High efficient trifunctional electrocatalyst based on bimetallic oxide with rich oxygen vacancies towards electrochemical oxidation of small molecules at high current density

Abstract

Exploiting low-cost, high-activity and robust-stability catalysts has become a meaningful and challenging research topic in the development of hydrogen production via electrochemical water splitting, meanwhile the as-synthesized materials exhibiting multi-functional electrocatalytic performance is highly desirable, but remains tremendous difficulty. Herein, a facile and scalable strategy is developed to synthesize nanowire-like NiCo2O4 arrays with space group Fd3¯m in-situ grown on cobalt foam (denoted as NiCo2O4/CF) via hydrothermal approach and air calcination treatment. The as-prepared nanoporous NiCo2O4/CF electrode possesses a high specific surface area, multiple redox couples and rich oxygen vacancies, thus displaying excellent tri-profitable catalytic activities towards hydrazine oxidation reaction (HzOR), urea oxidation reaction (UOR) and methanol oxidation reaction (MOR). Experimental results show that affording current densities of 10 and 100 mA cm−2 needs potentials of −0.172 and −0.149 V for HzOR, delivering 100 and 500 mA cm−2 current densities merely requires low potentials of 1.343 and 1.440 V for UOR. Impressively, for MOR, a potential of only 1.5 V is required to achieve a high current density of 1058 mA cm−2, outperforming most of the reported electrocatalysts. What's more, the NiCo2O4/CF electrode exhibits exceptional stability at a high current density of 100 mA cm−2 over 20 h for all of the three small molecules electro-oxidation. The current work provides a promising application opportunity for the nanowire-like NiCo2O4 in the aspect of energy-saving hydrogen generation with the assistance of small molecule electro-oxidation reaction.