Constructing Z-Scheme 0D/2D TiO2 Nanoparticles/Bi2O3 Nanosheet Heterojunctions with Enhanced Visible Light Induced Photocatalytic Antibiotics Degradation and Hydrogen Evolution

Photocatalysis has been regarded as a promising technology for degrading organic pollutants in wastewater and producing hydrogen. In this paper, TiO2 nanoparticles (NPs) were synthesized to improve the visible light absorption of TiO2, which were further combined with Bi2O3 nanosheets to synthesize a series of 0D/2D TiO2 NPs/Bi2O3 nanosheet heterojunctions. The visible light induced photocatalytic activities of the as-synthesized TiO2/Bi2O3 heterojunctions were studied. The optimized catalyst TB-3 with 15 wt% of Bi2O3/TiO2 exhibited the best photocatalytic degradation of tetracycline hydrochloride (TC). The degradation rate constant k of TC over TB-3 was approximately eight times and 39 times greater than that of P25 and Bi2O3, respectively. Additionally, TB-3 showed the highest amount of hydrogen evolution, while that of Bi2O3 was almost zero. The enhancement of photocatalytic performances was ascribed to the improved visible light absorption and the Z-scheme charge transfer path of the TiO2/Bi2O3 heterojunctions, which enhanced the separation efficiency and reduced recombination of photogenerated charge carries, as evidenced by UV-Visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electrochemistry measurements. The active species trapping experiments and the electron spin resonance (ESR) results revealed that center dot O-2(-) was the main active substance in the photocatalytic degradation. The possible degradation pathway and intermediate products of TC have been proposed. This work provides experimental evidence supporting the construction of Z-scheme heterojunctions to achieve excellent visible light induced photocatalytic activity.