Understanding the synergistic effect of Co-loading and B-doping in g-C3N4 for enhanced photocatalytic activity for overall solar water splitting

An effective approach of loading of metal (Co) and doping of non-metal (B) together has been considered to enhance the photocatalytic activity of tri-s-triazine based g-C3N4. Here, pristine and functionalized g-C3N4 with B-doping at bay C site (BC1–C3N4), corner C site (BC2–C3N4), Co-loading (Co–C3N4) and Co-loading and B-doping together [(Co–B)C1–C3N4 and (Co–B)C2–C3N4] have been studied for structural, electronic, optical and photocatalytic properties using hybrid density functional theory. B-doping in g-C3N4 formed p-type semiconductor while Co-loading revealed formation of n-type semiconductor with formation of Co-3d intermediate states while both together indicated partial charge compensation. All the functionalized films show lower overpotential value for oxygen evolution reaction (OER) as compared to g-C3N4 while for hydrogen evolution reaction (HER) lower overpotential values are obtained for Co–C3N4, (Co–B)C1–C3N4 and (Co–B)C2–C3N4. The present work, highlights the synergistic effects of Co-loading and B-doping in g-C3N4 in terms of formation of impurity states, high absorption, charge redistribution and lower OER and HER overpotential along with suitable redox potentials than g-C3N4 and suggests (Co–B)C1–C3N4 as potential candidate for overall photocatalytic water splitting.