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

Abstract

Solar-driven CO 2 conversion to precious fossil fuels has been proved to become a potential way to decrease CO 2 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-C 3 N 4 , abbreviated as CN) is applied in the CO 2 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-C 3 N 4 /CTF (CN/CTF) heterostructure. The introduced CTF demonstrated a great boosting photocatalytic activity for CN, bringing about the transform rates of CO 2 to CO reaching 151.1 μmol/(g·h) with a 30 h stabilization time, while negligible CH 4 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 CO 2 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 CO 2 reduction. 2D/2D metal-free g-C 3 N 4 /CTF heterostructure material promoted the interfacial charge transfer, which exhibited high efficiency and selectivity of photocatalytic CO 2 reduction to CO under visible-light illumination.