Introduction. Intermetallic compounds (IMCs), which have a homogeneous structure of active centers with controlled electronic structures and an atomic ensemble size, can be used to create catalysts with unsurpassed practical characteristics, including for demanding and stable electrochemical reactions such as nitrogen reduction (NRR), nitrate reduction (NO3RR), and nitrite reduction (NO2RR), which can serve as a replacement for the industrial Haber–Bosch process. An urgent task is to develop efficient electrocatalysts using cheap base metals, with partial or complete replacement of noble metals. For this purpose, the use of IMCs based on cobalt, iron, and silicon as well as some rare earth elements is proposed.
Methods. IMCs were synthesized using a facility for electric arc melting in a rarefied argon atmosphere. In this work, the following physicochemical methods for the characterization of the IMC samples were used: UV-vis spectroscopy, optical microscopy, SEM, EDX, XPS, and XRD. For electrochemical characterization, impedance spectroscopy and the method for determining the capacitance of the electrical double layer were employed. Linear voltammetry and chronoamperometry were used to determine the optimum conditions for the reactions and ammonia synthesis.
Results and Discussion. The results show the advantages of using electrocatalysts in the form of IMCs, which demonstrate increased values of Faraday efficiency and ammonia yield rates. Schemes of the mechanism of the studied reactions for IMCs and exhaustive clarifications of the actions of electrocatalysts are proposed. The chosen strategy, as well as methods, make it possible to confidently predict the advantages in the NO3RR reaction.
Acknowledgment. The research was carried out at the expense of the grant of the Russian Science Foundation (RSF) No 25-29-00488, https://rscf.ru/en/project/25-29-00488/.
The authors acknowledge support from Lomonosov Moscow State University Program of Development for providing access to the PS-20 potentiostat–galvanostat with an electrochemical impedance (EIS) measurement module FRA (SmartStat, Russia).
