Origins of hydrogen peroxide selectivity during oxygen reduction on organic mixed ionic-electronic conducting polymers
Journal article, 2023
Electrochemical reduction of atmospheric oxygen provides carbon emission-free pathways for the generation of electricity from chemical fuels and for the distributed production of green chemical oxidants like hydrogen peroxide. Recently, organic mixed ionic-electronic conducting polymers (OMIECs) have been reported as a new class of active electrode materials for the oxygen reduction reaction. This work sets out to identify the operative oxygen reduction mechanism of OMIECs through a multi-faceted experimental and theoretical approach. Using a combination of pH-dependent electrochemical characterization, operando UV-Vis and Raman spectroscopy, and ab initio calculations, we find that the n-type OMIEC, p(NDI-T2 P75), displays pH-dependent activity for the selective reduction of oxygen to the 2-electron hydrogen peroxide product. We use microkinetic simulations of the electrochemical behavior to rationalize our experimental observations through a polaron-mediated, non-adsorptive pathway involving chemical reduction of oxygen to the 1-electron superoxide intermediate followed by pH-dependent catalytic disproportionation to hydrogen peroxide. Finally, this pathway is applied to understand the experimental oxygen reduction reactivity across several n- and p-type OMIECs.
Author
Ana De La Fuente Durán
Stanford University
Allen Yu Lun Liang
Stanford University
Ilaria Denti
Stanford University
Hang Yu
Imperial College London
Drew Pearce
Imperial College London
Adam Marks
Stanford University
Emily Penn
Stanford University
Jeremy Treiber
Stanford University
Karrie Weaver
Stanford University
Lily Turaski
Stanford University
Iuliana P. Maria
Imperial College London
University of Oxford
Sophie Griggs
University of Oxford
Xingxing Chen
Anhui University
Alberto Salleo
Stanford University
William C. Chueh
Stanford University
J. Nelson
Imperial College London
Alexander Giovannitti
Stanford University
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
J. Tyler Mefford
Stanford University
Energy and Environmental Sciences
1754-5692 (ISSN) 17545706 (eISSN)
Vol. 16 11 5409-5422Subject Categories
Inorganic Chemistry
Materials Chemistry
DOI
10.1039/d3ee02102e