Few-layer graphene structures with a surface decorated with oxygen functional groups and sulfur-containing groups have been obtained during electrochemical exfoliation of graphite performed in the ...cathodic and anodic plasma modes. Conductivity of a synthesized carbon material has been estimated and its catalytic activity towards the oxygen reduction reaction has been studied. For the few-layer graphene structures synthesized in the anodic plasma mode, a considerable catalytic effect has been observed, which involved decrease in overpotential of the oxygen reduction and increase in contribution of a four-electron oxygen reduction in the overall process. This effect is shown to be determined by the surface carbonyl groups which are the active centres of the four-electron oxygen reduction at potentials less than −700 mV vs. Ag/AgCl.
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•Plasma-assisted electrochemical exfoliation of graphite was carried out.•Electrochemical exfoliation of graphite results in few-layer graphene structures.•XPS analysis reveals carbonyl groups on the surface of obtained carbon particles.•Either cathodic or anodic plasma mode leads to the different content of CO groups.•Surface concentration of carbonyl groups determines catalytic activity towards ORR.
The effect of plasma electrochemical activation of boron-doped diamond compact electrodes on the oxygen electroreduction reaction kinetics is studied. The conducting compact electrodes are prepared ...via graphite-to-diamond conversion in C–B growth system at high pressure and high temperature. The diamond compact electrode surface was modified in Na2SO4 aqueous solution by exposition to cathodic–anodic electrolytic plasma produced by the application of voltage pulses with amplitude up to 300 V. The cathodic–anodic plasma alone proved to produce but negligible catalytic effect with respect to the oxygen reduction reaction. However, on the cathodic reduction of thus treated electrode, it acquired significant electrocatalytical activity manifested itself in the predominant O2-to-H2O reduction by a four-electron pathway. At the same time, the cathodic treatment of the plasma-modified electrodes has no real impact on the rate constant of electron transfer in the “fast” Ru(NH3)62+/3+ and Fe(CN)64–/3– redox systems. The observed electrocatalytical effect with respect to the oxygen reduction reaction is assumed to be caused by the quinone groups formation at the boron-doped diamond electrode surface under the combined action of cathodic–anodic plasma and cathodic polarization, these groups being active centers for the four-electron oxygen reduction.
A comparative analysis of various methods of forming a copper (Cu) contact grid on the surface of silicon heterojunction solar cells (SHJ SC) as an alternative to the standard screen printing method ...using expensive silver-containing (Ag) pastes is presented. It has been shown that the use of inkjet printing for the formation of protective dielectric masks based on an organic polymer and thin buffer metal layers for the growth of a Cu contact grid by electroplating makes it possible to form a contact grid of the required shape and having sufficient adhesion to the surface of SHJ SC. Using this method, double-sided SHJ SC (size 157 × 157 mm
2
) with Cu contact mesh were fabricated, demonstrating an efficiency of 22.9% and an adhesion level of 3–5 N/mm compared to 22.6% and 1.5–2 N/mm using a similar contact mesh based on Ag paste.
Nitrogen-doped few-layered graphene structures are synthesized by plasma-assisted electrochemical exfoliation of graphite and used in the preparation of composites with phosphorene structures ...obtained by supersonic exfoliation of a porous black-phosphorus electrode covered with preliminarily deposited cobalt. The catalytic activity in the hydrogen evolution reaction is studied for the few-layered graphene and phosphorene structures, as well as their mixtures. The mixed electrocatalysts demonstrate the highest activity in the hydrogen evolution reaction.
A comparative study has been conducted on the cathode electrolysis plasma emission spectra recorded during the plasma-assisted electrochemical exfoliation of black phosphorus and graphite under ...maximally identical experimental conditions. It has been found that in the case of black phosphorus exfoliation, the concentration of active intermediates (OH radicals and O atoms) in electrolytic plasma is significantly lower than that in the case of the graphite electrode. It has been assumed that this effect is due to the fact that the rate of interaction of the above intermediates with the synthesized phosphorene structures is significantly higher than the rate of interaction with graphene-like particles. This assumption has been confirmed by the detection of a significantly higher oxygen content in the exfoliation products of black phosphorus than the oxygen content in the synthesized carbon nanoparticles.
Surface of boron-doped diamond film electrode was subjected to plasma-assisted electrochemical treatment by anodic plasma pulses, and a change in the rate constant of electron transfer for several ...model redox reactions was analyzed.
A nanocomposite of few-layer graphene structures with cobalt oxides is synthesized for the first time in an aqueous electrolyte containing Co
2+
ions by the method of plasma electrochemical ...exfoliation of graphite in its bipolar version. The high electrocatalytic activity of this composite in the oxygen reduction reaction is demonstrated with the use of a rotating disk electrode.
