Regulating charge separation and hole extraction kinetics: Integrating CoAl-LDH with NiO/α-Fe2O3 p-n junction for boosted PEC water splitting

In the face of fossil energy depletion and the resulting environmental issues, the production of “future energy” hydrogen through photoelectrochemical water splitting offers a highly promising low-carbon solution. Here, a CoAl-LDH/NiO/α-Fe 2 O 3 photoanode was constructed via electrophoretic deposition following hydrothermal treatment and calcination. Under AM 1.5G light irradiation and weakly corrosive neutral electrolyte conditions, the CoAl-LDH/NiO/α-Fe 2 O 3 photoanode exhibited a current density of 2.76 mA cm −2 at 1.23 V (vs. RHE), which was 7.5 times higher than that of α-Fe 2 O 3 (0.37 mA cm −2 ). The oxygen evolution rate of CoAl-LDH/NiO/α-Fe 2 O 3 reached 19.74 μmol h −1 , which was 6.4 times that of α-Fe 2 O 3 . The photoanode demonstrated a high average Faradaic efficiency of 94.7%, and maintained a stable current density of 2.2 mA cm −2 even after long-term operation. The enhanced performance of CoAl-LDH/NiO/α-Fe 2 O 3 stems from the p-n junction built-in electric field between NiO and α-Fe 2 O 3 , which improves charge separation, and the CoAl-LDH hole transport layer, which promotes hole injection, lowers overpotential and accelerates reaction kinetics.