Magnetic Field-Induced Control of Crystal Orientation in Porous CuNi Films for Enhanced Electrocatalytic Hydrogen Evolution.

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