硼掺杂SiC的制备、表征及其可见光分解水产氢性能

采用原位碳热还原法制备了硼掺杂的β-SiC (B_xSiC)光催化剂,并考察了其可见光下光催化分解水制氢的性能. 利用X射线衍射仪、X射线光电子能谱、扫描电镜及紫外-可见吸收光谱等测试方法对所制备催化剂的晶型、形貌、表面性质及能带结构进行了表征. 分析结果表明,硼原子掺杂进入SiC 晶格并取代了Si 位点,在价带上方形成了浅受主能级,从而导致了带隙宽变窄. 浅受主能级作为空穴的捕获中心可抑制光生电子和空穴的复合. 因此,与SiC相比,硼掺杂SiC光催化剂在可见光下催化分解水产氢的活性大大提高. 当B/Si 的摩尔比为0.05时,硼掺杂SiC表现出最高的光催化产氢活性.

Synthesis and Characterization of Boron-Doped SiC for Visible Light Driven Hydrogen Production

Boron-doped β-SiC (B_xSiC) photocatalysts were prepared by in-situ carbothermal reduction, and their photocatalytic performances for H₂ evolution under visible light irradiation were investigated. The crystal structure, surface property, morphology, and band gap structure of the B_xSiC photocatalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and ultraviolet-visible absorption spectroscopy. The characterization results indicate that B atoms have doped into the SiC lattice and substituted Si sites, leading to the formation of a shallow acceptor level above the valence band of SiC, resulting in a narrowed band gap energy. The shallow acceptor level acts as a hole trap, preventing the recombination of photo-excited electrons and holes. Therefore, the photocatalytic H₂ evolution activity of B-doped SiC was greatly improved compared with that of SiC. The highest hydrogen evolution rate was obtained when the B/Si molar ratio was 0.05.