光能驱动CO2还原技术有望减少CO2排放并同时提供高价值化学燃料，缓解能源转型带来的压力。发展高活性光催化剂是实现该技术应用的关键，负载贵金属是提高其光催化效率的有效途径，但由于贵金属成本昂贵、储量稀少等原因，限制了其大规模使用。因此，发展贵金属替代品对光催化CO2还原具有重要意义。Mo 2C是一种具有与贵金属相似的电子结构的过渡金属碳化物，采用尿素还原方式制备了Mo2 C和Cu共负载TiO2光催化剂，结合物理化学性质分析，对其在紫外光下的光催化活性进行评价。结果表明，在TiO2上负载Mo2 C后，在CO2催化转化过程中显著促进H2和CH4的产生，而Mo2 C和Cu共沉淀可抑制H2产生并促进CO2进一步转化为CH4；光照4 h后，其CH4累计产量达76.1 μmol/g，为纯TiO2的5.6倍。Cu沉积可促进CO2吸附并抑制水蒸气吸附，从而减少H2生成。Mo2 C和Cu的共沉积可有效减小TiO2带隙宽度、抑制光生电子与空穴对的复合并促进光生电荷在催化剂表面的分离与转移，从而提高其光催化反应的活性。

Light-driven CO2 reduction technology is expected to reduce CO2 emissions and provides high-value chemical fuels at the same time to alleviate the pressure during energy transition. Among them,the development of highly active photocatalysts is the key to realize the application of this technology. Loading noble metals is an effective way to improve their photocatalytic efficiency. However,the high cost and scarce reserves of noble metals limit their large-scale use. Therefore,the development of precious metal substitutes is great significance for photocatalytic CO2 reduction. Mo2C is a transition metal carbide with an electronic structure similar to that of noble metal. Mo2C and Cu co-loaded TiO2 photocatalysts were prepared by urea reduction. Their photocatalytic activity under UV light was evaluated by combining physical and chemical properties analysis. The results show that after loading Mo2C on TiO2,the production of H2 and CH4 is significantly promoted in the process of CO2 catalytic conversion,while Mo2C and Cu coprecipitation can inhibit the production of H2 and promote the further conversion of CO2 to CH4. After four hours of illumination,its cumulative CH4 production reaches 76.1 μmol/g,which is 5.6 times that of pure TiO2. Cu deposition can promote CO2 adsorption and inhibit water vapor adsorption,thereby reducing H2 generation. The co-deposition of Mo2C and Cu can effectively reduce the bandgap width of TiO2,inhibit the recombination of photo generated electrons and hole pairs,and promote the separation and transfer of photogenerated charges on the catalyst surface,thereby improving its photocatalytic activity.

0 引言

1 试验

   1.1 Mo2C和Mo2C-Cu的制备

   1.2 Mo2C/TiO2和Mo2C-Cu/TiO2的制备

   1.3 光催化剂的表征

   1.4 光催化CO2还原反应系统

2 结果与讨论

   2.1 催化剂的结构与形貌

   2.2 光催化CO2还原性能评价

   2.3 光催化剂的光电化学性质表征

   2.4 光催化剂的能带结构与光催化反应机理

3 结论