Synergistic Effect of the V<sub>2</sub>CT<sub><i>x</i></sub> MXene@V<sub>2</sub>O<sub>5</sub>/TiO<sub>2</sub> NP Composite for Stimulating Photocatalytic CO<sub>2</sub> Reduction through Bireforming of Methanol to Produce CO and CH<sub>4</sub>
Muhammad Tahir
Abstract
Vanadium carbide (V 2 C) MXene, a transition metal, exhibits significant potential as an innovative cocatalyst to enhance photocatalytic efficiency. In this study, we explored the construction of a self-assembled V 2 C@V 2 O 5 /TiO 2 composite through the sol–gel method, incorporating in situ grown vanadium oxide (V 2 O 5 ) with TiO 2 . Efficient charge carrier separation was achieved owing to the higher conductivity, abundant active sites, and higher light absorbance. When V 2 C@V 2 O 5 /TiO 2 was employed with a methanol–water mixture, the resulting CO and CH 4 production reached remarkable amounts of 20 075 and 17 567 μmol g –1 h –1, respectively. This represented a substantial enhancement in photocatalytic efficiency compared to using water/H 2 sacrificial reagents and pure TiO 2 nanoparticles. This enhanced photoactivity in the presence of methanol was attributed to efficient photoinduced carrier separation, facilitated by the synergistic effect of V 2 C/V 2 O 5 and increased proton production. Moreover, the performance of the V 2 C MXene-based composite for CO, CH 4, and H 2 formation was 1.45, 52.75, and 1.35 times higher, respectively, than that achieved with the V 2 AlC MAX-based TiO 2 composite. The advantages of V 2 C conductivity and its two-dimensional layered structure contributed to achieving higher photocatalytic efficiency compared to using the MAX structure. The maximum quantum yield of 9.7, 8.488, and 0.352% for CO, CH 4, and H 2, respectively, was achieved over the V 2 C@V 2 O 5 /TiO 2 composite with continuous photoactivity with consecutive cycles. This study not only demonstrates the promising prospects of V 2 C MXenes but also introduces an innovative approach for designing and fabricating highly efficient and stable photocatalytic systems for CO 2 recycling, with potential applications in various energy-related fields.