Green and chemical fuel driven solution combustion synthesis of La2O3 nanoparticles for their photocatalytic and electrochemical studies
摘要
The present work reports the synthesis of lanthanum oxide (La2O3) nanoparticles (NPs) prepared by using citric acid and banana peel powder as chemical and green fuels, labelled LO-C and LO-G, respectively. The nanoparticles (NPs) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR and diffuse reflectance spectra (DRS) to understand the morphology, crystallinity and band gap of La2O3 NPs. According to XRD studies, the NPs are found in a hexagonal crystal structure, with an average crystallite size of 20.78 nm for LO-C and 28.14 nm for LO-G. The morphological studies (SEM and TEM) confirm different morphologies and high crystallinity for the two samples. UV-DRS method was applied to arrive at the band gap values of 5.48 eV and 5.81 eV for LO-C and LO-G NPs, respectively. The synthesized nanoparticles were used as photocatalysts for the degradation of three anionic dyes, namely, Acid Red 88 (AR88), Acid Blue 88 (AB88) and Eriochrome Black-T (EBT). Both LO-C and LO-G achieve near complete degradation of AR 88 in 75 min with rates of 0.014 min−1 and 0.019 min−1, respectively. AB 88 is degraded with an efficiency of 84.5% by LO-C (90 min) and 88.45% by LO-G (90 min). LO-C and LO-G achieve 74.49% and 81.08% degradation of EBT in 120 min. The LO-G catalyst shows excellent stability towards AR 88 degradation with about 7% decrease in efficiency after five photocatalytic cycles. Further, scavenger studies indicate hydroxy radical mediated oxidation of the dye as the major mechanistic pathway involved. In addition, LO-G modified carbon paste electrode exhibited excellent sensing of paracetamol and lithium ions in 0.1 M HCl with a limit of detection of 1 × 10−3 mol L−1. Thus, the synthesized La2O3 nanoparticles can act as efficient photocatalysts and good sensors.