MXene热处理原位制备碗状TiO₂/C及其光催化CO₂还原性能研究

In situ synthesis of bowl-shaped TiO₂/C from MXene heat treatment for photocatalytic CO₂ reduction

摘要

使用Ti₃C₂ MXene材料原位合成TiO₂半导体光催化剂，通过将CO₂选择性还原为CH₄等有价值的化学物质，为缓解环境和能源挑战提供了一种非常有效的方法.然而，Ti₃C₂转化为TiO₂的过程中通常伴随着严重的颗粒团聚，这导致固有活性位点数量减少，对CO₂的吸附和转化产生不利影响.为了解决这个问题，使用聚甲基丙烯酸甲酯（PMMA）作为硬模板，通过煅烧法制备了碗状碳层负载TiO₂（TiO₂/C）混合光催化剂.结果表明：所得样品具有足够大的比表面积和丰富的CO₂吸附和活化位点.此外，碳层的优异导电性有利于TiO₂产生的光生载流子的分离.所得TiO₂/C复合物的CO₂还原为CO和CH₄的速率分别为1.84 μmol‧g^-1‧h^-1和5.32 μmol‧g^-1‧h^-1，CH₄选择性为74％.该工作展示了利用模板精确控制MXene氧化产物形貌的方法，为MXene在光催化的应用提供了一种切实可行的实践方案.

Abstract

The in situ synthesis of TiO₂ semiconductor photocatalysts using Ti₃C₂ MXene materials offers a highly effective approach to mitigate environmental and energy challenges by selectively reducing CO₂ to valuable chemicals like CH₄. However， the transformation of Ti₃C₂ into TiO₂ is usually accompanied by severe agglomeration of particles， which leads to a reduction in the number of intrinsic active sites， adversely affecting the adsorption and conversion of CO₂. To address this problem， polymethyl methacrylate （PMMA） was employed as a hard template to fabricate a bowl-shaped TiO₂ supported on carbon layer （TiO₂/C） hybrid photocatalyst by a calcination method. The results showed that the obtained sample had a sufficiently large specific surface area and numerous active sites for CO₂ adsorption and activation. The excellent conductivity of the carbon layer facilitated the separation of photogenerated carriers produced by TiO₂， enabling the obtained TiO₂/C complexes exhibit CO₂ reduction rates to CO and CH₄ of 1.84 μmol‧g^-1‧h^-1and 5.32 μmol‧g^-1‧h^-1， respectively， with the CH₄ selectivity of 74%. The precise utilization of templates to refine the morphology of MXene oxidation products was thus demostrated， offering a practical approach for the application of MXene in the photocatalysis.

关键词

光催化 / 二氧化碳还原 / 二氧化钛 / 碳化钛 / 甲烷

Key words

photocatalytic / CO₂ reduction / TiO₂ / Ti₃C₂ MXene / CH₄

基金资助

国家自然科学基金资助项目(21972171)