Construction of rutile/anatase Ohmic heterojunction of TiO2/Ti3C2 with robust built-in electric field for boosting photocatalytic organic pollutant and hydrogen evolution

Abstract

A rutile/anatase Ohmic heterojunction of TiO2/Ti3C2 was prepared through calcination. By adjusting the calcination temperature, the loading amount of TiO2 on Ti3C2 and the ratio of rutile/anatase phases could be controlled. The optimal temperature of 500 °C resulted in a mixture of rutile and anatase with a ratio of 32:68. Under visible light, the TiO2/Ti3C2-500 exhibited significantly superior performance in both TC degradation and hydrogen evolution compared to P25 TiO2. The TC degradation efficiency reached 93.4 ± 1.2 % within 180 min. The optimal hydrogen evolution efficiency was up to 784 ± 6 μmol·g−1·h−1. The presence of oxygen vacancies (OV) on the TiO2 surface provided more active sites, extended the light absorption range, and facilitated the generation of electron-hole pairs. The strong interfacial electric field effectively promoted the separation of space charges between Ti3C2 and TiO2. Additionally, the two-dimensional Ti3C2 nanosheets, as an Ohmic-junction, provided more electron transfer pathways and a large number of active sites for photocatalysis. Furthermore, the formed rutile/anatase heterojunction facilitated strong electron transfer from anatase to rutile and spontaneous electron transfer from rutile to anatase.