Study of Rh/TiO2\u2013SiO2 system in photolytic water splitting

Jolanta Wasilewska,Wincenty Skupiński,Michał Chmielarek

doi:10.1007/s11144-020-01924-3

Jolanta Wasilewska, Wincenty Skupiński + Show 1 more

Open Access

https://doi.org/10.1007/s11144-020-01924-3

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Abstract

Titania silicates (TiO2–SiO2) of various compositions were prepared by a sol–gel method. RhCl3 was used in 0.2 wt% of Rh quantity on the gel surfaces, which were subsequently exposed to UV irradiation in water under a 355-W UV lamp. λ > 370 nm. Both Rh [I] and Rh [III] surface complexes were formed, depending on the gels composition. They also exhibited various efficiency in photo water splitting reaction, the photocatalysts possessing as supports titania-silica gels containing 40 and 50 mol % of TiO2, were the most effective. According to our proposal, the rhodium complexes took part in the oxidative addition and reductive elimination cycle, where two water molecules in photo water splitting reaction, yielding hydrogen – H2 and two hydroxyl radicals. The two hydroxyls radicals, catalytically converted to oxygen atom and water, in the second cycle of the investigated water splitting reaction. Titanium octahedra and silicon tetrahedra linked by Ti–O–Si bridges were thought to be the grouping responsible for activity of the investigated catalysts. Their largest amounts are on the gels containing 40–58 mol % TiO2.

Highlights

Titanium dioxide is well known as photocatalyst active in many processes e.g.: the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution, and photoelectrochemical conversion [1,2,3,4] and as materials for photoeletrodes applied in water electrolysis, which is the most effective in solar water splitting processes [5,6,7,8,9]:
While the catalyst Ag, TiO2, decomposed the dye, used in experiment quantity, almost completely, the bare T iO2 support decomposed only half. Such an effect can be reached while silicon atoms are incorporated to the titanium oxide lattice, while titania-silica and TiO2 were applied as photocatalysts in the water splitting reaction
In order to confirm the composition of titania-silica gels obtained after their preparation, ESCA analysis as carried out as regards the quantity of silicon atoms in gel samples

Summary

Introduction

Titanium dioxide is well known as photocatalyst active in many processes e.g.: the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution, and photoelectrochemical conversion [1,2,3,4] and as materials for photoeletrodes applied in water electrolysis, which is the most effective in solar water splitting processes [5,6,7,8,9]:1 3 Vol.:(0123456789)Reaction Kinetics, Mechanisms and Catalysis (2021) 132:1165–1192Its activity in these processes, is enhanced while determined metal or their oxide are deposed on its surface [10,11,12].A very expressive example of T iO2 photocatalysts activation by metals, the systems Ag–TIO2 possessing various amount of silver, may be [13].It was applied to photo-decompose an OOL dye, under visible light.

Results

Conclusion