Bimetallic electrocatalysts based on polyoxometalate for hydrogen evolution and urea oxidation reaction

Abstract

Electrochemical water decomposition is an efficient and environmentally friendly method for producing hydrogen. Because of the high voltage required for water electrolysis, using anodic urea oxidation process (UOR) to replace the oxygen evolution reaction can significantly cut energy usage. In this paper, hydrogen evolution reaction (HER) and urea oxidation process (UOR) electrocatalysts were synthesized by one-step carbonization using giant polyoxomolybdate cluster Mo132 and triethylamine at different temperatures. Ni/MoN@NC obtained at 800 °C shows good HER effect in the acidic electrolyte, an overpotential of 94 mV can provide the current density of 10 mA cm−2. Ni/NiO@NC obtained by calcination at 400 °C exhibits good UOR performance, in which the potential is 1.41 V when the current density is 10 mA cm−2. Efficient HER performance depends on the synergy of Ni and MoN. The highly efficient UOR is derived from the hierarchical structure of Ni and NiO. Furthermore, the porous structure also enhances the full contact between electrolyte and active sites, the catalytic performance of the catalyst was improved benefit to improve the catalytic activity. This work affords a general approach to simply synthesize efficient hydrogen producing materials for HER and small molecules oxidation fields.