CuO/BiVO4光催化剂的制备及光催化CO2还原性能

基于类十面体钒酸铋(BiVO₄)和氧化铜(CuO)纳米颗粒, 构筑了CuO/BiVO₄异质结光催化剂; 利用X射线衍射仪(XRD)、 X射线光电子能谱仪(XPS)、 扫描电子显微镜(SEM)、 紫外-可见吸收光谱(UV-Vis)、 光电流响应谱(I-t)、 电化学阻抗谱(EIS)和荧光发射光谱(PL)对催化剂的形貌、 结构和光电性能进行了表征和分析. 结果表明, CuO纳米颗粒均匀地负载在BiVO₄的表面, 通过控制铜源的用量可以调节CuO的含量, 其含量对CuO/ BiVO₄异质结的可见光吸收能力和光生载流子的分离效率有很大的影响. 在气固反应体系下, 对CuO/BiVO₄异质结的光催化还原CO₂的性能进行了研究. 结果显示, 光催化还原CO₂的主要产物为CO和CH₄; 随着CuO含量的增加, CO的产率逐渐降低, 而CH₄的产率先增加后降低, 最优化催化剂CuO/BiVO₄的CO和CH₄的产率分别为0.62和1.81 μmol·g^-1·h^-1, 对CH₄的选择性达到最大值(93%). 能带结构分析和电子顺磁共振(EPR)测试结果表明, CuO/BiVO₄中光生电荷的转移符合Z型转移机制. Z型异质结构的形成, 促进了光生电子和空穴的分离, 提升了催化体系的氧化还原能力.

Preparation of CuO/BiVO4 Photocatalyst and Research on Carbon Dioxide Reduction

The CuO/BiVO₄ heterojunction photocatalyst was constructed based on decahedral bismuth vanadate （BiVO₄） and copper oxide（CuO） nanoparticles. The morphology， structure and optoelectronic properties of the catalysts were analyzed by X-ray diffractometer（XRD）， X-ray photoelectron spectroscopy（XPS）， scanning electron microscope（SEM）， ultraviolet-visible absorption spectroscopy（UV-Vis）， photocurrent response spectroscopy（I-t）， electrochemical impedance spectroscopy（EIS） and fluorescence emission spectroscopy（PL）. The results show that CuO nanoparticles are uniformly supported on the surface of BiVO₄， and the content of CuO can be adjusted by controlling the amount of copper source. The content of CuO has a great effect on the visible light absorption capacity and the separation efficiency of photogenerated carriers of the CuO/BiVO₄ heterojunction. The photocatalytic CO₂ reduction performance of CuO/BiVO₄ heterojunction under gas-solid reaction system was investigated. The results showed that the main products of photocatalytic reduction of CO₂ were CO and CH₄. With the increase of CuO content， the yield of CO decreased gradually， while the yield of CH₄ increased first and then decreased. The CO and CH₄ yields of the optimized catalyst CuO/BiVO₄ were 0.62 and 1.81 μmol·g^-1·h^-1， respectively， and the selectivity to CH₄ reached the maximum value（93%）. Band structure analysis and electron paramagnetic resonance（EPR） test results show that the transfer of photogenerated charges in CuO/BiVO₄ conforms to the Z-type transfer mechanism. The formation of the Z-type heterostructure promotes the separation of photogenerated electrons and holes and enhances the redox capacity of the catalytic system.