Abstract
Attaining meticulous dominion over the binding milieu of catalytic metal sites remains an indispensable pursuit to tailor product selectivity and elevate catalytic activity. By harnessing the distinctive attributes of a Zr(4+)-anchored thiacalix[4]arene (TC4A) metalloligand, we have pioneered a methodology for incorporating catalytic Ag(1+) sites, resulting in the first Zr-Ag bimetallic cluster, Zr(2)Ag(7), which unveils a dualistic configuration embodying twin {ZrAg(3)(TC4A)(2)} substructures linked by an {AgSal} moiety. This cluster unveils a trinity of discrete Ag sites: a pair ensconced within {ZrAg(3)(TC4A)(2)} subunits and one located between two units. Expanding the purview, we have also crafted ZrAg(3) and Zr(2)Ag(2) clusters, meticulously mimicking the two Ag site environment inherent in the {ZrAg(3)(TC4A)(2)} monomer. The distinct structural profiles of Zr(2)Ag(7), ZrAg(3), and Zr(2)Ag provide an exquisite foundation for a precise comparative appraisal of catalytic prowess across three Ag sites intrinsic to Zr(2)Ag(7). Remarkably, Zr(2)Ag(7) eclipses its counterparts in the electroreduction of CO(2), culminating in a CO faradaic efficiency (FE(CO)) of 90.23% at -0.9 V. This achievement markedly surpasses the performance metrics of ZrAg(3) (FE(CO): 55.45% at -1.0 V) and Zr(2)Ag(2) (FE(CO): 13.09% at -1.0 V). Utilizing in situ ATR-FTIR, we can observe reaction intermediates on the Ag sites. To unveil underlying mechanisms, we employ density functional theory (DFT) calculations to determine changes in free energy accompanying each elementary step throughout the conversion of CO(2) to CO. Our findings reveal the exceptional proficiency of the bridged-Ag site that interconnects paired {ZrAg(3)(TC4A)(2)} units, skillfully stabilizing *COOH intermediates, surpassing the stabilization efficacy of the other Ag sites located elsewhere. The invaluable insights gleaned from this pioneering endeavor lay a novel course for the design of exceptionally efficient catalysts tailored for CO(2) reduction reactions, emphatically underscoring novel vistas this research unshrouds.