复合半导体负载金属材料光催化性能研究

CO₂和烃类光催化直接合成烃类氧化物在合成化学、碳资源利用和环境保护等方面均有重大意义。用溶胶-凝胶和浸渍-还原相结合的方法制得M/V₂O₅-TiO₂(M=Pd、Cu、Ni和Ag)光催化剂。利用XRD、TPR、IR、TPD、UV-Vis DRS和光反应器等技术研究了负载金属复合半导体的物相结构、吸附性能、光吸收性能和光催化反应性能。结果表明：金属负载在复合半导体上延迟了TiO₂由锐钛矿向金红石相的转化,增强了V与载体TiO₂的相互作用,使TiO₂光吸收限发生蓝移,对可见光部分的吸收明显增加,拓宽了催化剂的光响应范围;材料吸光性能强弱顺序Pd/V₂O₅-TiO₂ >Cu/V₂O₅-TiO₂ >Ag/V₂O₅-TiO₂>Ni/V₂O₅-TiO₂;材料的吸附性能及反应物的吸附态是反应发生的关键,CO₂在Ag/V₂O₅-TiO₂表面无法形成卧式吸附态,没有目的产物甲基丙烯酸(MAA)生成,光量子效率低;光吸收性能较好的Pd/V₂O₅-TiO₂对CO₂吸附能力过强,卧式吸附态脱附温度高,光催化效率不高;Cu/V₂O₅-TiO₂对CO₂吸附能力适中,CO₂与C₃H₆脱附温度较接近,实现了“光-表面-热”的协同作用,光量子效率最高,达15.1%。

Study on Photocatalytic Performance of Coupled Semiconductor Supported Metal Materials

M/V2O5-TiO2(M=Pd, Cu, Ni and Ag) photo catalysts were prepared by sol-gel and impregnation-reduction methods. The surface structure, adsorption property, photo absorption performance and photo catalytic performance of M/V2O5-TiO2 catalysts were characterized by XRD, TPR, IR, TPD, UV-Vis DRS and photoreactor techniques. The results showed that the supported metallic M(M=Pd, Cu, Ag) on coupled semiconductor V2O5-TiO2 restrained the transformation from anatase TiO2 to rutile TiO2. Blue shifting of photo absorption edge and increasing of the photo absorption capacity to visible light of V2O5-TiO2 semiconductor were observed clearly after the addition of metallic M(M=Pd, Cu, Ag). The photo absorption performance decreases in the order of Pd/V2O5-TiO2, Cu/V2O5-TiO2, Ag/V2O5-TiO2 and Ni/V2O5-TiO2. It can be concluded from analysis results that the adsorption property of the solid materials and adsorption states of CO2 and C3H6 are the key to reaction. CO2 can not form the horizontal adsorption state on Ag/V2O5-TiO2, this results in no target products and low photo quantum efficiency. Pd/V2O5-TiO2 semiconductor with better photo absorption performance absorbs CO2 too strongly, thus increasing the desorption temperature of horizontal adsorption state and lowering its quantum efficiency. The Cu/V2O5-TiO2 with CO2 desorption temperature close to that of C3H6 realizes "photo-surface-thermal" synergistic effects and improves photo quantum efficiency to 15.1%.