[en] Defect engineering is a powerful strategy to activate wide-bandgap semiconductors, yet controlling the formation of specific vacancies remains challenging. Here, we introduce a general, solvent-directed approach to engineer defects, demonstrated with ZnO. By selecting methanol as the synthesis solvent and performing thermal annealing under nitrogen, the in-situ decomposition of the solvent generates a local reductive environment that selectively creates zinc-vacancy-related surface defect states (V Zn-related). These defects, absent in ethanol-derived ZnO, enable sub-bandgap absorption and improved charge separation, leading to enhanced visible-light photocatalytic activity. While solvent effects on morphology and defect populations have been occasionally noted, leveraging the catalytic decomposition of the solvent itself as a design principle for controlled, vacancy-centered defect formation has not, to our knowledge, been demonstrated. Comprehensive spectroscopic analyses, including steady-state and time-resolved photoluminescence, steady-state and time-resolved electron paramagnetic resonance, and positron annihilation spectroscopy, elucidate the nature, dynamics, and photoactivity of these vacancies. Under visible-light irradiation (λ > 395 nm), methanol-derived ZnO achieves up to a twofold increase in p-nitrophenol degradation compared to untreated samples. This work establishes a simple, dopant-free, and scalable route to defect engineering via solvent selection, offering a broadly applicable strategy for activating wide-bandgap semiconductors under visible light.
Disciplines :
Materials science & engineering Chemical engineering
Author, co-author :
Farcy, Antoine ; Université de Liège - ULiège > Chemical engineering
Mahy, Julien ; Université de Liège - ULiège > Chemical engineering
Cambré, Sofie; Theory and Spectroscopy of Molecules and Materials, Department of Physics, University of Antwerp, Antwerp, Belgium
Schut, Henk; Faculty of Applied Sciences, Department of Radiation Science and Technology, Delft University of Technology, Delft, the Netherlands
Fron, Eduard; Core Facility for Advanced Spectroscopy Leuven, Leuven, Belgium
Hermans, Sophie ; Institute of Condensed Matter and Nanosciences -Molecular Chemistry, Materials and Catalysis (IMCN/MOST), Université Catholique de Louvain (UCLouvain), Louvain-La-Neuve, Belgium
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