Investigation on Reactivity and Selectivity of Electrocatalytic CO2 Reduction in Photochemically Synthesized Ag19 and Alloyed Ag19Cu2 and Ag12Cu7 Nanoclusters

Atomically precise nanoclusters are desirable for understanding the structure–property relationships in the electrocatalytic CO2 reduction reaction (eCO2RR), but suitable related models are lacking, especially those of low- or zerovalent noble metal nanoclusters and their alloyed analogues. We first developed a photochemical method toward silver nanocluster Ag19(4-tBuPhC≡C)14(Dpppe)3(SbF6)3 (Ag19-2e) and then related copper-doped alloyed nanocluster Ag12Cu7(4-tBuPhC≡C)14(Dpppe)3Cl3(SbF6)2 (Ag12Cu7-0e). Herein, we present a larger alloyed nanocluster, Ag19Cu2(4-tBuPhC≡C)16(Dpppe)4(SbF6)3 (Ag19Cu2-2e) and investigate the relationship between the structures and the eCO2RR performance of those related nanoclusters. The UV–vis and mass spectra revealed that Ag19Cu2-2e forms via light-induced Ag19-2e generation followed by Cu­(II) attachment. eCO2RR tests showed that Ag19-2e is the least efficient, while its dicopper alloyed Ag19Cu2-2e favors formate, highlighting the important role of copper doping in regulating Ag cluster catalysis. This conclusion is further confirmed by the good catalytic performance of Ag12Cu7-0e, which demonstrated the best C1 product selectivity for both CO and formate. Experimental and theoretical calculations indicate that its excellent catalytic performance is attributed to the removal of Cl ligands, exposing active Ag sites for launching the eCO2RR process. This work not only demonstrates that copper-doped silver nanoclusters significantly enhance catalytic activity but also reveals that varying copper doping levels enable modulation of product selectivity in eCO2RR.