Oxide- and Silicate-Water Interfaces and Their Roles in Technology and the Environment

Interfacial reactions drive all elemental cycling onEarth andplay pivotal roles in human activities such as agriculture, waterpurification, energy production and storage, environmental contaminantremediation, and nuclear waste repository management.The onset of the 21st century marked the beginning of a more detailedunderstanding of mineral aqueous interfaces enabled by advances intechniques that use tunable high-flux focused ultrafast laser andX-ray sources to provide near-atomic measurement resolution, as wellas by nanofabrication approaches that enable transmission electronmicroscopy in a liquid cell. This leap into atomic- and nanometer-scalemeasurements has uncovered scale-dependent phenomena whose reactionthermodynamics, kinetics, and pathways deviate from previous observationsmade on larger systems. A second key advance is new experimental evidencefor what scientists hypothesized but could not test previously, namely,interfacial chemical reactions are frequently driven by anomaliesor non-idealities such as defects, nanoconfinement,and other nontypical chemical structures. Third, progress in computationalchemistry has yielded new insights that allow a move beyond simpleschematics, leading to a molecular model of these complex interfaces.In combination with surface-sensitive measurements, we have gainedknowledge of the interfacial structure and dynamics, including theunderlying solid surface and the immediately adjacent water and aqueousions, enabling a better definition of what constitutes the oxide-and silicate-water interfaces. This critical review discusseshow science progresses from understanding ideal solid-waterinterfaces to more realistic systems, focusing on accomplishmentsin the last 20 years and identifying challenges and future opportunitiesfor the community to address. We anticipate that the next 20 yearswill focus on understanding and predicting dynamic transient and reactivestructures over greater spatial and temporal ranges as well as systemsof greater structural and chemical complexity. Closer collaborationsof theoretical and experimental experts across disciplines will continueto be critical to achieving this great aspiration.

Automated summary

Interfacial reactions play important roles in elemental cycling on Earth and various human activities. Advances in techniques, such as ultrafast laser and X-ray sources, nanofabrication approaches, and computational chemistry, have enabled a more detailed understanding of mineral aqueous interfaces at atomic and nanometer scales. This critical review explores the progress made in the past 20 years and identifies challenges and future opportunities in understanding and predicting dynamic transient and reactive structures across greater spatial and temporal ranges, as well as systems of greater complexity.