A TiO2/Si carrier derived from photovoltaic solid waste to assemble Ag3PO4/Co3(PO4)2/TiO2/Si heterostructure for enhancing visible-light photocatalytic activity

Abstract

The rapid development of the photovoltaic solar industry has generated a huge amount of retired waste silicon panels. The management and value-added recycling of silicon wafer waste are highly important for both environmental remediation and economic efficiency. In this work, waste solar silicon wafers were ball-milled to obtain silicon powder that was employed to prepare TiO2/Si by hydrothermal synthesis, which then was converted to support Ag3PO4 and Co3(PO4)2 with a co-precipitation method to yield Ag3PO4/Co3(PO4)2/TiO2/Si (APO/CPO/TIO/Si) composite catalyst. The photocatalytic properties of the materials doped with different concentrations of APO or CPO were examined using methyl orange (MO) degradation rate as a performance metric. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectrometer (DRS), and ultraviolet-visible spectrophotometer (UV–vis) were used to characterize and analyze the morphology, grain size, material phase, and photocatalytic performance of the samples, respectively. Furthermore, the mechanism derived for the APO/CPO/TIO/Si catalyst in the photocatalytic degradation revealed that superoxide radical (•O2-), singlet oxygen (1O2), and hydroxyl radical (•OH) are the major active substances during the photocatalytic process, the enhanced photocatalytic activity contributing to a heterojunction electron transfer pathway. This work provides a promising approach for waste solar panels management as well as a high-performance photocatalyst for environmental decontamination.