The strong interfacial coupling effect of Nafion between LaFeO ₃ /electrolyte for efficient photoelectrochemical water reduction

Abstract Insufficient reduction capability and scanty active substance limit the application of LaFeO ₃ (LFO) in the field of photoelectrochemical (PEC) water splitting. This work demonstrates a judicious combination of LFO/Nafion composite to improve the PEC performance by a unique dip-coating method on the FTO. The photocurrent density of the LFO electrode coated with two layers Nafion increased to −23.9 μ A cm ⁻² at 0.47 V versus RHE, which is 4.1 times that of the pristine LFO. Based on the experimental data and theoretical analysis, the improvement of the PEC properties is attributed to the construction of organic/inorganic units, which would enable strong electronic coupling and favor interfacial charge transfer, resulting in a 30 mV downward shift of its flat band potential. Thus, the conduction band gets closer to the proton reduction potential of H ⁺ to H ₂ after decoration with Nafion, resulting in a stronger photogenerated electron reduction ability. Our study provides insights that organic materials modify semiconductor photoelectrodes for accelerating charge kinetics.