N-Doped carbon shelled bimetallic phosphates for efficient electrochemical overall water splitting

Abstract

Metal phosphates are regarded as promising electrocatalysts, while their activity and stability for overall water splitting are not yet fully satisfactory. In order to overcome these limitations, herein we develop a new class of N-doped carbon shelled bimetallic phosphates ((Fe_xCo_y)P₂O₇@N–C) as efficient electrocatalysts for overall water splitting. The shelled bimetallic phosphates can lower the OER overpotential by up to 100 mV compared with their unshelled phosphate counterparts as well as show superior stability up to 80 h at a high current density of 40 mA cm⁻² for alkaline water splitting. Detailed studies reveal that the newly formed metal oxyhydroxide/oxide/hydroxide during electrocatalysis plays key roles in the activity enhancement. In addition, the N-doped carbon shell can largely prevent serious corrosion/aggregation with the surface environment being largely maintained, showing a unique strategy for designing non-precious electrocatalysts with largely improved activity and stability for overall water splitting and beyond.