Bulky Thiolate-Protected Silver Nanocluster Ag213(Adm-S)44Cl33 with Excellent Electrocatalytic Performance toward Oxygen Reduction

Atomically precise gold and/or silver nanoclusters play a key role in crystallography and coordination chemistry. Compared with gold nanoclusters, silver nanoclusters become unstable and difficult to crystallize due to the high reactivity of metal silver. Herein, we report a silver nanocluster Ag-213(Adm-S)(44)Cl-33 (Ag-213) coprotected by bulky thiolates and chlorides. The low surface thiolate coverage (about 45%) endows Ag-213 with high catalytic activity. Supported on activated carbon, Ag-213 nanoclusters exhibit excellent electrocatalytic oxygen reduction performance with Eonset and E-1/2 values of 0.89 and 0.72 V, respectively, close to the values of commercial Pt/C catalyst. This is the first report on the electrocatalytic oxygen reduction reaction of nanoclusters with more than 100 silver atoms. Ag-213 with the diameter of 2.75 nm comprises a core-shell structure Ag-7@Ag-32@Ag-77@Ag-97. The strong plasmonic absorption band at 454 nm reveals the metallic nature of Ag-213. Interestingly, halide is of importance. Chloride facilitates the formation of Ag-213 and Ag-56(Adm-S)(33)Cl-16 (Ag56Cl) while bromide can promote the formation of Ag-56(Adm-S)(33)Br16 (Ag56Br). This work provides an example for the study of large sized metal nanoclusters and nanocluster-based electrocatalysts. [GRAPHICS] .

Automated summary

Atomically precise silver nanoclusters play a key role in crystallography and coordination chemistry. In this study, silver nanoclusters with high catalytic activity and excellent electrocatalytic oxygen reduction performance were developed, supported on activated carbon. This work provides an example for the study of large sized metal nanoclusters and nanocluster-based electrocatalysts.