Enhanced Visible and Ultraviolet Light-Induced Gas-Phase Photocatalytic Activity of TiO2 Thin Films Modified by Increased Amount of Acetylacetone in Precursor Solution for Spray Pyrolysis

Development of spray pyrolysis-synthesised Bi2O3 thin films for photocatalytic applications

Photocatalysis is a green and cost-effective approach to environmental remediation. While TiO2 is considered one of the benchmark photocatalysts, alternative materials such as Bi2O3 have recently attracted increasing scientific attention as prospective visible light photocatalysts. This study aimed to develop a strategy for Bi2O3 thin film deposition via ultrasonic spray pyrolysis and systematically study process variables for the deposition of β-Bi2O3 thin films for photocatalytic applications. To achieve the aim, the precursor solution concentration as well as deposition and annealing temperature were optimised. The structural, optical, morphological, chemical and wettability properties of the obtained Bi2O3 thin films were investigated with respect to the effect on the photocatalytic oxidation of 10 ppm methyl orange (MO). The highest photocatalytic activity (48% in 5 h) under UV-A was recorded for the β-Bi2O3 film deposited using 0.1 M precursor solution at 300 °C and heat-treated for 1 h in air at 350 °C. Deposition at 300 °C resulted in an amorphous film structure, whereas annealing at 350 °C led to the formation of the β-Bi2O3 phase with the dominant facet orientation (220). These results show the suitability of spray pyrolysis for the deposition of Bi2O3 thin films with promising results for MO dye degradation, expanding the range of suitable photocatalytic materials.

Synthesis Control of Charge Separation at Anatase TiO2 Thin Films Studied by Transient Surface Photovoltage Spectroscopy

For the efficient photocatalytic oxidation of organic pollutants at surfaces of semiconductors, photogenerated holes shall be separated toward the surface and transferred to reactive surface sites, whereas the transfer of photogenerated electrons toward the surface shall be minimized. In this Research Article, the identification of suitable synthesis control of charge separation combined with an in-depth understanding of charge kinetics and trapping passivation mechanisms at the related surfaces can provide tremendous opportunities for boosting the photocatalytic performance. In this work, a comprehensive transient surface photovoltage spectroscopy study of charge separation at anatase TiO₂ thin films, synthesized by ultrasonic spray pyrolysis from titanium(IV) isopropoxide (TTIP)-acetylacetone (AcacH) based precursor is reported. By varying the amount of AcacH in the precursor solution, an experimental approach of synthesis control of the charge transfer toward TiO₂ surface is provided for the first time. An increased amount of AcacH in the precursor promotes transition from preferential fast electron to preferential fast hole transfer toward anatase surface, correlating with a strong increase of the photocatalytic decomposition rate of organic pollutants. Suitable mechanisms of AcacH-induced passivation of electron traps at TiO₂ surfaces are analyzed, providing a new degree of freedom for tailoring the properties of photocatalytic systems.

Transparent TiO2 thin films with high photocatalytic activity for indoor air purification

Enhanced photocatalytic oxidation of indoor VOC mixtures on transparent polycrystalline spray-deposited TiO2 thin films under ultraviolet and visible light.

A post-deposition annealing approach for organic residues control in TiO2 and its impact on Sb2Se3/TiO2 device performance

We report a systematic investigation on the influence of the two-step post-deposition treatments (PDTs) on TiO2 buffer layers deposited by ultrasonic spray pyrolysis (USP) for emerging Sb2Se3 photovoltaics. Air annealing...