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The aim of this study is to present a straightforward methodology for the preparation of non-precious metal catalysts comprising MnO2 and carbonaceous materials, namely graphite powder (C), graphitic carbon nitride (gCN), and graphitic carbon nitride/graphite powder (gCN/C) substrates. The morphology and composition of the prepared MnO2/C, MnO2–gCN, and MnO2–gCN/C catalysts have been investigated using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrochemical performance of the prepared MnO2/C, MnO2–gCN, and MnO2–gCN/C catalysts has been investigated for the oxygen reduction reaction (ORR) and oxygen evolution (OER) reaction using cyclic and linear voltammetry. All of the investigated catalysts exhibited enhanced electrocatalytic activity with regard to the ORR and OER processes when compared with the bare substrates. The MnO2–gCN/C catalyst was found to be the most efficient catalyst for both investigated reactions when compared with MnO2/C and MnO2–gCN. The MnO2–gCN/C catalyst demonstrated the most positive ORR onset potential of 0.9 V and the most negative OER onset potential of 1.53 V. Furthermore, it demonstrated remarkable stability, retaining approximately 85% of its initial signal after a continuous test of 24 hours in both long-term ORR and OER processes. [ABSTRACT FROM AUTHOR]

The production of high-purity hydrogen from hydrogen storage materials with further direct use of generated hydrogen in fuel cells is still a relevant research field. For this purpose, nickel-molybdenum-plated copper catalysts (NiMo/Cu), comprising between 1 and 20 wt.% molybdenum, as catalytic materials for hydrogen generation, were prepared using a low-cost, straightforward electroless metal deposition method by using citrate plating baths containing Ni2+–Mo6+ ions as a metal source and morpholine borane as a reducing agent. The catalytic activity of the prepared NiMo/Cu catalysts toward alkaline sodium borohydride (NaBH4) hydrolysis increased with the increase in the content of molybdenum present in the catalysts. The hydrogen generation rate of 6.48 L min−1 gcat−1 was achieved by employing NiMo/Cu comprising 20 wt.% at a temperature of 343 K and a calculated activation energy of 60.49 kJ mol−1 with remarkable stability, retaining 94% of its initial catalytic activity for NaBH4 hydrolysis following the completion of the fifth cycle. The synergetic effect between nickel and molybdenum, in addition to the formation of solid-state solutions between metals, promoted the hydrogen generation reaction. [ABSTRACT FROM AUTHOR]

This document discusses the importance of renewable and sustainable energy sources in light of the negative impact of fossil fuels on climate change. It focuses on the development of advanced catalytic materials for fuel cells, batteries, electrolysers, and solar cells. The research explores various types of fuel cells and investigates the mechanisms and kinetics of energy conversion reactions. Specific contributions include the oxidation of borohydride and the oxygen evolution reaction. The document also explores the use of PET bottle waste and perovskite-structured catalysts for energy conversion. The goal is to develop cost-effective and efficient catalysts for renewable energy generation and storage. The article discusses several studies on the development of catalytic materials for energy conversion reactions. These studies highlight the importance of diverse catalysts in renewable energy applications. [Extracted from the article]

In this paper, the generation of hydrogen from alkaline sodium borohydride solution by hydrolysis is studied. To obtain catalysts for efficient hydrogen generation, Ni, Mn, Mo, and Co metals were deposited on the Cu surface by the simple electroless metal deposition method using morpholine borane as a reducing agent. Depending on the peculiarities of the deposition of each metal, the coating thickness was ca. 1 μm for all catalysts. The deposited coatings were compact and crack-free, with multilayer characteristics and a cauliflower-like structure. The prepared Ni/Cu, NiMn/Cu, NiMo/Cu, NiCo/Cu, NiCoMn/Cu, NiCoMo/Cu, and NiCoMoMn/Cu catalysts showed an efficient catalytic activity for sodium borohydride hydrolysis reaction. The lowest activation energy of 45.3 kJ mol−1 for sodium borohydride hydrolysis reaction was obtained using the NiCoMoMn/Cu catalyst. The highest hydrogen generation rate of 3.08 mL min−1 was also achieved using this catalyst at 303 K. With a further increase in temperature to 343 K, the hydrogen generation rate catalyzed by the NiCoMoMn/Cu increased 7.7 times and reached 23.57 mL min−1. [ABSTRACT FROM AUTHOR]

This paper describes the activity of PdCo3O4/C obtained by wet impregnation towards the oxygen reduction reaction (ORR). For this purpose, the Co3O4/C substrate was synthesized using the microwave irradiation heating method with further annealing of the substrate at 400 °C for 3 h (Co3O4/C-T). Then, the initial Co3O4/C substrate was impregnated with palladium chloride (Pd-Cl2-Co3O4/C), and then part of the obtained Pd-Cl2-Co3O4/C catalyst was annealed at 400 °C for 3 h (PdOCo3O4/C). The electrocatalytic activity of the prepared catalysts was investigated for the oxygen reduction reaction in alkaline media and compared with the commercial Pt/C (Tanaka wt. 46.6% Pt) catalyst. It was found that the annealed PdOCo3O4/C catalyst showed the largest ORR current density value of −11.27 mA cm−2 compared with Pd-Cl2-Co3O4/C (−7.39 mA cm−2) and commercial Pt/C (−5.25 mA cm−2). [ABSTRACT FROM AUTHOR]

AuCeO2/C and Au/C catalysts were obtained by adsorption of AuNPs on the CeO2/C and pure carbon (C) substrates from an Au colloidal solution. It has been found that AuNPs of ca. 50 nm in size were adsorbed on the surfaces of CeO2/C and C; however, electrocatalytic activity of the investigated AuCeO2/C and Au/C catalysts was different. Ethylene glycol oxidation current density values are ca. 3 times higher on the AuCeO2/C catalyst as compared to those of the bare Au/C catalyst. Moreover, the AuCeO2/C catalyst showed more positive onset potentials, as well as higher current in the mixed-kinetic-diffusion region towards the oxygen reduction reaction in an alkaline medium compared to that of the Au/C catalyst. [ABSTRACT FROM AUTHOR]

The aim of the study was to prepare and to investigate the catalytic activity of the Nb2O5/graphene-supported platinum-cobalt catalyst for the oxygen reduction reaction (ORR) in alkaline and acidic media. Electrocatalytic properties of the prepared catalyst towards the oxygen reduction reaction were characterized by using cyclic voltammetry (CV) and rotating disk electrode (RDE) linear sweep voltammetry (LSV). It has been found that the PtCoNb2O5/graphene catalyst shows more positive onset potentials, as well as higher current in the mixed-kineticdiffusion region towards the oxygen reduction reaction in both alkaline and acidic solutions as compared with those for the bare Pt/GR catalyst. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the activity of CeO2/C and Nb2O5/C supported platinum nanoparticles composites, prepared by the rapid microwave synthesis method, towards the oxidation of ethanol in an alkaline medium. The electrocatalytic activity of the Pt-CeO2/C and Pt-Nb2O5/C catalysts with respect to the electro-oxidation of ethanol was investigated by means of cyclic voltammetry. The electrochemical behaviour of the synthesized catalysts towards the oxidation of ethanol was compared with that of a carbon supported bare Pt catalyst. X-ray Diffraction and Transmission Electron Microscopy were used to determine the structure, shape and the size of catalysts particles. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was employed to determine the composition of the synthesized catalysts. It has been found that the both investigated Pt-CeO2/C and Pt-Nb2O5/C catalysts show a higher activity towards the electro-oxidation of ethanol when compared with that of the Pt/C catalyst, the Pt- Nb2O5/C catalyst being most active. [ABSTRACT FROM AUTHOR]

The paper describes fabrication of the graphene and Nb2O5/graphene supported Pt or PtCo nanoparticles catalysts by means of microwave synthesis. The electrocatalytic activities of the synthesized catalysts towards the reduction of oxygen were investigated by linear scan voltammetry. It has been found that the graphene and Nb2O5/graphene supported PtCo nanoparticles catalysts show exhibited electrocatalytic efficiency towards the reduction of oxygen when compared with that of bare Pt/GR catalyst. [ABSTRACT FROM AUTHOR]

The graphene (GR) supported PtCo catalysts with diferent Pt:Co molar ratios were fabricated by means of the rapid microwave heating method. The size and shape of catalyst nanoparticles were determined by means of Transmission Electron Microscopy. Electrochemical properties of the PtCo/GR catalysts were investigated towards the electro-oxidation of methanol in an acidic medium by means of cyclic voltammetry and chronoamperometry. The PtCo/GR catalysts with an average Pt particle size of ca. 1-3 nm were synthesized from the reaction mixture containing H2PtCl6, CoCl2 and ethylene glycol. It should be noted that the electrocatalytic activity of PtCo/GR catalysts depends on the molar ratio of Pt:Co in the catalysts. It was found that the synthesized PtCo/GR catalysts with the Pt:Co molar ratios equal to 1:3 and 1:6 exhibited an enhanced electrocatalytic activity for methanol electro-oxidation as compared with that of catalysts with the Pt:Co molar ratios equal to 1:20, 1:50 and 1:60 and 1:0. [ABSTRACT FROM AUTHOR]

Trisodium salt of 2-hydroxy-1,2,3-propanetricarboxylic acid (citric acid) forming sufficiently stable complexes with copper(II) ions in alkaline solutions was found to be a suitable ligand for copper(II) chelating in alkaline (pH > 12) electroless copper deposition solutions. The reduction of copper(II)-citrate complexes by hydrated formaldehyde was investigated and the copper deposits formed were characterized. The thickness of the compact copper coatings obtained under optimal operating conditions in 1 h reaches ca. 3 µm at ambient temperature. The plating solutions were stable and no signs of Cu(II) reduction in the bulk solution were observed. The results were compared to those for systems operating with other copper(II) ligands. Solution equilibria were discussed and itemized. [ABSTRACT FROM AUTHOR]

This paper describes the investigation of electrocatalytic activity of the AuCeO2/C catalyst, prepared using the microwave irradiation method, towards the oxidation of sodium borohydride and oxygen reduction reactions in an alkaline medium. It was found that the obtained AuCeO2/C catalyst with Au loading and electrochemically active surface area of Au nanoparticles (AuNPs) equal to 71 µg cm−2 and 0.05 cm2, respectively, showed an enhanced electrocatalytic activity towards investigated reactions, compared with the Au/C catalyst with an Au loading and electrochemically active surface area of AuNPs equal to 78 µg cm−2 and 0.19 cm2, respectively. The AuCeO2/C catalyst demonstrated ca. 4.5 times higher current density values for the oxidation of sodium borohydride compared with those of the bare Au/C catalyst. Moreover, the onset potential of the oxygen reduction reaction (0.96 V) on the AuCeO2/C catalyst was similar to the commercial Pt/C (0.98 V). [ABSTRACT FROM AUTHOR]