Electrochemical synthesis of Fe-containing composite for decomposition of methane into COx-free hydrogen and nano-carbon

Decomposition of methane is the most efficient method for obtaining pure hydrogen. As catalysts for decomposition of methane, in this work, Ni-foam and Ni–Fe composites obtained by the electrochemical method were used for the first time. Thin iron films were electrochemically grown by potential cycling on the Ni-foam surface. The obtained catalysts were tested for decomposition of methane in the temperature range of 650–850 °C and characterized using XRD, RAMAN, SEM, TGA/DTA, H2-TPR and BET analysis of specific surface area and pore size. The effect of cycles (75, 150, and 250) of iron deposition on Ni-foam on its activity in methane decomposition was studied. It has been determined that the highest catalytic activity is observed for the composite, where the iron deposition cycle on nickel foam is 150. The Ni-Fe150 catalyst showed an initial methane conversion of 91% at a temperature of 850 °C, which increased from 60 min to 96.7% and from 180 min to 98.6%, and was stable for 540 min, while the hydrogen yield was 76%. It has been stated that graphite-like carbon is formed on all catalysts, and the largest amount (32%) is formed on Ni-Fe150. The data obtained in the work indicate that the increase in the activity of Ni-Fe150 in the decomposition of methane is associated with the formation of a Ni–Fe alloy and an increase in the reducibility of iron cations in the composition of the Ni–Fe alloy. In addition, the formation of graphite-like carbon with a high defectiveness on the surface of the Ni-Fe150 catalyst promotes the decomposition of methane in areas not covered with carbon.