The photo is sourced from rscf.ru
Fuel cells converting the chemical energy of hydrogen into electricity offer an alternative to lithium-ion batteries, for which no efficient disposal methods are currently available. The operational principle of fuel cells is quite simple: hydrogen gives up electrons during the reaction, whereas oxygen receives charged particles and gets reduced to the level of water. However, such a reaction requires the use of catalysts that trigger and accelerate the conversion of oxygen into water. The most common type of catalysts used for this purpose are platinum catalysts, which are not only expensive but also quickly lose their properties due to interacting with organic and inorganic compounds.
An alternative to platinum catalysts has been brought forward by the scientists from the Krestov Institute of Solution Chemistry RAS, who have developed bimetallic porphyrin catalysts in the form of films. First, the authors of the study synthesised porphyrins – complex nitrogen-containing molecules consisting of four interconnected carbon rings. After that, they introduced into the structure a metal atom (iron or manganese), which was firmly fixed in the centre of the nitrogen-carbon ring. At the final stage of the study, the researchers used the electrochemical method to produce catalysts of two types: firstly, catalysts containing iron or manganese atoms separately, and secondly, bimetallic iron-manganese catalysts.
The scientists tested the ability of the films to catalyse the oxygen reduction reaction by placing the catalyst into an electrochemical cell that was filled with alkali and purging oxygen through the cell. The authors evaluated the efficiency of the chemical transformation based on the voltage on the cell electrodes, i.e., current-conducting elements. The intensity of the current generated at a lower voltage by the catalyst containing two metals was 1.5 times higher than that generated by the manganese or iron catalysts.
“Being relatively cheap, iron and manganese metalloporphyrins have low toxicity and can be used as catalysts for the operation of fuel cells. This makes it possible to improve these devices for storing and converting energy. In the future, we plan to evaluate the impact made on the activity of bimetallic porphyrin catalysts by the presence of cobalt, copper and nickel atoms. Plus, by changing the chemical structure of the porphyrin and the molecular environment of the metal atom, we will be able to fine-tune the operation of the catalyst for the desired reaction to occur,” Sergey Kuzmin, candidate of chemical sciences and senior researcher at the Krestov Institute of Solution Chemistry RAS, is quoted as saying by the Russian Science Foundation.
