Graphene-wrapped Ag₃PO₄/LaCO₃OH heterostructures for water purification under visible light

We demonstrated a unique synthesis approach of graphene (GR)-wrapped Ag₃PO₄/LaCO₃OH (APO/LCO) heterostructures by an in-situ wet chemical method. FESEM analysis reveals the formation of rhombic dodecahedrons of APO decorated with LCO and later wrapped with GR flakes. Optical studies shows two absorption edges corresponding to the band gap energies of APO (2.41 eV) and LCO (4.1 eV). Considering the absorption edge of the heterostructures in the visible region, the photocatalytic activities of photocatalysts containing different APO/LCO mass ratios were evaluated by the degradation of MB. GR-decorated composite with 20% LCO (APO/LCO20/GR) exhibited the highest photocatalytic activity for MB degradation, with a rate constant, k of 0.541 min⁻¹. The photocatalytic activity of APO/LCO20/GR more greatly enhanced than those of the individual constituents (APO, LCO, APO/LCO20). The enhanced photocatalytic activity of the heterostructure can be attributed to the co-catalytic effect of LCO as well as intriguing physicochemical properties of GR. To understand the enhanced photocatalytic activity of the heterostructures the photocatalytic reaction mechanism is proposed in detail. The recyclability of the APO/LCO/GR composite photocatalyst is further evaluated by reusing the catalyst in replicate photocatalytic experiments which shows consistent photocatalytic activity thereby confirms the stability and reusability of heterostructure photocatalyst.