A spin-polarized density functional study on monometallic Ni, In and bimetallic Ni–In nanoparticles: Structure, stability, electronic, magnetic properties and hydrogen evolution reaction activity

Bimetallic catalyst of Ni and In were reported to be a superior catalyst. Herein, the geometrical structure, stability, electronic, and magnetic properties of the 13-atom and 55-atom Ni, In and Ni–In NPs with the hydrogen evolution reaction (HER) activity were investigated using density functional theory methods. The change of the geometry structures of the 13-atom Ni–In NPs is negligible compared with the monometallic NPs, with difference around 0.1 Å in bond lengths. The Ni–Ni bonds are generally lengthened and the In–In bonds are shortened for bimetallic Ni–In 55-atom NPs. The total and excess energies show that the In atom favors to segregate to the surface-shell, while the Ni atom inclines to stay in the core site. The Bader charge analysis shows that the In atoms are positively charged and the Ni atoms are negatively charged in all the cases. Furthermore, the d-band centers of the bimetallic Ni–In NPs are closer to the Fermi energy than those of the monometallic Ni particles. And the Ni-rich structures show a smaller d-p band center distance. The monometallic Ni, In and bimetallic Ni–In NPs are all metallic. The pure Ni NPs exhibit the highest magnetic moment, while the addition of In reduces the magnetic moment. In addition, the surface shell atoms play an important role in the magnetic properties. Moreover, the In₁₃ cluster shows the best HER activity among the studied configurations and the addition of In atoms into the pure Ni clusters significantly enhances the performance, while the introduction of Ni atoms into the pure In clusters leads to a decrease in their HER activity.