Flexible construction of heteroatom-free g-C3N4/g-C3N4 homojunction with switching charge dynamics toward efficient photo-piezocatalytic performance

Photo-piezocatalysis based on homojunction emerges as an auspicious approach for the environmental crisis, while it is still in early stage with limited strategies and ambiguous reaction mechanisms. Herein, a heteroatom-free homojunction of ultrathin g-C3N4 with N vacancies/pristine g-C3N4 has been innovatively constructed through surface coupling effect. It achieves higher performance on both photo-piezocatalytic RhB degradation and H2O2 production than solely piezocatalysis or photocatalysis. The underlying causes lie in the synergistic effects of the internal electric field constructed in the type II homojunction and the polarized electric field stimulated by the non-centrosymmetric structure, which cooperatively facilitate the driving force of the charge carriers. Notably, due to the unfixed polarization direction, the charge transfer pathways undergo transitions between type-II and Z-scheme mechanisms, which both promote the spatial separation and migration dynamics of electrons and holes. This work provides new insights into structural design and mechanism exploration for highly efficient photo-piezocatalytic applications.