Electric-field-assisted proton coupling enhanced oxygen evolution reaction
Xuelei Pan, Mengyu Yan, Qian Liu, Xunbiao Zhou, Xiaobin Liao, Congli Sun, Jiexin Zhu, Callum D. McAleese, P. Couture, Matthew K. Sharpe, Richard W. Smith, Nianhua Peng, Jonathan England, Shik Chi Edman Tsang, Yunlong Zhao, Liqiang Mai
Abstract
Abstract The discovery of Mn-Ca complex in photosystem II stimulates research of manganese-based catalysts for oxygen evolution reaction (OER). However, conventional chemical strategies face challenges in regulating the four electron-proton processes of OER. Herein, we investigate alpha-manganese dioxide (α-MnO 2 ) with typical Mn IV -O-Mn III -H x O motifs as a model for adjusting proton coupling. We reveal that pre-equilibrium proton-coupled redox transition provides an adjustable energy profile for OER, paving the way for in-situ enhancing proton coupling through a new “reagent”— external electric field. Based on the α-MnO 2 single-nanowire device, gate voltage induces a 4-fold increase in OER current density at 1.7 V versus reversible hydrogen electrode. Moreover, the proof-of-principle external electric field-assisted flow cell for water splitting demonstrates a 34% increase in current density and a 44.7 mW/cm² increase in net output power. These findings indicate an in-depth understanding of the role of proton-incorporated redox transition and develop practical approach for high-efficiency electrocatalysis.