Tuning the size and chemisorption of FeP4 by trace Ru doping for hydrazine-assisted hydrogen evolution in seawater at large-current-density

Integrating thermodynamically favorable hydrazine oxidation reactions (HzOR) with seawater electrolysis will avoid chlorine evolution reaction (ClER) and realize decoupled hydrogen evolution. Herein, the self-supporting Ru-doped FeP4 nanosheets (Ru-FeP4/IF) grown on iron foam are successfully constructed as bifunctional electrocatalysts to facilitate H-2 production and HzOR simultaneously. Benefiting from trace Ru doping tuning the size and chemisorption of FeP4, the as-prepared Ru-FeP4/IF requires low potential of 318.0 mV and 335.0 mV to drive 1000 mA cm(-2) for HER and HzOR in alkaline seawater, respectively. Notably, only an ultralow voltage of 0.90 V is required to reach 1000 mA cm(-2) with outstanding long-term stability and 100% Faradaic efficiency when Ru-FeP4/IF is assembled in a two-electrode cell for overall hydrazine splitting (OHzS). Density functional theory (DFT) calculations show that Ru-doped modulates electronic structure to optimize adsorption free energy of H* (delta G(H)*) for HER and decrease dehydrogenation of *N2H4 to *N(2)H(3 )for HzOR on FeP4.

Automated summary

This study successfully constructed Ru-doped FeP4 nanosheets as bifunctional electrocatalysts for simultaneous H2 production and hydrazine oxidation reactions, avoiding chlorine evolution reaction.