Design of graphitic carbon nitride/metal oxide composite photoelectrocatalysts for energy-related applications

In the present work, graphitic carbon nitride (gCN) was used to develop composite photoelectrocatalysts for the ethanol oxidation reaction (EOR) and the oxygen evolution reaction (OER). Two different synthetic approaches were investigated: i) the first, employing gCN obtained from thiourea and acetylacetone as a support for ZnFe2O4 or ZnO deposited via radio frequency (RF)-sputtering; ii) the second, depositing gCN obtained from urea onto a Fe2O3 matrix, fabricated by plasma enhanced-chemical vapor deposition (PE-CVD). The use of selected precursors to control gCN morphology and its coupling with the target metal oxides were aimed at improving the system photoelectrocatalytic performances towards the desired processes. The developed composites were subjected to a multi-technique characterization, to elucidate the interplay between their chemico-physical properties and the resulting functional performances. The results confirm the favorable effects brought about by gCN/metal oxide combination, with composite samples displaying a significantly lower overpotential for both EOR and OER, while reaching higher current densities in comparison to the corresponding single-phase counterparts. Overall, the present findings pave the way to the implementation of the present systems as environmentally friendly photoelectrocatalysts for sustainable energy production.