Ru掺杂Ni_(3)N催化剂的电催化析氢反应

Ruthenium Dopant in Ni_(3)N Catalyst for Electrocatalytic Hydrogen Evolution Reaction

开发高催化活性和廉价催化剂是催化分解水制氢技术的关键。过渡金属氮化镍(Ni_(3)N)具有优异的热/化学稳定性、电化学活性和类贵金属特性,吸引了越来越多研究者的兴趣。然而,Ni_(3)N碱性电催化析氢反应过程中,水的解离效率低,且对反应中间体质子的吸附太强,这两个因素导致Ni_(3)N的性能远低于Pt,还有很大的改进空间。本文通过水热-氮化两步法成功制备了Ru掺杂多孔纳米片Ni_(3)N/Ru。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对Ni_(3)N/Ru材料的组成、形貌和结构进行表征,通过X射线光电子衍射仪(XPS)对催化机理进行分析,并研究Ru掺杂量对Ni_(3)N材料形貌和电催化性能的影响。结果表明,6.30%Ru负载的Ni_(3)N在1 mol/L KOH电解液中驱动10 mA·m^(-2)的电流密度仅需要49 mV过电位,可以和商业Pt/C相媲美(46 mV@10 mA·cm^(-2))。将其应用于两电极全解水体系,仅需1.54 V的电压即可获得10 mA·cm^(-2)的电流密度。突出的催化性能归因于Ru掺杂Ni_(3)N有效提升水解离,并使Ni_(3)N中Ni和N的电子云密度降低,促进吸附氢中间体的形成过程(H++e-=H*),改善析氢反应动力学,进而提升其电催化性能。

The development of high catalytic activity and cheap catalyst is the key of catalytic decomposition of water to produce hydrogen.The transition metal nickel nitride(Ni_(3)N)has excellent thermal/chemical stability,electrochemical activity and noble metal-like properties,which attracts more and more researchers’interest.However,in the process of Ni_(3)N alkaline electrocatalysis of hydrogen evolution reaction,the dissociation efficiency of water is low,and the adsorption of the intermediate proton is too strong,which result in the much lower performance of Ni_(3)N than Pt catalyst.In this work,Ru-doped porous Ni_(3)N nanosheets(Ni_(3)N/Ru)were prepared successfully by two-step method of hydrothermal and nitriding process.The composition,morphology and structure of Ni_(3)N/Ru materials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The catalytic mechanism was analyzed by X-ray photoelectron diffractometer(XPS),and the effect of Ru doping amount on the morphology and electrocatalytic performance of Ni_(3)N materials was also studied.The results show that Ni_(3)N loaded with 6.30%Ru needs only an overpotential of 49 mV to drive the current density of 10 mA·m^(-2)in 1 mol/L KOH electrolyte,which is comparable to commercial Pt/C(46 mV@10 mA·cm^(-2)).The Ni_(3)N/Ru were then assembled into a two-electrode system for overall water splitting,and the cell voltage required to reach the current density of 10 mA·cm^(-2)is only 1.54 V.The outstanding catalytic performance is attributed to the fact that Ru doping Ni_(3)N effectively improves the dissociation of water,reduces the electron cloud density of Ni and N in Ni_(3)N,promotes the formation process of adsorbed hydrogen intermediates(H++e-=H*),improves hydrogen evolution reaction kinetics,and thus enhances its electrocatalytic performance.