Utilizing 2D materials to enhance H2 generation efficiency via photocatalytic reforming industrial and solid waste.

Sustainable valorization of industrial and solid wastes by utilizing them as feedstock to generate H2 via the photocatalytic reforming (PR) process holds great promise. It can also be an effective method to treat solid waste that otherwise would require tedious and expensive processes. This approach has the potential to offer energy solutions and form value-added chemicals. In this direction, developing photocatalysts and tuning their properties play an essential role in advancing the H2 generation efficiency. This Review article explores the application of 2D photocatalysts to generate H2 via PR of industrial waste (H2S) and solid waste, such as plastic and biomass. Despite having favorable optoelectronic properties, 2D photocatalysts are not widely employed for the PR process. The latest progress in employing 2D photocatalysts to realize efficient H2 evolution from biomass, plastic, and industrial waste such as H2S is detailed in this Review. A correlation between the properties of 2D photocatalysts with H2 evolution rate is discussed. We also emphasize understanding the mechanism involved in the PR process and the importance of 2D photocatalysts design. Such rational insight aids in further enhancing the H2 generation efficiency by effectively using solid/industrial waste as a feedstock.

Gram-scale synthesis of ZnS/NiO core-shell hierarchical nanostructures and their enhanced H2 production in crude glycerol and sulphide wastewater.

Design and development of the efficient and durable photocatalyst that generates H2 fuel utilizing industrial wastewater under solar light irradiation is a sustainable process. Innumerable photocatalysts have been reported for efficient H2 production, but their large-scale production with the same efficiency of H2 production is a challenging task. In this study, a few gram-scale syntheses of ZnS wrapped with NiO hierarchical core-shell nanostructure via the surfactant-mediated process has been reported. Morphology and crystal structure analysis of ZnS/NiO showed spherical shaped hierarchical core-shell with cubic and face-centered cubic crystal structures. The surface examination confirmed the presence of Zn2+, S2-, Ni2+ and O2- ions in the nanocomposite. The photocurrent and photoluminescence studies of pristine and nanocomposites revealed that core-shell material is non-corrosive with a prolonged life-time of photo-excitons. Parametric studies on photocatalytic H2 generation in lab-scale photoreactor using crude glycerol in water recorded a high rate of H2 generation of 9.3 mmol h-1.g-1 of catalyst under the simulated solar light irradiation. Optimized reaction parameters are extended to a demonstrative photoreactor containing aqueous crude glycerol produced 18.5 mmol h-1 of H2 generation under the natural solar light irradiation. The same nanostructures were further tested with the simulated sulfide wastewater and the optimized catalyst showed H2 production of 350 mL h-1. The experimental results of time-on stream and catalytic stability demonstrated that ZnS/NiO hierarchical core-shell nanostructures can be recyclable and reusable for the continuous photocatalytic H2 generation.