In-situ self-sacrificed fabrication of insulator-based SrTiO₃/SrCO₃ heterojunction interface for gaseous HCHO and NO photocatalytic degradation

In this work, novel heterostructured SrTiO ₃/SrCO ₃ (STO/SCO) interface was constructed via the one-pot g-C ₃N ₄(CN) self-sacrificing hydrothermal strategy. The as-developed STO/SCO photocatalyst shows the air cleaning potential in continuous-flow reactors with degradation rates of NO and HCHO at 44 % and 40 %, respectively. From XRD, FTIR, and XPS analysis, CN participates in the crystallise process as the source of CO ₃ ²⁻ to form the STO/SCO interface viewed by TEM and HRTEM. Subsequent temperature-programmed desorption (TPD) analysis and density functional theory (DFT) calculation results revealed the enhanced chemisorption effects of O ₂ on the catalyst surface. The existence of oxygen vacancies combined with the formation of heterojunction surface induces intermediate levels, which leads to the photocatalytic oxidation under simulated solar light. Charge difference distribution simulation coupled with electrochemistry and photoluminescence tests confirmed the internal-built electron fields at the heterojunction interface which would be beneficial for photocarriers separation. Based on the above-mentioned effects, enhanced reactive oxygen species (ROS) ^[rad]OH and ^[rad]O ₂ ⁻ were detected under light irradiation by electron spin resonance (ESR). This work demonstrates the effectiveness of in-situ self-sacrificed strategy for construction of heterojunction interfaces and provides opportunities by utilising insulator-based materials for photocatalytic degradation of air pollutants.