金属镍掺杂g-C_3N_4的制备及其光降解性能

采用浸渍法制备不同掺杂量的负载型光催化剂Ni/g-C_3N_4,并考察其在可见光照下对亚甲基蓝的光降解性能。利用XRD、FT-IR、SEM、TEM、XPS、N2-sorption和ICP-OES等手段表征Ni/g-C_3N_4样品。研究表明,Ni/g-C_3N_4催化剂的光催化活性随着金属镍粒子掺杂量的增加而增大,随着亚甲基蓝浓度的增大而减小,其中金属镍掺杂量4.0wt%的样品4-Ni/g-C_3N_4表现出优异的光催化活性和光降解稳定性。这是由于4-Ni/g-C_3N_4样品的光降解过程中产生了超氧自由基、羟基自由基和空穴等活性物质,其中超氧自由基起主导作用。金属Ni0离子在光生电子作用下生成Ni~(2+),O_2分子得到电子生成O_2~·-自由基。这些活性物质的产生有助于光生电子-空穴对的分离和抑制其复合速率,从而实现可见光下高效催化降解亚甲基蓝。

Synthesis of Metallic Ni-doped g-C3N4 and Its Photodegradation Performance

The supported catalysts Ni/g-C3N4 with different Ni-doped contents were prepared by impregnation route, and performed for the UV-light driven photodegredation performance in methylene blue.The as-obtained Ni/g-C3N4 samples were characterized by several techniques, including XRD, FT-IR, SEM, TEM, XPS, N2-adsorption, and ICP-OES.The results suggest that the photocatalytic activity of Ni/g-C3N4 catalysts increase with the increasing doping content of metallic nickel nanoparticles while decease with the increasing concentration of methylene blue.The 4-Ni/g-C3N4 sample with Ni-doped dosage of 4.0wt% presented the excellent photocatalytic activity and photodegradation stability.It's ascribe to the active species of superoxide radical (O2·-), hole (h+), and hydroxyl radical (·OH) produced by 4-Ni/g-C3N4 sample in photocatalytic degradation system, of which the superoxide radical is the most important material.Metallic Ni0 species and O2 molecules are converted to the active Ni2+ ions and O2·-radicals under photoproduced ions, respectively.These excited species facilitate the separation of photogenerated electron-hole pairs and reduce the electron-hole recombination, leading to the enhanced in phtocatalytic degradation of methylene blue under visible light irradiation.