APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Yi Pei,Jie Li,Zhaoyang Wang,Wei Zhong,Chunxin Lu,Zhongquan Shen,Nianlong Qian,Xiaoming Liu
In this work, composite materials (Cu-Cu 2 O/MO 2 , M = Mo and W) and their thermally treated form were prepared and characterized by using a variety of spectroscopic techniques (XRD, SEM, HRTEM, XPS and UPS) and cyclic voltammetry. Their catalytic performance on aerobic oxidation of various alcohols under mild conditions was investigated with N-methylimidazole (NMI) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as the co-catalysts. Of the materials, the thermally treated MoO 2 -based material exhibited the best performance and durability. Compared to Cu-Cu 2 O, the involvement of MO 2 significantly enhances the catalytic activity on the oxidation. Our results suggest that the presence of MO 2 not only raises the energy level of VBM of Cu 2 O which is beneficial to O 2 activation and generates internal electric field pointing to the catalytic center (Cu 2 O) which would accelerate the electron transfer from the substrate to the catalyst through forming heterojunction with both Cu and MO 2 , but also disperses the catalytic center. Further, the Lewis acidity of MO 2 with appropriate strength can bring the substrate closer to the catalytic center via adsorption. But appropriate acidity is essential as easy on–off adsorption is desired in the catalysis. Thermal treatment generates oxidation state VI species of stronger acidity which offsets the effect of the raised VBM energy level.
研究领域:
催化
·
材料科学
·
化学工程
·
物理化学
✓ 已验证
DOI
高影响因子
Nano Life
·
2022
·
IF 0
Shanshan Niu,Lei-Lei Qian,Pan Du,Nan Si,Dawei Jiang,Yan Feng,Bin Huang,Xiaomin Gu,Qiang Zhao,Jiao Ji,Hua Zhu
Graphene coupling molybdenum-based nanocomposite structures were synthesized by changing the pyrolytic temperature to implement the molybdenum-based optimized microstructure. The structural and surface properties tests showed that the presence of the most variable species and a high proportion of divalent molybdenum on the surface of the material could effectively expose catalytic sites to improve reduction ability of N 2 and inhibited hydrogen evolution reaction. Electrochemical investigations indicated that the Mo-700/rGO nanocomposite exhibited a significantly enhanced electrochemical ammonia synthesis performance. In 0.05 M H 2 SO 4 , the Mo-700/rGO electrode achieved a Faradic efficiency of 12.7% at − 0.15 V versus reversible hydrogen electrode (RHE), and an ammonia yield of 3.93 μ g h − 1 cm − 2 at − 0.2 V versus RHE.
✓ 已验证
产品关联
DOI
POWDER METALLURGY AND METAL CERAMICS
·
2025
·
IF 0.6
Yang Xiao-Hui,Wang Ya-Long,Zhang Guo-Hua
Mo 2 FeB 2 -based cermets exhibit promising industrial manufacturing applications due to their excellent mechanical properties, higher oxidation resistance, and thermal stability. In this study, ternary boride solid solution powders of Mo 2 (Fe x , Ni 1– x )B 2 were successfully prepared with a unique technique via employing B 4 C powder as a boron source, Mo, Fe, and Ni powders as metal sources as well as Ca powder as the decarburization agent. The effect of the Fe/Ni ratio on the phase composition, morphological evolution and average grain size of powders was studied. The shift of diffraction peak in the XRD results and the homogeneous distributions of Mo, Fe, Ni, and B by the EDS energy spectrum validated the successful synthesis of ternary boride solid solution powders. The morphology of solid solution powders varied depending on the Fe/Ni ratio. For compositions with Fe/Ni ratios of 10 : 0, 7 : 3, and 5 : 5, the ternary solid solution powders exhibited pronounced spherical grains with average grain sizes of approximately 3, 1, and 1 μm, respectively. Conversely, when the Fe/Ni ratios were 3 : 7 and 0 : 10, the solid solution powders exhibited mixed morphologies of spherical (with diameters of approximately 1 μm) and prismatic grains (with lengths of about 8 μm and diameters of around 3 μm), corresponding respectively to the tetragonal and orthorhombic crystal structures of Mo 2 NiB 2 . Using ultrafine Mo powder as a raw material to boost reaction kinetics resulted in the product's stable phase being orthorhombic Mo 2 NiB 2 . Nonetheless, at a Fe/Ni ratio of 3 : 7, the product still consisted of orthorhombic and tetragonal Mo 2 NiB 2 phases.
研究领域:
材料科学
·
粉末冶金
✓ 已验证
DOI
高影响因子
ACS Catalysis
·
2016
·
IF 9.307
Jiajun Wang,Wei Wang,Zongyuan Wang,Jingguang G. Chen,Chang-jun Liu
Highly efficient and stable electrochemical catalysts of porous one-dimensional (1D) MS2/MO2 (M = W, Mo) nanorods have been developed for the hydrogen evolution reaction (HER). The materials are synthesized via a “low-temperature conversion” method. The as-prepared catalysts exhibit numerous advantages: abundant amount of exposed MS2 edges, high conductivity, and enhanced mass transport. The MS2/MO2 nanorods show efficient HER activity.
✓ 已验证
DOI
高影响因子
International Journal of Minerals Metallurgy and Materials
·
2025
·Vol. 32
·期 6
·1441-1450
·
IF 7.2
Chen Xunlei,Chen Lin,Tian Jiang,Xu Cheng,Liao Jiaxin,Li Tianyu,Wang Jiankun,Feng Jing
Thermal and mechanical properties of yttrium tantalate (YTaO 4 ), a top coat ceramic of thermal barrier coatings (TBCs) for aeroengines, are enhanced by synthesizing Y 1− x Ta 1− x M 2 x O 4 (M = Ti, Zr, Hf; x = 0.06, 0.12, 0.18, 0.24) medium-entropy ceramics (MECs) using a two-step sintering method. In addition, the thermal conductivity, thermal expansion coefficients (TECs), and fracture toughness of MECs were investigated. An X-ray diffraction study revealed that the Y 1− x Ta 1− x M 2 x O 4 MECs were monoclinic, and the Ti, Zr, and Hf doping elements replaced Y and Ta. The variations in atomic weights and ionic radii led to disturbed atomic arrangements and severe lattice distortions, resulting in improving the phonon scattering and reduced thermal conductivity, with Y 1− x Ta 1− x M 2 x O 4 MECs ( x = 0.24) exhibiting the lowest thermal conductivity of 1.23 W·m −1 ·K −1 at 900°C. The introduction of MO 2 increased the configurational entropy and weakened the ionic bonding energy, obtaining high TECs (10.4 × 10 −6 K −1 at 1400°C). The reduction in the monoclinic angle β lowered the ferroelastic domain inversion energy barrier. Moreover, microcracks and crack extension toughening endowed Y 1− x Ta 1− x M 2 x O 4 MECs ( x = 0.24) with the highest fracture toughness of (4.1 ± 0.5) MPa·m 1/2 . The simultaneous improvement of the thermal and mechanical properties of the MO 2 (M = Ti, Zr, Hf) co-doped YTaO 4 MECs can be extended to other materials.
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Jin-Feng Liao,Yang-Fan Xu,Xu-Dong Wang,Hong-Yan Chen,Dai-Bin Kuang
Though coating CsPbBr3 nanocrystal (NC) with an outer layer has been regarded as an effective strategy to address its instability issues, deep investigations into the electronic interaction between CsPbBr3 NC and coating layer have yet to be conducted. In this study, the dynamics of hot carrier and charge carrier of CsPbBr3 nanocrystal with various MO2 (M = Si, Ti, Sn) coating layers have been comprehensively studied. Combined transient optical characterizations (time-resolved photoluminescence and ultrafast transient absorption) and photoelectrochemical measurements reveal that coating with insulating SiO2 accelerates the hot carrier relaxation and enhances the radiative recombination by passivating surface traps, whereas efficient charge-carrier separation and extraction are observed after coating with SnO2 and TiO2. The electron injection from CsPbBr3 NC to SnO2 (1.14 × 108 s–1) is 2-fold faster than to TiO2 (5.4 × 107 s–1) owing to the lower conduction band edge and the higher electron mobility of SnO2. Particularly, the first time fabricated CsPbBr3 NC/SnO2 composite exhibits superior stability against UV light and moisture, as well as the best photocurrent response in this study. This work has implied that rational design of the coating layer for perovskite NC can not only improve the stability but also tailor the electronic and optoelectronic properties for various applications.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）