Photocatalytic CO2 Reduction Using Homogeneous Carbon Dots with a Molecular Cobalt Catalyst

A simple and precious‐metal free photosystem for the reduction of aqueous CO2 to syngas (CO and H2) is reported consisting of carbon dots (CDs) as the sole light harvester together with a molecular cobalt bis(terpyridine) CO2 reduction co‐catalyst. This homogeneous photocatalytic system operates in the presence of a sacrificial electron donor (triethanolamine) in DMSO/H2O solution at ambient temperature. The photocatalytic system exhibits an activity of 7.7 ± 0.2 mmolsyngas gCDs−1 (3.6 ± 0.2 mmolCO gCDs−1 and 4.1 ± 0.1 mmolH2 gCDs−1) after 24 hours of full solar spectrum irradiation (AM 1.5G). Spectroscopic and electrochemical characterization supports that this photocatalytic performance is attributed to a favorable association between CDs and the molecular cobalt catalyst, which results in improved interfacial photoelectron transfer and catalytic mechanism. This work provides a scalable and inexpensive platform for the development of CO2 photoreduction systems using CDs. This study establishes a scalable, inexpensive, and precious‐metal free photocatalytic system for aqueous CO2 reduction using carbon dots as the sole photosensitizer in combination with a molecular cobalt co‐catalyst. A favorable association between the carbon dot and the Co co‐catalyst is achieved by rational chemical design, allowing this homogeneous photocatalytic system to operate with an activity of 7.7 ± 0.2 mmolsyngas gCDs−1 after 24 h simulated solar light irradiation.