Enhancing hydrogen peroxide electrosynthesis by manipulating the three-phase interface microenvironment
Ding Zhang, Constantine Tsounis, Zhipeng Ma, Lingyi Peng, Zeheng Lin, Hang Yin, Furqan Hussain, Claudio Cazorla, Dewei Chu, Rose Amal, Zhaojun Han
Abstract
Oxygen reduction reaction through the two-electron pathway holds promise for on-site hydrogen peroxide production; however, achieving high activity without compromising selectivity remains a long-standing challenge in catalyst design. Herein, we overcome this challenge by engineering a solid-liquid-gas three-phase interface that creates a hydrophobic microenvironment to enhance interfacial mass and electron transfer while retaining active sites. The engineered vertical graphene electrode exhibits greater than 97% Faradaic efficiency in alkaline media and greater than 90% Faradaic efficiency in neutral media, both at a large potential window (0.7–1.0 V). Continuous hydrogen peroxide production at 1,200 mg L−1 h−1 is achieved in a flow cell with neutral medium utilizing the engineered electrode. Kelvin probe force microscopy and in situ Raman spectroscopy reveal that graphene step edges possess a low work function that promotes two-electron reaction kinetics, while ab initio molecular dynamics show that the hydrophobic three-phase interface microenvironment balances the contact of graphene edges, oxygen, and water.