Uncovering the electrochemical interface of low-index copper surfaces in deep groundwater environments

Joakim Halldin Stenlid,Egon Campos Dos Santos,Rosa M Arán-Ais,Alexander Bagger,Adam Johannes Johansson,Beatriz Roldan Cuenya,Jan Rossmeisl,Lars Gunnar Moody Pettersson

doi:10.1016/j.electacta.2020.137111

Abstract

Using a combination of a sophisticated modeling protocol and well-established electrochemical techniques, we unravel the chemical composition of the low-index surfaces of copper in groundwater environments at different ion concentrations, pHs, and redox potentials. By carefully linking density functional theory (DFT) and cyclic voltammetry (CV), we are able to extract fundamental information on interfaces of broad significance. Herein, we focus on the case of groundwater found in deep geological environments of importance to the planned constructions of disposal repositories for spent nuclear fuel around the world. Within the error margins of DFT, we can assign adsorption structures and compositions to the current peaks of the CVs. It is found that among the groundwater ions of main interest (i.e. sulfide, bisulfide, sulfate, chloride and bicarbonate), sulfides (HS−, S2−) bind strongest to the surface, and are likely to dominate at the interfaces under the deep geological conditions relevant for repositories of spent nuclear fuel.

Highlights

The electrified interface between the surface of an electrode and the liquid environment is central in many fields of science, including corrosion science, electrocatalysis, and nanochemistry.[1,2,3] The nanoscale structure and composition at the interface largely control the behavior of the material
We have recently described a procedure built on joint experimental and theoretical methods to provide detailed atomistic information on the electrochemical interface as a function of the local electrochemical environment.[4,5,6]
Our approach is based on a combination of experimental cyclic voltammetry (CV) and periodic density functional theory (DFT) calculations employed within the framework of the generalized computational hydrogen electrode (GCHE).[27]

Summary

Introduction

The electrified interface between the surface of an electrode and the liquid environment is central in many fields of science, including corrosion science, electrocatalysis, and nanochemistry.[1,2,3] The nanoscale structure and composition at the interface largely control the behavior of the material. We have recently described a procedure built on joint experimental (cyclic voltammetry - CV) and theoretical (density functional theory - DFT) methods to provide detailed atomistic information on the electrochemical interface as a function of the local electrochemical environment.[4,5,6] The latter includes the effects of pH, redox potential (U), and the concentration of dissolved species. We apply this procedure to obtain pH-, potential-, and concentration-resolved information on the atomic-scale nature of low-index copper surfaces in deep groundwater environments. Our investigation is of relevance to numerous applications of copper, including plumbing, construction engineering, electronics, preservation of historical artifacts, and catalysis.[7,8,9]

Methods

Results

Conclusion