Constructing the Ni4N/Ni3N Heterointerface of the Bicontinuous Ni4N/Ni3N/NiO/CFs Catalyst With Pore Connectivity Effects for Electrocatalytic Hydrogen Generation

Designing and fabricating well-defined heterointerface catalysts with high electrocatalytic performance for the hydrogen evolution reaction (HER) remains a huge challenge. Here, the bicontinuous nano-heterostructure consisting of ultrathin Ni₄N/Ni₃N particles on hollow tubular carbon fibers was fabricated, and it exhibits superior catalytic activity with a very low overpotential of 75 mV@10 mA cm⁻² for HER and stable performance for over 50 h. Theoretical calculation results revealed that the built-in interfacial electric field (BIEF) is formed due to the distinct lattice arrangements and uneven charge distribution in biphasic metal nitrides. The BIEF promotes the electron localization around the interface and enables high valence Ni and more exposed binding sites on the surface of Ni₄N/Ni₃N/NiO/CFs to accelerate the HER. Meanwhile, the pore connectivity effects facilitate the full exposure of the optimized Ni₄N/Ni₃N heterointerface, which possesses enhanced intrinsic catalytic activity as active sites. Moreover, the pore connectivity microstructure of the Ni₄N/Ni₃N/NiO/CFs is conceptualized and verified through the utilization of three-dimensional tomograph reconstruction technology. This study offers new insights into constructing heterostructure interfacial catalysts with three-dimensional spatial precision and provides strong references for practical applications in electrocatalytic hydrogen generation techniques.