Engineering CoN/Ni(OH)2 heterostructures with improved intrinsic interfacial charge transfer toward simultaneous hydrogen generation and urea-rich wastewater purification

Exploring cost-effective and efficient electrocatalysts for simultaneous hydrogen production and environment purification is of great charm. Herein, a bifunctional electrocatalyst is designed by integrating cobalt nitride (CoN) and nickel hydroxide (Ni(OH)2) on nickel foam. The generated CoN/Ni(OH)2 heterostructures are comprised of the CoN (111) and Ni(OH)2 (001) with the 2.8% low lattice mismatch, in which the polar plane of CoN (111) is beneficial for the charge transfer between interfaces, guaranteeing the excellent properties toward both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). For alkaline HER, the optimal electrocatalyst delivers the superior activity with a small overpotential of 40 mV at 10 mA cm−2 and low Tafel slope of 48 mV dec−1. Furthermore, an excellent UOR performance is also achieved (1.39 [email protected] mA cm−2, 64 mV dec−1). Based on the superior HER and UOR electrocatalytic activities, the assembled electrolytic cell by integrating two optimal NF/CNNH electrodes as the anode and cathode can drive the current density of 10 mA cm−2 with the small cell voltage of 1.43 V and possess good stability. Our work may provide a valuable way for designing bifunctional electrocatalysts for both efficient energy-saving hydrogen generation and urea-rich wastewater purification.