2D metal-free heterostructure of covalent triazine framework/g-C3N4 for enhanced photocatalytic CO2 reduction with high selectivity

Solar-driven CO2 conversion to precious fossil fuels has been proved to become a potential way to decrease CO2 with producing renewable fuels, which mainly relies on photocatalysts with efficient charge separation. In this work, a metal free heterostructure of covalent triazine framework (CTF) and graphite carbon nitride (g-C3N4, abbreviated as CN) is applied in the CO2 photoreduction for the first time. Detailed characterization methods such as photoluminescence (PL) and time-resolved PL (TR-PL) decay are utilized to reveal the photo-induced carries separating process on g-C3N4/CTF (CN/CTF) heterostructure. The introduced CTF demonstrated a great boosting photocatalytic activity for CN, bringing about the transform rates of CO2 to CO reaching 151.1 μmol/(g·h) with a 30 h stabilization time, while negligible CH4 was detected. The optimal CN/CTF heterostructure could more efficiently separate charges with a lower probability of recombination under visible light irradiation, which made the photoreduction efficiency of CO2 to CO be 25.5 and 2.5 times higher than that of CTF and CN, respectively. This investigation is expected to offer a new thought for fabricating high-efficiency photocatalyst without metal in solar-energy-driven CO2 reduction.