Two-dimensional bimetallic coordination polymers as bifunctional evolved electrocatalysts for enhanced oxygen evolution reaction and urea oxidation reaction

Abstract

Two-dimensional coordination polymers (CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible and active metal sites. However, it remains great challenge for CP-based catalysts to be utilized for electrocatalytic oxidation reactions due to their inefficient activities and low catalytic stabilities. Herein, we applied a mixed-metal strategy to fabricate two-dimensional CoxNi1−x-CPs with dual active sites for electrocatalytic water and urea oxidation. By metal ratio regulation in the two-dimensional layer, an optimized Co2/3Ni1/3-CP exhibits a water oxidation performance with an overpotential of 325 mV at a current density of 10 mA cm−2 and a Tafel slope of 86 mV dec−1 in alkaline solution for oxygen evolution reaction. Importantly, a lower potential than that of commercial RuO2 is observed over 20 mA cm−2. Co2/3Ni1/3-CP also displays a potential of 1.381 V at 10 mA cm−2 for urea oxidation reaction and a Tafel slope of 124 mV dec−1. This mixed-metal strategy to maximize synergistic effect of different metal centers may ultimately lead to promising electrocatalysts for small molecule oxidation reaction.