Preparation of Ni₂P nanochains with controllable geometry for the hydrogen evolution reaction by application of a high magnetic field

In this work, a new method for controlling the morphology of Ni₂P materials by using a high magnetic field (HMF) was proposed. In HMF, the Ni₂P nanoparticles become smaller and self-assemble into one-dimensional nanochain. The nucleation, growth, and assembly mechanism of Ni₂P in HMF was revealed. Thermodynamic calculations show that the magnetic Gibbs free energy of the reaction process increases by 219 kJ mol⁻¹ in 6T HMF and the saturation magnetization of Ni₂P is 12 times higher than without HMF. In addition, the obtained Ni₂P nanochains exhibit better electrocatalytic activity than Ni₂P nanoparticle, the overpotential of Ni₂P nanochain was 231 mV lower than that of Ni₂P particles (200 mA cm⁻²). The theoretical and experimental results both indicate that magnetic field can control material structure and properties effectively.