Abstract: Hydrogen is a clean and flexible energy carrier that has the promising to satisfy urgent demands of the energy crisis and environmental protection. Electrochemical hydrogen evolution reaction (HER), a critical half-reaction in water splitting, is one of the greenest and most common methods to obtain high-purity hydrogen. Designing preeminent activity and stability electrocatalysts for hydrogen precipitation reaction (HER) to reduce energy consumption is of great essential. 3D carbon-based materials have attracted widespread concern as the potential scaffolds of highly active and durable electrocatalysts for HER. To boost the HER activity and prolong the lifespan of electrocatalysts, multifarious 3D carbon architectures make an appearance to be engineered for accelerating electronic/mass transfer and maximizing the exposure of active sites. Herein, we designed and fabricated high-performance electrocatalysts based on a special caterpillar-like 3D graphene nanoscrolls@CNTs (GNS@CNTs) scaffold decorated with Co-doped MoSe₂ nanosheets for HER. In the caterpillar-like hierarchical structure, CNTs were seamlessly co-bonded and dilated the interlayer and outer spacing of GNS through CVD growth technology, and nickel nanoparticles were covered by the CNTs tips. Taking advantage of the plentiful hierarchical pore, larger specific surface area, and higher chemical stability of the caterpillar-like structure, the catalysts exhibited enhanced electrocatalytic properties than some existing data reported. Density functional theory calculations showed that the encapsulated nickel nanoparticle could tune the electronic structure of the outer anchored Co-doped MoSe₂ and optimize its ∆G of H* adsorption by electron traversing effect and doping effect. These indicate that caterpillar-like GNS@CNT is an ideal scaffold for anchoring actives substance and is suitable for high-efficient HER. This study provides new insights for designing hierarchical carbon composite nanostructures for catalysts, sensors, energy materials, and other applications.

Key words: Electron traversing effect, 3D graphene, Graphene nanoscrolls, CNT, MoSe₂, Hydrogen evolution reaction