Room-Temperature Deposition of δ-NiGa Thin Films and Nanoparticles via Magnetron Sputtering.

Magnetron sputtering is a versatile method for investigating model system catalysts thanks to its simplicity, reproducibility, and chemical-free synthesis process. It has recently emerged as a promising technique for synthesizing δ-NiGa thin films. Physically deposited thin films have significant potential to clarify certain aspects of catalysts by eliminating parameters such as particle size dependence, metal-support interactions, and the presence of surface ligands. In this work, we demonstrate the potential of magnetron sputtering for the synthesis and analysis of thin film catalysts, using NiGa as a model system. Initially, deposition conditions were optimized by varying the deposition pressure, followed by an investigation of the temperature effects, aiming to map a structure zone dependence on temperature and pressure as in the Thornton model. The evolution of film crystallinity was monitored using a combination of grazing incidence X-ray diffraction (GI-XRD) and high-resolution scanning electron microscopy (HR-SEM). Additionally, ultrathin films were synthesized and annealed in H at high temperatures to demonstrate the possibility of producing size-controlled nanoparticles by adjusting the annealing conditions. This work demonstrates the full potential of magnetron sputtering as a technique for synthesizing model system catalysts in various forms, opening new avenues for the research and development of additional catalytic systems.