NiO_x改性的层状Fe/K_2La_2Ti_3O_(10)催化剂光解水制氢

Layered Fe/K_2La_2Ti_3O_(10) Photocatalysts Modified with NiO_x for Hydrogen Production

采用溶胶-凝胶及浸渍法制备得到NiOx负载的新型光催化剂NiOx-Fe/K2La2Ti3O10,研究了所制得的新型催化剂的光解水制氢活性,并利用扫描电镜、X射线衍射、紫外-可见漫发射光谱、X光电子能谱等技术对其进行表征和分析.结果表明:制得的催化剂具有层状结构,对可见光有响应,NiOx的负载使催化剂活性得到提高,反应6 h累积产氢量达477.3μmol/g;相比于未负载的催化剂Fe/K2La2Ti3O10,NiOx-Fe/K2La2Ti3O10的光吸收带边蓝移、直接禁带能隙变宽、电子-空穴对的氧化-还原能力增强;化合物中La是主要的电子给体,NiOx的负载提供了更多的反应物吸附活性位,表面的NiO形成自由电子捕获阱,促进H+在催化剂表面的还原,体相中被还原的金属Ni成为光生电子捕获阱,并将光生电子及时向表面转移,减少电子和空穴的复合几率.

A novel kind of photocatalyst, namely NiOx-loading Fe/K2La2Ti3010, was prepared by means of sol-gel method and impregnation method, and the photocatalytic activity of the product for hydrogen generation from water splitting was investigated. Then, the photocatalyst samples were characterized and analyzed by means of SEM, XRD, UV-vis DRS and XPS. The results show that the prepared catalysts with layered structure are sensitive to vi- sible light, and that, after the loading of NiOx, the photocatalytic activity increases to 477.3 ~mol/g （calculated as the hydrogen production after 6 hours of accumulation） , the band-edge absorption value has a blue shift, the direct forbidden gap widens and the redox ability of electron-hole pairs improves. Moreover, as for the photoca-talytic mechanism, lanthanum in the compound serves as the main electron donor, the loading of NiOx provides added active sites for reactant adsorbing, and the NiO groups on the surface produce captures of free electrons, thus pro- moting the reduction of H ＋ on the catalyst surface. With this action, the reduced nickel in bulk produces captures of photo-induced electrons and transfers them to the surface timely, thus decreasing the recombination ratio of elec- trons and holes.