Boosting Synergy of Polymetal Phosphides by Core‐Shell Design of Prussian Blue Analogue Precursors as Electrocatalysts for Water Splitting

Oxygen and hydrogen evolution reactions (OER and HER) are crucial for electrochemical water splitting, which is however hindered by the high cost of noble metal catalysts. Here, we present that by designing the core‐shell distribution of Prussian blue analogues, NiFe‐P@CoFe‐P nanocubes with various shell‐thickness are obtained to unlock the synergy of metal phosphides. The NiFe‐P@CoFe‐P nanocubes display a low overpotential of 248 mV at 10 mA cm−2 and great stability that outperform commercial RuO2 catalyst towards OER. We find that the OER and HER activity of NiFe‐P@CoFe‐P are dependent on the shell thickness, suggesting both the surface and sublayers determine the catalytic performance. Moreover, we demonstrate the water splitting under alkaline condition in an H‐cell powered by commercial photovoltaics using NiFe‐P@CoFe‐P catalyst, which is a promising approach for the conversion of solar energy. By designing the core‐shell distribution of Prussian blue analogues, boosted catalytic synergy can be unlocked towards OER and HER of NiFe‐P@CoFe‐P, which catalytic activities are dependent on the shell thickness. A photovoltaic water splitting system is further demonstrated to enable conversion of solar energy into hydrogen and oxygen.