P–N homojunction and heteroatom active site engineering over Fe2O3 nanorods for highly efficient photoelectrochemical water splitting

Limited charge transfer and slow oxygen evolution (OER) kinetics significantly impede the practical realization of photoanodes for photoelectrochemical (PEC) water splitting. Here, pn-type-Fe 2 O 3 homojunction photoanode catalysts with P active sites are designed by doping phosphorus (P) into outer lattice of n-type Fe 2 O 3 nanorods (pn-P-Fe 2 O 3 ). The optimized pn-P-Fe 2 O 3 photoanode shows the maximum photocurrent density of 2.61 mA/cm 2 at 1.23 V RHE , and the value is 6.4 times greater than that of pristine Fe 2 O 3 . Experimental and theoretical results clearly show that the P–N homogeneous junctions constructed in Fe 2 O 3 through P-doping increase active sites for H 2 O adsorption and activation, reduce OER reaction energy barrier, and promote effective separation of photogenerated electron-hole pairs and water splitting kinetics. This not only makes the photoelectric water decomposition performance outstanding, but also produces excellent durability. This work provides a novel simple and environmentally friendly strategy for designing effective photoanodes for PEC water splitting.