Fabrication of Reduced Ag Nanoparticle Using Crude Extract of Cinnamon Decorated on ZnO as a Photocatalyst for Hexavalent Chromium Reduction

Abstract

The crude extract of cinnamon (after abbreviated as KM) was used to produce silver nanoparticles (AgKM). This was subsequently utilized for the hydrothermal production of a composite consisting of AgKM decorated on zinc oxide (AgKM/ZnO) as a photocatalyst for reducing hexavalent chromium (Cr(VI)). Several methods e.g., XRD, SEM, TEM, XPS, PL, and RDB-PAS were used to analyze the optical and physicochemical properties of ZnO/AgKM samples in order to better comprehend the impact of the development of the AgKM-ZnO heterojunction in comparison to pure ZnO. In 60 min, the optimized ZnO/AgKM reduced Cr(VI) by more than 98%, with a rate constant 63 times faster than that of pure ZnO. The enhancement of the separation and transportation of photogenerated electron-hole pairs, as proven by a decrease in photoluminescence intensity when compared with ZnO, was attributed to the composite’s higher Cr(VI) reduction rate. Also, the formation of a new electronic level was created when AgKM are loaded on the surface of ZnO in the composites, as shown by the energy-resolved distribution of the electron trap (ERDT) pattern resulting to enhancement of light absorption ability by narrowing the energy band gap. Thus, ZnO/AgKM composite’s photocatalytic efficacy was enhanced by its narrow energy band gap and reduced charge recombination. Therefore, the newly produced ZnO/AgKM composite can be used as a photocatalyst to purify Cr(VI)-containing wastewater.