Recent progress in crystalline carbon nitride-based photocatalysts for energy conversion and environmental remediation

Abstract

Polymeric carbon nitride (CN) has attracted extensive interest in the field of photocatalysis due to its excellent physical and chemical properties. However, the pristine CN synthesized by traditional thermal polymerization process suffers from low crystallinity and incomplete polymerization owing to the kinetic hindrance of high temperature solid-state reaction. Very recently, significant progress has been achieved to improve the crystallinity of pristine CN. In this review, we firstly introduce the outstanding advantages of crystalline CN in comparison with pristine CN. Then synthetic methods of crystalline CN are summarized, including direct molten salt synthesis, precursors-preheated molten salt synthesis, solid salt synthesis, solvothermal synthesis, microwave-assisted synthesis, and other synthetic methods. Subsequently, a variety of modification strategies to further enhance the photocatalytic performance of crystalline CN are discussed in detail, such as morphology modulation, bandgap engineering, junction construction, defect control and single atom modification. In addition, the application of crystalline CN in energy conversion and environmental remediation is described. Finally, current challenges related to the crystalline CN-based photocatalysts are proposed, which should be further studied and solved in this research field. We believe that this review can provide deep insights for design and synthesis of crystalline CN-based photocatalysts for energy conversion and environmental remediation.