Heterogeneous strategy constructing a built-in electric field: CoP/FeP bifunctional electrode for overall water splitting

Development of non-noble bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are of great significance under alkaline electrolytes for overall water splitting. In this work, CoP/FeP has been designed and constructed in situ on carbon fiber paper by using the bimetallic metal organic frameworks (MOFs) synthesis strategy. The heterogeneous CoP/FeP displays excellent catalytic activities in both HER and OER of the fully hydrolyzed semi-reaction. Remarkably, CoP/FeP is applied as the bifunctional electrode in anode and cathode to construct an overall water splitting apparatus, resulting in the low cell voltage and excellent stability. The exceptional electrocatalytic performance may be mainly attributed to the heterogeneous interface, which constructs a built-in electric field to provide electron to Co with electron-rich structure, resulting in the strong adsorption of H and weak adsorption of O2 on Co. This study provides an effective and controllable method for the design of self-supporting bimetal phosphide catalysts.