ScholarWorks@성균관대학교

초록

The vacancy-engineering approach is showing promise in modulating graphitic carbon nitride (g-C3N4) structures to accelerate catalytic yield. Nonetheless, current studies mainly focus on the catalytic influences of carbon or nitrogen monovacancies in the materials’ structures, resulting in the elusive roles of cluster vacancies, where the co-presence of nitrogen and carbon vacancies can create asymmetric or symmetric structures in the heptazine units of g-C3N4, influencing the total catalytic outcomes under light or/and ultrasound irradiation. In this work, taking the piezo-photocatalytic production of H2O2 from pure water as a model reaction and utilizing positron annihilation techniques, we realize the hiding roles of cluster vacancies in g-C3N4. The results show that asymmetric structures can help overcome adverse charge compensation effects. The disorders will act as trapping states to store excited electrons and avoid charge neutralization processes between photo- and piezo-induced processes. In contrast, the symmetry in a local heptazine unit will enhance the piezocatalytic activity but degrade the piezo-photocatalytic outcomes under light irradiation. Therefore, this study unveils the roles of symmetric and asymmetric structures in response to visible light, UV light, and ultrasound over g-C3N4−based catalysts, which would be necessary for material designs and developments at a molecular level. © 2024 Elsevier B.V.

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