Robust charge carrier engineering via plasmonic effect and conjugated Π-framework on Au loaded ZnCr-LDH/RGO photocatalyst towards H2 and H2O2 production

Abstract

In the present investigation, we examined the water and oxygen reduction ability of ZnCr-layered double hydroxide decorated with Au nanoparticles and reduced graphene oxide, prepared via in situ crystallization and photoreduction method. The fabricated Au@LDH/RGO composite was well characterized by different analytical instruments like PXRD, FTIR, Raman, XPS, EDX, FESEM, and TEM, suggesting strong interaction between the components of the ternary hybrid. Further, the Au@LDH/RGO catalyst shows the best hydrogen evolution reaction (HER), i.e., 918.76 μmol/2 h (no. evolved H₂ gas is 4.9903 × 10¹⁵ cm⁻² s⁻¹) with an ACE of 10.5% and excellent reusability up to 8 h with little change in activity. Additionally, the ternary nanohybrid depicts robust photocatalytic O₂ reduction reaction performance, i.e., 24.3 μmol/2 h of H₂O₂ (SCC = 0.23%), which goes via a superoxide radical mechanism as confirmed through tracing experiments. The observed high photocatalytic activity is attributed to the synergetic effect of both plasmonic Au nanoparticles and conjugated Π-skeleton of RGO, which resulted in high charge carrier density and reduction of the recombination process. This observation is well justified by Mott–Schottky, EIS, PL, and photocurrent measurements. Further, the HER performance was also tested under different hole scavengers to figure out their effect. The SPR effect of Au and conjugated cyclic carbon network of RGO plays a pivotal part in improving the H₂ and H₂O₂ generation ability of LDH under visible light illumination.