Novel P-n Li2SnO3/g-C3N4 Heterojunction With Enhanced Visible Light Photocatalytic Efficiency Toward Rhodamine B Degradation

Abstract

The design of highly efficient and stable photocatalysts to utilize solar energy is a significant challenge in photocatalysis. In this work, a series of novel p-n heterojunction photocatalysts, Li₂SnO₃/g-C₃N₄, was successfully prepared via a facile calcining method, and exhibited superior photocatalytic activity toward the photodegradation of Rhodamine B solution under visible light irradiation as compared with pure Li₂SnO₃ and g-C₃N₄. The maximum kinetic rate constant of photocatalytic degradation of Rhodamine B within 60 min was 0.0302 min^-1, and the composites still retained excellent performance after four successive recycles. Chemical reactive species trapping experiments and electron paramagnetic resonance demonstrated that hydroxyl radicals (·OH) and superoxide ions ( $·{\text{O}}_2^{-}$ ) were the dominant active species in the photocatalytic oxidation of Rhodamine B solution, while holes (h⁺) only played a minor role. We demonstrated that the enhancement of the photocatalytic activity could be assigned to the formation of a p-n junction photocatalytic system, which benefitted the efficient separation of photogenerated carriers. This study provides a visible light-responsive heterojunction photocatalyst with potential applications in environmental remediation.

Keywords: Li2SnO3; Photoelectrochemistry; Rhodamine B; g-C3N4; p-n heterojunction; photocatalysis.