Oxide Carbon Electrode Research Articles

Selective lithium extraction using capacitive deionization with fabricated zeolitic imidazolate framework encapsulated manganese oxide carbon electrode

Presently, substantial research focus is being placed on alternative lithium (Li) extraction from natural water sources such as seawater and salt brine to meet the growing demand for Li, a crucial component for energy storage. Electrochemical capacitive deionization (CDI) shows promising capacity to rapidly extract Li from brine solutions with selective electrodes. This study fabricated activated carbon (AC)-based Li-selective electrodes with hydrogen manganese oxide (HMO) ion-exchange nanomaterial, HMO@AC, and zeolitic imidazolate frameworks encapsulated HMO (HMO@ZIF-AC) electrodes. The incorporation of HMO@ZIF-AC electrode into CDI resulted in rapid Li-ion adsorption and a notable reduction in Mg-ion uptake compared to HMO-AC electrode. In mixed solutions, HMO@ZIF-AC displayed promising Li selectivity over other ions (ρNa+Li+ = 13.14, ρK+Li+ = 6.60, ρMg2+Li+ = 1.69). Also, HMO@ZIF-AC exhibited enhanced Li selectivity in highly saline conditions (Na: Li molar ratio of 96:1). The high performance of HMO@ZIF-AC compared to HMO-AC was attributed to its higher surface area that provided higher vacant sites and the presence of Zn. This was evident as a significantly higher Li uptake (46–48 %) was achieved with a Zn doped HMO electrode (Zn-HMO-AC) compared to HMO-AC and HMO@ZIF-AC electrodes. Meanwhile, compared to HMO-AC, the high Li to Mg selectivity of HMO@ZIF-AC was attributed to the small cavity size of the activated ZIF, creating specialized pathways for Li ions and impeding the ion conduction of Mg2+.

Influence of surface chemistry of activated carbon electrodes on electro-assisted adsorption of arsenate

In this work, the influence of oxygen-containing surface groups of activated carbon electrodes on the charge efficiency of electro-assisted adsorption of As(V) was investigated. It was distinguished between activated carbons modified through acidic (oxidation) and thermal (reduction) treatments, starting with a granular pristine commercial activated carbon of bituminous origin. The textural characterization of the three materials showed that the treatments did not produce significant changes in the surface area and in the distribution of pores. The three carbon samples were used to fabricate packed electrodes with stainless-steel mesh as electric current collector. This work report that the application of anodic potentials (1.01 and 1.41 V vs. NHE) increased the adsorption capacity and rate of arsenate uptake in solutions containing only this contaminant (2.5 mg L−1) at pH 7. The oxidized carbon electrode presented the lowest capacitance and adsorption capacity during electroadsorption (0.33 mg g−1), compared to pristine material (1.77 mg g−1). On the other hand, the reduced electrode displayed the highest adsorption capacity of arsenate (3.14 mg g−1) when applying a potential of 1.01 V. The results were correlated with the potential of zero charge values. In addition, for this material, the rate of kinetics increased 26.7 % compared to experiments without applied potential.

Amorphous Si-island/graphene oxide-carbon hybrid anode thin film for a lithium-ion battery

A multi-layered graphene oxide-carbon/Si-island thin film/graphene oxide-carbon electrode is prepared as a very promising anode material for rechargeable Li-ion batteries. In this approach, graphene oxide-carbon layers are introduced to improve the adhesion (between the Si-island and copper current collector) and conductivity. The Si-island (diameter: 700μm; array distance: 480μm) is sputtered using a metal shadow mask. The strain during the insertion and extraction of the Li ions is adequately suppressed by the space among the neighboring Si-islands. This results in a superior cycle retention of 86.3% with a reversible discharge capacity of 940mAhg−1 after 105cycles.

Three-dimensional hierarchical metal oxide–carbon electrode materials for highly efficient microbial electrosynthesis

The production of hierarchical hybrid conductive materials that are mesoporous, with pores spanning from sub-microns to microns in size, is important for large-area electrode applications.

Real-time detection of carboplatin using a microfluidic system.

A microfluidic sensor system based on a carbon nanotube-epoxy composite electrode was fabricated to allow detection of the presence of the anti-cancer drug carboplatin in healthy tissue in real time during chemotherapy. Detection of carboplatin was carried out by observing the effects of the drug on the differential pulse voltammetry of free purine bases using a novel carbon nanotube-epoxy composite electrode. In free solution these electrodes performed better than glassy carbon electrodes for oxidation of the free purine bases AMP and GMP, and than DNA-modified carbon nanotube-epoxy composite sensors for detection of carboplatin. On-line carboplatin detection was performed using a computer-controlled microfluidic platform. The methodology for on-line carboplatin detection was optimised in terms of the analysis time and to allow repeated carboplatin measurement using the same electrode. Microdialysis sampling and our microfluidic platform were combined to give a proof-of-concept system for real-time carboplatin detection with a limit of detection of 0.014 μM carboplatin in the sampled media. This paper is dedicated to Craig Lunte's pioneering work in analysis and microdialysis.

Electrode-assisted catalytic water oxidation by a flavin derivative

The success of solar fuel technology relies on the development of efficient catalysts that can oxidize or reduce water. All molecular water-oxidation catalysts reported thus far are transition-metal complexes, however, here we report catalytic water oxidation to give oxygen by a fully organic compound, the N(5)-ethylflavinium ion, Et-Fl(+). Evolution of oxygen was detected during bulk electrolysis of aqueous Et-Fl(+) solutions at several potentials above +1.9V versus normal hydrogen electrode. The catalysis was found to occur on glassy carbon and platinum working electrodes, but no catalysis was observed on fluoride-doped tin-oxide electrodes. Based on spectroelectrochemical results and preliminary calculations with density functional theory, one possible mechanistic route is proposed in which the oxygen evolution occurs from a peroxide intermediate formed between the oxidized flavin pseudobase and the oxidized carbon electrode. These findings offer an organic alternative to the traditional water-oxidation catalysts based on transition metals.

Investigation of polymer electrolyte hybrid supercapacitor based on manganese oxide–carbon electrodes

A hybrid supercapacitor based on manganese oxide, activated carbon and polymer electrolyte was developed and electrochemically investigated. The capacitive performance obtained from the polymer electrolyte based supercapacitor was similar to that of an aqueous electrolyte based supercapacitor, tested for comparison in the same operative conditions. A durability test carried out for 2500 cycles showed stable and slowly increasing performance. The specific capacitance of hybrid supercapacitor was 48 F g −1 (192 F g −1 as a mean one electrode capacitance), in which that of the positive electrode was 384 F g −1 of MnO 2 and that of negative electrode 117 F g −1 of carbon. The impedance analysis evidenced that although the polymer electrolyte based hybrid supercapacitor showed higher resistance compared to that of the liquid electrolyte based supercapacitor, this drawback was counterbalanced by better ion transport features, which were evident at lower frequencies, where similar values of capacitances were obtained from the different supercapacitors.

Electrochemically oxidized carbon anode in direct l-ascorbic acid fuel cells

The activity of electrochemically oxidized carbon electrode was investigated in the operation of a direct l-ascorbic acid fuel cell anode. The surface oxygen species placed on electrochemically oxidized carbon electrode were analyzed by X-ray photoelectron spectroscopy and cyclic voltammetry. The electrochemical oxidation process of carbon electrode can facilitate the pore-filling process (i.e., wetting) of the electrolyte into the microstructure of the carbon electrode by increasing the number of more polar functional groups on the electrode surface. The electrochemically oxidized carbon electrode exhibited significantly enhanced electro-catalytic oxidation activity of l-ascorbic acid compared to an unmodified carbon electrode. Moreover, the simplified electrode structure using carbon paper without an additional powder-based precious catalyst layer is very favorable in creating percolation network and generates power density of 18 mW/cm 2 at 60 °C.