An Ingenious Strategy to Integrate Multiple Electrocatalytically Active Components within a Well-Aligned Nitrogen-Doped Carbon Nanotube Array Electrode for Electrocatalysis

In this paper, an ingenious strategy was developed to construct a well-aligned nitrogen-doped carbon nanotube (NCNT) array electrode integrated with multiple electrocatalytically active components of single cobalt atoms with CoN4 configuration (CoSAs), cobalt nanodots (Co), and molybdenum- or tungsten-carbide (WC or MoC) for hydrogen evolution reaction (HER). The well-aligned nitrogen doped carbon nanotube array is fabricated via an in situ NCNT growth process using a MO4 unit-exchanged lamellar cobalt hydroxide–nitrate MO4–CoLHN (M = Mo or W) as both catalytic species and precursor and dicyandiamide as nitrogen/carbon source under a high-temperature carbonization process. The electrocatalytic performance with low overpotentials of 23 and 47 mV at 10 mA cm–2 in acidic electrolyte can be achieved in WC-Co@CoSAs-NCNTs/CC and MoC-Co@CoSAs-NCNTs/CC electrodes, respectively. Moreover, these electrodes also show good stability, which could maintain 30 h of stable performance. Coupling various characterizations with density functional theory calculations, it is disclosed that the synergistic coupling interactions exist among NCNTs, CoSAs, Co, and MC as well as N-dopants, facilitating effective regulations on exposed active sites, d-band center, vectorial electron transfer from Co and MC to NCNTs, and enhanced electrical conductivity derived from NCNTs array, which may account for the significant promotion of HER performance.