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Abstract In the present work, nitrogen-doped mesoporous carbon nanosheets (NMCNs) are prepared and extensively investigated for the oxygen reduction reaction. Initially, by using dual templates, viz. graphene oxide and a cationic surfactant, silica films (thickness: 1.0 nm) are synthesized and characterized using transmission electron microscope (TEM), nitrogen adsorption-desorption (N 2 ad/des) measurements, and small-angle X-ray diffraction (SA-XRD). Morphology and structure of silica evolve along with graphene oxide concentration, while the co-operative assembly and the final structure are determined by the electrostatic interaction between the dual templates. The effect of silica template on the resultant NMCNs is investigated physicochemically by photoelectron spectroscopy (XPS), TEM, N 2 ad/des and electrochemically by cyclic voltammetry (CV), and linear sweep voltammetry (LSV). NMCNs are featured of a high content of nitrogen dopant, high specific surface area (SSA) and ultrathin thickness (1.5 nm), favoring catalysis and facilitating the mass transport of the reactive species. From the electrochemical tests, it is confirmed that NMCNs yield a high oxygen reduction reaction (ORR) electrocatalytic activity in acid and alkaline environment; this activity is similar or even better as compared with the one measured over carbon supported platinum commercial catalyst (40 wt % Pt/C). Graphical abstract Image 1 Highlights • Nitrogen-doped mesoporous carbon nanosheets (NMCNs) are prepared by a nanocasting method. • NMCNs presents high content of nitrogen dopant, ultrathin thickness and high specific surface area. • Electrochemical tests confirm that NMCNs yield a high oxygen reduction reaction (ORR) activity. • ORR activity is comparable or even better when compared with that of commercial Pt/C catalyst. [ABSTRACT FROM AUTHOR]

In the present work, the steady-state current-overpotential characteristics of the Fe|BaCe 0.5 Zr 0.3 Y 0.08 Yb 0.08 Cu 0.04 O 3-δ |Fe interface as a function of the gas phase composition and temperature are investigated. To this purpose a BaCe 0.5 Zr 0.3 Y 0.08 Yb 0.08 Cu 0.04 O 3–δ dense ceramic material is successfully synthesized by solid state synthesis and sintered at 1400 °C. Then its crystal structure, ceramic and electrical properties are investigated. It is found that the ceramic has a high relative density (more than 90%) and acceptable proton conductivity (1.5 and 6.8 mS cm −1 at 500 and 900 °C, respectively). On the as prepared BaCe 0.5 Zr 0.3 Y 0.08 Yb 0.08 Cu 0.04 O 3–δ electrolyte disk, three thin Fe porous layers are deposited by painting on both sides (three electrode system), which is then immersed in a tubular single-chamber continuous electrochemical reactor. The polarization measurements are carried out in the temperature range between 500 and 700 °C and at three different H 2 /He wet (3% steam) compositions. The apparent anodic and cathodic charge transfer coefficients (Tafel region) are found to be: α a = α c = 0.8, while the apparent activation energy is calculated to be approximately 0.55 ± 0.05 eV. It is also found that by increasing the hydrogen concentration the current density increases, especially at higher temperature values. [ABSTRACT FROM AUTHOR]