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 <i>p-n</i> 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 ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>·</mml:mo> <mml:msubsup><mml:mrow><mml:mtext>O</mml:mtext></mml:mrow> <mml:mrow><mml:mn>2</mml:mn></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msubsup> </mml:math> ) 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 <i>p-n</i> 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.