摘要
本文制备了一种双金属IrNi修饰的花状NiCo_2O_4复合材料,并研究了其对于氧析出反应的电化学活性,结果显示其电化学活性明显提升.NiCo_2O_4和IrNi分别通过水热法和热分解法制备,再通过超声复合,使得双金属附着在复合氧化物表面.通过与纯NiCo_2O_4,IrNi以及IrNi/Co_3O_4相比较,所制备的IrNi/NiCo_2O_4对于氧析出反应的性能最为优异.在各个参数指标中,拥有最低的过电势210mV,在540mV的过电势下具有最高的电流密度.电子转移数和塔菲尔斜率分析表明该复合材料由于修饰上了双金属材料,极大地降低了极化,具有更高效的电子转移速率.此外本文还对电催化机理进行了研究,发现复合材料结合反应位点有效改善了反应速率决定步骤.其中,协同效应起着至关重要的作用,这一效应明显提高电子传输效率的同时提供了更多的活性位点.IrNi/NiCo_2O_4是一种出色的氧析出反应电催化剂.
In this work,we demonstrated the enhanced oxygen evolution reaction（OER） activity of flower-shaped cobalt-nickel oxide（NiCo_2O_4） decorated with iridium-nickel bimetal as an electrode material.The samples were prepared by carefully depositing pre-synthesized IrNi nanopartides on the surfaces of the NiCo_2O_4 nano-flowers.Compared with bare NiCo_2O_4,IrNi,and IrNi/Co_3O_4,the IrNi/NiCo_2O_4 exhibited significantly enhanced electrocatalytic activity in the OER,including a lower overpotential of 210 mV and a higher current density at an overpotential of 540 mV.We found that the IrNi/NiCo_2O_4 showed more efficient electron transport behavior and reduced polarization because of its bimetal IrNi modification by analyzing its Tafel slope and turnover frequency.Furthermore,the electrocatalytic mechanism of IrNi/NiCo_2O_4 in the OER was studied,and it was found that the combined active sites of the composite effectively improved the rate determining step.The synergic effect of the bimetal and metal oxide plays an important role in this reaction,enhancing the transmission efficiency of electrons and providing more active sites for the OER.The results reveal that IrNi/NiCo_2O_4 is an excellent electrocatalyst for OER.
基金
supported by the National Natural Science Foundation of China(61371021 and 61671284)
the support of Shanghai Education Commission(Peak Discipline Construction)
