Synergistic electronic structure modulation of nickel-based ternary alloy surface for hydrogen and oxygen evolution reactions
Yuanmei Chen;Rongfu Hong;Lei Du;Siyu Ye;[Objective] Non-noble metal Ni-based electrocatalysts represent an important class of electrode materials for alkaline water electrolysis. Exploring optimization strategies for bifunctional Ni-based catalysts for both hydrogen evolution reaction(HER) and oxygen evolution reaction(OER) is crucial for enhancing the core competitiveness of hydrogen energy as a new energy source. [Method] The surface electronic structure of Ni-based catalysts was synergistically modulated by Cu and Cr co-doping. NiCuCr/C alloy catalysts with good activity for HER were prepared by impregnation combined with H2/Ar high-temperature reduction. Citric acid(CA) and urea(U) were then introduced to regulate the surface and interface properties to enhance the OER performance. The phase structure, microstructure, surface electronic states, and electrocatalytic performance of the catalysts were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), and electrochemical tests to clarify the structure-activity relationship. [Result] The optimized NiCu0.1Cr0.02/C catalyst exhibited excellent HER activity in 1.0 mol/L KOH solution, with an overpotential of 174 mV at a current density of 10 mA/cm2. Cu and Cr co-doping promoted electron transfer to surface Ni active centers, significantly increasing surface electron density and optimizing the adsorption-desorption kinetics of hydrogen intermediates. The NiCu0.05Cr0.02/CA-U catalyst obtained through CA-U morphology regulation showed good OER performance, with an overpotential of 348 mV at 10 mA/cm2, outperforming the Ru-containing reference catalyst Ru0.03NiCu0.05Cr0.02/CA-U. [Conclusion] A multicomponent and morphologyregulating strategy was used to prepare NiCuCr ternary alloy catalysts and regulate their surface electronic structure. The materials exhibited good HER and OER performance, providing a new idea for developing low-cost, high-efficiency bifunctional Ni-based electrocatalysts.
Magnesium fluoride coating-modified zinc anode and its performance in aqueous zinc-ion batteries
Qian Qu;Jinxi Ye;Yuyun Xie;Jiayuan Luo;Hui Guo;Jing Feng;Bingchun Jiang;Tong Zhang;[Objective] To address the issues of dendrite growth and side reactions on zinc anodes that severely restrict the cycling stability of aqueous zinc-ion batteries(AZIBs), an artificial interfacial layer was constructed to enhance the electrochemical performance of zinc anodes. [Method] A Zn@MgF2 composite anode was successfully fabricated by coating magnesium fluoride(MgF2) on the surface of zinc foil. The material characteristics and electrochemical behavior of the composite anode were systematically characterized. [Result] The MgF2 coating was compact, uniform, and highly hydrophobic, effectively isolating the direct contact between the electrolyte and the zinc substrate, thereby suppressing side reactions such as hydrogen evolution and corrosion. Electrochemical tests showed that the coating inhibited the two-dimensional surface diffusion of Zn2+, reduced the interfacial charge transfer resistance, induced uniform zinc deposition, and significantly improved the reversibility of the electrode reaction. In symmetric cell and half-cell tests, the Zn@MgF2 anode exhibited significantly prolonged cycling life and higher Coulombic stability at various current densities as compared with the pure Zn anode. In full-cell testing with VO2 as the cathode at a current density of 1 A/g, the Zn@MgF2| VO2 cell maintained a specific discharge capacity of 99.3 mA·h/g after 1 194 cycles, much higher than that of Zn||VO2 cell(43.6 mA·h/g). [Conclusion] Through the synergistic effect of physical isolation and ion flux regulation, the MgF2 artificial interfacial layer effectively suppresses dendrite growth and interfacial side reactions, significantly improving the cycling stability of the zinc anode. This provides a simple and effective strategy for the anode design of high-performance AZIBs.
Preparation of MXene-based nanofluid aqueous cleaner and its rust removal and lubrication performance
Chunping Liu;Xiaohua Zhang;Naimeng Yao;Lanhe Zhang;Shiheng Xing;Shengquan Huai;Limin Wang;Mingrui Qu;[Objective] In response to the serious pollution and strong corrosiveness of traditional strong acid cleaner, this study aims to develop an environmentally friendly water-based cleaner that integrates efficient rust removal, good lubricity, and low corrosiveness. [Method] Using MXene(a two-dimensional layered material) as the core and silane coupling agent KH560 and polyetheramine M2070 as the shell, a core–shell structured solvent-free nanofluid(MXene NFs) was synthesized via covalent grafting. The MXene NFs were then dispersed in a water-based system(GHC) composed of glycerol, 1-hydroxyethylidene-1,1-diphosphonic acid(HEDP), and citric acid, with thiourea added as a corrosion inhibitor to obtain the MXene NFs/GHC cleaner. The structure and composition of MXene NFs were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM), thermogravimetric analysis(TG), and X-ray diffractometry(XRD). The comprehensive performance was evaluated through rust removal test, electrochemical measurements, and friction and wear test. [Result] The mass fraction of organic shell of MXene NFs was 72.9%, and the nanofluid remained stably dispersed in the GHC system without sedimentation after standing for one month. With the optimized formulation of 100 g/L HEDP, 100 g/L citric acid, and 50 g/L thiourea, the MXene NFs/GHC cleaner achieved a rust removal rate of 0.066 g/h on Q235 steel, and a corrosion inhibition efficiency of 48.1%. Citric acid and HEDP dissolved the rust layer through coordination, forming soluble complexes that avoided secondary residues, while thiourea formed a physically adsorbed film on the steel surface, effectively inhibiting corrosion. Compared with the pure GHC system, the friction coefficient of MXene NFs/GHC decreased from 0.162 to 0.106, the wear volume decreased from 8.76 × 10-2 mm3 to 7.36 × 10-3 mm3, and the wear rate dropped to 6.81 × 10-7 mm3/(N·m), demonstrating significantly enhanced lubrication performance. [Conclusion] The MXene NFs/GHC cleaner integrates multiple functions of cleaning, lubrication, and anti-corrosion, showing promising prospects for environmentally friendly applications. This study provides a new strategy for developing multifunctional and eco-friendly water-based cleaners.
Generation of nanoparticles on gel film surface induced by atmospheric pressure plasma jet(APPJ)
Chenyan An;Ying Wang;Zongquan Liu;Xinchun Tian;Zhuang Ma;[Objective] The surface modification of SiO2 gel films prepared by the sol-gel method was performed using an atmospheric pressure plasma jet(APPJ). [Method] By optimizing jet parameters such as argon flow rate and input voltage, uniform and low-temperature plasma treatment was achieved, avoiding surface damage caused by filamentary discharge. [Result] Under suitable APPJ conditions, a large number of dispersed SiO2 nanoparticles were generated in situ on the gel film surface, significantly increasing the surface roughness and specific surface area. The formation of nanoparticles is closely related to the crosslinking density of the gel, with incompletely cured wet gels or cracked regions more prone to inducing nucleation and growth. The results of Fourier-transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS) indicated that the treatment effectively promotes further hydrolysis and condensation of the tetraethyl orthosilicate(TEOS) precursor, removes residual organic groups, and forms a porous Si─O─Si network structure. [Conclusion] A mechanism for APPJ-induced surface nanoparticle generation was proposed: active species promote local network reconstruction and nucleation, combined with migration and attachment growth of oligomeric fragments produced on the surface. This study provides theoretical and experimental foundations for achieving controllable surface nanostructuring of gel films using APPJ technology under low-temperature and atmospheric pressure conditions, with potential applications in catalysis, sensing, and related fields.
Laser-clad NiCoCrFeAlHfY high-entropy alloy coating: microstructure, wear resistance, and corrosion resistance
Zhengyang Wang;Meng Li;Zhen Zhang;Yujun Han;Qingchun Zhou;Hongya Li;Xiansheng Yang;Baosen Zhang;Wei Zhao;Chao Zhang;[Objective] To improve the wear resistance and corrosion resistance of 42 CrMo+Ni steel for wind turbine main shafts in complex service environments, a NiCoCrFeAlHfY high-entropy alloy cladding coating was prepared on its surface by laser cladding technology. [Method] The phase composition, microstructure, and element distribution of laser-clad coating were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and energy-dispersive spectroscopy(EDS). Combined with microhardness testing, friction and wear tests, and electrochemical tests, its microhardness, wear resistance, and corrosion resistance were evaluated. [Result] The cladding coating formed a good metallurgical bond with the substrate and was mainly composed of a body-centered cubic(BCC) solid solution and(Co,Fe,Ni)Al strengthening phase. The synergistic effect of Hf and Y microalloying elements promoted grain refinement and microstructural densification. The average microhardness of the cladding coating was 529.6 HV1.0, about 49% higher than that of the substrate, and the friction coefficient was lower than that of the substrate. The wear rate under 30 N and 40 N loads was lower than that of the substrate, but failure occurred at 50 N. In 3.5% NaCl solution, the corrosion potential was -0.375 5 V, and the corrosion current density was 1.58 × 10-6 A/cm2, with stable surface passive film. [Conclusion] The laser-clad NiCoCrFeAlHfY high-entropy alloy cladding coating can significantly improve the surface hardness, wear resistance, and corrosion resistance of 42 CrMo+Ni steel, providing a feasible approach for surface strengthening of wind turbine main shafts; however, the wear resistance under high load still needs optimization.
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