The study aimed to investigate the photocatalytic performance of nano-porous thick films of gallium oxide spinel, specifically MGa2O4 (M = Co, Fe, Cu, and Zn) oxides, grown on 2D structures. These gallium oxide nano-porous thick films, deposited on substrates such as graphene, were utilized as electrodes in photocatalytic fuel cells, serving as photocathodes. 

The structural parameters of these films were analyzed in relation to their photocatalytic performance, focusing on the electronic energy configuration changes due to the positioning of gallium atoms within the spinel oxide lattice. Rietveld refinements were conducted, considering three potential phase formations, and accounting for the ratios of crystal phases across the lattice. These assumptions encompassed a standard spinel lattice and various partial inverse spinel crystalline phase formations.

Significant alterations in electronic energy configurations were observed, reflected in the trend of band gap values as cations were substituted within the lattice. Consequently, the adjustment of cation atom positions also exerted an influence on the photocatalytic performance of the nanoporous thick films.

Keywords: photocatalytic fuel cell, oxide semiconductor, metal gallate, spinel oxide 

Acknowledgement: This work was supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) with project numbers 118F373 and 123F141.