High-density low-coordination Ni single atoms anchored on Ni-embedded nanoporous carbon nanotubes for boosted alkaline hydrogen evolution

Abstract

Modulating the coordination environment of single-atom catalysts is considered an effective way to boost the electrocatalytic activity of the hydrogen evolution reaction. Herein, a novel electrocatalyst comprising high-density low-coordination Ni single atoms anchored on Ni-embedded nanoporous carbon nanotubes (Ni-N-C/Ni@CNT-H) is constructed through a self-template assisted synthetic strategy. We demonstrate that the <i>in situ</i> generated AlN nanoparticles not only serve as the template for the formation of the nanoporous structure, but also contribute to the coordination between Ni and N atoms. Benefiting from the optimized charge distribution and hydrogen adsorption free energy of the unsaturated Ni-N₂ active structure and nanoporous structure of the carbon nanotube substrate, the resultant Ni-N-C/Ni@CNT-H exhibited outstanding electrocatalytic hydrogen evolution activity with a low overpotential of 175 mV at a current density of 10 mA cm^-2, and a long-term durability for over 160 h in continuous operation. This work provides a new insight and approach to the design and synthesis of efficient single-atom electrocatalysts toward hydrogen fuel production.