NiFe nanosheets as urea oxidation reaction electrocatalysts for urea removal and energy-saving hydrogen production.

The preparation of high-performance electrocatalysts is a breakthrough to solve the increasingly prominent problems of environmental degradation and energy depletion. Urea oxidation reaction (UOR) plays a vital role in treating urea-rich wastewater and assisting hydrogen production with low energy consumption. To alleviate the sluggish intrinsic reaction kinetic barrier of six-electron transfer involved in UOR, we develop a NiFe ultra-thin two-dimensional nanosheet array supported on nickel foam as UOR electrocatalyst by one-step hydrothermal method. Benefiting from the in-situ synthesis strategy, abundant mesoporous structure, and the electronic structure change of Ni after the introduction of Fe, NiFe nanosheets (NiFe NSs) exhibit remarkable UOR catalytic activity and excellent long-term stability. Moreover, we assemble a two-electrode electrolytic cell with NiFe NSs/NF as the anode. The results show that the cell voltage of urea assisted water electrolysis for hydrogen production decreased by 15.2% rather than the regular water splitting, as well as that the urea concentration in electrolyte is degraded 55.6% after electrolysis for 36 h at 1.70 V. This work indicates a feasibility verification for the electrocatalytic removal of urea in wastewater treatment, and an efficient and energy-saving method for urea-assisted electrolytic hydrogen production based on NiFe nanosheets.