Rational design of charge-functional materials: Insights from molecular engineering and operando imaging

Abstract

Emerging charge-functional electronic and electrochemical materials exhibit increasingly complex structure. Critical fundamental processes (e.g., charge transport, electrocatalysis) must work cooperatively across multiple time-and length scales to realize desired properties. Performance optimization in these materials demands an ultimate multifaceted, multiscale understanding of structure versus charge-function relationships, in order to address longstanding challenges associated with, for example, climate change, clean water, and humanmachine interfacing. Across seemingly different applications (e.g., energy conversion, water desalination, biosensing), the overall system performance is governed by the same set of interrelated fundamental physiochemical processes, such as electronic transport, ionic transport, and interfacial electrocatalysis. In this article, we discuss how to approach rational design of charge-functional electronic and electrochemical materials by elucidating performance-governing fundamental processes, with a particular focus on insights obtained from molecular engineering and operando imaging of emerging material systems important for sustainability and health care.

Review—Understanding and Controlling Charge Functions in Materials for Electrochemically Mediated Water Treatment

“…17 In these materials, many charge-functional processes, such as electron conduction, ionic adsorption, and surface redox reactions, occur simultaneously and interact strongly with one another, dictating the overall water treatment performances, including ion selectivity, cycle stability, removal capacity and rate. 18,19 Rationally designed charge-functional materials with high water treatment performance display increasingly complex structure and functionality, demanding multifaceted characterizations of critical processes (e.g., charge transport and surface catalysis) across multiple length and time scales. 17 While conventional techniques such as electron microscopy and X-ray photoelectron spectroscopy can offer important information such as materials morphology and chemical compositions, such multiscale understanding of highly complex systems demands the development of in situ, operando characterization tools with high spatiotemporal resolutions that can, for example, capture kinetic phenomena during electrochemical operations 20,21 and quantify local functional parameters (e.g., charge carrier mobility and electrocatalytic activity).…”

“…Imaging charge transport.-Electronic and ionic transport in charge-functional materials significantly affect the redox reactions at the electrode/electrolyte interface, governing the key performance metrics for electrochemical mediated water remediation such as selectivity, capacity and rate. 18 For instance, the mobility or diffusion length of photogenerated charge carriers in semiconductors affects electron-hole separation, which in turn controls the surface hole/electron activities toward photoelectrochemical oxidative pollutant decomposition. 37 The forms (e.g., hydrated ions) and valences (e.g., monovalent, divalent and trivalent) of intercalated ions have a critical impact on the ion removal capacity and rate capability in water deionization processes.…”

“…High spatiotemporal resolution imaging in realistic liquid environments (i.e., multiple species of varying concentrations) can be powerful tools to probe the critical underlying dynamic processes ( i.e., surface restructuring, interface instability, time-dependent molecular binding). Particularly, functional imaging techniques 18,22,98,105,122 can quantitatively probe local charge function such as pollutant adsorption strength and carrier mobility, and thus should be leveraged to build local structure-activity relationship in emerging water treatment electrodes of highly complex, heterogeneous structures and morphologies, providing insights complementary to those from structural imaging to yield a holistic picture of fundamental processes and mechanisms that govern water treatment efficiency. For instance, the complex water matrix will lead to ion co-insertion and surface passivation of electrode materials, detrimental to electrode cycle stability and target ions selectivity.…”

ChemTSv2: Functional molecular design using de novo molecule generator

“…[1][2][3] In chemical laboratories, exploring and optimizing chemical compounds are commonly performed for functionalizing and novelizing them by experts with professional knowledge. [4][5][6][7][8][9][10][11][12][13][14][15] A vast amount of knowledge has been accumulated to facilitate the exploration and optimization processes in the long history of chemistry. 1 Meanwhile, the vast amount of knowledge complicates and perplexes these processes, which causes numerous trial-and-error routines even for the experts.…”

“…Controlling phenomena and properties of molecules at the atomic level is a challenging task 1–3 . In chemical laboratories, exploring and optimizing chemical compounds are commonly performed for functionalizing and novelizing them by experts with professional knowledge 4–15 . A vast amount of knowledge has been accumulated to facilitate the exploration and optimization processes in the long history of chemistry 1 .…”