镍铜合金立方体纳米晶的脉冲电沉积及电催化析氢性能

以泡沫镍(NF)为基体, 采用常规脉冲伏安法合成了独立分相的金属Ni, Cu为主晶相、 平均粒径为70 nm的规则立方体结构镍铜合金电催化剂(NiCu/NF). 在电催化析氢反应中, NiCu/NF表现出优良的催化活性和优异的催化稳定性, 在电流密度为10 mA/cm ²时, 在1.0 mol/L KOH溶液中需要的析氢过电位仅为86 mV, 催化24 h的电位波动仅为12 mV. 二级复合纳米立方体结构使NiCu/NF展现出15.5倍于空白NF的电化学活性面积(ECSA), 为电催化反应提供了大量催化活性位点, 也为电极表面的电荷传输、 物质传递提供了充足的通道; Cu的引入以及NiO/Ni异质结的形成改善了邻近Ni原子的活性, 使镍基材料本征析氢活性得以改善, 三者协同促进了NiCu/NF电催化活性的提升. NiCu/NF电极在析氢过程中遵循Volmer-Heyrovsky机理, 反应速率由电极表面吸附氢原子的电化学脱附过程决定.

Enhancing Hydrogen Evolution Performance of a Regular Cube NiCu Nanocrystalline Electrocatalyst Fabricated by Normal Pluse Electrodeposition †

Herein, a regular cube structured nickel-copper alloy electrocatalyst on nickel foam(NF) with phase-separated metallic Ni and Cu as the main crystal phase, and the average particle size of 70 nm, denoted as NiCu/NF, was prepared by normal pluse voltammetry. The as-obtained catalyst displays superior electroca-talytic activity towards hydrogen evolution reaction(HER), requiring an overpotential of merely 86 mV to afford 10 mA/cm ² current density in 1 mol/L KOH. Moreover, NiCu/NF exhibits remarkable stability with a potential fluctuation of merely 12 mV during a 24 h continuous HER electrolysis. As a result, the two-stage composite cube-nanocrystalline structure gives rise to the 14.5-fold increased electrochemical active surface area(ECSA), exposing a huge number of catalytic active sites for HER, providing sufficient channels for charge transfer and material transfer on the electrode surface. On the other hand, the strong synergistic effect induced by Cu-introduction and the formation of NiO/Ni heterojunction brings prominent improvement of intrinsic HER activity of electrode materials via alteration of the electronic property of the adjacent Ni atoms. The three factors contribute collectively to the superior electrocatalytic performances of NiCu/NF electrode towards HER. Meanwhile, NiCu/NF electrode follows the Volmer-Heyrovsky mechanism with the reaction rate determined by the electrochemical desorption of hydrogen adsorbent on the electrode surface during HER. This study provides a new perspective for multi-structural nanoscale synthesis and promotes the development of NiCu-based electrode materials in energy conversion applications.