Graphdiyne: A New Photocatalytic CO2 Reduction Cocatalyst

Exploring new and efficient cocatalysts to boost photocatalytic CO2 reduction is of critical importance for solar-to-fuel conversion. As an emerging carbon allotrope, graphdiyne (GDY) features 2D characteristics and unique carbon-carbon bonds. Herein, a novel GDY cocatalyst coupled TiO2 nanofibers for boosted photocatalytic CO2 reduction, synthesized by an electrostatic self-assembly approach is reported. First-principle calculation and in situ X-ray photoelectron spectroscopy measurement reveal that the delocalized electrons in GDY can hybrid with the empty orbitals in TiO2 within the TiO2/GDY network, leading to the formation of an internal electric field at the interfaces, pointing from GDY to TiO2. The theoretical simulation further implies strong chemisorption and deformation of CO2 molecules upon GDY, which can be verified by in situ diffuse reflectance infrared Fourier transform spectroscopy. These effects, in combination with the photothermal effect of GDY, result in enhanced charge separation and directed electron transfer, enhanced CO2 adsorption and activation as well as accelerated catalytic reactions over the TiO2/GDY heterostructure, thereby resulting in significantly improved CO2 photoreduction efficiency and meanwhile with remarkable selectivity. This work demonstrates that GYD can function as a highly effective cocatalyst for solar energy harvesting and may be used in other catalysis processes.