Magnetic Field-Induced\nControl of Crystal Orientation\nin Porous CuNi Films for Enhanced Electrocatalytic Hydrogen Evolution

Porous CuNi films are promising candidates for electrocatalytic\nwater splitting, with their catalytic performance largely influenced\nby the crystallographic structure and chemical state. In this study,\nby employing a magnetic field-controlled bubble template-assisted\nelectrodeposition method, CuNi films with a preferred Ni(111) crystal\norientation were synthesized. Moreover, adjusting the magnetic field\ndirection during deposition can affect the degree of preferred orientation\nand, consequently, the electrochemical activity of the films. The\ndeposited porous CuNi films under the up/down Lorentz force conditions\nshow a preferred orientation along the Ni(111) direction, although\nthe extent of this orientation varies. For the sake of comparison,\nporous CuNi films electrodeposited under the condition of magnetic\nstirring and undistributed were also synthesized. The electrochemical\nperformance was evaluated using cyclic voltammetry and Tafel analysis,\nrevealing that the preferred Ni(111) orientation enhances hydrogen\natom migration, thereby improving the hydrogen evolution reaction\n(HER) efficiency. The porous CuNi film deposited with upward Lorentz\nforce exhibits the highest HER activity, and the onset potential is\nas low as −3 mV vs a reversible hydrogen electrode (RHE). This\nwork emphasizes the importance of the magnetic field in optimizing\nthe crystal orientation and electrochemical performance of CuNi films\nfor sustainable energy applications.