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Abstract The artificial photocatalytic synthesis based on graphitic carbon nitride (g-C3N4) for H2O2 production is evolving rapidly. However, the simultaneous production of high-value products at electron and hole sites remains a great challenge. Here, we use transformable potassium iodide to obtain semi-crystalline g-C3N4 integrated with the I-/I3 - redox shuttle mediators for efficient generation of H2O2 and benzaldehyde. The system demonstrates a prominent catalytic efficiency, with a benzaldehyde yield of 0.78 mol g−1 h−1 and an H2O2 yield of 62.52 mmol g−1 h−1. Such a constructed system can achieve an impressive 96.25% catalytic selectivity for 2e- oxygen reduction, surpassing previously reported systems. The mechanism study reveals that the strong crystal electric field from iodized salt enhances photo-generated charge carrier separation. The I-/I3 - redox mediators significantly boost charge migration and continuous electron and proton supply for dual-channel catalytic synthesis. This groundbreaking work in photocatalytic co-production opens neoteric avenues for high-value synthesis.

Abstract Artificial photosynthesis using carbon nitride (g-C3N4) holds a great promise for sustainable and cost-effective H2O2 production, but the high carrier recombination rate impedes its efficiency. To tackle this challenge, we propose an innovative method involving multispecies iodine mediators (I−/I3 −) intercalation through a pre-photo-oxidation process using potassium iodide (suspected deteriorated “KI”) within the g-C3N4 framework. Moreover, we introduce an external electric field by incorporating cationic methyl viologen ions to establish an auxiliary electron transfer channel. Such a unique design drastically improves the separation of photo-generated carriers, achieving an impressive H2O2 production rate of 46.40 mmol g−1 h−1 under visible light irradiation, surpassing the most visible-light H2O2-producing systems. Combining various advanced characterization techniques elucidates the inner photocatalytic mechanism, and the application potential of this photocatalytic system is validated with various simulation scenarios. This work presents a significative strategy for preparing and applying highly efficient g-C3N4-based catalysts in photochemical H2O2 production.

In our quest to leverage the capabilities of the emerging single-atom catalysts (SACs) for wastewater purification, we confronted fundamental challenges related to electron scarcity and instability. Through meticulous theoretical calculations, we identified optimal placements for nitrogen vacancies (Nv) and iron (Fe) single-atom sites, uncovering a dual-site approach that significantly amplified visible-light absorption and charge transfer dynamics. Informed by these computational insights, we cleverly integrated Nv into the catalyst design to boost electron density around iron atoms, yielding a potent and flexible photoactivator for benign peracetic acid. This exceptional catalyst exhibited remarkable stability and effectively degraded various organic contaminants over 20 cycles with self-cleaning properties. Specifically, the Nv sites captured electrons, enabling their swift transfer to adjacent Fe sites under visible light irradiation. This mechanism accelerated the reduction of the formed "peracetic acid-catalyst" intermediate. Theoretical calculations were used to elucidate the synergistic interplay of dual mechanisms, illuminating increased adsorption and activation of reactive molecules. Furthermore, electron reduction pathways on the conduction band were elaborately explored, unveiling the production of reactive species that enhanced photocatalytic processes. A six-flux model and associated parameters were also applied to precisely optimize the photocatalytic process, providing invaluable insights for future photocata- lyst design. Overall, this study offers a molecule-level insight into the rational design of robust SACs in a photo-Fenton-like system, with promising implications for wastewater treatment and other high-value applications. [ABSTRACT FROM AUTHOR]