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-C 3 N 4 ) for the piezo-photocatalytic generation of fine chemicals, such as hydrogen peroxide (H 2 O 2 ) from oxygen (O 2 ) and water (H 2 O), is of current interest due to its flexibility in molecular structures to boost catalytic properties. However, due to its intrinsic nature, bulk g-C 3 N 4 suffers from low catalytic outcomes. To enhance catalytic performances, we, in this research, engineered g-C 3 N 4 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 (V C ) to form N-V C @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 H 2 O 2 . 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.