Effects of Different Ni-Fe/Ni Foam Catalysts on In Situ Preparation of CNTs@Ni Foam Electrode Materials and H2 during Steam Reforming of Pyrrole

New catalysts of Ni-Fe loading Ni foam (Ni-Fe/NF) were used in catalytic reforming of pyrrole for the co-production of H2 and CNTs@Ni foam electrode materials. Ni-Fe/NF with different Fe/ Ni ratios (0.5, 1, 2, and 3) and Ni/NF and Fe/NF catalysts were tested. The Ni-Fe alloy was formed on Ni-Fe/NF and remarkably promoted pyrrole conversion and H2 yield. They showed a trend of first increasing and then decreasing with the increase of the Fe/Ni ratio, and the N1F2/ NF (Fe/Ni ratio is 2) reached the maximum. The H2 yield over N1F2/ NF was 20 times larger than that over Ni/NF and Fe/NF. The high amount of Fe-Ni alloy with a small crystallite size boosted the catalytic activity of Ni-Fe/NF. After the reforming reaction, large amounts of CNTs were observed on the surface of Ni foam's skeleton network. The structures of CNTs@Ni foam were prepared and promoted by the Ni- Fe alloy. It proved that the CNTs on Ni-Fe/NF catalysts follow the tip-growth and vapor-liquid-solid (VLS) mechanisms. The Ni-Fe alloy contributed to the formation of liquid carbide and carbon intermediates, thus promoting the CNTs' growth. Compared with the pristine Ni foam, the prepared CNTs@Ni foam materials showed excellent electrochemical performance and had promising application potential in supercapacitors. The spent N1F1/NF (Fe/Ni ratio is 1) showed the best charging and discharging capacity.