Robust Gold Nanocluster Protected with Amidinates for Electrocatalytic CO 2 Reduction

The first all‐amidinate‐protected gold nanocluster [Au 28 (Ph−form) 12 ](OTf) 2 (Ph‐form= N , N ′‐diphenylformamidinate) ( Au 28 ) has been synthesized and structurally resolved. Single crystal X‐ray diffraction reveals that Au 28 has a compact Au 4 @Au 24 tetrahedral core–shell structure of T symmetry, which is fully protected by 12 bridging formamidinate ligands. This cluster is quite robust as indicated by the fact that it can stay intact in solution at 80 °C for 6 d. It exhibits excellent catalytic performance for the electroreduction of CO 2 with 96.5 % Faradaic efficiency (FE) at −0.57 V and a maximum TOF of 1731 h −1 at −0.87 V. Its superior stability is also manifested in the fact that the supported catalyst Au 28 /CNTs maintains stable potentials at ca. −0.69 V for 40 h with FE(CO)s>91 %. A superatomic electron configuration of 1S 2 1P 6 2S 2 1D 4 has been clarified by DFT computations, and the strong gold–ligand binding and geometric shell closure account for the superior stability of Au 28 .