Carbon nanotube directed synthesis of blue TiO2 with oxygen vacancy for sonocatalytic H2 production

Sonocatalytic hydrogen evolution has emerged as a promising field for the collection and utilization of mechanical energy, as well as for generating sustainable energy throughout the day. In this report, a blue TiO2 with oxygen vacancy was ingeniously designed by the incorporation of carbon nanotubes (CNTs) in the building-up process, which exhibited an excellent sonocatalytic hydrogen production performance in the present of CH3OH sacrificial agent. The optimal carbon nanotubes/TiO2 (CNT-TiO2) composite material, namely 5%CNT-TiO2, displays the highest sonocatalytic performance than that of nude TiO2 and the other CNT-TiO2 samples. Its average hydrogen production rate is 6 mmol g−1 h−1, which is nearly 3 times that of nude TiO2. Moreover, H2O2 production performance also is evaluated over 5%CNT-TiO2 sample, indicating its multi-functional application values. In the CNT-TiO2 system, the main reasons for the increased sonocatalytic performance have been clarified due to the introduction of CNTs and oxygen vacancy, which may alter centrosymmetric structure of TiO2 and be beneficial to the formation of piezoelectric polarization field. Furthermore, a possible mechanism of sonocatalytic H2 production from water over CNT-TiO2 material is proposed. This work opens an additional channel to design the efficient piezoelectric material for hydrogen production from water splitting.