Operando characterization of interfacial charge transfer processes

TL;DR

This paper reviews current X-ray spectroscopic techniques for studying interfaces in energy and information technologies, highlighting challenges and proposing new methods to improve interface sensitivity and understanding of charge transfer during operation.

Contribution

It introduces a novel approach to extract interface information from bulk-sensitive techniques and evaluates the selection of X-ray energies for meniscus X-ray photoelectron spectroscopy.

Findings

Interface sensitivity remains a major challenge in current techniques.

Proposed method enhances interface information extraction from bulk-sensitive data.

Advancements will enable sub-nanometer resolution in probing charge transfer processes.

Abstract

Interface science has become a key aspect for fundamental research questions and for the understanding, design and optimization of urgently needed energy and information technologies. As the interface properties change during operation, e.g. under applied electrochemical stimulus, and because multiple bulk and interface processes coexist and compete, detailed operando characterization is needed. In this perspective, I present an overview of the state-of-the art and challenges in selected X-ray spectroscopic techniques, concluding that among others, interface-sensitivity remains a major concern in the available techniques. I propose and discuss a new method to extract interface-information from nominally bulk sensitive techniques, and critically evaluate the selection of X-ray energies for the recently developed meniscus X-ray photoelectron spectroscopy, a promising operando tool to characterize the solid-liquid interface. I expect that these advancements along with further developments in time and spatial resolution will expand our ability to probe the interface electronic and molecular structure with sub-nm depth and complete our understanding of charge transfer processes during operation.