Scalable solar-driven reforming of alcohol feedstock to H2 using Ni/Zn3In2S6 photocatalyst

Abstract

Organic photoreforming represents a promising pathway for solar H₂ generation with the coproduction of valuable byproducts. However, its development has been limited by separate studies on photocatalysts or photoreactors, with little focus on cost and scalability. Here we integrate photocatalyst design, upscaled photoreactor engineering, and cost analysis for the solar-driven reforming of alcohol feedstock to H₂. The process was optimized by examining various alcohol compounds and Ni cocatalyst impact on Zn₃In₂S₆ photocatalytic activity. Strong interactions between Zn₃In₂S₆ and both aromatic benzyl alcohol substrate and Ni intensified H₂ evolution and benzaldehyde formation, achieving an apparent quantum yield of 63.8 % at 420 nm and an areal H₂ evolution activity of 278 mmol h⁻¹ m⁻² under simulated sunlight. Using the optimum conditions established in a laboratory environment, an upscaled slurry photoreactor prototype was designed and operated under natural sunlight with a 0.5 m² light receiving area. The upscaled solar-driven reforming of benzyl alcohol over Ni/Zn₃In₂S₆ delivered a H₂ production rate of 1.67 normal L h⁻¹, corresponding to an areal H₂ evolution activity of 139 mmol h⁻¹ m⁻², with benzaldehyde as the major organic byproduct. A pathway for commercially viable large-scale solar-driven organic reforming was defined through techno-economic assessment. The findings are a crucial advancement in scaling photoreforming towards commercialization.