亚甲基蓝协同Ti3C2增强TiO2光催化还原CO2制CH4

Methylene blue coupled with Ti3C2 MXene for boosting photocatalytic CO2 reduction to CH4 over TiO2

  • 摘要: 二氧化钛(TiO2)光催化还原CO2制CH4在热力学上具备可行性,然而受限于光利用率低、光生载流子易复合及产物选择性差等核心问题,因此开发高性能TiO2基光催化剂是亟待攻克的重要挑战。以Ti3C2 MXene为原料和模板,借助超声作用诱导TiO2纳米粒子原位生长于Ti3C2 MXene表面,同步耦合亚甲基蓝(MB),成功制备了TiO2/Ti3C2/MB(TTM)复合物用于CH4光合成。结果表明,TTM复合物具有二维风琴状结构,MB的引入窄化了能带带隙,提高了CO2吸附容量,促进小尺寸TiO2纳米粒子的形成。优化后的TTM复合物(TTM-0.20)使CH4产率达到54.34 μmol·g−1·h−1,分别是风琴状TiO2和TiO2/Ti3C2复合物的12.9倍和3.1倍,CH4选择性达到96.1%。增强的光催化活性归因于,MB敏化作用增强可见光利用率,紧密的TiO2/Ti3C2肖特基结和多重紧密界面加速光生载流子的分离和转移,以及Ti3C2作为反应位点能有效捕获CO2分子并稳定反应中间体。利用染料敏化和异质结策略,成功构筑TiO2/Ti3C2/MB三元复合物,多组分协同作用实现了高选择性CO2到CH4的光转化,为CO2资源化利用提供了新的思路。

     

    Abstract: Photocatalytic CO2 reduction to CH4 over titanium dioxide (TiO2) is thermodynamically feasible, but it is restricted by core shortcomings such as low light utilization, rapid recombination of photo-generated charge carriers, and poor product selectivity. Therefore, developing high-performance TiO2-based photocatalysis remains a critical challenge. In this work, using Ti3C2 MXene as raw materials and template, the in situ growth of TiO2 nanoparticles on Ti3C2 MXene was synchronously coupled with methylene blue (MB) to successfully fabricate the TiO2/Ti3C2/MB (TTM) composites via one-step ultrasonic method for photocatalytic CH4 generation. The resulting TTM composites display the accordion-like layered structure, and the introduction of MB narrows band gap, boosts CO2 adsorption capacity, and induces the formation of small-sized TiO2 nanoparticles. The optimized TTM sample (TTM-0.20) displays the CH4 yield rate of 54.34 μmol·g−1·h−1, surpassing accordion-like TiO2 and TiO2/Ti3C2 composite by 12.9 and 3.1 folds, and achieves a 96.1% CH4 selectivity. The enhanced photocatalytic performance may be attributed to the improved visible light utilization by the MB photosensitizer, the accelerated separation and transfer of photo-generated charge carriers through the tight Schottky junction and multiple tight interfaces, and effective capture of CO2 molecules along with the stabilization of reaction intermediates at Ti3C2 MXene reactive sites. By employing dye-sensitization and heterojunction strategies, the TiO2/Ti3C2/MB ternary composite was successfully constructed. The synergistic effect of multiple components achieves highly selective photoconversion of CO2 to CH4, providing a new approach for CO2 resource utilization.

     

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