Approaching theoretical performances of electrocatalytic hydrogen peroxide generation by cobalt‐nitrogen moieties

DOI: 10.1002/anie.202301433

Authors: Runjia Lin (University College London) , Liqun Kang (Max-Planck-Institute for Chemical Energy Conversion) , Karolina Lisowska (University College London) , Weiying He (Max-Planck-Institute for Chemical Energy Conversion) , Siyu Zhao (University College London) , Shusaku Hayama (Diamond Light Source) , Dan Brett (University College London) , Graham Hutchings (Cardiff University) , Furio Corà (University College London) , Ivan Parkin (University College London) , Guanjie He (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: March 2023
Diamond Proposal Number(s): 29254 , 29207

Abstract: Electrocatalytic oxygen reduction reaction (ORR) has been intensively studied for efficient and environmentally benign energy conversion processes. However, insufficient understanding of ORR 2e--pathway mechanism at the atomic level inhibits rational design of electrocatalysts with both high activity and selectivity, causing concerns including catalyst degradation due to Fenton reaction or poor efficiency of H2O2 electrosynthesis. Herein we show that the generally accepted ORR electrocatalyst design based on a Sabatier volcano plot argument optimises activity but is unable to account for the 2e--pathway selectivity; an extended “dynamic active site saturation” model that examines in addition the hydrogenation kinetics linked to the OOH* adsorption energy enables us to resolve the activity-selectivity compromise. Through electrochemical and operando spectroscopic studies on the ORR process governed by a series of Co-N x /carbon nanotube hybrids, a construction-driven approach that aims to create the maximum number of 2e- ORR sites by directing the secondary ORR electron transfer step towards the 2e- intermediate is proven to be attainable by manipulating O2 hydrogenation kinetics. Control experiments reveal the O2 hydrogenation chemistry is related to a catalyst reconstruction with lower symmetry around the Co active centre induced by the application of a cathodic potential. The optimised catalyst exhibits a ~100% H2O2 selectivity and an outstanding activity with an ORR potential of 0.82 V versus the reversible hydrogen electrode to reach the ring current density of 1 mA cm-2 by using rotating ring-disk electrode measurement, which is the best-performing 2e- ORR electrocatalyst reported to date, and approaches the thermodynamic limit.

Subject Areas: Chemistry

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E01-JEM ARM 200CF , E02-JEM ARM 300CF , I20-Scanning-X-ray spectroscopy (XAS/XES)

Added On: 28/03/2023 21:24

Documents:
Angew Chem Int Ed - 2023 - Lin - Approaching theoretical performances of electrocatalytic hydrogen peroxide generation by.pdf

Discipline Tags:

Physical Chemistry Catalysis Chemistry

Technical Tags:

Microscopy Spectroscopy Electron Microscopy (EM) X-ray Absorption Spectroscopy (XAS) High Energy Resolution Fluorescence Detected XAS (HERFD-XAS) Scanning Transmission Electron Microscopy (STEM)