Photoelectrocatalytic conversion of CO2 by transition metal functionalized diamond nanoparticles under solar illumination

Overcoming the energy barrier in CO2 reduction is a key avenue in the development of sustainable carbon capture and recycling systems spearheading against the climate emergency. Diamond, a wide-bandgap material, has shown promise in this aspect due its ability to produce highly reductive solvated electrons when irradiated with deep UV light. This requirement for high-energy optical illumination, however, hampers its sustainable application and limits its useful lifetime. Here we show the photosensitization of nanoscale detonation diamond in reductive photoelectrocatalysis through surface functionalisation with a ruthenium-based dye, demonstrating solar-light driven turnover of CO2 using the unique properties of diamond. The hybrid photosensitizer-nanodiamond materials demonstrated good colloidal and photochemical stability. The nature of electronic conjugation between diamond and photosensitizer was elucidated through X-ray absorption, transient optical absorption, and ultraviolet photoemission spectroscopies, with CO2 turnover significantly improved under solar conditions for photosensitized systems. The potential for photoexcited electron transfer (PET) mediated photosensitization in reductive diamond catalysis opens the way for further sustainable applications using diamond as a sustainable photoelectrocatalyst.