Using batteries to produce hydrogen peroxide from air
“What we are doing is that along with producing H2O2, we are storing energy because it takes place inside the cell”
The Indian Institute of Science (IISc) report:
Hydrogen peroxide (H2O2) is widely used as a bleach, disinfectant, and oxidising agent, among other things. However, industrial production of H2O2 is expensive and uses a lot of energy owing to the rare and precious metal catalysts used in its production. Researchers at the Indian Institute of Science (IISc) have developed an alternative, onsite production strategy for H2O2 that can also degrade industrial pollutants like toxic dyes.
The scientists have utilised a zinc-air battery in which oxygen reduction generates H2O2. “Zinc is an abundant and historically-used element … it is very cheap and abundant in India,” says Aninda J Bhattacharyya, Professor in the Interdisciplinary Centre for Energy Research (ICER) and Solid State and Structural Chemistry Unit (SSCU), and corresponding author of the study published in Small Methods.
A metal-air battery has a metal like zinc as the anode (negative electrode) and ambient air as the cathode (positive electrode). When the battery discharges – releases energy – oxygen from ambient air gets reduced at the cathode, producing H2O2.
The electrochemical reduction of oxygen proceeds through two ways, one of which forms H2O2. “The strategy here is to control the extent of the oxygen reduction reaction. If you don’t control it at some level, it will just go and form water,” explains Bhattacharyya.
This control can be achieved using specific catalysts. “We are using a metal-free catalyst based on carbon,” says Asutosh Behera, first author and PhD student at SSCU. These inexpensive catalysts usually drive the reaction along the route that forms water where the selectivity towards H2O2 is less. However, incorporating certain chemical modifications in these catalysts, like adding oxygen functional groups, directs the reaction selectivity towards the production of H2O2.
Bhattacharyya explains that using a battery to directly produce H2O2 is a novel approach. “You don’t have to do other things. You have a battery, and you run it. We have curtailed the voltage such that it is only producing H2O2.”
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