Photocatalytic recovery of H2 from H2S containing wastewater: Surface and interface control of photo-excitons in Cu2S@TiO2 core-shell nanostructures

This study focuses on the synthesis of Cu2S particles as the core wrapped-up with thin layer of TiO2 -shell for improved surface and interface control of photo-excitons for H-2 production. Chemical states of metal Cu+, Ti4+ ions were confirmed by X-ray Photo-electron and Electron Paramagnetic Resonance (g-factor of 2.03) Spectroscopy. Transmission Electron Microscopic images revealed the hexagonal shape of Cu2S wrapped-up with TiO2 having the shell thickness varying from 12.0 to 16.7 nm. Time resolved transient photoluminescence decay spectra confirmed that three folds prolonged life-time of excitons generated on Cu2S@TiO2 core-shell than pristine Cu2S. The batch photo-ractor used to evaluate the performance of photocatalysts in an aqueous solution containing Na2S/Na2SO4 promoted oxidation reaction for H+ generation. The control over shell thickness directly influenced the optical and surface-interface properties, resulting in the enhanced H-2 production of 41.6 mmol h(-1) g(-1) of catalyst for an optimized catalyst with UV-vis light to H-2 production efficiency of 10.3%. The same catalyst also exhibited excellent stability for un-interrupted H-2 production upto 30 h, along with good results on recyclability and reusable efficiency. Scale-up operation performed to recover H-2 from sulphide wastewater in tank photo-reactor triggered H-2 gas 16.1 mmol h(-1) g(-1) of catalyst.