Partially exposed RuP 2 surface in hybrid structure endows its bifunctionality for hydrazine oxidation and hydrogen evolution catalysis.

Replacing the sluggish anode reaction in water electrolysis with thermodynamically favorable hydrazine oxidation could achieve energy-efficient H-2 production, while the shortage of bifunctional catalysts limits its scale development. Here, we presented the scalable one-pot synthesis of partially exposed RuP2 nanoparticle-decorated carbon porous microsheets, which can act as the superior bifunctional catalyst outperforming Pt/C for both hydrazine oxidation reaction and hydrogen evolution reaction, where an ultralow working potential of -70 mV and an ultrasmall overpotential of 24 mV for 10 mA cm(-2) can be achieved. The two-electrode electrolyzer can reach 10 mA cm(-2) with a record-low cell voltage of 23 mV and an ultrahigh current density of 522 mA cm(-2) at 1.0 V. The DFT calculations unravel the notability of partial exposure in the hybrid structure, as the exposed Ru atoms are the active sites for hydrazine dehydrogenation, while the C atoms exhibit a more thermoneutral value for H* adsorption.