Ni/MoC@NC as bifunctional electrocatalyst coupled HER and Urea oxidation for energy-efficient hydrogen production

UOR is seen as very powerful candidate to replace water oxidation reaction. Meantime, UOR also provides a good way to treat wastewater rich in urea. Since anode UOR involves the 6 e− transfer process, inexpensive and high-performance electrocatalysts are required to improve electrochemical efficiency. Polyoxometalate are mostly used as precursor materials for HER researches, but are rarely used for UOR performance. Most of the bound UOR and HER electrocatalysts are Ni-based catalysts and MoXC, respectively. Here, polyoxometalate (PMo12) coupled with transition metal Ni as the precursor was synthesized the bimetallic Ni/MoC@NC electrocatalyst by high-temperature calcination. Ni/MoC@NC exhibits powerful bifunctional catalytic performance. For HER, a current density of 10 mA cm−2 can be driven in 0.5 M H2SO4 and 1.0 M KOH at overpotentials of 111 mV and 143 mV, respectively. As for UOR, 1.384 V is needed to realize a current density of 10 mA cm−2. Furthermore, for urea electrolysis (HER||UOR), 1.372 V can drive the current density of 10 mA cm−2, much less than water electrolysis. The synergistic effect of Ni and MoC nanoparticles and the doping of N endow the bimetallic catalyst excellent HER and UOR performance. Therefore, POMs can be used not only as an excellent precursor for HER catalysts, but also for UOR catalysts, which provides a possibility for the material selection of UOR catalysts and a good catalyst design scheme for high-efficiency and energy-saving hydrogen production.