Employing a Zn‐air/Photo‐Electrochemical Cell for In Situ Generation of H2O2 for Onsite Control of Pollutants

Abstract Industrial production of hydrogen peroxide (H 2 O 2 ) is energy‐intensive and generates unwanted byproducts. Herein, an alternative production strategies of H 2 O 2 are demonstrated in a Zn‐air and a photoelectrochemical cell. Employing an optimally produced reduced graphene oxide (rGO) electrocatalyst@air‐cathode, an impressive power density of 320 Wm geo −2 (geo = geometric area) is achieved along with a high H 2 O 2 production rate of 3.17 mol m geo −2 h −1 (operating potential = 0.8 V). Systematic investigations reveal the critical role of specific functional groups (viz. C─O─C, chemisorbed O 2 , C≐C) to be responsible for enhancing the yield of H 2 O 2 . The in situ generated superoxide (O 2 ˙ ) and hydroxyl radicals ( ˙ OH) act as oxidants to efficiently degrade onsite, a model textile dye pollutant (viz. rhodamine B) inside the Zn‐air cell. Using the identical rGO as the photoelectrode in an H‐type cell, the H 2 O 2 production is remarkably enhanced under visible light illumination. Simultaneously, the onsite pollutant degradation occurs five times faster than the Zn‐air cell (at the same operating potential = 0.8 V). This work opens a new paradigm for electrosynthesis, wherein an underlying redox can be utilized to synthesize industrial chemicals for onsite control of environmental pollution sustainably.