Constructing cerium dioxide and ruthenium-cobalt phosphide Lewis acid-base pairs to boost hydrazine oxidation reaction in alkaline seawater.

Hydrazine-assisted alkaline seawater electrolysis is a promising route to low-energy hydrogen production. However, the hydrazine oxidation reaction (HzOR) is a complex, four-electron transfer process involving multiple reaction intermediates, including in N2H3* and N2H2*. Consequently, overcoming the sluggish kinetics of HzOR remains a significant challenge. This study presents Lewis acid-base pair (LABP) structure, where CeO2 acts as Lewis acid (LA) site for substrate adsorption and electron-rich RuCoP acts as Lewis base (LB) site for adsorption and desorption of intermediates. This synergistic interaction endows catalyst with exceptional HzOR performance: at current density of 100 mA cm-2, overpotentials are -43 mV (alkaline) and 180 mV (alkaline seawater), respectively. In addition, Ru-CeCoP@NF maintained stable operation for more than 100 h in a two-electrode seawater electrolysis system. Advanced in situ spectroscopic measurements, together with d-band center calculations, suggest that strong interfacial electronic coupling promotes intermediate adsorption and accelerates HzOR kinetics. This study provides new insights into designing highly efficient LABP-based electrocatalysts to enhance alkaline HzOR activity.