Novel trifunctional electrocatalyst of nickel foam supported CoP/NiMoO heterostructures for overall water splitting and urea oxidation.

The process of electrocatalytic water splitting for hydrogen generation is significantly limited by sluggish kinetics of the anodic oxygen evolution reaction (OER). The efficiency of H electrocatalytic generation can be improved by reducing the anode potential or substituting urea oxidation reaction (UOR) for oxygen evolution process. Here, we report a robust catalyst based on CoP/NiMoO heterojunction arrays supported on nickel foam (NF) for water splitting and urea oxidation. In the hydrogen evolution reaction in alkaline media, the optimized catalyst CoP/NiMoO/NF displayed a lower overpotential (169 mV) at a large current density (150 mA cm) compared to 20 wt% Pt/C/NF (295 mV@150 mA cm). In the OER and UOR, the potentials were as low as 1.45 and 1.34 V. These values surpass (for OER), or compare favorably to (for UOR), the most advanced commercial catalyst RuO/NF (at 10 mA cm). This outstanding performance was attributed to the addition of CoP, which has a significant effect on the chemical environment and electron structure of NiMoO, while increasing the number of active sites and promoting charge transfer across the CoP/NiMoO interface. This work proposes a high-performance and cost-effective electrocatalyst for water splitting and urea oxidation.