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

A palladium phosphide electrocatalyst supported on carbon black (PdP 2 @CB) shows efficient water splitting in both alkaline and neutral electrolytes. Significantly lower overpotentials are required for PdP 2 @CB (27.5 mV in 0.5  m H 2 SO 4 ; 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 H 2 SO 4 ; 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 PdP 2 @CB to catalyze OER in 1  m KOH and 1  m PBS electrolytes, which is better OER activity than the benchmark IrO 2 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 PdP 2 @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.