Microwave-Assisted Synthesis of Cobalt Oxide/Reduced Graphene Oxide (Co₃O₄–rGo) Composite and its Sulfite Enhanced Photocatalytic Degradation of Organic Dyes

Abstract

One-pot synthesis of Co3O4 nanocrystals on reduced graphene oxide (rGO) was carried out by reacting cobalt nitrate, L-arginine, extract of Laportae aestuans as oxidant, fuel and reducing agent, respectively, in a domestic microwave. Morphologies of Co3O4–rGo (RGCO) composite was elucidated using UV-Vis, FT-IR, TEM, SEM, EDX, XRD and photoluminescence spectroscopies. The synthesized RGCO composite was applied as heterogeneous photocatalyst in the activation of Na2SO3 (sulfite) as sacrificial agent to degrade cationic dyes: rhodamine B (RhB) and methylene blue (MB), under visible light, at neutral pH 7.0. Photocatalytic performance of as-prepared RGCO was significantly enhanced in the presence of Na2SO3. Enhanced photocatalytic activity of RGCO was attributed to the synergistic effects between sulfite radicals generated in situ, and reduced graphene oxide, in which rGO served as electron sink to suppress recombination of photogenerated charge carriers. Plausible mechanistic pathways responsible for the activation of sulfite anions in situ are presented in this paper.

Metal Oxide Wrapped by Reduced Graphene Oxide Nanocomposites as Anode Materials for Lithium-Ion Batteries

“…The characteristic split vibrational bands of the Co–O bonds and observed O–H stretching at 3449 cm −1 in the FTIR spectrum of the Co 3 O 4 are also consistent in the spectrum of the rGO/Co 3 O 4 T−5 nanocomposite. Except for the peaks due to the Co–O bonds (in Co 3 O 4 ), the FTIR spectra of the rGO/Co 3 O 4 T−5 nanocomposite affirmed that the Co 3 O 4 was satisfactorily packed onto nanosheets of reduced graphene oxide (rGO), with the exception of the peaks due to the Co−O bonds (in Co 3 O 4 ) [ 54 ].…”

Dual Applications of Cobalt-Oxide-Grafted Carbon Quantum Dot Nanocomposite for Two Electrode Asymmetric Supercapacitors and Photocatalytic Behavior

“…Interestingly, the Co 3 O 4 planes 220, 311, 400, 511, and 440 are also present in the Co 3 O 4 –CQD composite, but the position is slightly shifted and the peaks have sharply appeared. These results confirm that CQD is present in the Co 3 O 4 –CQD composite, where it acts as a surfactant and improves the crystalline nature of the cobalt …”

“…These results confirm that CQD is present in the Co 3 O 4 −CQD composite, where it acts as a surfactant and improves the crystalline nature of the cobalt. 47 The composite has been confirmed by Raman spectral data. In Co 3 O 4 , the peak appears at 585 cm −1 , and the E g and A 1g mode 56 of cobalt oxide is ascribed to 678 cm −1 , as shown in Figure 4b.…”

Nanostructured Graphene Oxide-Based Hybrids as Anodes for Lithium-Ion Batteries

“…Another popular technique of fabrication is the one-pot microwave-assisted synthesis. Typical experiments are carried out in a domestic microwave at a power of 1600 W for 30 min [479].…”