Palladium Phosphide as a Stable and Efficient Electrocatalyst for Overall Water Splitting

Abstract

A palladium phosphide electrocatalyst supported on carbon black (PdP₂ @CB) shows efficient water splitting in both alkaline and neutral electrolytes. Significantly lower overpotentials are required for PdP₂ @CB (27.5 mV in 0.5 m H₂ SO₄ ; 35.4 mV in 1 m KOH; 84.6 mV in 1 m PBS) to achieve a HER electrocatalytic current density of 10 mA cm^-2 compared to commercial Pt/CB (30.1 mV in 0.5 m H₂ SO₄ ; 46.6 mV in 1 m KOH; 122.7 mV in 1 m PBS). Moreover, no loss in HER activity is detectable after 5000 potential sweeps. Only 270 mV and 277 mV overpotentials are required to reach a current density of 10 mA cm^-2 for PdP₂ @CB to catalyze OER in 1 m KOH and 1 m PBS electrolytes, which is better OER activity than the benchmark IrO₂ electrocatalyst (301 mV and 313 mV to drive a current density of 10 mA cm^-2 ). 1.59 V and 1.72 V are needed for PdP₂ @CB to achieve stable water splitting catalytic current density of 10 mA cm^-2 in 1 m PBS and 50 mA cm^-2 in 1 m KOH for 10 h, respectively.