High entropy materials (HEMs) are regarded as potential electrocatalytic materials for high-performance electrochemical applications including hydrogen electrolysers. However, their long-term durability especially in acidic environments are yet to be improved. In this context, incorporating small elements such as nitrogen into the microstructure at varying concentrations can creates defects and structural, compositional, electronic and surface interaction modifications, enhancing the catalyst’s activity and stability. We synthesized Ni-Fe-Cr-Ru-Mo-(N) high-entropy alloys and nitrides in form of thin films via RF/DC co-sputtering, by controlling nitrogen incorporation and N-metal atoms bound formation. The effect of N-integration in enhancing the electrocatalytic properties were evaluated with respect to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media. Preliminary results revealed outstanding catalytic properties for the N-integrated catalyst with respect to HER in acidic media, even showing kinetic and thermodynamic improvements after 15 h of stability test at 10 mA cm-2. In fact, Tafel slope as well as the overpotential values, measured at 10 mA cm-2, decreased to 34 mV/dec and to 80 mV, respectively, while in the same media, the base alloy showed unvaried and inferior HER catalytic properties. Notably, the N-integrated sample resulted in strongly catalysing both OER and HER in alkaline media, offering the possibility to build-up an overall water splitting catalyst. They showed Tafel slopes of 100 and 44 mV/dec, respectively, in alkaline media. These results suggested the N-integration can effectively tune and enhance both the stability and catalytic properties of HEMs.
N-integration in Ni-Fe-Cr-Ru-Mo High-Entropy Electrocatalytic Materials
Eslami M;Zorzi S.;Bordin M.;Di Gregorio G.;Gottardi G.;Testi M.;Crema L.
2025-01-01
Abstract
High entropy materials (HEMs) are regarded as potential electrocatalytic materials for high-performance electrochemical applications including hydrogen electrolysers. However, their long-term durability especially in acidic environments are yet to be improved. In this context, incorporating small elements such as nitrogen into the microstructure at varying concentrations can creates defects and structural, compositional, electronic and surface interaction modifications, enhancing the catalyst’s activity and stability. We synthesized Ni-Fe-Cr-Ru-Mo-(N) high-entropy alloys and nitrides in form of thin films via RF/DC co-sputtering, by controlling nitrogen incorporation and N-metal atoms bound formation. The effect of N-integration in enhancing the electrocatalytic properties were evaluated with respect to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both acidic and alkaline media. Preliminary results revealed outstanding catalytic properties for the N-integrated catalyst with respect to HER in acidic media, even showing kinetic and thermodynamic improvements after 15 h of stability test at 10 mA cm-2. In fact, Tafel slope as well as the overpotential values, measured at 10 mA cm-2, decreased to 34 mV/dec and to 80 mV, respectively, while in the same media, the base alloy showed unvaried and inferior HER catalytic properties. Notably, the N-integrated sample resulted in strongly catalysing both OER and HER in alkaline media, offering the possibility to build-up an overall water splitting catalyst. They showed Tafel slopes of 100 and 44 mV/dec, respectively, in alkaline media. These results suggested the N-integration can effectively tune and enhance both the stability and catalytic properties of HEMs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
