Structure regulated catalytic performance of gold nanocluster- MOF nanocomposites

Atomically precise gold (Au) nanoclusters (NCs) as visible light photosensitizers supported on the substrate for photoredox catalysis have attracted considerable attentions. However, efficient control of their photocatalytic activity and long-term stability is still challenging. Herein, we report a coordination-assisted self-assembly strategy in combination with electrostatic interaction to sandwich Au₂₅(Capt)₁₈ (abbreviated as Au₂₅, Capt = captopril) NCs between an inner core and an outer shell made of UiO-66, denoted as UiO-66@Au₂₅@UiO-66. Notably, the sandwich-like nanocomposite displays significantly enhanced catalytic activity along with an excellent stability when used in the selective photocatalytic aerobic oxidation of sulfide to sulfoxide. As comparison, Au₂₅ NCs simply located at the outer surface or insider matrix of UiO-66 (short as Au₂₅/UiO-66 and Au₂₅@UiO-66) show poor stability and low conversion, respectively. This structure regulated difference in the catalytic performances of three nanocomposites is assigned to the varied distribution of active sites (Au NCs) in metal-organic frameworks (MOFs). This work offers the opportunity for application of nanoclusters in catalysis, energy conversion and even biology.