2D/2D Heterojunction of Ultrathin MXene/Bi 2 WO 6 Nanosheets for Improved Photocatalytic CO 2 Reduction

Exploring cheap and efficient cocatalysts for enhancing the performance of photocatalysts is a challenge in the energy conversion field. Herein, 2D ultrathin Ti 3 C 2 nanosheets, a kind of MXenes, are prepared by etching Ti 3 AlC 2 with subsequent ultrasonic exfoliation. A novel 2D/2D heterojunction of ultrathin Ti 3 C 2 /Bi 2 WO 6 nanosheets is then successfully prepared by in situ growth of Bi 2 WO 6 ultrathin nanosheets on the surface of these Ti 3 C 2 ultrathin nanosheets. The resultant Ti 3 C 2 /Bi 2 WO 6 hybrids exhibit a short charge transport distance and a large interface contact area, assuring excellent bulk‐to‐surface and interfacial charge transfer abilities. Meanwhile, the improved specific surface area and pore structure endow Ti 3 C 2 /Bi 2 WO 6 hybrids with an enhanced CO 2 adsorption capability. As a result, the 2D/2D heterojunction of ultrathin Ti 3 C 2 /Bi 2 WO 6 nanosheets shows significant improvement on the performance of photocatalytic CO 2 reduction under simulated solar irradiation. The total yield of CH 4 and CH 3 OH obtained on the optimized Ti 3 C 2 /Bi 2 WO 6 hybrid is 4.6 times that obtained on pristine Bi 2 WO 6 ultrathin nanosheets. This work provides a new protocol for constructing 2D/2D photocatalytic systems and demonstrates Ti 3 C 2 as a promising and cheap cocatalyst.