A novel strategy for modulating the crystalline-amorphous composites and electronic structure to enhance hydrogen evolution reaction

H2O molecules first adsorb on the NiMoOx surface and split into H and OH. The absorption energy value of H2O on the NiMo-NiMoOx is -1.22 eV, which is much smaller than that in Ni-NiOₓ, greatly decreasing the energy barrier for water dissociation. Additionally, the H adsorption energy on the NiMo surface is only -0.75 eV, much closer to the optimal value for H2 evolution. @ Nano Research, Tsinghua University Press

Alkaline water splitting has the advantages of low cost, long lifetime and ease of maintenance, and is widely applied commercially. However, the sluggish kinetics of HER inhibits the further development of alkaline water splitting. Though noble catalysts can greatly boost the process of HER, they are hard to meet the requirement of industrial production due to the high price and scarcity. Thus, it is urgent to develop low cost and highly efficient catalysts for alkaline water splitting.

A team of material scientists led by Qiang Wang and Shuang Yuan from Northeastern University in Shenyang, China recently have provided a novel strategy for modulating crystalline-amorphous composites and electronic structures to enhance the hydrogen evolution reaction. Through the electrodeposition method, they successfully synthesized the NiMo-NiMoOx electrocatalyst with crystalline-amorphous heterointerface. Theoretical calculations and experimental results confirm that the introduction of Mo atoms can not only lower the energy barrier of water dissociation and optimize the capacity for hydrogen adsorption/desorption, but also modulate the ratio between crystalline and amorphous phase, increasing the heterostructure interfaces and enriching active sites. As a result, NiMo-NiMoOx electrocatalyst exhibits remarkable HER catalytic properties and durability. It requires a low overpotential of 30 mV at the current density of 10 mA cm-2 in 1.0 M KOH, as well as a long-term stability with slight degradation after operating for over 80 h. Moreover, it also exhibits excellent activity and stability with negligible declination in the simulated alkaline seawater, making it highly promising for seawater electrolysis applications.

The team published their article in Nano Research on April 18, 2025.

Nickel-based transition metal catalysts are promising for large-scale hydrogen production due to their abundance and low cost. Ni-NiO catalysts exhibit good activity for the synergistic effect between Ni and NiO component and strong electronic coupling effect on the heterostructure interface. However, it still far away from precious metal catalysts. Therefore, it is of great significance to modulate the electronic structure of the Ni-NiO heterostructure interface to optimize intermediate adsorption energy for enhancing catalytic activity.

Recently, phase and interface engineering via crystalline-amorphous heterostructures has become an attractive strategy for fabricating highly active HER electrocatalysts due to the synergistic effect and intriguing phase properties. Compared to the crystalline phase, the amorphous phase exhibits a distinctively disordered atomic arrangement with abundant defects and unsaturated coordination environments, providing more active site. In addition, the isotropic and flexible properties of the amorphous phase enable an easily adjustable local electronic structure at the active sites, which can optimize the intermediates' adsorption/dissociation capability. The crystalline phase, on the other hand, possesses high electrical conductivity and lower metal ion leaching. Thus, the integration of the crystalline phase with the amorphous phase can improve the electrical conductivity and stability of the catalysts, which are the shortcomings of the amorphous phase.

Although there are studies on constructing crystalline-amorphous heterostructures for hydrogen evolution reaction catalysts, the focus has been on designing the crystalline-amorphous compositions, while the ratio of compositions on the catalytic performance has been neglected. Additionally, the synthesis process for crystalline-amorphous electrocatalysts is often complex, typically involving heat treatment or acid/alkali soaking. We have directly synthesized the NiMo-NiMoOx crystalline-amorphous electrocatalyst via a one-step electrodeposition method, which is simple and mild. Moreover, by adjusting the Mo content, we can control the ratio between the crystalline and amorphous phases and the charge distribution at the heterojunction, thereby enhancing the catalyst's activity.

The research team expects this study will spur the development of crystalline-amorphous heterostructure electrocatalysts. Such crystalline-amorphous heterostructures are common in the catalysts. For example, the surface reconstruction may eventually result in crystalline-amorphous heterostructure. Thus, it is of great significance to pay attention to the study of the crystalline-amorphous heterostructure. Reference Synthesis of NiMo–NiMoOx with crystalline/amorphous heterointerface for enhanced hydrogen evolution reaction

Xinjia Tan, Zhong Wang, Jiaqi Liu, Jinshuo Yang, Qiang Wang, Shuang Yuan https://www.sciopen.com/article/10.26599/NR.2025.94907368 Tsinghua University