Thin films of Ni-Fe-Cr-Ru-Mo-(N) high-entropy alloy and high-entropy nitride were synthesized using RF/DC co-sputtering in different N2/Ar environments. The base Ni35Fe18Cr17Ru10Mo20 (at. %) alloy composition was finely tuned by adjusting the sputtering power applied to Ni50Fe25Cr25 (at. %), Mo, and Ru targets. Deposition was carried out at temperatures ranging from 20 to 400 °C. The nitrogen (N) content and degree of nitride formation were controlled by varying the N₂/Ar flow ratio and temperature. Post-deposition, the films were characterized using energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) to determine composition and phase formation, while scanning electron microscopy (SEM) was used to examine the microstructure. The effect of temperature, nitrogen doping, and nitridation degree on the hydrogen evolution reaction (HER) in an acidic environment (0.5 M H2SO4) and oxygen evolution reaction (OER) in an alkaline environment (0.5 M KOH) was systematically investigated. Electrochemical testing demonstrated promising catalytic activity. According to the preliminary results, the Tafel slope for HER for the base alloy with and without ca. 40 at% N was ca. 50 mV/dec, which, interestingly, for the nitrogen-containing film decreased to 34 mV after 15 hr of long-term stability testing during hydrogen production. Furthermore, the effect of N incorporation on enhancing the HER in an alkaline environment was also studied aiming for the production of an overall water-splitting catalyst. These findings provide an insight into the compositional and structural engineering of high entropy alloys to enhance the efficiencies in water electrolysis applications. Figure 1
Effect of Nitrogen Incorporation on Electrocatalytic Performance of Co-Sputtered Ni-Fe-Cr-Ru-Mo-(N) High-Entropy Films for Hydrogen and Oxygen Evolution
Zorzi Sandro;di Gregorio Giulia;Gottardi Gloria;Testi Matteo;Crema Luigi
2025-01-01
Abstract
Thin films of Ni-Fe-Cr-Ru-Mo-(N) high-entropy alloy and high-entropy nitride were synthesized using RF/DC co-sputtering in different N2/Ar environments. The base Ni35Fe18Cr17Ru10Mo20 (at. %) alloy composition was finely tuned by adjusting the sputtering power applied to Ni50Fe25Cr25 (at. %), Mo, and Ru targets. Deposition was carried out at temperatures ranging from 20 to 400 °C. The nitrogen (N) content and degree of nitride formation were controlled by varying the N₂/Ar flow ratio and temperature. Post-deposition, the films were characterized using energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) to determine composition and phase formation, while scanning electron microscopy (SEM) was used to examine the microstructure. The effect of temperature, nitrogen doping, and nitridation degree on the hydrogen evolution reaction (HER) in an acidic environment (0.5 M H2SO4) and oxygen evolution reaction (OER) in an alkaline environment (0.5 M KOH) was systematically investigated. Electrochemical testing demonstrated promising catalytic activity. According to the preliminary results, the Tafel slope for HER for the base alloy with and without ca. 40 at% N was ca. 50 mV/dec, which, interestingly, for the nitrogen-containing film decreased to 34 mV after 15 hr of long-term stability testing during hydrogen production. Furthermore, the effect of N incorporation on enhancing the HER in an alkaline environment was also studied aiming for the production of an overall water-splitting catalyst. These findings provide an insight into the compositional and structural engineering of high entropy alloys to enhance the efficiencies in water electrolysis applications. Figure 1I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
