Controlled synthesis of Sn doped Cu-Ni3S2 on Ni foam as efficient electrocatalyst for urea oxidation reaction and oxygen evolution reaction

Hydrogen production technology by urea-assisted electrocatalytic water decomposition has become one of the important means to alleviate carbon emissions and water pollution. In this paper, we first doped Sn and Cu element into the Ni3S2 material by hydrothermal method on the Ni foam support. This Cu-Sn-Ni3S2 material exhibits superior urea (potential of 1.42 V at 100 mA cm- 2) and water oxidation (potential of 1.63 V at 100 mA cm- 2) properties, which is one of the best electrochemical performance reported up to now. Analysis of experiment demonstrate that the increase in catalytic performance is assigned to faster charge transfer, more exposure of reaction centres and smaller resistance owing to doping of Sn and Cu. Density functional theory (DFT) analysis demonstrates that introduction of Sn and Cu increases the adsorption energy of urea and improves the conductivity of the Cu-Sn-Ni3S2 material, and the co-doping of the two changes the electron state density of the active site, thereby promoting the catalytic performance. This work provides insights into the development of efficient bifunctional electrodes for urea oxidation and oxygen evolution reaction through doping strategies.