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.

N-doped graphene is not only a promising metal-free catalyst, but also a convenient carrier of metal nanoparticles for the creation of effective catalysts. Graphitic carbon nitride (g-C3N4) is used more often in photocatalytic processes and less often as electrocatalysts. This paper describes the preparation of N‑containing carbon composites consisting of reduced graphene oxide (rGO) and g-C3N4 for the further creation of metal-carbon catalytic systems. These composites were prepared by the heat treating dry mixtures of graphene oxide (GO) and melamine (MA) in the temperature range of 450-550 °C in air. Oxygen-containing groups were identified in the graphene oxide samples synthesized by the modified Hummers method and in its reduced form. The thermogravimetric analysis method was used to determine the ranges of relative thermal stability of the GO + MA mixtures, which were found to be almost identical for the studied compositions with different component ratios. The structure of the graphene oxide and its composites with MA after heat treatment was studied by scanning electron spectroscopy, X-ray diffraction analysis, FTIR spectroscopy and elemental analysis. The effect of the ratio of the initial components on the formation of the heat treatment products was determined. It was shown that to obtain the rGO+g-C3N4 composites with a high content of carbon nitride, the ratio of the initial reagents should be taken equal to 1:2, and the heat treatment should be carried out at 550 °C.

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.

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 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.