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1. Anisotropic Thermal Boundary Resistance across 2D Black Phosphorus: Experiment and Atomistic Modeling of Interfacial Energy Transport

   https://doi.org/10.1002/adma.201901021  

   Li, Man; Kang, Joon Sang; Nguyen, Huu Duy; Wu, Huan; Aoki, Toshihiro; Hu, Yongjie (June 2019, Advanced Materials)

   Interfacial thermal boundary resistance (TBR) plays a critical role in near‐junction thermal management of modern electronics. In particular, TBR can dominate heat dissipation and has become increasingly important due to the continuous emergence of novel nanomaterials with promising electronic and thermal applications. A highly anisotropic TBR across a prototype 2D material, i.e., black phosphorus, is reported through a crystal‐orientation‐dependent interfacial transport study. The measurements show that the metal–semiconductor TBR of the cross‐plane interfaces is 241% and 327% as high as that of the armchair and zigzag direction‐oriented interfaces, respectively. Atomistic ab initio calculations are conducted to analyze the anisotropic and temperature‐dependent TBR using density functional theory (DFT)‐derived full phonon dispersion relation and molecular dynamics simulation. The measurement and modeling work reveals that such a highly anisotropic TBR can be attributed to the intrinsic band structure and phonon spectral transmission. Furthermore, it is shown that phonon hopping between different branches is important to modulate the interfacial transport process but with directional preferences. A critical fundamental understanding of interfacial thermal transport and TBR–structure relationships is provided, which may open up new opportunities in developing advanced thermal management technology through the rational control over nanostructures and interfaces. 

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2. Determination of protein conformation and orientation at buried solid/liquid interfaces

   https://doi.org/10.1039/d2sc06958j  

   Guo, Wen; Lu, Tieyi; Crisci, Ralph; Nagao, Satoshi; Wei, Tao; Chen, Zhan (March 2023, Chemical Science)

   Protein structures at solid/liquid interfaces mediate interfacial protein functions, which are important for many applications. It is difficult to probe interfacial protein structures at buried solid/liquid interfaces in situ at the molecular level. Here, a systematic methodology to determine protein molecular structures (orientation and conformation) at buried solid/liquid interfaces in situ was successfully developed with a combined approach using a nonlinear optical spectroscopic technique – sum frequency generation (SFG) vibrational spectroscopy, isotope labeling, spectra calculation, and computer simulation. With this approach, molecular structures of protein GB1 and its mutant (with two amino acids mutated) were investigated at the polymer/solution interface. Markedly different orientations and similar (but not identical) conformations of the wild-type protein GB1 and its mutant at the interface were detected, due to the varied molecular interfacial interactions. This systematic strategy is general and can be widely used to elucidate protein structures at buried interfaces in situ . 

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3. Interfacial processes in electrochemical energy systems

   https://doi.org/10.1039/d1cc01703a  

   Wang, Maoyu; Feng, Zhenxing (October 2021, Chemical Communications)

   Electrochemical energy systems such as batteries, water electrolyzers, and fuel cells are considered as promising and sustainable energy storage and conversion devices due to their high energy densities and zero or negative carbon dioxide emission. However, their widespread applications are hindered by many technical challenges, such as the low efficiency and poor long-term cyclability, which are mostly affected by the changes at the reactant/electrode/electrolyte interfaces. These interfacial processes involve ion/electron transfer, molecular/ion adsorption/desorption, and complex interface restructuring, which lead to irreversible modifications to the electrodes and the electrolyte. The understanding of these interfacial processes is thus crucial to provide strategies for solving those problems. In this review, we will discuss different interfacial processes at three representative interfaces, namely, solid–gas, solid–liquid, and solid–solid, in various electrochemical energy systems, and how they could influence the performance of electrochemical systems. 

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4. Hierarchically hydrogen-bonded graphene/polymer interfaces with drastically enhanced interfacial thermal conductance

   https://doi.org/10.1039/C8NR08760A  

   Zhang, Lin; Liu, Ling (February 2019, Nanoscale)

   Interfacial thermal transport is a critical physical process determining the performance of many material systems with small-scale features. Recently, self-assembled monolayers and polymer brushes have been widely used to engineer material interfaces presenting unprecedented properties. Here, we demonstrate that poly(vinyl alcohol) (PVA) monolayers with hierarchically arranged hydrogen bonds drastically enhance interfacial thermal conductance by a factor of 6.22 across the interface between graphene and poly(methyl methacrylate) (PMMA). The enhancement is tunable by varying the number of grafted chains and the density of hydrogen bonds in the unique hierarchical hydrogen bond network. The extraordinary enhancement results from a synergy of hydrogen bonds and other structural and thermal factors including molecular morphology, chain orientation, interfacial vibrational coupling and heat exchange. Two types of hydrogen bonds, i.e. PVA–PMMA hydrogen bonds and PVA–PVA hydrogen bonds, are analyzed and their effects on various structural and thermal properties are systematically investigated. These results are expected to provide new physical insights for interface engineering to achieve tunable thermal management and energy efficiency in a wide variety of systems involving polymers and biomaterials. 

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5. Mechanisms for oxygen vacancy defect migration in SrTiO3/NiO heterostructures: Effect of interface layer chemistry and misfit dislocation structure

   https://doi.org/10.1063/5.0283278  

   More, Anish; Ebmeyer, William; Dholabhai, Pratik P (September 2025, Journal of Applied Physics)

   Perovskite-based oxide heterostructures display promising properties resulting from interface phenomena, making them good candidates for next-generation solid oxide fuel cell electrolytes. Among the different features exhibited by these interfaces, misfit dislocations play an important role in influencing ionic transport, yet their role remains poorly understood, a phenomenon also observed in rock salt–perovskite interfaces. In SrTiO3/NiO heterostructures, we investigate oxygen vacancy migration near misfit dislocations using atomistic simulations in conjunction with a high-throughput nudged elastic band-based framework. By comprehensively mapping activation energy barriers across different interfacial chemistries and asymmetric structural features, we explore how the dislocation structure, which is dependent on the local interfacial chemistry, modulates oxygen vacancy migration. This study aims to shed light on the role of dopants, oxygen vacancies, interfacial chemistry, and extended defects in shaping ionic migration at the atomic scale. Misfit dislocations are often considered thermodynamic sinks for oxygen vacancies, oftentimes hindering ionic conductivity at such interfaces. We report dynamic behavior at interfaces that is largely dependent on the local coordination environment, challenging this conventional perspective. The study attempts to bridge the crucial gap in understanding interface-governed ion transport mechanisms in complex oxide heterostructures. 

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