The design of heterojunction with superior performance of light absorption and appropriate conduction band and valence band potentials is a promising approach for the applications in efficient environmental remediation and the solar energy storage. In recent years, many studies have been devoted to the applications of graphitic carbon nitride (g-C3N4)-based heterojunction photoactive nanomaterials under visible light irradiation due to its excellent physical, optical, and electrical properties, which inspired us to compile this review. Although many reviews demonstrated about the syntheses and applications of g-C3N4 composites, a targeted review on the systematic application and photocatalytic mechanisms of g-C3N4-based heterojunction, in which components are in intimate linkage with each other rather than a physical mixture, is still absent. In this review, the applications of g-C3N4-based heterojunction photoactive nanomaterials in environmental remediation and solar energy storage, such as photocatalytic treatment of persistent organic pollutants, heavy-metal-ion redox, oxidative decomposition of pathogens, water splitting for H2 evolution, and CO2 reduction, are systematically discussed. In addition, some emerging applications, such as solar cells and biosensors, are also introduced. Meanwhile, a comprehensive assessment on the basis of first-principles calculations and the thermodynamics and kinetics of surface catalytic reaction for the electronic structure and photocatalytic properties of g-C3N4-based heterojunction are valued by this review. In the end, a brief summary and perspectives in designing practical heterojunction photoactive nanomaterials also showed the bright future of g-C3N4-based heterojunction. Altogether, this review systematically complements the information that previous reviews have frequently ignored and points out the future development trends of g-C3N4-based heterojunction, which expected to provide important references and right directions for the development and practical applications of g-C3N4-based heterojunction photoactive nanomaterials.
Abstract The activation of persulfates to degrade refractory organic pollutants is a hot issue in advanced oxidation right now. Here, it is reported that single‐atom Fe‐incorporated carbon nitride (Fe‐CN‐650) can effectively activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. Through some characterization techniques and DFT calculation, it is proved that Fe single atoms in Fe‐CN‐650 exist mainly in the form of Fe‐N 3 O 1 coordination, and Fe‐N 3 O 1 exhibited better affinity for PMS than the traditional Fe‐N 4 structure. The degradation rate constant of SMX in the Fe‐CN‐650/PMS system reached 0.472 min −1 , and 90.80% of SMX can still be effectively degraded within 10 min after five consecutive recovery cycles. The radical quenching experiment and electrochemical analysis confirm that the pollutants are mainly degraded by two non‐radical pathways through 1 O 2 and Fe(IV)═O induced at the Fe‐N 3 O 1 sites. In addition, the intermediate products of SMX degradation in the Fe‐CN‐650/PMS system show toxicity attenuation or non‐toxicity. This study offers valuable insights into the design of carbon‐based single‐atom catalysts and provides a potential remediation technology for the optimum activation of PMS to disintegrate organic pollutants.
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