Boosting photocatalytic CO2 reduction efficiency by graphene nanoflakes (GNF) decorated ZIF-67 under visible light irradiation

Abstract

The design and development of sustainable and cost-effective photocatalysts necessitate significant effort for improved CO2 reduction efficiency. Metal-organic frameworks (MOFs), with high surface area, are gaining popularity in photocatalysis, but their high electron-hole (e-, h+) recombination and low light harvesting capacity limit their utility. Graphene nanoflake (GNF) is a novel, low-cost carbon nanomaterial which has received attention owing to its non-toxicity, high aqueous solubility, unique photoluminescence properties, and excellent photostability. In this work, graphene nanoflake (GNF) decorated zeolitic imidazole framework ZIF-67 (GNF(X)/ZIF-67) has been synthesized for improving visible light-driven photocatalytic CO2 reduction performance. The composite GNF6/ZIF-67 decorated with 6% GNF nanoflake achieves the highest methanol generation of 50.93 µmolg−1 and the highest ethanol generation of 33.97 µmolg−1 after 8 h of visible light irradiation, compared to pure ZIF-67 which is 1.93 and 1.59 times respectively. The effect of GNF on boosting the visible-light photocatalytic activity of ZIF-67 was explored based on the UV-Vis DRS spectra, electrochemical impedance spectra (EIS), transient photocurrent response, and photoluminescence (PL) experiment. This work may discover a new way to synthesize photocatalysts for applying CO2 photoreduction.