Highly efficient photocatalytic H2 production from refined crude glycerol via CuO/TiO2 nanocomposites: Process optimization and role of co-catalysts

Abstract

In this work, highly efficient photocatalytic H<inf>2</inf> production from refined crude glycerol from a biodiesel production plant was achieved using CuO/TiO<inf>2</inf> nanocomposites (xCuO/MT). Both CuO and TiO<inf>2</inf> were separately synthesized via precipitation and microwave-assisted method, respectively, and subsequently combined together by thermal treatment. The results demonstrated that the xCuO/MT with x ≤ 5.0 wt% exhibited higher activity for H<inf>2</inf> than the pristine counterparts, arising from their well-constructed composite structure and generated defects. The addition of Au and Pt as co-catalysts enhanced photocatalytic H<inf>2</inf> production to 0.67 and 1.13 mmol/g, respectively, approximately 1.16 and 1.67 times higher than that of the best-performing CuO/MT nanocomposite (e.g. 0.63CuO/MT). The quantity of H<inf>2</inf> produced from the refined crude glycerol–water mixture was comparable to that from the commercial glycerol-water mixture during short-term operation (e.g., 4 h), while it slightly declined ∼4.8 % during long-term operation (e.g., 12 h), probably due to the impact of contaminants. From the economic perspective, the cost of refined crude glycerol is approximately 21.3 times cheaper than that of commercial glycerol, making it a more economically advantageous feedstock for sustainable H<inf>2</inf> production.