Homogeneous NiMoO4–Co(OH)2 bifunctional heterostructures for electrocatalytic oxygen evolution and urea oxidation reaction

Abstract

Developing bifunctional electrocatalysts for catalyzing water oxidation and urea oxidation reactions is of vital importance for alleviating the energy crisis and environmental damage, but it is still formidably challenging. Here, the potential of a heterostructure of NiMoO4 nanorods conformally covered by metal-organic framework (MOF) derived Co(OH)2 nanosheets is demonstrated. Under the assistance of a series of advanced characterizations and electrochemical measurements, the rich heterointerfaces in the NiMoO4–Co(OH)2 are found to be beneficial for promoting the electrocatalytic performance. As a bifunctional catalyst for the electrooxidation of water and urea, the optimized NiMoO4–Co(OH)2-100 demonstrates higher catalytic activity, kinetics and durability than individual NiMoO4 and Co(OH)2. Specifically, an overpotential as low as 285 mV can drive 10 mA cm−2 for oxygen evolution reaction (OER), and a voltage of 1.32 V is demanded for achieving 10 mA cm−2 towards urea oxidation reaction (UOR), significantly lower than the benchmarked catalysts. Presented outcomes can greatly contribute to the industrial application of urea-containing wastewater purifying, by offering a deep understanding on the interface engineering of nanocatalysts.