Yue Hua

Abstract Alloying is an efficient chemistry to tailor the properties of metal clusters. As a class of promising radiosensitizers, most previously reported metal clusters exhibit unitary function and cannot overcome radioresistance of hypoxic tumors. Here, atomically precise alloy clusters Pt 2 M 4 (M = Au, Ag, Cu) are synthesized with bright luminescence and adequate biocompatibility, and their composition‐dependent enzyme mimicking activity and radiosensitizing effect is explored. Specifically, only the Pt 2 Au 4 cluster displays catalase‐like activity, while the others do not have clusterzyme properties, and its radiosensitizing effect is the highest among all the alloy clusters tested. By taking advantage of the sustainable production of O 2 via the decomposition of endogenous H 2 O 2 , the Pt 2 Au 4 cluster modulates tumor hypoxia as well as increases the efficacy of radiotherapy. This work thus advances the cluster alloying strategy to produce multifunctional therapeutic agents for improving hypoxic tumor therapy.

Abstract Thiolate‐protected Cu clusters with well‐defined structures and stable low‐coordinated Cu + species exhibit remarkable potential for the CO 2 RR and are ideal model catalysts for establishing structure‐electrocatalytic property relationships at the atomic level. However, extant Cu clusters employed in the CO 2 RR predominantly yield 2e − products. Herein, two model Cu 4 (MMI) 4 and Cu 8 (MMI) 4 ( t BuS) 4 clusters (MMI=2‐mercapto‐1‐methylimidazole) are prepared to investigate the synergistic effect of Cu + and adjacent S sites on the CO 2 RR. Cu 4 (MMI) 4 can reduce CO 2 to deep‐reduced products with a 91.0 % Faradaic efficiency (including 53.7 % for CH 4 ) while maintaining remarkable stability. Conversely, Cu 8 (MMI) 4 ( t BuS) 4 shows a remarkable preference for C 2+ products, achieving a maximum FE of 58.5 % with a C 2+ current density of 152.1 mA⋅cm −2 . In situ XAS and ex situ XPS spectra reveal the preservation of Cu + species in Cu clusters during CO 2 RR, extensively enhancing the adsorption capacity of *CO intermediate. Moreover, kinetic analysis and theoretical calculations confirm that S sites facilitate H 2 O dissociation into *H species, which directly participate in the protonation process on adjacent Cu sites for the protonation of *CO to *CHO. This study highlights the important role of Cu−S dual sites in Cu clusters and provides mechanistic insights into the CO 2 RR pathway at the atomic level.