ZnO HoMS@ZIF-8 Nanoreactors for Efficient Enrichment and Photoreduction of Atmospheric CO2

The ultimate goal of photocatalytic CO2 reduction is to efficiently convert atmospheric CO2 into value-added products by designing hierarchical photocatalysts that combine effective harvesting and accelerate activation capabilities of CO2 molecules. In this work, we demonstrated direct air -level CO2 reduction by hollow multishell structure (HoMS) nanoreactors with zeolitic imidazolate framework -8 (ZIF-8)-modified ZnO heteroshells, which offers a promising solution to optimize the mass transfer process via selective sieving and effective enrichment of CO2 molecules from the atmospheric environments. Specifically, heteroshells with ZIF-8 matrix act as pumps that effectively capture CO2 molecules, while the cavities serve as tanks to hold these molecules, thus significantly enhancing the transfer kinetics for CO2 photoreduction. The periodic shell -cavity configuration allows the nanoreactor to effectively gather CO2 molecules near the catalytic sites, thus increasing conversion opportunities for activated molecules. Simultaneously, the surface atomic steps on the ZnO/ZIF-8 heterointerfaces with staggered geometry expedite charge transfer and adsorption efficiency, which synergistically boosts the CO2-CO yield up to 3.7 mu mol/h under CO2 flow and 0.7 mu mol/h under atmospheric conditions with almost complete CO selectivity. Hopefully, the HoMS nanoreactors offer a potential strategy for solving the "last mile" challenge in practical CO2 valorization. Keywords: hollow multishelled structures, atmospheric CO2 photoreduction, ZnO, ZIF-8, heterointerface