Low-Cost and High Efficiency Hydrogen Evolution Catalyst Derived from Photovoltaic Solid Waste

Abstract

With the rapid development of the global photovoltaic industry, silicon wafer cutting has become an indispensable process, as silicon solar panels are a crucial component. Diamond wire sawing is widely used in silicon wafer processing due to its significant advantages over the traditional loose abrasive sawing. However, approximately 35% of high purity silicon ingots become diamond wire sawing silicon waste (DSSW), making efficiently reutilization an urgent problem. To enhance the efficiency of DSSW utilization, a simple metal-assisted chemical etching (MACE) method was employed to synthesize composite silicon nanomaterials. These materials improve the light absorption and specific surface area of photocatalysts, leveraging semiconducting properties of silicon to enhance hydrogen evolution efficiency, using DSSW as the raw material. The structure, composition and optical properties of DSSW were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV-vis). Additionally, the morphology of DSSW was characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The objective was to investigate the correlation between preparation conditions, material structure and hydrogen evolution performance. The results demonstrate that a visible light responsived porous/sheet-like Psi/SiNSs/Cu2O (Cu2ONPS/PSi/SiNSs) heterostructure was successfully obtained. This simple one-step preparation process not only increased the composite's specific surface area to 37.9 m2 g−1, a 43% enhancement over DSSW (26.5 m2 g−1), but also triggered the quantum confinement effect and broadening the DSSW bandgap from 1.12 to 1.37 eV. Consequently, the hydrogen evolution rate reached 1,408.3 μmol g−1 during the first hour and an average rate of 2,319.4 μmol g−1 h−1 over six hours, yielding a solar-to-hydrogen (STH) conversion efficiency of 0.76% and an apparent quantum yield (AQY) of 7.5%. Moreover, the concentration of Cu2O also has an important effect on the morphologies and hydrogen evolution performance of the composite. This work establishes a connection between the photovoltaic and hydrogen energy sectors, offering a novel pathway for the high-value utilization of DSSW while providing a high-energy-density hydrogen production strategy.

Keywords: DSSW, MACE, Cu2ONPS/PSi/SiNSs, Photocatalysis, Hydrogen evolution