BiVO4 synthesized by the combustion method: a comparison between orange peel powder and urea used as fuel.

Reyes-Vallejo, O., Sánchez-Albores, R., Ashok, A. et al.

Abstract
In this study, BiVO4 particles were synthesized via the combustion method using orange peel powder as a fuel for photocatalytic methylene blue (MB) degradation. The novelty lies in using biomass as a fuel source and leveraging orange peel phytochemicals as stabilizing and complexing agents, eliminating the need for nitric acid required in conventional methods. XRD patterns showed that the orange peel promotes ternary phase formation (Dreyerite and Clinobisvanite phases), while urea supports the binary and ternary phase combination (i.e., V6O13 and BiVO4). Raman, XPS, and FTIR analyses confirmed the BiVO4 monoclinic phase formation using both fuels, with a band gap of approximately 2.4 eV. Increasing annealing temperature reduced structural disorder, V–O bond length, and surface area, which are more pronounced with orange peel. Photocatalytic experiments revealed the significant MB removal by adsorption with urea, while orange peel primarily drove photocatalysis in both cases, following a pseudo-first-order kinetic model. Scavenger experiments showed holes as the main reactive species promoting MB degradation. With a rise in catalyst dosage, removal is primarily enhanced through adsorption, confirmed by dark condition experiments. The BiVO4 sample annealed at 350 ºC with orange peel fuel exhibited the best photocatalytic performance that can completely remove MB after 270 min under 200 W LED light.
https://doi.org/10.1007/s10854-024-13001-9