Low Zn-doped Co3O4 nanorods for enhanced hydrogen evolution reaction

Transition metal oxides have been identified as the best potential candidates to replace Pt-based HER catalysts. But they are still limited by the high HER overpotential, due to the undesirable adsorption/desorption of surface hydrogen. In this work, Zn with low concentrations were incorporated into the tetrahedral Co2+ sites of Co3O4 by hydrothermal and subsequent annealing treatment. They exhibit excellent HER performance. Particularly, when the Zn content in Co3O4 is 6.3 at%, an overpotential of 79.2 mV at the current density of 10 mA cm(-2) was obtained in alkaline medium, which significantly better than pure Co3O4 catalyst (196.3 mV). Moreover, the current density of the Zn-doped Co3O4 catalyst can maintained 93 % after 10 h and 80 % after 20 h. DFT calculations reveal that the Delta G(H*) of Zn-doped Co3O4 (0.827 eV) is smaller and closer to zero than pure Co3O4 (1.023 eV). This work provides a deep insight into the rational design of low-level metal-doped cobalt oxidebased electrocatalysts.