Facile synthesis and characterization of γ-Al2O3 loaded on reduced graphene oxide for electrochemical reduction of CO2

Abstract

Electrocatalytic reduction of CO₂ to valuable organic compounds and fuels using energy efficient techniques is presently of great importance. In this work, we show the synthesis of Al₂O₃-decorated reduced graphene oxide (rGO) electrocatalysts and their catalytic properties for the conversion of CO₂ into formate. These hybrid nanostructured materials are prepared using chemical synthesis, followed by chemical vapor deposition. The materials are characterized by X-ray diffraction and Raman spectroscopy, and the results confirm the formation of γ-Al₂O₃ on defect-rich rGO. Transmission electron microscope images reveal the formation of γ-Al₂O₃ with particle sizes of 8 ± 0.3 nm on rGO sheets that are ∼100 × 100 nm in length and width and composed of a few-layers of graphene. X-ray photoelectron spectroscopy confirms the presence of Al–O, C–C and C–O bonds in the material. The amount of Al is ∼2.8%, as determined by inductively coupled plasma-mass spectrometry (ICP-MS). The material catalyzes the electrochemical reduction of CO₂ at a potential of −0.434 V vs. RHE in 0.5 M KHCO₃ solution, which is used as an electrolyte. The potential dependent bulk electrolysis shows that the reduction product is formate, which formed with a faradaic efficiency (FE) of 31.90, 37.25, 42.50, 55.10 and 91.20% at potentials of −0.434, −0.534, −0.634, −0.734 and −0.934 V vs. RHE, respectively. Based on these findings, these noble metal-free electrocatalysts may find industrial applications to convert CO₂ into valuable chemicals, and thereby to mitigate CO₂-related global warming issues.