Scalable Photocatalyst Panels for Photoreforming of Plastic, Biomass and Mixed Waste in Flow

Abstract

Solar-driven reforming uses sunlight and a photocatalyst to generate H₂ fuel from waste at ambient temperature and pressure. However, it faces practical scaling challenges such as photocatalyst dispersion and recyclability, competing light absorption by the waste solution, slow reaction rates and low conversion yields. Here, the immobilisation of a noble-metal-free carbon nitride/nickel phosphide (CN_x |Ni₂ P) photocatalyst on textured glass is shown to overcome several of these limitations. The 1 cm² CN_x |Ni₂ P panels photoreform plastic, biomass, food and mixed waste into H₂ and organic molecules with rates comparable to those of photocatalyst slurries. Furthermore, the panels enable facile photocatalyst recycling and novel photoreactor configurations that prevent parasitic light absorption, thereby promoting H₂ production from turbid waste solutions. Scalability is further verified by preparing 25 cm² CN_x |Ni₂ P panels for use in a custom-designed flow reactor to generate up to 21 μmol_H ${}_{{}_2}$ m^-2 h^-1 under "real-world" (seawater, low sunlight) conditions. The application of inexpensive and readily scalable CN_x |Ni₂ P panels to photoreforming of a variety of real waste streams provides a crucial step towards the practical deployment of this technology.

Keywords: immobilisation; photocatalysis; photoreforming; scaling; waste.