The oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co₃O₄ and CoO/Co₃O₄ nanostructures using flame spray pyrolysis (FSP), as electrocatalysts for ORR in acidic and alkaline media. A detailed study of the effect of (Co-oxide)/Pt ratio on ORR efficiency shows that the present FSP-made Co-oxides are able to perform ORR at very low-Pt loading, 0.4% of total metal content. In acid medium, an electrode with (5.2% Pt + 4.8% Co₃O₄), achieved the highest ORR performance (J_max = 8.31 mA/cm², E_1/2 = 0.66 V). In alkaline medium, superior performance and stability have been achieved by an electrode with (0.4%Pt + 9.6% (CoO/Co₃O₄)) with ORR activity (J_max = 3.5 mA/cm², E_1/2 = 0.08 V). Using XRD, XPS, Raman and TEM data, we discuss the structural and electronic aspects of the FSP-made Co-oxide catalysts in relation to the ORR performance. Cyclic voltammetry data indicate that the ORR process involves active sites associated with Co³⁺ cations at the cobalt oxide surface. Technology-wise, the present work demonstrates that the developed FSP-protocols, constitutes a novel scalable process for production of co-oxides appropriate for oxygen reduction reaction electrodes.

Proton-exchange membrane fuel cells are one of the most promising energy conversion technologies for both automotive and stationary applications. Scientists are testing a number of solutions to increase the durability of cells, especially catalysts, which are the most expensive component. These solutions include, among others, the modification of the composition and morphology of supported nanoparticles, the platinum–support interface, and the support itself. A detailed understanding of the mechanism of platinum degradation and the subsequent improvement of the durability of the entire cell requires the development of methods for effectively monitoring the behavior of catalytic nanoparticles under various cell operating conditions. The Identical-Location Transmission Electron Microscopy (IL-TEM) method makes it possible to visually track structural and morphological changes in the catalyst directly. Because the tests are performed with a liquid electrolyte imitating a membrane, they provide better control of the degradation conditions and, consequently, facilitate the understanding of nanoparticle degradation processes in various operating conditions. This review is primarily intended to disseminate knowledge about this technique to scientists using electron microscopy in the study of energy materials and to draw attention to issues related to the characterization of the structure of carbon supports.

The climate crisis has become the most serious concern of human beings and environments worldwide in the 21st century. Global concerns about cancer epidemiology mainly originate from anthropogenic activities, particularly fossil-based operations. A key solution to this problem is the use of fuel cells—devices—capable of the direct conversion of fuel chemical energies like urea into electricity. To make their commercialization reasonable, one of the problems that needs to be solved is the development of anodic materials. The majority of investigations on urea oxidation are based on nickel, but its inadequate activity limits the efficiency of these devices. In this work, we propose and synthesize a Ni-Cu-Fe ternary electrocatalyst for urea oxidation through a fast and facile electrodeposition method. The properties of the synthesized material are examined by Scanning Electron Microscopy (SEM) conjugated with Energy Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). Its electrochemical properties were also examined in a 1 M KOH solution with and without 0.15 M urea. We found that the prepared powder is active in the electro-oxidation of urea, with 1.65 V_{vs RHE} required for a current density of 10 mA cm⁻² and a stable potential of 2.38 V_{vs RHE} required for 3 h of polarization at 10 mA cm⁻².