Construction of La1−xSrxNiO3/g-C3N4 type-Z heterojunctions with enhanced visible-light photocatalytic degradation of organic pollutants

Abstract

Lanthanum nickelate (LaNiO3), known for its high visible-light absorption, is a promising photocatalyst for water purification. However, the low conduction band position and high photogenerated carrier complexation rate of pure LaNiO3 limit its photocatalytic activity. To address this issue, we investigated the synergistic effects of doping and constructing heterojunctions. A La0.9Sr0.1NiO3 (20%)/g-C3N4 (L2CN8) heterojunction was successfully created. In addition, various characterisation techniques were then employed to analyse the structure–performance relationships of these heterojunction photocatalysts in degrading organic dyes. Results revealed that at a 10% Sr doping level, the oxygen vacancy content was 0.68, which is significantly higher than that of LaNiO3 (0.05). The increased number of oxygen vacancies enhanced the electron capture ability and improved the separation efficiency of photogenerated carriers. Furthermore, the optimised L2CN8 (20 mg) achieved 81.2% and 73.8% removal of methylene blue (50.0 mL, 10 mg L−1) and tetracycline (50.0 mL, 10 mg L−1) under simulated visible-light irradiation (λ > 420 nm). Furthermore, an active species capture experiment confirmed the significant role of superoxide radicals (·O2−) in the degradation process. Based on these experimental findings, we proposed a rational Z-type charge transfer mechanism. This study holds great importance for water pollution control and environmental protection.