Unassisted Water Splitting with a Mesoporous Hematite Photocatalyst containing Entrapped Nanoparticles for Visible-Light Driven Hydrogen Evolution
Sprache des Titels:
Visible light driven water cleavage into hydrogen and oxygen is the most fundamental energy storing process of both natural and artificial photosynthesis. To date, only a very limited number of photocatalyst materials has been reported to achieve a successful combination of both oxidative and reductive partial reactions of water splitting within two coupled photosystems. Using the well-known mesoporous silica, SBA-15, as template, a solvent free method to generate a large amount of highly porous and dispersed hematite is developed here. The amount of hematite in SBA-15 is varied to study the stability of the porous structure upon incorporation of hematite, and SBA-15 with 20% hematite (S15-H20) produced maximum amount of oxygen, and the photocatalyst was found stable even after multiple runs. In order to achieve a complete water splitting cycle following a Z-scheme type electron flow powered by visible light, CdS nanoparticles are also included into the pores of mesoporous hematite, and the simultaneous generation of hydrogen and oxygen is demonstrated. A plausible mechanism for the observed performance of the photocatalysts in artificial photosynthetic water splitting is proposed, suggesting that the efficient recombination of holes of CdS and electrons of hematite can help to overcome unproductive processes within the coupled semiconductor system.