Unraveling Precise Locations of Indium Atoms in g-C3N4 for Ameliorating Hydrogen Peroxide Piezo-Photogeneration

Abstract Increasing active sites in catalysts is of utmost importance for catalytic processes, frequently fascinating global scientists. In recent years, using graphitic carbon nitrides (g-C3N4) for the piezo-photocatalytic generation of fine chemicals, such as hydrogen peroxide (H2O2) from oxygen (O2) and water (H2O), is of current interest due to its flexibility in molecular structures to boost catalytic properties. However, due to its intrinsic nature, bulk g-C3N4 suffers from low catalytic outcomes. To enhance catalytic performances, we, in this research, engineered g-C3N4 by atomically dispersing aluminum (Al) or indium (In) sites to provide catalytic active centers via one-step thermal shock polymerization. The empirical analyses show that In atoms would occupy the near positions of carbon vacancies (VC) to form N-VC@In-O bonds. This replacement would produce the highest formation energy based on the theoretical calculations, improving the stability of atom-dispersive materials. In addition, under catalytic conditions, the formation of oxygenic radicals would strongly be associated with the enhanced formation of H2O2. Unhappily, hydroxyl radicals would induce catalytic deactivation due to the attacks of these highly oxidative radicals on the active centers, thus changing the catalysts' structures and reducing the catalytic outcomes.