Materials containing cobalt phosphide nanoparticles are among the most promising electrocatalysts for the hydrogen evolution reaction in terms of compromise between activity, cost, and durability. A simple and effective approach to fabricating a nanocomposite of graphene–phosphorene structures decorated with CoP nanoparticles 2–5 nm in size is proposed. The nanocomposite was fabricated by the electrochemical exfoliation of black phosphorus followed by the solvothermal synthesis. The synthesis was carried out in the presence of few-layer graphene structures doped with nitrogen atoms in the solution containing Co2+ ions. The electrocatalyst exhibited high activity and stability towards hydrogen evolution reaction in the acidic medium. In order to achieve a current density of 10 mA cm–2, an overpotential of 220 mV was required, and the Tafel slope was 63 mV dec–1. It is suggested that this result is due to both the synergistic effect of the interaction between graphene and phosphorene structures and the electrocatalytic activity of CoP nanoparticles, which are located at the edges of phosphorene structures.

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.

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 of the emission spectra of cathode electrolysis plasma during plasma electrochemical cleavage of black phosphorus and graphite under maximally identical experimental conditions has been carried out. A significantly lower concentration of active intermediates (OH radicals and O atoms) in the electrolysis plasma during the cleavafe of black phosphorus was found compared with a graphite electrode. It is assumed that this effect is due to a significantly higher rate of interaction of these intermediates with synthesized phosphorene structures than with graphene-like particles. This is confirmed by the detection of a much higher oxygen content in the products of black phosphorus cleavage than in synthesized carbon nanoparticles.

Nanocomposites of few-layer graphene structures with PdNi-alloy nanoparticles are synthesized using the electrochemical dispersion method. The composites’ chemical modification is shown to lead to a significant increase in their electrocatalytic activity in the methanol oxidation reaction.

На основании анализа спектров оптической и акустической генерации, формы осциллограмм тока и напряжения, наряду с данными по характеризации электронной микроскопией, РФЭ- и ИК-спектроскопией синтезированных малослойных графеновых структур, предложена эмпирическая модель одностадийного расщепления графита под воздействием импульсной амбиполярной электролизной плазмы.

The search for new hydrogen evolution reaction (HER) electrocatalysts with lower cost and higher activity and stability than noble metal catalysts is essential. In this regard cobalt phosphide is considered one of the most promising nanomaterials. The present work proposes a simple and efficient method for the synthesis of a nanocomposite of graphene–phosphorene structures decorated with CoP nanoparticles 2–5 nm in size via the electrochemical exfoliation of black phosphorus carried out in the presence of nitrogen-doped few-layer graphene structures and followed by solvothermal synthesis in a Co2+-containing solution. The obtained CoP/EEBP/N-FLGS nanocomposite demonstrates high electrocatalytic activity and stability towards HER in an alkaline medium. The nanocomposite is characterized by an overpotential of 190 mV at a current density of 10 mA cm−2 as well as a small Tafel slope (78 mV dec−1). These characteristics make the CoP/EEBP/N-FLGS nanocomposite superior to most electrocatalysts based on cobalt phosphides. The results of this study could be in demand for the future design and improvement of HER electrocatalysts.

Using the method of plasma-assisted electrochemical exfoliation of graphite, a nanocomposite, which consists of few-layer graphene structures with surface decorated with manganese oxides nanoparticles, is synthesized in one-step process. It is found that this material exhibits a high electrocatalytic activity towards the oxygen reduction reaction due to the presence of manganese in the +2 and +3 oxidation states, and also carbonyl (quinone) functional groups on the surface of graphene structures.

A boron-doped diamond electrode with a network structure of PdNi alloy nanowires, which is deposited onto its surface by laser ablation in superfluid helium, is considered as a possible sensor for formaldehyde. It is shown that the electrode is highly sensitive to trace amounts of formaldehyde.

Electrochemical behaviour of 4.8 +/- 0.2 nm graphene films on nickel and copper foams was investigated by cyclic voltammetry (CV). The graphene films were prepared by chemical vapor deposition and characterized by electron energy loss spectroscopy, elastic peak electron spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The CV of the [Ru(NH3)(6)](+2/+3) redox reaction was performed using these substrates. The obtained results demonstrated a high continuity of the deposited graphene film and independence of the electron transfer rate on them from the metal substrate used. The rate of outer-sphere electron transfer on the graphene surface appeared to be substantially less than that on the polished glassy carbon. Partial splitting of graphene layers due to wedged action of 2D adsorption layers, formed by camphor solution, led to the increase in double-layer capacitance.

An empirical model of the single-stage exfoliation of graphite under the influence of a pulsed ambipolar electrolysis plasma was proposed based on an analysis of optical and acoustic generation spectra, the shapes of current and voltage oscillograms, and data on the characterization of the synthesized few-layer graphene structures by electron microscopy, XPS, and IR spectroscopy.

A nanocomposite of few-layer graphene structures with cobalt oxides is synthesized for the first time in an aqueous electrolyte containing Co2+ 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.

A nanocomposite consisting of nitrogen-doped few-layer graphene structures, the surface of which is decorated with nanocrystallites of Mn1.5Co1.5O4 spinel oxide, was prepared by a single-stage method of plasma-assisted electrochemical exfoliation of graphite in a solution of 1 m NaNO3 + 0.005 m MnSO4 + 0.005 m CoSO4 + 0.01 m melamine. The high catalytic activity of the synthesized catalyst in the oxygen reduction reaction is due to pyridine nitrogen atoms and Mn1.5Co1.5O4 spinel nanoparticles.

By using a rotating disk electrode, it is shown for the first time that the network structures formed by long ultrathin (diameter ~4 nm) platinum nanowires deposited onto the surface of a glassy carbon electrode demonstrate the high specific catalytic activity in the oxygen reduction reaction.

Diamond compacts were synthesized by thermobaric processing of graphite and amorphous boron mixtures under the conditions of the diamond thermodynamic stability (at a pressure of 8–9 GPa and temperature of ∼2500 K). The boron-doped diamond-compact electrode surface was modified by its subjecting to the action of cathodic, anodic, and cathodic–anodic electrolytic plasma formed under the applying of voltage pulses with amplitude up to 300 V in Na2SO4 aqueous solution. It was found by using rotating disc electrode that the applying of sole cathodic–anodic plasma provides negligible catalytic effect with respect to the oxygen reduction reaction. However, thus pre-processed electrode acquired significant electrocatalytical activity upon the cathodic treatment, with the consequence that the reaction of O2 reduction to H2O passed predominantly by the four-electron mechanism. At the same time, the cathodic polarization of the plasma-modified electrode produced no effect on the rate constant of the electron transfer in the [Ru(NH3)6]2+/3+ redox couple; yet, the rate constant in the [Fe(CN)6]4–/3– one increased significantly. Hypothetically, the observed electrocatalytical effect in the oxygen reduction reaction is due to the formation, under the combined action of the cathodic–anodic plasma and cathodic polarization, of quinone groups at the boron-doped diamond surface; they play the role of active sites for the oxygen four-electron reduction.

For the first time, graphene-phosphorene structures were synthesized using the plasma-assisted electrochemical method. The catalytic activity of the composite obtained in the electrolytic plasma mode and its mixtures with few-layer graphene structures toward the hydrogen evolution reaction was studied. A substantial increase in the catalytic activity of the phosphorene structures towards the hydrogen evolution reaction was realized by mixing them with few-layer graphene structures. The catalyst demonstrates excellent activity towards the hydrogen evolution reaction in alkaline media with a low overpotential of 940 mV at a current density of 10 mA·cm−2 and a small Tafel slope of 130 mV dec−1.

A simple method for the mechanochemical synthesis of an effective metal-free electrocatalyst for the oxygen reduction reaction was demonstrated. A nitrogen-doped carbon material was obtained by grinding a mixture of graphene oxide and melamine in a planetary ball mill. The resulting material was characterized by XPS, EPR, and Raman and IR spectroscopy. The nitrogen concentration on the N-bmGO surface was 5.5 at.%. The nitrogen-enriched graphene material (NbmGO has half-wave potential of −0.175/−0.09 V and was shown to possess high activity as an electrocatalyst for oxygen reduction reaction. The electrocatalytic activity of NbmGO can be associated with a high concentration of active sites for the adsorption of oxygen molecules on its surface. The high current retention (93% for 12 h) after continuous polarization demonstrates the excellent long-term stability of NbmGO.

We present the method of conjugated bipolar plasma electrochemical synthesis of aqueous suspensions of composites of few-layer graphene structures with Co3O4 and Mn3O4 oxides and creation of mixed electrocatalysts based on them. As shown by the rotating disk electrode method, the best catalytic activity towards oxygen reduction reaction exceeding that for each individual component is demonstrated by the composition containing equal amounts of these composites.