Oxygen- and Ozone-Functionalized Electronic Structure Modulation in C2N Monolayer for Efficient Photocatalytic Water Splitting

Photocatalytic water splitting has emerged as a promising strategy for sustainable hydrogen production using solar energy. In this work, we investigate the photocatalytic performance of the C2N monolayer under O2 and O3 exposure. Upon adsorption on C2N, both molecules form weakly interacting states, resulting in a metallic solution. However, after dissociation into atomic oxygen, the band gap of the oxidised monolayer increases relative to the pristine C2N, indicating a strong hybridisation of the C-O bond. These oxidised configurations exhibit band-edge positions that span the water redox potential, thereby reducing the likelihood of charge recombination and enhancing their separation. Interestingly, the optical absorption spectra show a blue shift relative to the pristine sample and lie in the visible region. These findings highlight the potential of oxygen- and ozone-modified C2N monolayers for applications in photocatalytic water splitting and sustainable hydrogen production.