Dual-independent active sites for efficient hydrogen production

Redox bifunctional electrocatalysts play a significant role in driving electrochemical cells, which is hardly achieved by a single active site due to the totally different catalytic reaction mechanism. Herein, we propose dual-independent active sites as a proof-of-concept to design Mo 2 C@C/Co@C bifunctional catalysts for efficient hydrogen production, where carbon coated Mo 2 C nanoparticles (Mo 2 C@C) serve as desirable hydrogen evolution reaction (HER) active sites, while Co encapsulated in carbon layers (Co@C) provides favorable active sites for the hydrazine oxidation reaction (HzOR). During the thermal reorganization, Mo 2 C and Co can be self-assembled from the precursor into dispersed and uniform nanoparticles to construct dual-independent active sites with a tightly contacted hierarchical structure, beneficial for bifunctional properties, with low overpotentials of −83 mV and 71 mV to reach 10 mA cm −2 for the HzOR and HER, respectively. When applied in symmetric OHzS, the electrolyzer requires 0.49 V to achieve 300 mA cm −2 . The Mo 2 C@C/Co@C assembled Zn-Hz battery exhibits excellent durability for 300 cycles with an energy efficiency of 94%. Dual-independent active sites are achieved on Mo 2 C@C/Co@C as a general model to incorporate bifunctional active sites and maximize activities.