Tuning of lattice oxygen reactivity and scaling relation to construct better oxygen evolution electrocatalyst

Zhen-Feng Huang,Zhichuan J Xu,Xin Wang,Shuo Dou,Caozheng Diao,Jiajia Song,Yonghua Du,Shibo Xi,Xiaogang Li

doi:10.1038/s41467-021-24182-w

Abstract

Developing efficient and low-cost electrocatalysts for oxygen evolution reaction is crucial in realizing practical energy systems for sustainable fuel production and energy storage from renewable energy sources. However, the inherent linear scaling relation for most catalytic materials imposes a theoretical overpotential ceiling, limiting the development of efficient electrocatalysts. Herein, using modeled NaxMn3O7 materials, we report an effective strategy to construct better oxygen evolution electrocatalyst through tuning both lattice oxygen reactivity and scaling relation via alkali metal ion mediation. Specifically, the number of Na+ is linked with lattice oxygen reactivity, which is determined by the number of oxygen hole in oxygen lone-pair states formed by native Mn vacancies, governing the barrier symmetry between O–H bond cleavage and O–O bond formation. On the other hand, the presence of Na+ could have specific noncovalent interaction with pendant oxygen in *OOH to overcome the limitation from linear scaling relation, reducing the overpotential ceiling. Combining in situ spectroscopy-based characterization with first-principles calculations, we demonstrate that an intermediate level of Na+ mediation (NaMn3O7) exhibits the optimum oxygen evolution activity. This work provides a new rational recipe to develop highly efficient catalyst towards water oxidation or other oxidative reactions through tuning lattice oxygen reactivity and scaling relation.

Highlights

Developing efficient and low-cost electrocatalysts for oxygen evolution reaction is crucial in realizing practical energy systems for sustainable fuel production and energy storage from renewable energy sources
AxMn3O7 (0 < x ≤ 2) materials, as one type of alkali metal-incorporated metal oxides, can be a good platform for unveiling how to rationally design better oxygen evolution reaction (OER) electrocatalysts through tuning lattice oxygen reactivity and scaling relation mediated by alkali metal ion
We investigated six representative O2 coordination environments for NaxMn3O7 to quantify the lattice oxygen reactivity using the number of oxygen holes

Summary

Introduction

Developing efficient and low-cost electrocatalysts for oxygen evolution reaction is crucial in realizing practical energy systems for sustainable fuel production and energy storage from renewable energy sources. As confirmed from the projected density of states and partial charge density near EF (Fig. 1b, c and Supplementary Table 1), more oxygen holes from |O2p are generated upon activating lattice oxygen as the number of Na+ reduces. For S6, A3 is 0.53 eV/intermediate higher in energy than R4 due to the increased numbers of oxygen hole, the ΔG‡ for direct O–O coupling is as high as 1.20 eV (Fig. 1e and Supplementary Fig. 7).

Results

Conclusion