Surface phosphorization coupled polypyrrole modification on CoMoO4 for highly efficient hydrogen evolution

Highly efficient and stable electrocatalysts toward hydrogen evolution reaction (HER) under large current density are essential for alkaline water splitting. Herein, an active and durable CoMoO 4 -based HER electrocatalyst is developed, with a coupling of surface phosphorization and polypyrrole (PPy) modification to accelerate water dissociation and prevent alkaline corrosion during HER process, ensuring great catalyst stability. The prepared PPy-CoMoO 4 /P@NF catalyst achieves perfect HER activity with only 242.1 mV overpotential at the industrial current density of 1000 mA·cm −2 in 1.0 M KOH as well as a low Tafel slope of 39.0 mV dec −1 . Moreover, PPy modification greatly inhibits the alkaline corrosion and the catalyst exhibits stable operation for 100 h at 1000 mA·cm −2 with a conservation rate of 98.5 %. Electrochemical tests and theoretical calculations reveal that the multiple interfaces formed by CoMoO 4 /CoP/PPy significantly reduce the energy barrier of hydrolysis and improve the interfacial adsorption of H ads . Meanwhile, the surface phosphating changes the Gibbs free energy of rate-determining step (RDS) from −0.54 to −0.29 eV, optimizing the energy barriers for hydrogen adsorption-desorption. Remarkably, an electrolyzer with PPy-CoMoO 4 /P @NF as cathode catalyst only needs a cell voltage of 1.92 V at 1000 mA cm −2 for overall water splitting. This study provides an effective way to develop highly efficient and stable HER catalysts toward industrial water splitting.