Oxygen Vacancies Modified TiO2/O-Terminated Ti3C2 Composites: Unravelling the Dual Effects between Oxygen Vacancy and High-Work-Function Titanium Carbide

Abstract

The rational design of Ti3C2Tx MXene-derived TiO2-based photocatalysts with broad light absorption and efficient charge separation has recently attracted considerable attention for antibiotic degradation. However, the complementary effects of each component, especially oxygen vacancies (OVs) and high work function O-terminated Ti3C2 (O-Ti3C2), in affecting light absorption and photocatalytic activity remain controversial. In this study, Ti3C2Tx-derived TiO2/Ti3C2Tx photocatalysts are regulated by alkalization in the controlled KOH solution and calcination in different heating atmospheres to reveal the contribution of OVs, Ti3+, carbon species, and high work function titanium carbide. Carbon species and rich OVs co-exist in TiO2/O-Ti3C2 (OV/C-TT-1K(N2)) which exhibit superior photocatalytic performance in tetracycline hydrochloride degradation with a kinetic constant of 0.0217 min−1. Combined with experimental and DFT computational results, the broadened visible light response and desirable redox properties are caused by OVs and carbon dopants, as well as decreased Schottky barrier height and enhanced electronic conductivity caused by high work function O-Ti3C2.