Graphitic carbon nitride (g‐C 3 N 4 ), an emerging metal‐free semiconductor, has attracted considerable attention in photocatalytic energy conversion and environmental remediation owing to its notable advantages, including low cost, eco‐friendliness, physicochemical stability, and an appropriate bandgap structure. However, bulk g‐C 3 N 4 made by conventional methods suffers from fast charge recombination, low surface area, poor light absorption, and inefficient mass transport, limiting its practical use. One‐dimensional tubular g‐C 3 N 4 , with its hollow structure, overcomes these issues by shortening charge transport paths, increasing surface area, improving light utilization through internal scattering, and enhancing reactant diffusion. It also exhibits good piezoelectric properties, making it a candidate for advanced photocatalysis. This review covers recent progress in tubular g‐C 3 N 4 photocatalysts, focusing on their structure, properties, synthesis methods (e.g., supramolecular calcination, nanosheet curling, molten salt–mediated methods), and characterization techniques. In addition, representative modification strategies such as heterojunction construction, elemental doping, defect engineering, and the photo‐piezoelectric synergy effect are discussed, along with their applications in water splitting, pollutant degradation, CO 2 reduction, H 2 O 2 synthesis, and plastic photoreforming. The review concludes by analyzing current challenges related to precise structural control, mechanistic understanding, and scalable production. Future research directions are also proposed to guide the rational design of high‐performance tubular g‐C 3 N 4 –based photocatalytic systems.
Xue et al. (Sun,) studied this question.