Multi-hierarchical cobalt-based electrocatalyst towards high rate H2 production

Herein, a rational design of “cobalt/cobalt oxide/cobalt molybdate/nickel foam” multi-hierarchical tandem type electrocatalyst was achieved, where in situ reduced Co and CoO nanoparticles were dispersed uniformly and stabilized by CoMoO3 cuboids. This novel tandem type structure enables strong hydroxyl adsorption on CoO and moderated hydrogen adsorption on Co and therefore promotes the dissociation of water and the recombination of hydrogen intermediates into molecular hydrogen, respectively, and both act synergistically to catalyze the HER reaction. As a result, the current densities were up to 1.3 A cm−2 at only 173 mV overpotential in 1.0 M KOH and 379 mV in 1.0 M PBS solution, respectively. The high rate H2 production of 4.35 ml min−1 at − 1.18 V (vs. SCE) and the outstanding performance of 10 A lasting for more than 800 h in a MEA electrolyzer both indicate the prospect for the usage in practical. [Display omitted] •The special multi-hierarchical tandem type electrocatalyst Co/CoO/CoMoO3 was designed.•Co/CoO/CoMoO3 exhibited low overpotentials to reach 1.3 A cm−2 in alkaline and neutral media, with excellent long-term stability of 400 h.•DFT calculation and methanol probe demonstrate that the CoO is more qualified to adsorb OH* while Co to adsorb H* to promote the water dissociation and hydrogen generation.