Intrabandgap States Engineering in Functionalized Nanodiamond to Generate Solvated Electrons for Photocatalysis Under Solar Illumination

Diamond, a wide‐bandgap material with unique electronic properties, has shown great promise as a photoreduction catalyst due to its ability to produce highly reductive solvated electrons. However, this requires deep UV illumination, which hampers its sustainable application for real‐world photocatalytic processes. Here, it is reported that the tailored introduction of suitable intra‐bandgap states in diamond can be achieved by functionalizing nanoscale detonation diamond with a ruthenium‐based photosensitizer. The nature of the electronic interaction between the diamond, its surface and the surface‐bound moieties is elucidated through X‐ray absorption, transient optical absorption, and ultraviolet photoemission spectroscopies both in vacuum and water. The electron emission upon irradiation with visible light is enabled by the surface‐induced bangdap engineering. Solar‐light‐driven reduction of CO 2 to formate is performed as a proof‐of‐concept reaction. The potential for photoexcited electron transfer (PET) mediated photosensitization in reductive diamond catalysis opens the way for the application of surface‐engineered diamond as a sustainable photo(electro)catalyst.