ZnO增强MxCo3-xO4电催化析氧性能研究

氢能因热值高、燃烧产物无污染等优良特性,成为目前新型能源研究的焦点,有望成为化石能源的理想替代品。电催化水分解作为最具前景的氢气制备方法,包含两个半反应:析氧反应(OER)和析氢反应(HER)。其中OER目前主要采用贵金属作为催化剂,但其高成本极大地限制了电催化产氢的工业化。基于Co 3O 4的Co基掺杂氧化物具有成本低廉、催化活性高且稳定性强等优良特性。目前对于Co基掺杂氧化物的研究主要集中于探究掺杂不同金属元素(Zn,Ni,Fe等)对其催化活性的影响,极少研究掺杂惰性氧化物对其催化活性的影响。合成了一种CoFeNiZn复合氧化物,且具有优良的电催化活性和稳定性。在1 mol/L KOH的电解液中,10 mA/cm 2的电流密度下,CoFeNiZn复合氧化物过电势(η10)为310 mV,塔菲尔斜率(Tafel slope)为40 mV/dec,相比原始CoFeNi氧化物(η10为400 mV)过电势降低了90 mV。CoFeNiZn催化剂催化性能的提高主要是由于以惰性ZnO作为基质可有效地分散催化活性物质,并充分暴露CoFeNi氧化物的催化活性位点。这一基于催化材料掺杂非活性物质提高催化剂催化活性的发现可以为现有催化剂开发提供新的思路。

MxCo3-xO4 Mixed with ZnO as an Excellent Electrocatalyst for the Oxygen Evolution Reaction

Hydrogen,with high calorific value and environmental friendliness,is expected to become a potential alternative energy to replace exhaustible fossil fuels.Electrochemical water splitting is the most promising method to generate hydrogen,which is composed of two half-reactions:oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,conventional catalysts for OER are mainly based on precious metals,whose high cost interrupts the further practical applications in HER.In contrast,Co 3O 4-based oxides doped with transition metals have advantages of low cost,high catalytic activity and strong stability.But the researches of Co-based oxides mainly focus on the effect of doping transition metals(such as Zn,Ni and Fe)on catalytic performance,few of them explore the influence of electrochemically inactive materials.In this paper,a new CoFeNi oxide mixed with ZnO is synthetized.This CoFeNiZn oxide has a superior performance with small Tafel slope(40 mV/dec)and long-term stability.In 1 mol/L KOH electrolyte,the overpotential of the CoFeNiZn oxide is as low as 310 mV at the current density of 10 mA/cm 2,which is 90 mV lower than the overpotential of original CoFeNi oxide.The electrochemically inactive ZnO is the critical factor for this remarkable improvement,which can effectively disperse the active materials and fully expose the active sites of CoFeNi oxide.This discovery provides a strategy to design novel catalysts structures for improving electrochemical performance.