Atomically Precise Fcc-Amorphous Homometal Heterojunction with ∼1 nm Size

The emerging of ultrasmall gold nanoparticles (nanoclusters) with atomic precision provides opportunities for precisely studying crystalline–amorphous heterostructures, despite the construction of such structures being challenging. In this work, we developed an acid-induction method and synthesized a Au52(TBBT)30 (TBBTH = 4-tert-butylbenzenelthiol) nanocluster with the kernel composed of two parts: the amorphous Au22 part and the fcc Au21 part, which represents the first construction of fcc-amorphous homometal heterojunction with ∼1 nm size. Density function theory (DFT) revealed that the HOMO–LUMO majorly distributed in the amorphous part and the HOMO–LUMO gap was dominated by the amorphous part, indicating the redox activity of the amorphous Au22 part in contrast to the fcc Au21 part, which was experimentally confirmed by differential pulse voltammetry, antioxidation test and anti-Galvanic reaction. But for electro-catalyzing reduction of CO2 to CO, the crystalline surface sites were revealed to be more catalytically active than the amorphous surface sites in catalyzing the reduction of CO2 to CO, and the most active sites were assigned to the cosurface sites of amorphous Au22 and fcc Au21, which is also responsible for the high performance of Au52(TBBT)30 relative to the pure fcc-structured Au52(TBBT)32 (the highest CO FE: 96.7% at −0.67 V vs 73.3% at −0.57 V; CO partial current density at the corresponding potential: −7.3 vs −2.7 mA cm–2).