Milica Vujković

Carbon-supported Mo2C electrocatalysts for hydrogen evolution reaction

Molybdenum carbide (Mo2C) nanoparticles supported on two different carbon materials, carbon nanotubes and carbon xerogel, were prepared and characterised using X-ray diffraction, thermogravimetric analysis, scanning and transmission electron microscopy, nitrogen sorption and X-ray photoelectron spectroscopy. The analyses showed similar composition (ca. 27 wt% of Mo2C) and crystallite size (22–28 nm) for the two samples, but significantly different morphologies and specific surface areas. These were subsequently tested as electrocatalysts for hydrogen evolution reaction (HER) in acid media. Using linear scan voltammetry and electrochemical impedance measurements the main reaction parameters were determined, including Tafel slope, charge transfer coefficient and exchange current density. Capacitance properties were examined and correlated with the electrocatalysts activity for HER. The stability of the two materials was also investigated and proved to be very good.

Molybdenum Carbide Nanoparticles on Carbon Nanotubes and Carbon Xerogel: Low-Cost Cathodes for Hydrogen Production by Alkaline Water Electrolysis.

Low-cost molybdenum carbide (Mo2 C) nanoparticles supported on carbon nanotubes (CNTs) and on carbon xerogel (CXG) were prepared and their activity for the hydrogen evolution reaction (HER) was evaluated in 8 m KOH aqueous electrolyte at 25-85 °C. Measurements of the HER by linear scan voltammetry allowed us to determine Tafel slopes of 71 and 74 mV dec(-1) at 25 °C for Mo2 C/CNT and Mo2 C/CXG, respectively. Stability tests were also performed, which showed the steady performance of the two electrocatalysts. Moreover, the HER kinetics at Mo2 C/CNT was enhanced significantly after the long-term stability tests. The specific activity of both materials was high, and a higher stability was obtained for the activated Mo2 C/CNT (40 A g(-1) at -0.40 V vs. the reversible hydrogen electrode).

Synthesis and electrochemical properties of Na1.2V3O8/LTX as anodic material in sodium ion batteries

In this paper, the synthesis of composite Na1.2V3O8/LTX by sol-gel method was described. The synthesized powders were characterized by X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA) while the electrochemical performances were investigated by cycling voltammetry (CV) by different scan rate. After thermal treatment, the part of carbon was 7%. The initial discharge capacity was 100.44 mAhg-1. The most capacity fade was after 2nd cycle (14%) but capacity fade from 6th to 10th cycle was only 10%. The efficiency of Na1.2V3O8/LTX is around 95%.