In Situ Etching–Hydrolysis Strategy To Construct an In-Plane ZnIn2S4/In(OH)3 Heterojunction with Enhanced CO2 Photoreduction Performance

The in-plane heterojunctions with atomic-level thickness and chemical-bond-connected tight interfaces possess high carrier separation efficiency and fully exposed surface active sites, thus exhibiting exceptional photocatalytic performance. However, the construction of in-plane heterojunctions remains a significant challenge. Herein, we prepared an in-plane ZnIn2S4/In­(OH)3 heterojunction (ZISOH) by partial conversion of ZnIn2S4 to In­(OH)3 through the addition of H2O2. This in situ oxidation etching–hydrolysis approach enables the ZISOH heterojunction to not only preserve the original nanosheet morphology of ZnIn2S4 but also form an intimate interface. Moreover, generated In­(OH)3 serves as an electron-accepting platform and also promotes the adsorption of CO2. As a result, the heterojunction exhibits a remarkably enhanced performance for photocatalytic CO2 reduction. The production rate and selectivity of CO reach 1760 μmol g–1 h–1 and 78%, respectively, significantly higher than those of ZnIn2S4 (842 μmol g–1 h–1 and 65%). This work puts forward a feasible and facile approach to construct in-plane heterojunctions to enhance the photocatalytic performance of two-dimensional metal sulfides.