Cobalt/Cobalt Oxide Nanorods-Decorated Reduced Graphene Oxide (Co/Co₃O₄-rGO) for Enhanced Electrooxidation of Glycerol

Abstract

Reduced graphene oxide with cobalt/cobalt oxide (Co/Co 3 O 4 -rGO) nanorod decorations was made by using a chemical synthesis process. The as-synthesized Co/Co 3 O 4 -rGO, reduced graphene oxide (rGO), and cobalt/cobalt oxide (Co/Co 3 O 4 ) nanocomposite were tested for electrocatalytic activity toward the electrooxidation of glycerol in 1 M KOH solution and oxygen evolution reaction simultaneously. The as-synthesized electrocatalytic system was characterized by various techniques, including electrochemical (cyclic voltammetry, electrochemical impedance spectroscopy, and i−t chronoamperometry), spectroscopic (Fourier transform infrared, Raman, and X-ray photoelectron spectroscopy), and morphological (scanning electron spectroscopy and transmission electron microscopy) analyses. Transmission electron microscopy analysis of the Co/Co 3 O 4 -rGO nanocomposite showed an average size of ∼36 nm of Co/Co 3 O 4 on rGO. The electrochemical studies exhibited that Co/Co 3 O 4 -rGO showed excellent electrocatalytic performance compared to those of rGO and Co 3 O 4 individually. Among these, Co/Co 3 O 4 -rGO showed the smallest onset potential (∼1.42 V vs RHE), lowest Tafel slope (56 mV dec −1 ), lower charge-transfer resistance R ct (600 Ω), and higher stability than Co 3 O 4 and rGO. High-performance liquid chromatography analysis confirmed the formation of formic acid with conversion after 5, 15, and 20 h (∼13.43, 41.93, and 59.44%, respectively) and demonstrated higher Faradaic efficiency (∼63%) toward oxidative product (i.e., formic acid) formation. The improved electrochemical performance of rGO after the decoration of Co/Co 3 O 4 on the GO surface reflected that Co/Co 3 O 4 -rGO has good structural and potential stability than Co 3 O 4 nanoparticles and rGO substrate toward glycerol electrooxidation.

Electrocatalytic Glycerol Conversion: A Low-Voltage Pathway to Efficient Carbon-Negative Green Hydrogen and Value-Added Chemical Production

“…Oh et al demonstrated the effect of nanostructuring of the Au catalyst and the local KOH concentration on GLYOR . Many earth-abundant catalysts have been reported for GLYOR with high formic acid selectivity. , A cobalt oxide nanorod decorated on reduced graphene oxide (RGO) is effective for GLYOR with high formate selectivity; however, the high selectivity of formic acid production required a longer reaction time and a high potential . Other strategies, such as defect creation on the electrocatalyst surface, are also suggested to boost the GLYOR performance .…”

Deploying used solid carbon dioxide to assist graphite exfoliation

“…Two-dimensional graphene, containing a lattice of sp 2 carbons, has garnered much attention for its multiple applications in composite materials, energy storage devices, electrocatalysts, 1,2 sensors, 3 etc. 4–6 Additionally, extensive scientific and industrial research on the exfoliation of graphite/graphene into fewer sheets, is also being undertaken. 7–9 During exfoliation, the multiple layers of graphene, which are held together by weak van der Waals forces, are separated/moved apart, producing a 2D material that can be used for various applications such as in electronics, photonics, energy storage, composites, sensors etc .…”