Distinctive p-d orbital hybridization in RuSb nanobranches for simultaneously enhanced hydrogen evolution and hydrazine oxidation in alkaline seawater

Orbital hybridization is a powerful tool for modulating electronic structures toward various electrocatalytic reactions. Compared to the widely reported d-d hybridization in d-block metal alloys, the p-d orbital hybridization between d-block metals and p-block elements could provide new opportunities for regulating the electronic properties and thus promoting the electrocatalytic activities. Herein, we report a distinctive p-block metalloid-regulating p-d orbital hybridization to realize the fabrication of RuSb nanobranches for bifunctional hydrogen evolution (HER) and hydrazine oxidation (HzOR), which exhibits huge potential in overall hydrazine splitting (OHzS) by utilizing thermodynamically favorable HzOR instead of sluggish oxygen evolution on the anode. To our delight, RuSb delivers an impressively low overpotential of 39 mV for HER and 252 mV for HzOR at 10 mA cm⁻² in alkaline seawater. The two-electrode OHzS electrolyzer with RuSb||RuSb couple can achieve outstanding electrocatalytic activity with an extraordinarily small cell voltage of 35 mV to drive 10 mA cm⁻² in alkaline seawater, outperforming the Pt/C||Pt/C couple under the same condition. Density functional theory calculations further indicate that the Sb doping can not only mediate the adsorption energy for hydrogen but also the energy barrier for the dehydrogenation of *N₂H₃. Therefore, our work verifies the huge potential of p-d orbital hybridization for the development of a bifunctional OHzS system in alkaline seawater.