Effectiveness of NiO in replacing Pt in the photochemical generation of hydrogen by (TiO2)1−x(NiO)x/Cd0.8Zn0.2S heterostructures

• A study of hydrogen generation has been carried out with (TiO2)1−x(NiO)x/Cd0.8Zn0.2S by varying NiO mole fraction from 0 to 1.
• Three times higher hydrogen evolution activity than that of equivalent Pt containg heterostructures has been obtained, from (TiO2)0.17(NiO)0.83/Cd0.8Zn0.2S heterostructures.
• Enhancement in the photocatalytic activity of heterostructures was observed with benzyl alcohol-acetic acid sacrificial agents.
• It seems likely that p–n junctions between n-TiO2 and p-NiO help in the separation of the photogenerated charge carriers, formed in the Cd0.8Zn0.2S nanoparticles.

Hydrogen evolution activity of semiconductor heterostructures of the type (TiO2)1−x(NiO)x/Cd0.8Zn0.2S has been investigated in detail to examine the role of NiO, used in the place of Pt by making use of nanoparticles and nanotubes of TiO2. Combination of NiO and TiO2 markedly changes the photocatalytic efficiency of the heterostructures. While the H2 evolution activity increases smoothly with NiO mole farction up to x~0.50, it increases further reaching a maximum at x~0.83, yielding 1.6 mmol h−1 g−1 (AQY ~2.9%) with Na2S–Na2SO3 as sacrificial agents, under visible-light irradiation, and 6.84 mmol h−1 g−1 (AQY ~11.7%) and 13.5 mmol h−1 g−1 (AQY ~10%) with benzyl alcohol-acetic acid as sacrificial agents under visible and UV–visible light irradiation respectively. High hydrogen evolution activity to the tune of three times that yielded by equivalent Pt containg heterostructures has been attained, with a NiO mole fraction of 0.83 in the heterostructures.

NiO can replace Pt effectively in semiconductor heterostructures to produce good yield of hydrogen under visible-light irradiation.Figure optionsDownload high-quality image (106 K)Download as PowerPoint slide