Scalable Production of Graphene Oxide Using a 3D-Printed Packed-Bed Electrochemical Reactor with a Boron-Doped Diamond Electrode

Abstract

Although graphene oxide (GO) has shown enduring popularity in the research community, its synthesis remains cost prohibitive for many of its demonstrated applications. While significant progress has been made on developing an electrochemical route to GO, existing methods have key limitations regarding their cost and scalability. To overcome these challenges, we employ a combination of commercially available fused-deposition-modeling-based 3D printing and highly robust boron-doped diamond with a wide electrochemical potential window to fabricate a scalable packed-bed electrochemical reactor for GO production. The scalability of the reactor along the vertical and lateral dimensions was systematically demonstrated to facilitate its eventual industrial application. Our current reactor is cost-effective and capable of producing electrochemically derived GO (EGO) on a multiple-gram scale. By oxidizing flake graphite directly in an 11.6 M sulfuric acid electrolyte, the production of EGO was streamlined to a one-step electrochemical reaction, followed by a simple water-wash purification. Almost all of the converted graphite oxide can be recovered, and the final mass yield is typically 155% of the starting graphite material. The as-produced EGO is dispersible in water and other polar organic solvents (e.g., ethanol and dimethylformamide) and can be exfoliated down to predominantly single-layered GO. Through a detailed study of the product intermediates, the graphite was found to first form a stage III or higher graphite intercalation compound, followed by electrochemical oxidation proceeding from the top of the packed graphite bed down. The EGO can be easily deoxygenated with low-temperature thermal annealing (<200°C) to produce thermally converted EGO with significantly enhanced conductivity, and its promising application as a conductive nanofiller in lithium-ion battery cathodes was demonstrated. The simplicity, cost-effectiveness, and unique EGO properties make our current method a viable contender for large-scale synthesis of GO.

Fast and cost-effective room temperature synthesis of high quality graphene oxide with excellent structural intactness

“…In addition, GO samples showed a weak broad peak centered at around 22°( see Fig. S1), and it is attributed to the less oxidized parts in GO [35][36][37]. For the GO oxidized at 25°C, the intensity of this broad peak is highest in GO-25C3h and decreases to the same level in both GO-25C5h and GO-25C9h.…”

Room temperature production of graphene oxide with thermally labile oxygen functional groups for improved lithium ion battery fabrication and performance

“…31 Mild thermal annealing in ambient air is a simple and effective route to deoxygenate GO. 52 By comparing the weight changes for GOGIC annealed at different constant temperatures (Figure 4d-f), GOGIC-25-8h saw the most weight loss at 150 °C, relative to other conditions, while GOGIC-45-4h lost more weight at 175 and 200 °C, implying deoxygenation of GOGIC-25-8h occurred more readily at lower temperature than GOGIC-45-4h. As shown in Table S1, the percentage of residual mass changed from 69% to 65% in GOGIC-25-8h as raising the annealing temperature from 150 to 200 °C.…”

Facile Synthesis of Boron-Doped Reduced Electrochemical Graphene Oxide for Sodium Ion Battery Anode

“…4d reveal that rEGO and B-rEGO have very high C/O ratios of 42.88 and 54.08, and a weak B1s peak at 192.2 eV in the B-rEGO sample indicates a tiny amount of boron (0.21 at.%), which has been doped in the final products. Compared with chemically made GO, electrochemically made GO shows higher thermal lability of oxygen groups, 8,62,63 which accounts for the high C/O ratio in the rEGO and B-rEGO. The elemental proportions in Table SIII and the deconvolution of XPS C1s spectra in Figure S4 revealed in detail the proportion of oxygen groups in EGO, and H 3 BO 3 -EGO was hugely reduced.…”

“…The B-rEGO contains even fewer oxygen functional groups than rEGO, because during annealing the intercalated tetraborate anion attached to C-O-C in H 3 BO 3 -EGO can assist in creating functional group-free vacancy sites instead of formation of C=O group at the vacancy site, which can facilitate the fast ion transport in electrode material. 8,31,62,63 TEM and selected area electron diffraction (SAED) were used to uncover the lattice structure of rGO. During the thermal reduction process, the layered structure of GO would be distorted and reorganized.…”

“…Graphene, a two-dimensional (2D) carbon allotrope, can provide short paths for charge transportation and ultra-large surface areas to accommodate metal ions in rechargeable batteries, making it a potential reliable platform for sodium storage. [6][7][8][9][10][11][12][13] Nevertheless, both experimental and theoretical calculations have indicated that atomically thin graphene is energetically unfavorable for Na ion adsorption unless high defect density is introduced to graphene. 14 With this motivation, a variety of graphene-derived materials, with a major focus on oxidation and elemental doping of graphene, 15,16 for high performance anodes of SIBs have been reported over the past decade.…”