NiCoMo层状双氢氧化物纳米催化剂的制备及其电催化析氧性能研究

Preparation of NiCoMo layered double hydroxide nanocatalyst and its electrocatalytic oxygen evolution performance

以泡沫镍(NF)为基底,通过一步水热法制备不同镍钴比的层状双氢氧化物(NiCoMo-LDH/NF)纳米催化剂,并借助X射线衍射和扫描电镜对催化剂的物相和形貌进行表征分析,研究催化剂元素组分调控对其电催化性能的影响。通过元素组分的调控,改变催化剂的显微结构,当Ni∶Co=1∶2(摩尔比,下同)时,Ni_(1)Co_(2)Mo-LDH/NF催化剂密集的纳米片结构,有利于活性位点的暴露和中间体吸脱附,以及电荷的快速传输,进而促使析氧反应的进行。电化学测试表明,在1mol/L KOH溶液中,电流密度达到10mA/cm^(2)时,Ni∶Co=1∶2的纳米材料过电势仅为266mV,塔菲尔斜率为82.45mV/dec。此外,经12h的时间-电流稳定性测试后,材料的催化性能和形貌未有明显改变。可见,当Ni∶Co=1∶2时,材料表现出优异的催化活性和稳定性。

NiCoMo-LDH/NF nanocatalysts with different nickel-cobalt ratios were prepared by one-step hydrothermal method using nickel foam as the substrate.The phase and morphology of the catalysts were characterized by X-ray diffraction and scanning electron microscopy.The effect of catalyst element composition regulation on its electrocatalytic performance was investigated.The microstructure of the catalyst could be changed by adjusting the element composition.When molar ratio Ni∶Co=1∶2,the dense nanosheet structure of the Ni_(1)Co_(2)Mo-LDH/NF catalyst was beneficial to the exposure of active sites,the adsorption and desorption of intermediates and the rapid transfer of charge,which in turn promoted the oxygen evolution reaction.Electrochemical tests showed that in 1 mol/L KOH solution,when the current density reached 10mA·cm^(-2),the overpotential of the nanomaterial with molar ratio Ni∶Co=1∶2 was only 266mV,and the Tafel slope was 82.45mV·dec^(-1).In addition,the catalytic performance and morphology of the material did not change significantly after 12 h of time-current stability test.It was proven that when molar ratio Ni∶Co=1∶2,the material exhibited excellent catalytic activity and stability.