The use of lanthanum-based intermetallic compounds as a catalyst in the electrochemical process of ammonia synthesis

Introduction.

Modern environmental challenges and the need to the decarbonization the chemical industry are stimulating an active research for alternative methods for the synthesis of ammonia, which is a key part for the production of fertilizers and a promising hydrogen carrier. In this case, electrochemical reduction of nitrates (NO₃RR) is of particular interest, which makes it possible not only to obtain a valuable product, but also to solve the problem of wastewater treatment from nitrogen pollution. Recent studies demonstrate that intermetallic compounds (IMC) open up new possibilities for creating highly efficient catalytic systems for this process. In this work, for the first time, studies were conducted on the use of La-containing IMC as catalysts in the NO₃RR reaction.

Experimental.

The samples (Cu-La and Co-La) were prepared using arc melting in an argon atmosphere at the AM-200 facility. Mass control of the samples after fusion showed that melting losses did not exceed 1 mass%. The physicochemical methods of characterization of La-IMC samples were used in the work: UV-vis spectroscopy, XRD. Linear voltammetry and chronoamperometry were used to determine the optimal conditions for the reactions and synthesis of ammonia, respectively. Autolab PGSTAT302N potentiostat and PS-20 potentiostat-galvanostat were used. The synthesis of ammonia and NO3RR tests were performed in alkali media for 1 h.

Results and Discussion.

The results show that the use of electrocatalysts in the form of IMC is promising, since in the work carried out, high values of both the Faraday efficiency (FE) and the values of the ammonia yield rate were achieved. La and Cu compounds exhibit higher efficiency compared to IMC La based on Co.

Acknowledgment.

The research was carried out at the expense of the grant of Russian Science Foundation (RSF) No 25-29-00488, https://rscf.ru/en/project/25-29-00488/.