石墨氮化碳(g-C3N4)是一种可见光响应的非金属半导体材料。g-C3N4具有廉价易得，物理化学性质稳定，无毒无污染等优点，在环境净化和能源催化领域具有良好的应用前景。然而，体相g-C3N4存在比表面积小，可见光吸收能力差，光生电子和空穴复合效率高等缺点，从而严重限制了其在实际中的应用。本文在概述了g-C3N4的结构、特性及制备方法的基础上，着重归纳了g-C3N4的改性方法，其中包括元素掺杂、形貌调控、贵金属沉积等改性手段的研究进展。最后，本文探讨了g-C3N4光催化反应机理，以及对g-C3N4在水体环境净化领域的研究进行了展望。

Graphite carbon nitride (g-C3N4) is a non-metallic semiconductor material with visible light response. g-C3N4 has the characteristics of low cost and easy availability, stable physical and chemical properties, non-toxic and non-polluting, and has good application prospects in the field of environmental purification and energy catalysis. However, the bulk phase g-C3N4 has such shortcomings as small specific surface area, poor visible light absorption ability, and high recombination efficiency of photogenerated electrons and holes, which severely limit its application in practice. In this paper, based on the introduction of the structure, characteristics and preparation methods of g-C3N4, the modification methods of g-C3N4 are mainly summarized, including the research progress of the modification methods such as element doping, morphology control, precious metal deposition and so on. Finally, the reaction mechanism of g-C3N4 in photocatalytic reaction is discussed, and the research of g-C3N4 photocatalyst in the field of purification of water environment is prospected.