Spatially and temporally controlled photoconversion of metal nanoclusters

Although metal clusters show efficient photoresponse transformation behavior in dilute solution, the photoresponse of their solid materials is significantly reduced because of the limited molecular/atomic motion, and the kinetics of photoinduced structure reconstruction is seriously inhibited. Therefore, how to accurately control the photoresponse behavior of metal clusters in solid state is still a key challenge.

To address this challenge, the Zhu group from Anhui University cooperated with the Pei group from Xiangtan University designed a pair of copper-based metal clusters M₁Cu₁₇H₂(SPh^pF)₁₅[P(Ph^pF)₃]₆(SbF₆)₁ (M = Cu/Ag) with related frameworks. Based on the adjustable core composition, the cluster materials are endowed with controllable photoelectric conversion efficiency. Among them, the monoatomic alloy analogue Ag₁Cu₁₇ showed significantly enhanced light-induced conversion efficiency, and the final product was completely consistent with the homogeneous cluster Cu₁₈ system. Capitalizing on the excellent light conversion efficiency of alloy clusters in crystals, the research team further combined with femtosecond cold laser micromachining technology and controllable time-sequence ultraviolet irradiation to realize accurate time/space regulation of solid-state materials on the micron scale.

Under 365 nm ultraviolet excitation, M₁Cu₁₇ rapidly converts into the Cu₁₄ cluster, a process comprehensively characterized by time-dependent absorption spectroscopy, mass spectrometry, and ¹H NMR spectroscopy. Density functional theory calculations further reveal that while Ag doping does not significantly alter the electronic structure of Cu₁₈, it markedly enhances the structural instability of the excited state, thereby promoting its structural reorganization under photoexcitation. Consequently, compared to the pure copper cluster Cu₁₈, the single-atom alloy cluster Ag₁Cu₁₇ exhibits a substantially enhanced photoinduced conversion rate and overall reaction extent (Figure 1).

Furthermore, by employing ultraviolet irradiation with partial mask shielding, Ag₁Cu₁₇ crystals can achieve localized color change from yellow to orange, realizing spatially selective crystalline transformation (Figure 2). Furthermore, the team utilized femtosecond laser processing technology to successfully fabricate well-defined patterns with feature sizes as small as 150 μm on the crystal surface, with the minimum line width of laser writing reaching 310 nm, which is far below the theoretical diffraction limit of the optical system. These results demonstrate its potential for application in high-precision micro‑/nanofabrication.

In summary, this study presents a structurally correlated nanocluster pair, elucidating the relationship between cluster structure and photoinduced conversion efficiency at the atomic level. The findings provide important theoretical foundations and technical pathways for developing cluster-based solid-state nanomaterials with programmable compositions and customizable photoresponse properties.

The related research findings have been published in the National Science Review (Natl Sci Rev). Ying Xu (doctoral student) and Mengfan Chang (master student) from Anhui University are co-first authors of the paper. Professors Manzhou Zhu and Xi Kang from Anhui University, and Professors Yong Pei and Pu Wang from Xiangtan University, are corresponding authors.

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