Structure and stability of partially chlorinated molybdenum carbide composite materials synthesised via high temperature chlorination

Composite materials of molybdenum carbide and porous carbon were synthesised from molybdenum carbide using high temperature chlorination method with different applied chlorination times in order to use them as catalyst supports and electrode materials in various devices. X-ray diffraction, Raman spectroscopy, low temperature N2 sorption and high resolution transmission electron microscopy methods were used to characterise the structure of synthesised materials. The microporous-mesoporous material particles consist of β-Mo2C surrounded by porous amorphous carbon material. The partially chlorinated Mo2C particles were not surrounded by a graphitised shell. The specific surface area of the powders increased from 180 m2 g−1 up to 2020 m2 g−1 with increasing chlorination depth, i.e. decreasing carbon content in the particles. The stability and electrochemical behaviour of the synthesised composite materials were studied in 0.5 M H2SO4 solution using cyclic voltammetry and electrochemical impedance spectroscopy. The Mo2C phase in the studied composite materials was not stable in the acidic solution and dissolution of Mo2C was observed. The electrochemically treated working materials from which the Mo2C phase had been electrochemically dissolved had very good stability. The gravimetric capacitance increased with the increase of specific surface area and reached values up to 140 F g−1.