Effect of Porphyrin Molecular Structure on Water Splitting Activity of a KTaO3 Photocatalyst

Abstract

Photocatalytic water splitting is one of the ideal methods for solving the global energy crisis and its associated environmental problems. In this study, the effect of altering the molecular structure of porphyrins was investigated to improve the water splitting activity of Zr-doped KTaO 3 (KTa(Zr)O 3 ) modified with porphyrin dyes. UV-vis spectra indicated that porphyrins with long alkoxy chains tended to form well-developed H-aggregates on the KTa(Zr)O 3 surface. The photocatalytic activity of Pt-loaded KTa(Zr)O 3 was improved by using porphyrins with longer alkoxy chains because of the improvement in the charge migration between porphyrin dye molecules. While the charge transfer between the inorganic semiconductor and porphyrin dye interface is important, it was found that the formation of H-aggregation was more effective in improving the water splitting activity of the porphyrin-modified photocatalysts.

Recent Progress on Titanium Dioxide Nanomaterials for Photocatalytic Applications

“…Thus,a ll the photocatalystst hat satisfy the abovementioned requirements are capable of reducing hydrogen or oxidizing water.T iO 2 , [311] SrTiO 3 , [312] KTaO 3 , [313,314] and CdS [315,316] are the most used candidates for water splitting 3) Mechanism of an alcohol reforming:p hotocatalytic reforming of organic compounds such as alcohols is another method of hydrogen production.T hese reactions generally consist of several successive steps leading to the formation of CO 2 and H 2 .V arious alcohols have been used in this type of photocatalytic reforming reactions uch as methanol and ethanol. [317,318] Theh ydrogen produced by photocatalysis is not pure.…”

Dye-sensitized photocatalyst for effective water splitting catalyst

“…Modification of the organic molecule showed a positive effect on the water-splitting activity. Hagiwara et al [ 152 ] estimated the aggregation structure of porphyrins on photocatalysts. The parent Cr-porphyrin-treated KTa(Zr)O 3 showed characteristic absorption spectra around 613–531 nm for Q bands; however, the alkylated Cr-porphyrin-treated catalysts showed red-shifted and broad peaks around 644–532 nm.…”

In-Situ Growth of Au on KTaO3 Sub-Micron Cubes via Wet Chemical Approach for Enhanced Photodegradation of p-Nitrophenol

“…Potassium tantalates and their derivatives are wide-band gap semiconductors that are extensively applied in many fields, including gas phase condensation, photo-transporting, photo-detector, air-treatment, photo-conducting and photo-electronic response [1,2,3,4,5,6]. Furthermore, potassium tantalates are considered one kind of the most stable photoelectric catalysts and are widely employed in photonically-driven CO 2 reduction [7,8], water splitting and hydrogen evolution [7,8,9,10]. While potassium tantalates exhibit excellent stability in photocatalysis, their absorption locates at Ultra-violet (UV) range and limits the employment of visible light.…”

“…In order to make use of solar energy with higher efficiency, various methods are explored to modify potassium tantalates, such as cations doping [11,12] and construction of hetero-structure [13,14]. For instance, porphyrin was used as mixing dyes to sensitize potassium tantalates for photo-splitting water to H 2 or O 2 [8]. Design and construction of hetero-structure is a facile method to enhance the light absorption and facilitate the charge separation [9,15,16,17].…”