g-C3N4-based S-scheme heterojunction photocatalysts

With the vigorous progress of industrialization, energy shortage and environmental contamination emerge increasingly serious. Photocatalysis technology is known as a hopeful approach to resolving the above crises owing to its numerous prominent advantages and widespread applications. Among various photocatalysts, graphitic carbon nitride (g-C3N4) has been broadly applied in fields of fuel production and environment purification because of its unique electronic structure, extreme thermal stability, and prominent photoelectrical activity. However, single-component g-C3N4, similar to other photocatalysts, usually suffer from low photocatalytic efficiency due to the fact that single-constituent photocatalysts cannot synchronously equip with strong redox abilities of photogenerated charges and high light energy utilization. Fortunately, constructing Step-scheme (S-scheme) heterojunctions between g-C3N4 with other semiconductor photocatalysts can simultaneously overcome the typical shortcomings of low light energy utilization, rapid recombination, and weak redox abilities of carriers, thus prominently boosting its catalytic reaction rate. In view of the currently extensive reports of g-C3N4-based S-scheme heterojunctions, this review presents a relatively comprehensive comment on the latest research progress of the background, the proposal of conception, fundamental theory, design and preparation, characterization methods of g-C3N4-based S-scheme heterojunctions. Additionally, various applications of g-C3N4-based S-scheme heterojunctions have been detailly illustrated through example discussion and list comparison, involving photocatalytic H2 generation, CO2 reduction, H2O2 evolution, pollutant degradation, and others. Finally, the research progress and shortcomings of g-C3N4-based S-scheme heterojunctions are summarized, and the future research direction is prospected.