In-situ grafting of N-doped carbon nanotubes with Ni encapsulation onto MOF-derived hierarchical hybrids for efficient electrocatalytic hydrogen evolution

Developing highly efficient and cost-effective catalysts for the hydrogen evolution reaction (HER) is of paramount importance to solve the problems arising from the depletion of non-renewable fossil fuels and increasing air pollution issues. Herein, an in-situ heterogeneous catalytic synthesis approach is developed for constructing hierarchical Ni/carbon hybrids via grafting nitrogen-doped-carbon (NC) nanotubes with Ni encapsulation onto the metal-organic framework (MOF)-derived carbon matrix. Following the “nanotube tip-growth model” involved in the in-situ catalytic synthesis process, the morphology and size of the nanotubes and encapsulated particles of the as-prepared hierarchical Ni-based carbon hybrids can be controlled by regulating the conditions during the thermal decomposition of the Ni-MOF in the presence of melamine. The grafting and decoration of the Ni-encapsulated carbon nanotubes on the MOF-derived architecture rapidly enhance the HER electrocatalytic performance of the bare thermally decomposed Ni/N-doped carbon composite. Due to the synergistic effects of the stable metallic Ni active sites and the N-doped carbon support, the optimized Ni@NC6-600 sample exhibits stable and high catalytic activity, only requiring an overpotential of 181 mV to drive 10 mA/cm2 towards the HER in alkaline media.