Bimetallic CuPd nanoparticle-decorated MgAl-LDH/g-C3N4 composites for efficient photocatalytic reduction of aqueous Cr(VI)

Constructing a high-performance photocatalyst is one of the most effective approaches to remove heavy metals from wastewater. Here, we successfully synthesized MgAl-layered double hydroxide/graphitic carbon nitride/ (CuPd/LDH/CN) decorated with CuPd bimetallic nanoparticles for the first time to photocatalytically reduce hexavalent chromium (Cr(VI)) in an aqueous solution. The ternary CuPd/LDH/CN heterojunction exhibited superior photocatalytic reduction of Cr(VI) under visible light compared to those of pure CN, LDH, and the binary composites. The CuPd bimetallic nanoparticles were deposited onto the LDH/CN surfaces, as confirmed by morphological observations. Our results revealed that unique structural features endow CuPd/LDH/CN catalysts with excellent photocatalytic performance, likely attributed to abundant active sites, large specific surface areas, as well as enhanced separation and transfer efficiencies of photo-generated charge carriers. Particularly, the nanocomposite (with LDH and CuPd contents of 15 wt% and 1 wt%) exhibited the highest catalytic efficiency with 98% removal of aqueous Cr(VI) (40 mg/L) within 40 min. Furthermore, no significant change in the degradation activity of the CuPd/LDH/CN nanocomposites was observed through four successive experimental runs. This study provides new insights into the design and construction of high-performance photocatalysts with potential applications in environmental remediation and energy conversion.