Engineering
the Sulfide Semiconductor/Photoinactive-MOF
Heterostructure with a Hollow Cuboctahedral Structure to Enhance Photocatalytic
CO2‑Epoxide-Cycloaddition Efficiency
Providing
efficient electronic transport channels has always been
a promising strategy to mitigate the recombination of photogenerated
charge carriers. In this study, a heterostructure composed of a semiconductor/photoinactive-metal–organic
framework (MOF) was constructed to provide innovative channels for
electronic transport. Prepared using a previously reported method
(Angew. Chem., Int. Ed. 2016, 55, 15301–15305) with slight modifications to temperature
and reaction time, the CuS@HKUST-1 hollow cuboctahedron was synthesized.
The CuS@HKUST-1 heterostructure possessed a well-defined cuboctahedral
morphology with a uniform size of about 500 nm and a hollow structure
with a thickness of around 50 nm. The CuS nanoparticles were uniformly
distributed on the HKUST-1 shell. Structural characterization in cooperation
with density functional theory (DFT) calculations revealed that CuS
can effectively transfer photogenerated electrons to HKUST-1. CuS@HKUST-1
hollow cuboctahedrons were first introduced to the photocatalytic
cycloaddition reaction of CO2 with epoxides, demonstrating
excellent photocatalytic activity and stability at mild conditions
(room temperature, solvent-free, and 1 atm CO2 pressure).
The high photocatalytic performance of the CuS@HKUST-1 hollow cuboctahedron
could be attributed to (1) the unique hollow cuboctahedron morphology,
which provided a large specific surface area (693.1 m2/g)
and facilitated the diffusion and transfer of reactants and products;
and (2) CuS@HKUST-1 providing electronic transport channels from CuS
to HKUST-1, which could enhance the adsorption and activation of CO2. Cu2+ carrying surplus electrons can activate
CO2 to CO2–. The charge separation
and transfer in the photocatalytic process can also be effectively
promoted. This work provides a cost-effective and environmentally
friendly approach for CO2 utilization reactions under ambient
conditions, addressing the critical issue of rising atmospheric CO2 levels.