Correlating orbital composition and activity of LaMnxNi1–xO3 nanostructures toward oxygen electrocatalysis

DOI: 10.1021/jacs.1c11757

Authors: Mohammed A. Alkhalifah (University of Bristol) , Benjamin Howchen (University of Bristol) , Joseph Staddon (University of Bristol) , Veronica Celorrio (Diamond Light Source) , Devendra Tiwari (University of Bristol; Northumbria University) , David J. Fermin (University of Bristol)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: March 2022
Diamond Proposal Number(s): 10306

Abstract: The atomistic rationalization of the activity of transition metal oxides toward oxygen electrocatalysis is one of the most complex challenges in the field of electrochemical energy conversion. Transition metal oxides exhibit a wide range of structural and electronic properties, which are acutely dependent on composition and crystal structure. So far, identifying one or several properties of transition metal oxides as descriptors for oxygen electrocatalysis remains elusive. In this work, we performed a detailed experimental and computational study of LaMnxNi1–xO3 perovskite nanostructures, establishing an unprecedented correlation between electrocatalytic activity and orbital composition. The composition and structure of the single-phase rhombohedral oxide nanostructures are characterized by a variety of techniques, including X-ray diffraction, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. Systematic electrochemical analysis of pseudocapacitive responses in the potential region relevant to oxygen electrocatalysis shows the evolution of Mn and Ni d-orbitals as a function of the perovskite composition. We rationalize these observations on the basis of electronic structure calculations employing DFT with HSE06 hybrid functional. Our analysis clearly shows a linear correlation between the OER kinetics and the integrated density of states (DOS) associated with Ni and Mn 3d states in the energy range relevant to operational conditions. In contrast, the ORR kinetics exhibits a second-order reaction with respect to the electron density in Mn and Ni 3d states. For the first time, our study identifies the relevant DOS dominating both reactions and the importance of understanding orbital occupancy under operational conditions.

Subject Areas: Chemistry, Materials, Energy


Instruments: B18-Core EXAFS

Added On: 08/03/2022 15:17

Discipline Tags:

Energy Storage Energy Physical Chemistry Catalysis Chemistry Materials Science Perovskites Metallurgy

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)