Oxygen Electroreduction on Pt Nanoparticles Deposited on Reduced Graphene Oxide and N-doped Reduced Graphene Oxide Prepared by Plasma-assisted Synthesis in Aqueous Solution

One-Pot Synthesis of Pd Nanoparticles Supported on Carbide-Derived Carbon for Oxygen Reduction Reaction

We explored two methods for synthesizing Pd nanoparticles using three different carbide-derived carbon (CDC) support materials, one of which was nitrogen-doped. These materials were studied for oxygen reduction reaction (ORR) in 0.1 M KOH solution, and the resulting CDC/Pd catalysts were characterized using TEM, XRD, and XPS. The citrate method and the polyol method using polyvinylpyrrolidone (PVP) as a capping agent were employed to elucidate the impact of the support material on the final catalyst. The N-doping of the CDC material resulted in smaller Pd nanoparticles, but only in the case of the citrate method. This suggests that the influence of support is weaker when using the polyol method. The citrate method with CDC1, which is predominantly microporous, led to a higher degree of agglomeration and formation of larger particles in comparison to supports, which possessed a higher degree of mesoporosity. We achieved smaller Pd particle sizes using citrate and NaBH4 compared to the ethylene glycol PVP method. Pd deposited on CDC2 and CDC3 supports showed similar specific activity (SA), suggesting that the N-doping did not significantly influence the ORR process. The highest SA value was observed for CDC1/Pd_Cit, which could be attributed to the formation of larger Pd particles and agglomerates.

Enhanced oxygen reduction reaction activity and durability of Pt nanoparticles deposited on graphene-coated alumina nanofibres

The oxygen reduction reaction (ORR) activity and stability of Pt catalysts deposited on graphene-coated alumina nanofibres (GCNFs) were investigated. The GCNFs were fabricated by catalyst-free chemical vapour deposition. Pt nanoparticles (NPs) were deposited on the nanofibres by sonoelectrochemical and plasma-assisted synthesis methods. Scanning and transmission electron microscopy analyses revealed different surface morphologies of the prepared Pt catalysts, depending on the synthesis procedure. Sonoelectrochemical deposition resulted in a uniform distribution of smaller Pt NPs on the support surface, while plasma-assisted synthesis, along with well-dispersed smaller Pt NPs, led to particle agglomeration at certain nucleation sites. Further details about the surface features were obtained from cyclic voltammetry and CO stripping experiments in 0.1 M HClO₄ solution. Rotating disk electrode investigations revealed that the Pt/GCNF catalyst is more active towards the ORR in acid media than the commercial Pt/C (20 wt%). The prepared catalyst also showed significantly higher durability than commercial Pt/C, with no change in the half-wave potential after 10 000 potential cycles.

Oxygen reduction reaction on Pd nanocatalysts prepared by plasma-assisted synthesis on different carbon nanomaterials

In this work He/H₂ plasma jet treatment was used to reduce Pd ions in the aqueous solution with simultaneous deposition of created Pd nanoparticles to support materials. Graphene oxide (GO) and nitrogen-doped graphene oxide (NrGO) were both co-reduced with the Pd ions to formulate catalyst materials. Pd catalyst was also deposited on the surface of carbon black. The prepared catalyst materials were physically characterized using transmission electron microscopy, scanning electron microscopy and x-ray photoelectron spectroscopy. The plasma jet method yielded good dispersion of small Pd particles with average sizes of particles being: Pd/rGO 2.9 ± 0.6 nm, Pd/NrGO 2.3 ± 0.5 nm and Pd/Vulcan 2.8 ± 0.6 nm. The electrochemical oxygen reduction reaction (ORR) kinetics was explored using the rotating disk electrode method. Pd catalyst deposited on nitrogen-doped graphene material showed slightly improved ORR activity as compared to that on the nondoped substrate, however Vulcan carbon-supported Pd catalyst exhibited a higher specific activity for oxygen electroreduction.

Graphene and Graphene-Like Materials for Hydrogen Energy

The review is devoted to current and promising areas of application of graphene and materials based on it for generating environmentally friendly hydrogen energy. Analysis of the results of theoretical and experimental studies of hydrogen accumulation in graphene materials confirms the possibility of creating on their basis systems for reversible hydrogen storage, which combine high capacity, stability, and the possibility of rapid hydrogen evolution under conditions acceptable for practical use. Recent advances in the development of chemically and heat-resistant graphene-based membrane materials make it possible to create new gas separation membranes that provide high permeability and selectivity and are promising for hydrogen purification in processes of its production from natural gas. The characteristics of polymer membranes that are currently used in industry for the most part can be significantly improved with small additions of graphene materials. The use of graphene-like materials as a support of nanoparticles or as functional additives in the composition of the electrocatalytic layer in polymer electrolyte membrane fuel cells makes it possible to improve their characteristics and to increase the activity and stability of the electrocatalyst in the reaction of oxygen evolution.

A Review on the Promising Plasma-Assisted Preparation of Electrocatalysts

Electrocatalysts are becoming increasingly important for both energy conversion and environmental catalysis. Plasma technology can realize surface etching and heteroatom doping, and generate highly dispersed components and redox species to increase the exposure of the active edge sites so as to improve the surface utilization and catalytic activity. This review summarizes the recent plasma-assisted preparation methods of noble metal catalysts, non-noble metal catalysts, non-metal catalysts, and other electrochemical catalysts, with emphasis on the characteristics of plasma-assisted methods. The influence of the morphology, structure, defect, dopant, and other factors on the catalytic performance of electrocatalysts is discussed.