Engineering P-Fe2O3-CoP nanosheets for overall freshwater and seawater splitting

Tailoring surface composition and coordinative environment of catalysts in a nano-meter region often influence their chemical performance. It is reported that CoP exhibits a low dissociation ability of H–OH, originating from the poor desorption of intermediate species. Herein, we provide a feasible method to construct P-Fe 2 O 3 -CoP nanosheets through a gas-phase phosphorization process. P doping induces the formation of interfacial structure between Fe 2 O 3 and CoP and the generation of defective structures. The resulting P-Fe 2 O 3 -CoP nanosheets afford high freshwater/seawater oxidation activity (250/270 mV@10 mA/cm 2 ) in 1 mol/L (M) KOH, which is even lower than commercial RuO 2 . Compared with CoP||CoP, P-Fe 2 O 3 ||P-Fe 2 O 3 , and Co 3 O 4 ||Co 3 O 4 , the assembled P-Fe 2 O 3 -CoP||P-Fe 2 O 3 -CoP exhibits the superior water/seawater electrolysis performance with 1.61/1.65 V@10 mA/cm 2 . The synergistic effect of P doping, defective structure, and heterojunction leads to high water oxidation efficiency and water splitting efficiency.