From Event: SPIE Optics + Optoelectronics, 2023
The development of cost-competitive materials capable of producing fuels or electricity directly from the energy harvested from sunlight offers a desirable approach to fulfilling the need for clean, sustainable, and secure energy. Semiconductor metal oxides (e.g., TiO2, Fe2O3, or BiVO4) are abundant, photoactive, stable and cheap; and thus they have been among the most widely adopted materials for the conversion of solar energy into storable and transportable chemical energy such as e.g. hydrogen (H2). However, despite a huge scientific effort, their overall efficiency for solar-driven applications remains rather low due to several crucial limitations such as particularly fast recombination of photo-generated charges (electron-hole pairs) and sluggish kinetics of the redox surface reactions that hinder the practical application in this field. Defect engineering has become an attractive research direction for improving the optical and electronic properties of semiconductor photocatalysts towards boosting their photo(electro)chemical performance. For example, so-called non-stoichiometric black TiO2 has demonstrated unexpectedly enhanced photo(electro)chemical activity, which has been attributed to the co-catalytic effect of unsaturated Ti3+ ion at the titania surface due to the presence of oxygen vacancies (VO). Additionally, these unsaturated defects/sites provide a strong affinity to tightly bond or anchor various species such as transition metals single atoms, or carbon dots that can be used as even more effective co-catalysts. In this contribution, recent advancements regarding defect engineering toward significantly enhanced photocatalytic activity of oxide semiconductors will be summarized.
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Stepan Kment, Alberto Naldoni, and Radek Zboril, "Defect engineering in photoactive semiconductors," Proc. SPIE PC12584, Smart Materials for Opto-Electronic Applications, PC1258407 (Presented at SPIE Optics + Optoelectronics: April 26, 2023; Published: 8 June 2023); https://doi.org/10.1117/12.2665477.6328695121112.