Bimetallic Ni/Cu core–shell and Cu-Ni heterostructural micro- and nanoparticles were prepared using two simple successive reduction procedures. Monometallic Ni and Cu particles were synthesized for comparison. The phase constitutions and morphological features of the particles were studied by means of X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy methods. All the prepared mono- and bimetallic particles were applied as electrocatalysts in the electrohydrogenation of p-nitrophenol (p-NPh). An additional electrochemical reduction of copper cations during the hydrogen saturation of Cu-containing particles was established. The prepared Ni/Cu particles exhibited the highest electrocatalytic activity with an increase in the hydrogenation rate of p-NPh by more than three times compared to its electrochemical reduction on the nonactivated cathode, and p-NPh conversion yielded the maximum values. The main product of p-NPh electrocatalytic hydrogenation over Ni-Cu particles is p-aminophenol, which is an intermediate in the synthesis of many drugs. p-Aminophenol formation is confirmed by UV-Vis spectra.

Copper- and cobalt-containing carbon composites were prepared by pyrolysis of an aniline-formaldehyde polymer (AFP) doped with the metal oxides, followed by the reduction of metal cations in an electrochemical cell. AFP + metal oxide nanocomposites were synthesized by introducing a metal salt during the polycondensation of aniline with formaldehyde and by alkaline precipitation of metal oxides into the polymer matrix. The heat treatment was carried out at 400, 500 and 700 °C. Microscopic studies revealed the formation of CuO crystallites in the shape of "stars" on the heat-treated carbon material. The resulting composites were saturated with hydrogen in an electrochemical system, which was accompanied by the reduction of copper and cobalt cations, and the appearance of the metals in zero-valence state. The so-prepared Cu + copper oxides/C and Co + Co(OH)₂/C composites were used as electrocatalysts in the electrohydrogenation of acetophenone (APh). Compared to the electrochemical reduction of APh on a copper cathode (without catalysts), an increase in the rate of this process (by 2–4 times) in the presence of the composites and an increase in the APh conversion with the selective formation of 1-phenylethanol were established.

The N-doped metal-carbon composites based on the carbonized melamine-formaldehyde polymer (MFP) with silver, silver-copper, and silver-cobalt particles were synthesized. Mono- and bimetallic silver-containing composites were prepared by the reduction of metal nitrates with hydrazine hydrate in an aqueous ethanol medium in the presence of carbon black particles obtained by the heat treatment of MF-polymer at 500 °C. The structural-phase changes before and after the use of metal-carbon composites as electrocatalysts in the electrohydrogenation of p-nitroaniline (p-NA) were studied by X-ray diffraction analysis. The morpho-logical features of the created MFBC + Ag, MFBC + (Ag+Cu) and MFBC + (Ag+Co) composites were stud-ied by electron microscopy. It was established that the synthesized composites mainly contain crystalline phases of the corresponding reduced metals or their alloys. The monometallic MFBC(1) + Ag(1) composite contains reduced silver crystallites of various shapes and localization on porous MF carbon black particles. Higher electrocatalytic activity of the synthesized Ag-containing composites in the p-NA electrohydro-genation was shown in comparison not only with the electrochemical reduction of p-NA but also with MFBC + (Ag+Cu) composites with electrocatalytic hydrogenation of p-NA on Ag + Cu particles (without MFBC). It was found that the use of the studied MFBC-composites increases the selectivity of the formation of the main hydrogenation product (p-phenylenediamine) and decreases the yields of by-products.

Bimetallic Ni/Cu core-shell and Cu-Ni heterostructural micro- and nanoparticles were prepared using two simple successive reduction procedures. Monometallic Ni and Cu particles were synthesized for comparison. The phase constitutions and morphological features of the particles were studied by means of X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscopy methods. All the obtained mono- and bimetallic particles were applied as electrocatalysts in the electrohydrogenation of p-nitrophenol (p-NPh). An additional electrochemical reduction of copper cations during the hydrogen saturation of Cu-containing particles was established. Some of the prepared particles exhibited high catalytic activity with an increase in the hydrogenation rate of p-NPh by more than 3 times compared to its electrochemical reduction on the non-activated cathode, and p-NPh conversion yielded the maximum values. The main product of p-NPh electrocatalytic hydrogenation over Ni-Cu particles is p-aminophenol, which is an intermediate in the synthesis of many drugs. p-Aminophenol formation is confirmed by UV-Vis spectra.

A facile co-precipitation method was employed to synthesize copper(II) ferrite composites with carbon materials (reduced graphene oxide, graphitic carbon nitride, and their mixture), followed by heat treatment at 700 °C. To obtain Fe-Cu-containing catalysts, copper ferrite composites were electrochemically reduced. Structures, compositions, and morphologies of the composites were studied using scanning electron microscopy, X-ray diffraction techniques, and thermogravimetric analysis. The results showed that graphitic carbon nitride had the strongest effect on the phase composition of copper ferrite. Crystalline phases of reduced copper and iron metals appear in the CuFe₂O₄/g-C₃N₄ composite during the annealing process, facilitating further complete electrochemical reduction of copper ferrite and shortening its duration. The resulting Fe-Cu/C composites were used as catalysts in the electrohydrogenation of acetophenone as a model compound. The activation of the cathode with Fe-Cu/C catalysts increases the rate of acetophenone hydrogenation and leads to the selective formation of a single product, 1-phenylethanol, in high yields.

Bimetallic Fe-Ag composites were fabricated based on silver (I) ferrite (AgFeO2) synthesized using a co-precipitation method with and without the polyvinyl alcohol as a nanoparticle stabilizer, followed by the heat treatment at 500, 700 and 900°C and electrochemical reduction. Phase compositions and morphological features of AgFeO2 samples produced after heat treatment and after electrochemical experiments were determined by X-ray diffraction analysis and electron microscopy. A decrease in the temperature of the thermal decomposition of silver ferrite prepared with polyvinyl alcohol was established. The possibility of the electrochemical reduction of AgFeO2 in aqueous alkaline catholyte on a copper cathode with the formation of crystalline phases of both metals or their alloy was shown. The Fe-Ag composites formed during heat treatment and electrochemical reduction were used as electrocatalysts in the electrohydrogenation of p- and o-isomers of nitrobenzoic acid and exhibited high activity. Compared to their electrochemical reduction under similar conditions, the hydrogenation rate and hydrogen utilization coefficient were increased, and their conversion reached the maximum values. The main products of electrocatalytic hydrogenation are p- and o-isomers of aminobenzoic acid, which are widely used in the production of drugs (for example, benzocaine, novocaine., etc.).