Thiolate-protected metal (e.g., Au and Ag) nanoclusters or Au/Ag NCs for short, typically containing a few to hundreds of metal atoms, are a subclass of metal nanoparticles (NPs).^1–3  Thiolate-protected Au/Ag NCs are smaller than 2 nm and can be denoted as M_n(SR)_m, where M and SR represent Au/Ag and thiolate ligand, respectively. Particles in this sub-2 nm size range have strong quantum confinement of free electrons,¹  resulting in discrete electronic transitions^4–6  and unique atomic packing structures.^7,8  These two features are distinctively different from that of large Au/Ag NPs (>2 nm). In particular, Au/Ag NPs show quasi-continuous electronic states and have a face-centered cubic (fcc) atomic packing, leading to a characteristic surface plasmon resonance (SPR) property.^9–11  In contrast, the discrete and size-dependent electronic transitions in NCs provide them with unique molecular-like properties such as HOMO–LUMO transitions,^5,12,13  optical chirality,^14–16  quantized charging,^12,17  magnetism,¹⁸  and luminescence.^3,19,20  These interesting properties make Au/Ag NCs attractive for both fundamental studies and application explorations, which have also motivated a rapid development of efficient synthesis methods for high-quality Au/Ag NCs.^3,19–23