Host-guest assemblies of anchoring molecular catalysts of CO2 reduction onto CuInS2/ZnS quantum dots for robust photocatalytic syngas production in water

Simultaneously fulfilling CO2-to-CO and 2H(+)-to-H-2 reactions in water via photocatalyst represents an alternative to produce syngas driven by solar energy. To this end, photocatalyst having ability of simultaneously producing CO and H-2 with controllable ratio should be exploited. In this work, we report a self-assembly photocatalyst C1@CD-CuInS2/ZnS quantum dots (QDs) that enabling to produce syngas robustly in CO2-saturated water under visible light irradiation. C1 is a molecular catalyst of linking an adamantine moiety to [Co(TPA)Cl]Cl (TPA = tris (2-pyridylmethyl) amine), while CD-CuInS2/ZnS QDs are semiconductor QDs with structure of CuInS2 core and ZnS shell and containing beta-cyclodextrin (CD) on the surface. The C1@CD-CuInS2/ZnS QDs assemblies form by anchoring molecular cobalt catalyst C1 onto cyclodextrin (CD) modified CuInS2/ZnS quantum dots (CD-CuInS2/ZnS QDs) based on host-guest interaction between adamantine in C1 and cyclodextrin in the QDs. In which, C1 functions a molecular catalytic center mainly for CO2 reduction, and CD-CuInS2/ZnS QDs functions as both a light harvester and a hydrogen production center. The C1@CD-CuInS2/ZnS QDs system maintains syngas pro-duction activity over 200 h, and produces 184.21 mu mol syngas with a CO/H-2 ratio of 0.74 (ca. 2:3), exhibiting obvious advantages of syngas production efficiency in comparison to the non-assembled system and pristine CD-CuInS2/ZnS QDs system. Mechanism studies revealed that photoinduced electron transfer between CD-CuInS2/ ZnS QDs and C1 occurs. The host-guest interaction improves syngas production activity and stability as well as plays positive role on stability of the molecular catalyst.

Automated summary

This work reports a self-assembly photocatalyst C1@CD-CuInS2/ZnS quantum dots (QDs) that can robustly produce syngas under visible light irradiation. The system exhibits advantages of syngas production efficiency and stability compared to non-assembled and pristine CD-CuInS2/ZnS QDs systems.