中文摘要：

采用尿素热解聚合法合成了g-C_3N_4,并通过NaBH_4还原法制备了银（Ag）负载g-C_3N_4（Ag/g-C_3N_4）催化剂。采用XRD,TEM,UV-vis DRS,PL手段对催化剂进行了表征分析。研究了不同Ag负载量的催化剂在紫外可见光照射下还原CO_2的活性。结果表明：在紫外可见光作用下,摩尔比为1%的1Ag/g-C_3N_4催化剂表现出最佳的催化活性,CO及CH_4产量分别是纯g-C_3N_4的1.6倍和32倍。Ag负载可促进g-C_3N_4表面电子-空穴对的分离,其表面等离子体共振效应（SPR）还可增强电子能量,因此Ag负载显著提高了g-C_3N_4的光催化CO_2还原活性。

英文摘要：

A series of Ag/g-C_3N_4 catalysts were prepared through a NaBH4-reduction method using g-C_3N_4 from pryolysis of urea as precursor.The catalysts were characterized by XRD,TEM,UV-vis DRS and PL analysis.The performance of catalysts with different Ag loadings was studied under ultraviolet visible light irradiation for CO_2 photoreduction.1Ag/g-C_3N_4 catalyst with Ag to g-C_3N_4mole ratio of 1%showed the best catalytic activity.Under ultraviolet visible light irradiation,the yield of CO and CH4 over the 1Ag/g-C_3N_4 catalyst was 1.6 and 32 times higher than over the pure g-C_3N_4.With UV light excitation,the deposited Ag facilitated the separation of electron-hole pairs on the g-C_3N_4 surface.With the presence of visible light,the surface plasmon resonance effect of Ag strengthened electron energy.Therefore,Ag loading significantly improved CO2 photoreduction performance of the g-C_3N_4 under UV-vis irradiation.