Interconnected Co‐Entrapped, N‐Doped Carbon Nanotube Film as Active Hydrogen Evolution Cathode over the Whole pH Range

The use of electrocatalysts with low metal content (metal-deficient) or metal free for the hydrogen evolution reaction (HER) can prevent or decrease metal ion release, which reduces environmental impact; development of such catalysts with high activity and durability over the whole pH range is thus highly desired but still remains a huge challenge. Herein, we describe the direct growth of a film consisting of interconnected Co-entrapped, N-doped carbon nanotubes on carbon cloth using chemical vapor deposition from dicyanodiamine using a Co3 O4 nanowire array as catalyst. This integrated architecture is used as a flexible 3D electrode for the electrolytic hydrogen evolution with outstanding catalytic activity and durability in acidic media. Moreover, this electrode is also highly efficient under neutral and basic conditions. It offers us an attractive carbon-based metal-deficient HER catalyst outperforming most transition-metal and all metal-free/deficient catalysts.