Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Abstract

Type of publicationArticle (peer-reviewed) AbstractThis progress review describes our work on the design of new TiO2 based photocatalysts. The key concept is the formation of composite structures through the modification of anatase and rutile TiO2 with molecular-sized nanoclusters of metals oxides. Our density functional theory (DFT) level simulations have been compared with experimental work synthesizing and characterizing surface modified TiO2. We use DFT to show that nanoclusters of metal oxides such as TiO2, SnO/SnO2, PbO/PbO2, ZnO and CuO are stable when adsorbed at rutile and anatase surfaces and can lead to a significant red shift in the absorption edge which will induce visible light absorption; this is the first requirement for a useful photocatalyst. We determine the origin of the red shift and the fate of excited electrons and holes. For p-block metal oxides the oxidation state of Sn and Pb can be used to modify the magnitude of the red shift and its mechanism. We describe comparisons of recent experimental studies of surface modified TiO2 that validate our DFT simulations. These nanocluster-modified TiO2 structures 2 form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with a correct choice of nanocluster modified can be applied to other reactions.

One dimensional hierarchical nanostructures composed of CdS nanosheets/nanoparticles and Ag nanowires with promoted photocatalytic performance

“…The smaller semicircle in the EIS Nyquist plot suggests a fast interfacial charge transfer in the semiconductor. 58,59 This result also demonstrates that the 1D Ag@CdS hierarchical nanowires display superior efficiency compared to that of the CdS nanoflower in separating the electron-hole pairs, which is consistent with the results of PL spectroscopy.…”

Same titanium glycolate precursor but different products: successful synthesis of twinned anatase TiO2 nanocrystals with excellent solar photocatalytic hydrogen evolution capability

“…As a matter of fact, in the EIS Nyquist plot, the smaller semicircle size indicates fast interfacial charge transfer in the semiconductor. 47,48 The above result suggests that more effective interfacial charge transfer occurs on the twinned anatase TiO 2 photocatalyst rather than anatase and brookite TiO 2 under these conditions. Based on these results, it was concluded that the enhancement of the photocatalytic hydrogen evolution activity of the twinned anatase TiO 2 nanocrystals was attributed to the faster separation of photogenerated carriers and lower recombination of photoinduced electron-hole pairs.…”

Photocatalytic reduction of CO 2 with H 2 O over graphene oxide-supported oxygen-rich TiO 2 hybrid photocatalyst under visible light irradiation: Process and kinetic studies

“…Despite that, pure unmodified TiO 2 suffers from several drawbacks such as low quantum efficiency resulting from rapid recombination of charge carriers and the limit to UV-light absorption due to its wide band gap [29][30][31][32][33]. Great endeavours have been made to resolve these drawbacks, including cationic metal and anionic doping to manipulate the properties of TiO 2 [34][35][36][37][38][39][40][41][42][43][44]. However, these techniques could result in the generation of secondary impurities and oxygen vacancies, respectively, which could ultimately reduce the photocatalytic activity of TiO 2 [45,46].…”