Intrinsic and extrinsic doping to construct hematite nanorod p-n homojunctions for highly efficient PEC water splitting

•α-Fe2O3 photoanode was doped by O-vacancies and Cu2+ to generate p-n homojunctions.•The p-n homojunctions effectively separated the photogenerated electron-hole pairs.•The photoanode had highly efficient PEC water splitting performance.•Its photocurrent density was higher than most similar photoanodes at 1.6 V vs. RHE.•The new photoanode was made of a low-cost, non-toxic abundant stable hematite.