Moutsiou Areti, Olivati Andrea, Cipriano Luis A, Sivo Alessandra, Collins Sean M, Ramasse Quentin M, Kwon Ik Seon, Di Liberto Giovanni, Kanso Mohamad, Wojcieszak Robert, Pacchioni Gianfranco, Petrozza Annamaria, Vilé Gianvito
Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
Center for Nanoscience and Technology, Italian Institute of Technology, Via Giovanni Pascoli 70/3, 20133 Milano, Italy.
ACS Catal. 2025 Mar 21;15(7):5601-5613. doi: 10.1021/acscatal.4c05208. eCollection 2025 Apr 4.
Understanding charge transfer in light-driven processes is crucial for optimizing the efficiency and performance of a photocatalyst, as charge transfer directly influences the separation and migration of photogenerated charge carriers and determines the overall reaction rate and product formation. However, achieving this understanding remains challenging in the context of single-atom photocatalysis. This study addresses this gap and investigates an Ag-based single-atom catalyst (Ag@CN ) in the photocatalytic oxidation of benzyl alcohol to benzaldehyde. Comprehensive characterization was conducted using a battery of diffractive, textural, spectroscopic, and microscopic methods, confirming the catalyst crystallinity, porosity, elemental composition, and atomic dispersion of silver atoms. This material displayed efficient performance in the selective oxidation of benzyl alcohol to benzaldehyde. Density functional theory calculations were used to rationalize the catalyst structure and elucidate the reaction mechanism, unveiling the role of the photogenerated holes in lowering the reaction energy barriers. Time-resolved transient spectroscopic studies were used to monitor the dynamics of photogenerated charges in the reaction, revealing the lifetimes and behaviors of excited states within the catalyst. Specifically, the introduction of silver atoms led to a significant enhancement in the excited state lifetime, which favors the hole-transfer in the presence of the benzyl alcohol. This indicated that the photoexcited carriers were effectively transferred to the reactant, thereby driving the oxidation process in the presence of oxygen. These mechanistic insights are pivotal in spectroscopically elucidating the reaction mechanism and can be practically applied to design single-atom photocatalysts more rationally, targeting materials that combine both rapid reductive quenching and efficient charge transfer to the metal.
了解光驱动过程中的电荷转移对于优化光催化剂的效率和性能至关重要，因为电荷转移直接影响光生电荷载流子的分离和迁移，并决定整体反应速率和产物形成。然而，在单原子光催化的背景下，实现这种理解仍然具有挑战性。本研究弥补了这一差距，研究了一种基于银的单原子催化剂（Ag@CN ）在光催化氧化苯甲醇生成苯甲醛中的应用。使用一系列衍射、结构、光谱和显微镜方法进行了全面表征，证实了催化剂的结晶度、孔隙率、元素组成以及银原子的原子分散情况。这种材料在苯甲醇选择性氧化生成苯甲醛方面表现出高效性能。采用密度泛函理论计算来合理化催化剂结构并阐明反应机理，揭示了光生空穴在降低反应能垒中的作用。时间分辨瞬态光谱研究用于监测反应中光生电荷的动力学，揭示催化剂内激发态的寿命和行为。具体而言，银原子的引入导致激发态寿命显著延长，这有利于在苯甲醇存在下的空穴转移。这表明光激发载流子有效地转移到反应物上，从而在氧气存在下驱动氧化过程。这些机理见解对于光谱阐明反应机理至关重要，并且可以实际应用于更合理地设计单原子光催化剂，目标是兼具快速还原猝灭和高效电荷转移到金属的材料。
