Recently, Professor Yang Minghui's team at Dalian University of Technology has developed a highly lattice-matched structure of biphasic metal nitride materials. They efficiently produce hydrogen gas by coupling hydrazine decomposition, which is beneficial for advancing the development of metal nitride-based electrocatalysts. This approach holds broad application prospects in low-energy hydrogen production and environmental protection. The related findings were published in the Journal of Applied Chemistry.
Developing high-purity, high-energy-density green hydrogen through water electrolysis holds immense promise. However, it heavily relies on expensive and limited-lifetime precious metals, as well as the sluggish thermodynamic process of anodic oxygen evolution, leading to high hydrogen production costs and hindering its commercialization.
In this work, addressing the issue of low energy transfer efficiency at heterogeneous interfaces, the team proposed a novel regulation strategy. They established an enhanced local electric field between electron-rich nickel nitride (Ni3N) and electron-deficient cobalt nitride (Co3N), then introduced manganese as an electric field engine to further activate electron redistribution at the biphasic interface. The team found that Ni3N and Co3N belong to the same hexagonal crystal system, possessing similar unit cell shapes and lattice parameters, with very close interplanar spacings. Constructing these two lattice-matched nitrides together artificially can build high-quality heterogeneous structures.
Excellent electron transfer efficiency is crucial for the electrocatalytic performance of materials. To investigate the electron transfer at the interface between the two phases, the team utilized ultraviolet photoelectron spectroscopy combined with density functional theory calculations, confirming that the introduction of manganese activated electron rearrangement at the Ni3N-Co3N interface. This electron redistribution, akin to manganese acting as an engine, activates a continuous electron flow at the interface, greatly enhancing electron transfer efficiency.
Introduction of manganese element. Image courtesy of Dalian University of Technology
The Mn@Ni3N-Co3N/NF electrocatalyst demonstrated exceptional performance in the overall hydrazine splitting (OHzS) reaction, requiring just 0.49 V of cell voltage to deliver an industrial-level current density of 500 mA cm^-2 with no degradation over time, surpassing the performance of recently reported advanced OHzS systems. Compared to traditional water electrolysis, it reduces the cell voltage by 1.95 V, lowering energy consumption by 53.3%.
Moreover, the team's design of in situ grown biphasic metal nitride nanoray arrays on nickel foam has a synergistic catalytic effect on hydrogen evolution and hydrazine oxidation reactions, showing excellent performance in hydrogen production assisted by hydrazine degradation.
For more details on the study: https://doi.org/10.1002/ange.202401364
