自从Fujishima和Honda利用TiO2光阳极和Pt电极成功实现太阳能光电化学分解水之后，光催化被认为是解决环境污染和能源短缺两大问题最有前景的方法之一，因为该技术可以有效的利用太阳能这种地球上最丰富的能源来驱动多种不同的催化反应实现能源生产和环境净化，比如：水分解、CO2还原、有机污染物降解和有机合成等。除了金属氧化物、金属硫化物和金属氮氧化物等多类金属化合物半导体光催化剂，近几年，石墨相氮化碳(g-C3N4)因其原料来源广泛、无毒、稳定以及相对较窄的带隙(2.7 eV)而具备可见光响应等特点，在光催化领域获得了广泛的重视。然而，g-C3N4对太阳光谱中可见光的吸收效率较低且光生电子和空穴复合严重，导致其光催化活性处于较低水平。至今，研究人员已经开发出多种提高g-C3N4光催化活性的方法，如元素掺杂、微纳结构和异质结构设计和助催化剂修饰等。元素掺杂被证明是调节g-C3N4独特电子结构和分子结构的有效方法，可以大幅扩展其光响应范围，并促进光生电荷分离。特别地是，非金属元素掺杂以提高g-C3N4的光催化活性已经得到很好的研究。通常用于掺杂g-C3N4的非金属元素是氧(O)、磷(P)、硫(S)、硼(B)、卤素(F、Cl、Br、I)和其他非金属元素(如碳(C)和氮(N)自掺杂)，因为这些非金属元素有着易于获取的原材料并可以较为简单的引入g-C3N4骨架结构中。在这篇综述文章中，作者首先介绍了g-C3N4的结构和光学性质，接着简要介绍了光催化剂的g-C3N4的改性；然后详细回顾了非金属掺杂改善g-C3N4光催化活性的进展，同时总结了光催化机理以期更好地理解光催化的本质并指导新型g-C3N4光催化剂的开发。最后，对g-C3N4光催化剂的后续研究进行了展望。
Since Fujishima and Honda demonstrated the photoelectrochemical water splitting on TiO2 photoanode and Pt counter electrode, photocatalysis has been considered as one of the most promising technologies for solving both the problems of environmental pollution and energy shortage. This process can effectively use solar energy, the most abundant energy resource on the earth, to drive various catalytic reactions, such as water splitting, CO2 reduction, organic pollutant degradation, and organic synthesis, for energy generation and environmental purification. Except for the various metal-based semiconductors, such as metal oxides, metal sulfides, and metal oxynitrides, developed for photocatalysis, graphitic carbon nitride (g-C3N4) has attracted significant attention in the recent years because of its earth abundancy, non-toxicity, good stability, and relatively narrow band gap (2.7 eV) for visible light response. However, g-C3N4 suffers from insufficient absorption of visible light in the solar spectrum and rapid recombination of photogenerated electrons and holes, thus resulting in low photocatalytic activity. Until now, various strategies have been developed to enhance the photocatalytic activity of g-C3N4, including element doping, nanostructure and heterostructure design, and co-catalyst decoration. Among these methods, element doping has been found to be very effective for adjusting the unique electronic and molecular structures of g-C3N4, which could significantly expand the range of photoresponse under visible light and improve the charge separation. Especially, non-metal doping has been well investigated frequently to improve the photocatalytic activity of g-C3N4. The non-metal dopants commonly used for the doping of g-C3N4 include oxygen (O), phosphorus (P), sulfur (S), boron (B), and halogen (F, Cl, Br, I) and also