Photoelectrochemical water splitting performance of LaFeO3 thin film photocathode prepared by spray gun deposition

•Fabrication of thin film LaFeO3 photocathode via spray gun deposition is proposed.•The high surface roughness results in optical function improvement towards visible light response.•Photocurrent density enhances almost double as surface recombination is suppressed.•Photoelectrochemical performance exhibits a stable operation in strong alkaline media. To date, numerous methods have been employed in fabricating lanthanum iron oxide (LaFeO3) photocathodes. However, producing practical and stable single thin film LaFeO3 photocathodes for photoelectrochemical (PEC) operation remains a challenge as the photocurrent produced is too low. In the present work, LaFeO3 photocathodes were fabricated via spin coating and spray deposition using an inexpensive commercialized disinfectant spray gun. The study discovered that applying the spray gun deposition onto the spin-coated layer resulted in enhanced LaFeO3 micro-structural formation with a high degree of surface roughness. The visible light absorption improved with the energy band gap reduced from (2.45 ± 0.1) eV to (2.42 ± 0.1) eV due to the enhancement of morphological formation. Furthermore, the PEC performance showed a good photocathodic response with the photocurrent density increased from 15.2 μA cm−2 to 27.0 μA cm−2 at 0.6 V (vs. Ag/AgCl), resulting in good charge transfer behavior and stability in the strong alkaline solution. Therefore, the LaFeO3 thin film fabricated in this study could provide valuable information, hence, would be reliable to apply on scalable optoelectronic device production particularly the PEC photocathodes with simple processes and low-cost equipment.