Enhanced Photochemical CO2 Reduction in the Gas Phase by Graphdiyne
Photocatalytic CO2 reduction is promising for reducing greenhouse effect and producing renewable energy, but still shows low activity and selectivity due to the ineffective utilization of photogenerated charge carriers and insufficient active sites of CO2 adsorption and activation. Taking the CdS nanocrystals as the model semiconductor, we demonstrate that graphdiyne, a new type of two-dimensional carbon allotrope uniquely formed by sp- and sp2- hybridized carbon, enhances CO2 photoreduction over CdS with higher activity, selectivity, and stability in the gas phase without any sacrificial agent compared to graphene. Both experimental and theoretical results prove that the chemical bonding between graphdiyne and CdS, and sufficient CO2 adsorption sites due to the strong interfacial interaction-induced sulfur vacancies in CdS and more electron-deficient acetylenic linkages in graphdiyne, lead to more efficient electron transfer and storage for subsequent CO2 reduction reaction. The excellent properties of graphdiyne make it promising for applications in solar energy conversion.