Insights into interface engineering of g-C3N4/NaNbO3 heterojunction for photoelectrochemical water splitting

Green hydrogen is a very attractive energy source, a widely studied strategy among scientists to produce it is using metal oxide semiconductors as photoanodes for photoelectrochemical water splitting. The main challenge is to produce a photocatalyst that is stable and efficient enough to be commercially viable. In this sense, several different combinations of materials have been studied. Here, we report the preparation of g-C3N4/NaNbO3 coupled to Pt-based species (Pt-g-C3N4/NaNbO3) and its potential application as a photoanode for water photosplitting. NaNbO3 was chosen for its suitable properties, g-C3N4 was used to enhance the visible light activity, and Pt species were added to perform as a co-catalyst avoiding recombination of photogenerated charges. The main innovations are the reduced time and energy-consuming procedure to prepare NaNbO3 and the direct polymerization of the g-C3N4 on the NaNbO3. Results demonstrate the successful synthesis of the Pt-g-C3N4/NaNbO3 heterojunction; however, the resultant system showed low efficiency, probably for forming a layer of g-C3N4 on the top of NaNbO3 and electrically active surface states at the semiconductor/solution interfaces. Besides that, this study contributes valuable insights into the design of photoelectrodes for sustainable hydrogen production, especially due to the detailed research on the formation of the heterojunction.