Synergistic Effect of N‐NiMoO<sub>4</sub>/Ni Heterogeneous Interface with Oxygen Vacancies in N‐NiMoO<sub>4</sub>/Ni/CNTs for Superior Overall Water Splitting
Guang‐Lan Li, Xiang‐Yue Qiao, Yingying Miao, Tianyu Wang, Fei Deng
Abstract
Abstract The exploring of economical, high‐efficiency, and stable bifunctional catalysts for hydrogen evolution and oxygen evolution reactions (HER/OER) is highly imperative for the development of electrolytic water. Herein, a 3D cross‐linked carbon nanotube supported oxygen vacancy (V o )‐rich N‐NiMoO 4 /Ni heterostructure bifunctional water splitting catalyst (N‐NiMoO 4 /Ni/CNTs) is synthesized by hydrothermal‐H 2 calcination method. Physical characterization confirms that V o ‐rich N‐NiMoO 4 /Ni nanoparticles with an average size of ≈19 nm are secondary aggregated on CNTs that form a hierarchical porous structure. The formation of Ni and NiMoO 4 heterojunctions modify the electronic structure of N‐NiMoO 4 /Ni/CNTs. Benefiting from these properties, N‐NiMoO 4 /Ni/CNTs drives an impressive HER overpotential of only 46 mV and OER overpotential of 330 mV at 10 mA cm −2 , which also shows exceptional cycling stability, respectively. Furthermore, the as‐assembled N‐NiMoO 4 /Ni/CNTs||N‐NiMoO 4 /Ni/CNTs electrolyzer reaches a cell voltage of 1.64 V at 10 mA cm −2 in alkaline solution. Operando Raman analysis reveals that surface reconstruction is essential for the improved catalytic activity. Density functional theory (DFT) calculations further demonstrate that the enhanced HER/OER performance should be attributed to the synergistic effect of V o and heteostructure that improve the conductivity of N‐NiMoO 4 /Ni/CNTs and facilitatethe desorption of reaction intermediates.