Morphology-interface synergy in MoS2/Si NWs heterostructures derived from silicon wafer debris for photoelectrochemical hydrogen evolution

The rapid growth of the photovoltaic (PV) industry has resulted in massive generation of silicon wafer debris, posing both environmental and resource-utilization challenges. Achieving sustainable and high-value use of this silicon waste for photoelectrochemical hydrogen evolution reaction (PEC-HER) remains highly desirable yet technically challenging. Silicon wafer debris was etched via a metal-assisted chemical etching (MACE) process to obtain silicon nanowires (Si NWs). The morphology of MoS 2 was further tailored through a polyvinylpyrrolidone (PVP)-assisted hydrothermal method, followed by the formation of MoS 2 /Si NWs heterostructures. This sustainable strategy integrates resource recycling with morphology control and heterostructure engineering, enabling uniform MoS 2 coverage, optimized interfacial coupling, and accelerated charge transfer, thereby enhancing the PEC-HER efficiency. The Nano-MoS 2 /Si NWs exhibited a Tafel slope of 167 mV⋅dec −1 , significantly lower than that of pristine Si NWs (524 mV⋅dec −1 ), indicating accelerated hydrogen evolution kinetics. The hydrogen production rate reached 404.77 μmol cm −2 , corresponding to a 196.3% enhancement compared with Si NWs (136.62 μmol cm −2 ). Finite element analysis further revealed markedly enhanced and uniformly distributed current density and surface H + concentration for MoS 2 /Si NWs, attributed to their abundant exposed active edge sites and improved interfacial charge transfer, which collectively contribute to the enhanced PEC-HER performance. This work advances a sustainable upcycling route that converts PV silicon wafer debris into functional photocathodes and offers a general approach to morphology control and heterostructure engineering for efficient, eco-friendly solar-to-hydrogen conversion.