanced visible-light-driven hydrogen evolution
Dashui Yuan, Zongyuan Li, Xueru Chen, Jing Ding, Hui Wan, Guofeng Guan
2022, 7(5): 1119-1127. doi: 10.1016/j.gee.2021.01.012
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Abstract:
Proper interface and band alignment always play essential roles in the separation of photoexcited charge of photocatalysts. In this work, we prepared a homodispersed S-scheme carbon nitride homojunction with local electron structure difference by a facile pre-doping and two-step calcination approach. Boron doping into heptazine created extra acceptor impurity, and phosphorus doping into heptazine created extra donor impurity, which eventually modulated the electronic structure of carbon nitride. As heptazines with different element doping were integrated into carbon nitride by recalcination, B–CN and P–CN formed a homodispersed homojunction and thus produced a rich interface. Meanwhile, caused by Fermi energy levels equilibrium, the band bending constructed an S-scheme homojunction, which stimulated photogenerated electrons to transfer from CB of B–CN to VB of P–CN. The homodispersed S-scheme homojunction structure led to efficient suppression of recombination of photoinduced charge and retained stronger redox charge. Consequently, the photocatalytic performance was dramatically boosted to 2620 μmol g-1 from 60 μmol g-1 of pure CN in 4-h hydrogen evolution from water. This novel method for electron structure engineering helped to provide a new strategy for designing homojunction photocatalysts with excellent photocatalytic performance.

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