Spyrou Anastasia V, Zindrou Areti, Sidiropoulos Christos, Deligiannakis Yiannis
Laboratory of Physical Chemistry of Materials & Environment, Department of Physics, University of Ioannina, Ioannina 45110, Greece.
ACS Catal. 2025 Jul 23;15(15):13595-13610. doi: 10.1021/acscatal.5c03183. eCollection 2025 Aug 1.
Engineering of single-atom catalysts (SACs) or subnanoclusters (SnCs) as cocatalysts is a powerful strategy for enhancing photocatalytic performance. However, a more concrete understanding of the role of SAC vs SnC remains a challenge. A prerequisite to achieving this task is a systematic selective synthesis of SACs and SnCs as cocatalysts for a given process. Herein, we have employed a modified flame spray pyrolysis (FSP) process for deposition of either single Cu atoms or Cu subnanoclusters on NaTaO nanoparticles, producing a library of Cu-(SAC)@NaTaO or Cu-(SnC)@NaTaO with controlled amounts of Cu-(SAC) and Cu-(SnC), respectively. Electron Paramagnetic Resonance (EPR) spectroscopy was used as a state-of-the-art tool to map the precise configuration of the Cu species on NaTaO, as well as the photoinduced electron transfer from NaTaO to surface-anchored Cu. Photocatalytic H production from HO demonstrates that Cu-(SnC)@NaTaO i.e. decorated with Cu subnanoclusters, exhibits significantly superior activity vs their single Cu-atom counterpart, achieving enhanced H photogeneration of >10,900 μmol/g/h, corresponding to an apparent quantum yield of 1.5%, with no noble metal added as a cocatalyst. EPR data show that Cu subnanoclusters in Cu-(SnC)@NaTaO are ∼300% more efficient electron acceptors compared to Cu monomers in Cu-(SAC)@NaTaO. Transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) data reveal that FSP-deposited Cu SnC forms a tight interface with the NaTaO surface, leading to an improved energy-level configuration. Overall, the present data showcase, for this particular photocatalytic system, that Cu subnanoclusters rather than the currently believed single Cu atoms are the preferable cocatalyst in HO photocatalysis by NaTaO. This postulate probably can be verified for other pertinent systems. Moreover, we demonstrate that FSP-made Cu-(SnC)@NaTaO is a highly promising, noble-metal-free photocatalyst.
设计单原子催化剂（SACs）或亚纳米团簇（SnCs）作为助催化剂是提高光催化性能的有效策略。然而，更具体地了解SAC与SnC的作用仍然是一个挑战。实现这一任务的前提是系统地选择性合成作为给定过程助催化剂的SACs和SnCs。在此，我们采用改进的火焰喷雾热解（FSP）工艺，将单个铜原子或铜亚纳米团簇沉积在NaTaO纳米颗粒上，分别制备了具有可控量Cu-(SAC)和Cu-(SnC)的Cu-(SAC)@NaTaO或Cu-(SnC)@NaTaO库。电子顺磁共振（EPR）光谱被用作一种先进的工具，以绘制NaTaO上铜物种的精确构型，以及从NaTaO到表面锚定铜的光致电子转移。由H₂O光催化产氢表明，用铜亚纳米团簇修饰的Cu-(SnC)@NaTaO相对于单个铜原子对应物表现出明显更优异的活性，在不添加贵金属作为助催化剂的情况下，实现了>10900 μmol/g/h的增强的H₂光生成，对应表观量子产率为1.5%。EPR数据表明，与Cu-(SAC)@NaTaO中的铜单体相比，Cu-(SnC)@NaTaO中的铜亚纳米团簇是效率高约300%的电子受体。透射电子显微镜（TEM）、拉曼光谱和X射线光电子能谱（XPS）数据表明，FSP沉积的Cu SnC与NaTaO表面形成紧密界面，从而导致改善的能级构型。总体而言，目前的数据表明，对于这个特定的光催化系统，在NaTaO光催化分解H₂O过程中，铜亚纳米团簇而非目前认为的单个铜原子是更优的助催化剂。这一假设可能适用于其他相关系统。此外，我们证明FSP制备的Cu-(SnC)@NaTaO是一种极具前景的无贵金属光催化剂。
