Property-governed performance of platinum-modified titania photocatalysts

Abstract

Titania is probably the most widely investigated semiconductor photocatalyst because of various advantages, such as high activity, thermal and chemical stability, low price, abundance, and negligible toxicity. However, pristine titania is also characterized by charge carriers’ recombination, and thus lower quantum yields of photocatalytic reactions than theoretical 100%. Moreover, its wide bandgap, despite being recommended for excellent redox properties, means also inactivity under visible part of solar radiation. Accordingly, titania has been surface modified, doped and coupled with various elements/compounds. For example, platinum deposited on the surface of titania has shown to improve both UV activity and the performance under vis. Although the studies on titania modification with platinum started almost half a century ago, and huge number of papers have been published up to now, it is unclear which properties are the most crucial and recommended to obtain highly efficient photocatalyst. In the literature, the opposite findings could be found on the property-governed activities that could result from huge differences in the reaction systems, and also examined photocatalysts. Considering the platinum properties, its content, the size of nanoparticles and the oxidation state, must be examined. Obviously, the characteristics of titania also influence the resultant properties of deposited platinum, and thus the overall photocatalytic performance. Although so many reports on Pt/TiO2 have been published, it is hardly possible to give indispensable advice on the recommended properties. However, it might be concluded that usually fine platinum NPs uniformly deposited on the titania surface result in high photocatalytic activity, and thus in the low optimal content of necessary platinum. Moreover, the aggregation of titania particles might also help in the lowering the necessary platinum amount (even to 0.2 wt%) due to the interparticle electron transfer mechanism between titania particles in one aggregate. In respect of platinum state, it is thought that it is highly substrate-specific case, and thus either positively charged or zero valent platinum is the most recommended. It might be concluded that despite huge number of papers published on platinum-modified titania, there is still a lack of comprehensive study showing the direct correlation between only one property and the resultant photocatalytic activity.

Evaluation of Antifungal Properties of Titania P25

“…20 and 13 times for 0.5Pt-HomoP25 and 2.0Pt-HomoP25, respectively). Moreover, a lower content of platinum shows to be better, which is directly connected with the "shielding" effect, i.e., a decrease in photoabsorption by titania (competing with platinum for photons), as previously reported for optimized conditions of hydrogen evolution on platinized titania [34,43].…”

“…The properties of platinum deposits, estimated from XRD and XPS analyses, are summarized in Figure 2d. Since platinum photodeposition on the titania surface is usually very fast (reaction completion within several minutes), it commonly results in the aggregation of formed platinum nanoparticles (NPs) [34,42,43]. Accordingly, larger content of platinum used for photodeposition causes the formation of its larger NPs.…”

Laser-Treated MXene as an Electrochemical Agent to Boost Properties of Semitransparent Photoelectrode Based on Titania Nanotubes

“…1−3 Among others, titania is undoubtedly the most investigated semiconductor metal oxide, owing to its outstanding photoactivity under UV light. 4,5 In addition, semitransparent materials based on titania can be fabricated simply by anodizing Ti film sputtered onto transparent conducting oxides (TCO). 1,2 Highly ordered titania nanotubes (TNTs) with both tunable tube-to-tube spacing and large surface area available for photoelectrochemical processes can be produced directly on TCO by optimizing the anodization conditions 1 and can provide an ordered platform for further modifications.…”

“…The increasing interest in the fabrication of high-efficiency semitransparent electrodes at low manufacturing cost for practical application in photoelectrochemical and optoelectrochemical devices has initiated fundamental research in the field of semiconductors. − Among others, titania is undoubtedly the most investigated semiconductor metal oxide, owing to its outstanding photoactivity under UV light. , In addition, semitransparent materials based on titania can be fabricated simply by anodizing Ti film sputtered onto transparent conducting oxides (TCO). , Highly ordered titania nanotubes (TNTs) with both tunable tube-to-tube spacing and large surface area available for photoelectrochemical processes can be produced directly on TCO by optimizing the anodization conditions and can provide an ordered platform for further modifications. However, several issues associated with TiO 2 materials still need to be addressed.…”

Semiconductor-metal-semiconductor TiO2@Au/g-C3N4 interfacial heterojunction for high performance Z-scheme photocatalyst

“…Thus, the surface heterojunction may provide a novel technique for building highly effective photocatalysts, which merits further research. For instance, noble metals (Pt, Au, Ag, Cu) that induce plasmons can act as excellent electron mediators when deposited on the surface of semiconductor heterostructures, promoting charge carrier transfer due to its localized surface plasmon resonance (LSPR) ( Lu et al, 2019 ; Wang and Kowalska, 2022 ). The metal-free graphitic carbon nitride (g-C 3 N 4 ) proved to be stable, non-toxic, and easy to prepare 2D material, that can effectively activate molecular oxygen and generate superoxide free radicals for photocatalytic degradation of organic pollutants ( Zhao et al, 2018 ; Yang et al, 2022 ).…”