Bio-based Au/g-CN plasmonic nanophotocatalyst for superior degradation of Rhodamine B under visible light illumination

Synthesis of bio-based Au/g-CN plasmonic nanophotocatalyst using A. carambola leaf extract for superior degradation of Rhodamine B under visible light illumination. [Display omitted] •One-pot, single-step, in-situ green synthesis approach for the synthesis of Au/g-CN plasmonic photocatalyst was proposed.•Polyphenolic groups in the leaf extract of A. carambola played important role to decorate AuNPs of average diameter 25±1 nm of g-CN.•Photocatalytic efficiency of 3wt % Au on g-CN was found 99.4% for 10 ppm of RhB aqueous solution and can be reused up to 5 cycles.•Pseudo-first-order kinetic constant for the photocatalytic degradation was calculated to be 0.169 min−1. Residual dyes on the earth’s surface are considered the most endangered and hazardous chemical waste, which severely contaminates the environment. Hence, systematic and strategic protocols should be carried out to degrade these dyes. The utilization of solar energy as the renewable energy carrier and semiconductor photocatalysts as the recyclable and sustainable catalyst for dye degradation is considered a promising method to monitor environmental remediation. Here we report a sustainable photocatalyst using room temperature-assisted green synthesis of hybrid plasmonic Au/g-CN photocatalyst using A. carambola leaf extract as a reducing as well as a stabilizing agent for Au nanoparticles (AuNPs) for degradation of RhB. The biomolecules present in the leaf extract reduce Au+3 to Au0 over the 2D surface of g-CN without using any toxic chemical-reducing agents. The structural, elemental, morphological, and optical properties of prepared nanocomposites are characterized by XRD, FTIR, XPS, TEM, HAADF-STEM, and PL techniques. The AuNPs successfully anchored on the surface of g-CN, having an average diameter of 25±1 nm. The photocatalytic degradation efficiency of 3Au/g-CN was found to be 99.4% for 10 ppm of RhB aqueous solution. The kinetics of the degradation were found to follow a pseudo-first-order reaction with a rate constant of 0.169 min−1. The photo-harvesting ability is enhanced by both the surface plasmon resonance (SPR) effect of Au and the electron-acceptor property of g-CN. Moreover, the 3Au/g-CN plasmonic composite was reusable up to 5 cycles.