Researchers have identified the exact chemical reactions that slow down the process of electrocatalysis — an important technique used in the area of renewable energy1. The finding, made using a tweaked Raman spectroscopy method, could help develop more efficient catalysts and, in turn, better fuel cells for clean and sustainable energy.
Technical processes such as electrocatalytic oxygen reduction, oxygen evolution, hydrogen evolution and hydrogen oxidation are employed to construct fuel cells. Traditionally, heme and porphyrin based electrocatalysts have been used for these processes. However, no direct spectroscopic investigations have been done to find what intermediates are formed on the electrodes during these processes. This has limited the detailed understanding of the mechanism of the catalysts.
The researchers have now developed a technique that can be extended to all of the above environmentally important transformations. They modified the traditionally used method — Surface enhanced resonance Raman spectroscopy (SERRS) — to accommodate a conventional rotating disk electrochemistry setup and were able to understand the reactions better. With this modified technique they identified three intermediates in two different types of iron porphyrins.
"We have identified the chemical reactions which slow the process down. Identifying these is the first step towards developing better catalysts," says one of the researchers Abhishek Dey. The data provides direct first-hand information about the nature of intermediates involved in steady-state O2 reduction and helps define the mechanism of these catalysts, Dey adds.
The technique could become a handy routine probe for electrochemical systems using synthetic as well as biological catalysts.
