MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
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2023
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IF 6.4
Shu-Xin Yan,Guo-Dong Sun,Jian-Ping Xu,Jia Xu,Fu-Fa Wu
Simultaneous achieving the second-phase particle strengthening, high density, and fine grain is a great difficulty for designing and preparing Mo alloys . In this study, the effects of γ-Al 2 O 3 and Y 2 O 3 nanoparticles on the microstructures and properties of Mo composites prepared via spark plasma sintering (SPS) were systematically investigated. It was found that for pure Mo and Mo–Y 2 O 3 powders, Mo compact with both high density and fine grain size can't be achieved. However, Mo-Al 2 O 3 composite with both a relatively high density (98%) and a fine grain size (1.67 μm) was synthesized successfully. The small γ-Al 2 O 3 particles transformed into larger κ-Al 2 O 3 particles by obvious grain boundary migration and grain growth in the sintering process, which effectively pinned the migration of Mo grain boundary with few effects on the surface atom diffusion of Mo. Moreover, there was a crystallographic orientation relationship between the κ-Al 2 O 3 particles and Mo matrix (Mo (110)//Al 2 O 3 ( 13 4 ‾ 1 )). Ultrafine Mo composite containing dispersed Al 2 O 3 particles with stable boundary adhesion can efficiently hinder dislocation movement and crack propagation , resulting in the obvious enhancements of bending strength , hardness and compressive yield strength.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2023
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IF 7.2
Peilin Wu,Lin Gao,Liuyan Dong,Zihan Lin,Lili Cui
To prepare bifunctional electrocatalyst towards HER and OER is extremely important for promoting the development of electrochemical water splitting technology. Herein, the element doping method is employed to tune the electron environment of cobalt phosphide (CoP). The Mo-doped CoP supported on carbon cloth (CC) is constructed by solvothermal and annealing method. The effect of Mo on the electron modulation of CoP during different phosphating time was studied carefully. It is noted that the Mo play an important role in tuning the electron state of Co and P elements which can trap the electron and was reduced to low valence, then transfer the electron to Co and P. With increasing the phosphating time, the electron transfer phenomenon between Mo and CoP is obvious. Benefiting from the electron engineering of Mo, Co and P as well as thin and wrinkle sheets structure, the optimal electrocatalyst only requires 39 mV and 251 mV to deliver 10 mA cm −2 for HER and OER, respectively. Also, as for the whole water splitting performance, it delivers 10 mA cm −2 at cell voltage of 1.56 V. Importantly, Faraday efficiency of the optimal catalyst achieves 99.9% for HER due to the tuned electron state of Co and P, high ECSA and low R ct .
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APPLIED SURFACE SCIENCE
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2023
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IF 6.7
Xinyang Dong,Yundong Cao,Jiayuan Zhang,Linlin Fan,Mingliang Wang,Hong Liu,Guanggang Gao
Lithium-sulfur batteries (LSBs) present wide range of market and tremendous application potential. Nevertheless, the “shuttle effect” of lithium polysulfides (LiPSs) and the sluggish redox kinetics restrict their large-scale application. We report herein the Mo-substituted Keggin type H 3 PW 10 Mo 2 O 40 (PW 10 Mo 2 ) evenly decorated on the MWCNTs conductive framework by electrostatic attraction as the functional interlayer materials. W and Mo atoms in PW 10 Mo 2 provide chemical adsorption sites for polysulfides, and density functional theory (DFT) calculations further confirm that Mo sites possess stronger capture ability to LiPSs than that of W sites. Meanwhile, the Mo implantation can effectively expedite the redox reaction of LiPSs. Furthermore, MWCNTs afford the plentiful attachment points for PW 10 Mo 2 , thus exposing abundant active sites to adsorb and catalyze polysulfides. The resulting cells demonstrate superior discharge capacity of 1064.9 mAh g −1 under 0.2C up to 100 cycles as well as excellent long-life cycling stability with low recession rate of 0.051 % under 3C up to 1000 cycles. Our work illustrates the effect of Mo atom substitution of polyoxotungstates as interlayer materials and thereby provides a new strategy for developing LSBs with superior reversible capacity and long cycling performance.
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Carbon Energy
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2023
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IF 20.5
Zhichao Jia,Yang Yuan,Yanxing Zhang,Xiang Lyu,Chenhong Liu,Xiaoli Yang,Zhengyu Bai,Haijiang Wang,Lin Yang
Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions (OERs). Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts. Herein, Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mA cm −2 . Additionally, it had an overpotential of 260 mV (glassy carbon) or 215 mV (nickel foam), which was 78 mV lower than that of IrO 2 (338 mV). In situ, Raman spectroscopy revealed the transformation process of CoOOH. Calculations using the density functional theory showed that during OER, doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process, which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials. Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.
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Catalysis Science & Technology
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2022
·Vol. 12
·期 24
·7510-7519
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IF 6.177
Biyun Fang,Jiahui Li,Fangming Liu,Chuanfeng Zhang,Chunyan Li,Jun Ni,Jianxin Lin,Bingyu Lin,Lilong Jiang
The development of a Co–Mo bimetallic catalyst played a crucial role in ammonia synthesis. However, its underlying mechanism is not well understood and the optimal catalyst has yet to be obtained. Herein, we designed two methane-treated ceria-supported Co–Mo bimetallic catalysts with different dispersions and segregations of Mo and Co species by changing the order of addition of Mo and Co species. There is the segregation of Mo and Co species on the surface of the catalyst with the subsequent addition of Co and Mo species (Mo/Co–C), leading to a higher proportion of low oxidation states of Mo species as well as a larger amount of exposed Mo and Co species, oxygen vacancies and concentration of Ce3+. As a result, there is a larger amount of nitrogen and hydrogen species adsorbed on Mo/Co–C, and the migration and exchange of the adsorbed hydrogen species are also boosted. Mo/Co–C shows 1.7 times higher ammonia synthesis activity and a superior pressure effect in ammonia synthesis than its counterpart obtained by the simultaneous addition of Co and Mo species. These findings are essential for the further development of bimetallic catalysts.
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Biomass Conversion and Biorefinery
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2022
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IF 4.05
Chen Jiajia,Xiu Pengcheng,Gu Xiaoli
Lignin is the world’s greatest renewable aromatic biomass resource, with considerable potential for the development of high-value-added compounds. Herein, wet impregnation was employed to create Co-Mo/ATP-CZO bimetallic catalysts, which were then used to catalyze the depolymerization of lignin in ethanol and isopropanol. The findings of the characterization revealed that doping Mo metals resulted in the change of metallic oxide phase, which increased the oxygen vacancy (O V ), improved metal-carrier interaction, and decreased acid center content. The results of the experiments demonstrated that catalytic hydrogenation with a 12Mo-20Co/ATP-CZO catalyst at 240 °C for 8 h produced the maximum yield of bio-oil (57.44 wt%, including 37.58 wt% of monomer). Under these conditions, the bio-oil had a higher heating value of 33.20 MJ/kg, which was significantly higher than the alkali lignin’s 19.62 MJ/kg. Catalyst stability tests also revealed good recyclability. This research will provide an efficient method for depolymerizing lignin. Graphical abstract
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
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IF 7.139
Wenhao Chen,Junrong Zeng,Gaowei Zhang,Jie Yu,Yejun Qiu
Developing efficient bifunctional catalysts for hydrogen and oxygen evolution reactions (HER/OER) has attracted great interest in hydrogen production from water splitting. In this work, a novel material of Mo-doped NiFe x nanospheres on 3D graphene fibers (Mo-NiFe x /3DGFs) has been successfully fabricated through a simple and cheap one-step electrodeposition method. The Mo-NiFe x /3DGFs possessed ultra-high conductivity and specific surface area, greatly benefiting to electrocatalytic hydrolysis activity. And it was found that Fe element could obviously promote OER process, while Mo doping facilitated both OER and HER reactions. We proved that there existed synergetic roles between Fe and Mo element, which could realize the control of the electronic structure and optimize the adsorption/desorption of intermediates. And electrochemical tests showed that the Mo–Ni/3DGFs exhibited a relatively smaller overpotential of 109.9 mV for HER, while the Mo-NiFe x /3DGFs presented better OER performance with an overpotential of 240.8 mV at the current density of 100 mA cm -2 in 1.0 M KOH. Finally, a system for overall water splitting constructed by Mo–Ni/3DGFs||Mo–NiFe 0.68 /3DGFs electrodes has a low cell voltage of 1.52 V at 10 mA cm −2 and long-term stability, exceeding most of literature results. Our findings provide insight into possibilities for the simple synthesis of high-performance and cheap catalysts, and laid the foundation for the practical application of transition metal catalysts .
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CERAMICS INTERNATIONAL
·
2022
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IF 5.532
Yisheng Xu,Yaoheng Liang,Zeng Yuai,Hangyu Long,Qizhi He,Kaijin Guo,Yuyuan Zhang,Dongchu Chen,Xuejun Xu,Huawen Hu
Although g-C 3 N 4 (CN) materials have been extensively explored for the photocatalytic degradation of organic pollutants, their weak response to visible light and fast recombination of photoexcited electron-hole pairs restrain their practical applications. Herein, we deeply mediated the CN's energy-band structure, morphology, and surface properties by non-metal (P) and metal (Mo) co-doping based on the thermal treatment of a phosphomolybdic acid hydrate and dicyandiamide mixture in a straightforward one-step manner. Meanwhile, cyano groups and nitrogen vacancies were generated as a result of the co-doping, and the resulting P, Mo co-doped CN (PM-CN) exhibited thinner layers, smaller sizes, and superior visible-light harvesting capacity and charge separation efficiency. Consequently, highly active PM-CN was obtained for photocatalytic tetracyclines (TC) degradation, and the rate was calculated to be 0.01 min −1 , 3.3 times greater than that of the pure CN, outstripping the single P- and Mo-doped counterparts. A free radical scavenging test demonstrated that the reactive species •O 2− and h + were critical in TC degradation. The present work is expected to shed light on co-doping CN with non-metal and metal elements to obtain high-performance, visible-light-responsive photocatalysts for practical environmental remediation.
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ENERGY & FUELS
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2022
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IF 4.654
Cheng Lan,Heping Xie,Yifan Wu,Bin Chen,Tao Liu
Electrochemical seawater splitting using efficient HER (hydrogen evolution reaction) and OER (oxygen evolution reaction) electrocatalysts have become an appropriate method for the mass production of green hydrogen. In this study, a noble-metal free OER electrocatalyst consisting of Mo-doped Ni3S2 nanocluster arrays on Nickle foam (Mo–Ni3S2/NF)─fabricated using a modified one-step solvothermal approach─is developed and evaluated. The proposed electrocatalyst demonstrates exceptional OER activity, requiring overpotentials of only 212 and 291 mV to deliver OER current densities of 10 and 100 mA cm–2, respectively, in alkaline seawater. The presence of Mo promotes Ni–S coordination, resulting in strong electronic interactions and substantially enhanced OER kinetics. Meanwhile, surface sulfate ions and (oxy)hydroxide (NiOOH) generated during the OER lead to enhanced activity and corrosion resistance, enabling Mo–Ni3S2/NF to operate continuously at 100 mA cm–2 for 500 h in alkaline natural seawater. This study is expected to inform the progression of sulfur-based transition-metal electrocatalysts for seawater oxidation.
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CHEMICAL PHYSICS LETTERS
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2022
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IF 2.719
Lifeng Han,Yuheng Liu,Chaoqun Chang,Meng Liu,Zhikun Peng,Feilong Gong
We reported the design of cactus-like Mo-WO 3 nanoarchitecture assembled of 1D nanoneedles and 2D nanosheets for achieving a highly improved NO 2 sensing performance. The nanoneedles were vertically studding between the nanosheets forming a cactus-like WO 3 nanoarchitecture, leading to highly exposed absorption sites. Mo was introduced in the WO 3 nanoarchitecture to introduce oxygen vacancy, resulting in highly activated sites. The resultant 2%Mo-WO 3 delivered the sensitivity (Rg/Ra) of 285 to 10 ppm NO 2 , which was nearly three-times higher than that of pristine WO 3 . The recovery time was only 24 s, which was greatly decreased, compared with 172 s of pristine WO 3 .
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2022
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IF 9.965
Xiaoqiang An,Li Quan,Jianqiao Liu,Qingwen Tang,Huachun Lan,Huijuan Liu
Designing non-precious electrocatalysts with multiple active centers and durability toward overall water splitting is of great significance for storing renewable energy. This study reports a low-cost Mo, Fe codoped NiCoP x electrocatalysts derived from Co-Fe Prussian blue analogue and following phosphorization process. Benefitted from the optimized electronic configuration, hierarchical structure and abundant active sites, the Mo,Fe-NiCoP x /NF electrode has shown competitive oxygen evolution reaction ( ƞ 10 = 197 mV) and hydrogen evolution reaction performance ( ƞ 10 = 99 mV) when the current density is 10 mA cm −2 in 1 M KOH solution. Moreover, the integrated water splitting device assembled by Mo,Fe-NiCoP x /NF as both anode and cathode only needs a voltage of 1.545 V to reach 10 mA cm −2 . Density functional theory results further confirm that the Mo, Fe codoped heterostructure can synergistically optimize the d-band center and Gibbs free energy during electrocatalytic processes, thus accelerating the kinetics of electrochemical water splitting. This work demonstrates the importance of rational combination of metal doping and interface engineering for advanced catalytic materials.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
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IF 13.273
Yao Xu,Jack Yang,Ting Liao,Riyue Ge,Yang Liu,Jiujun Zhang,Ying Li,Mingyuan Zhu,Sean Li,Wenxian Li
Molybdenum carbide (Mo 2 C) exhibits unique competitive advantages in electrochemical water splitting due to its physicochemical properties . The high intrinsic activity is essential for the high-efficient Mo 2 C catalysts. Herein, transition metal (Ni, Co, or Fe)-Mo 2 C-embedded in N-doped carbon sheets grown on Ni foam (TM/Mo 2 C-NCSs) are synthesized to enhance the intrinsic activity of Mo 2 C by optimizing the Mo-H bonding energy through the interfacial interactions between Ni, Co, or Fe, and Mo 2 C. Owing to the superior intrinsic activity, fast ternary channels, and abundant active sites, the Ni/Mo 2 C-NCSs possess the lowest overpotential for HER (131 mV) and the Fe/Mo 2 C-NCSs show the lowest overpotential for OER (293 mV) at a current density of 100 mA cm −2 in 1 M KOH. The results analyzed with the Density function theory (DFT) calculation indicate that the most superior H adsorption site is at the interface between Mo 2 C and Ni hybrid. H was adsorbed on interface Mo&Ni@Ni/Mo 2 C with proper hydrogen adsorption free energies (ΔG H* ), achieving a fast desorption process in HER. This mechanism is absent in the pristine Mo 2 C catalysts. An alkaline electrolyzer with a cathode of Ni/Mo 2 C-NCSs and anode of Fe/Mo 2 C-NCSs demonstrates a small voltage of 1.66 V at a current density of 100 mA cm −2 . This work offers an elaborated strategy of interface engineering to enhance the intrinsic catalytic activity of Mo 2 C by accelerating H 2 desorption in HER and enhancing the catalytic kinetics of OER simultaneously.
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