Surface Chemistry Engineering Research Articles

Surface Passivation toward Multiple Inherent Dangling Bonds in Indium Phosphide Quantum Dots.

Indium phosphide (InP) quantum dots (QDs) have become the most recognized prospect to be less-toxic surrogates for Cd-based optoelectronic systems. Due to the particularly dangling bonds (DBs) and the undesirable oxides, the photoluminescence performance and stability of InP QDs remain to be improved. Previous investigations largely focus on eliminating P-DBs and resultant surface oxidation states; however, little attention has been paid to the adverse effects of the surface In-DBs on InP QDs. This work demonstrates a facile one-step surface peeling and passivation treatment method for both In- and P-DBs for InP QDs. Meanwhile, the surface treatment may also effectively support the encapsulation of the ZnSe shell. Finally, the generated InP/ZnSe QDs display a narrower full width at half-maximum (fwhm) of ∼48 nm, higher photoluminescence quantum yields (PLQYs) of ∼70%, and superior stability. This work enlarges the surface chemistry engineering consideration of InP QDs and considerably promotes the development of efficient and stable optoelectronic devices.

Extremely Stable Ag-Based Photonics, Plasmonic, Optical, and Electronic Materials and Devices Designed with Surface Chemistry Engineering for Anti-Tarnish.

Silver (Ag) metal-based structures are promising building blocks for next-generation photonics and electronics owing to their unique characteristics, such as high reflectivity, surface plasmonic resonance effects, high electrical conductivity, and tunable electron transport mechanisms. However, Ag structures exhibit poor sustainability in terms of device performance because harsh chemicals, particularly S2- ions present in the air, can damage their structures, lowering their optical and electrical properties. Here, the surface chemistry of Ag structures with (3-mercaptopropyl)trimethoxysilane (MPTS) ligands at room temperature and under ambient conditions is engineered to prevent deterioration of their optical and electrical properties owing to S2- exposure. Regardless of the dimensions of the Ag structures, the MPTS ligands can be applied to each dimension (0D, 1D, and 3D). Consequently, highly sustainable plasmonic effects (Δλ < 2nm), Fabry-Perot cavity resonance structures (Δλ < 2nm), reflectors (ΔRReflectance < 0.5%), flexible electrodes (ΔRelectrical < 0.1 Ω), and strain gauge sensors (ΔGF < 1), even in S2- exposing conditions is achieved. This strategy is believed to significantly contribute to environmental pollution reduction by decreasing the volume of electronic waste.

The Intersection of Computational Design and Wearable‐Optimized Electrospun Structural Nanohybrids for Electromagnetic Absorption

AbstractBy leveraging the principles of electromagnetic theory and materials science, the characteristics of dielectric polymer composites can be optimized, eliminating repetitive trial‐and‐error in their application as electromagnetic absorbers (EMAs). Herein, a systematic framework for optimizing the thickness and composition of double‐layer EMAs is proposed, using a combination of transmission line, Debye relaxation, and Maxwell–Garnett theories. Following theoretical optimization, a double‐layered electrospun EMA is fabricated, which comprises a ≈1.17 mm thick matrix of styrene–butadiene–styrene (SBS) decorated with MXene on its fibrous structure. The second SBS layer, with a thickness of ≈0.52 mm, incorporates a hybrid of MXene and graphene nanoribbons (GNR) as conductive additives. The EMA exhibits durable electrical performance after 2000 tensile cycles, owing to the surface chemistry engineering and the novel in situ assembly technique. It is capable of shielding 99.9% of the incident wave and &gt;80% absorptivity (A) over almost the entire Ku‐band. The EMA also exhibits desirable mechanical characteristics, such as &gt;300% stretchability and full twist and wrinkle recoveries, making it an excellent choice for protective attire applications. Additionally, the introduced approach provides solutions for the advancement of tailorable polymer composite EMAs, with respect to specific criteria of the target wave frequency, effective absorption bandwidth, and absorption levels.

Surface chemistry engineering and the applications of MXenes

MXenes have captured extensive attention in various fields by virtue of unique hydrophilicity, high conductivity and tunable surface terminations. In this review, the state-of-the-art progresses of designing functional MXenes have been summarized. Firstly, the synthesis methods of MXenes are summarized and classified into HF etching, in-situ HF etching and fluoride-free etching approaches based on the effect on the surface chemistry of MXenes. Secondly, the factors that affect the surface termination groups are discussed, including synthesis methods, heat treatment temperature and atmosphere. Thirdly, this review gives an overview of the synthetic routes of functional MXenes including termination modification by synthesis methods and heat treatment, heteroatom (N, S, or P) doping, cation and organic molecule intercalation and hybridization with polymer, which inhibit restacking and increase active sites for intrinsically enhancing the inherent physical and chemical properties of MXenes. Finally, the applications with respect to energy storage and conversion, catalysis, sensors, electromagnetic interference shielding and microwave absorption of functional MXenes are introduced. Additionally, the critical challenges and development prospects of functional MXenes are also highlighted.

Surface chemistry engineering enables polar solvent resistant and highly emissive perovskite nanocrystals for multifunctional applications

The extremely poor stability of perovskite nanocrystals (NCs) in polar solvent is a critical unsolved problem and seriously hinder their practical application scenarios. Herein, a surface chemistry engineering strategy is proposed for synthesizing robust CsPbX3 (X = Cl, Br, I) NCs in non-toxic ethanol-based solvent by building an extensive inter-ligand H-bond network on perovskite lattice. The obtained unsealed CsPbX3 NCs show unprecedented year-long stability in ethanol. Notably, a water (∼6–50%, v/v) post-treatment can obviously decrease surface defects of NCs, thus yielding a significant enhancement in their emission efficiency (increased from 9.6% to 83.4% for CsPbBr3 NCs in ethanol). We further translated the obtained CsPbBr3 NCs to fluorescent sensor and visible-light-driven photocatalysts, achieving ultra-high sensitivity (limit of detection is 11 nM) and high photocatalytic efficiency (>99% removal within 10 min). Overall, the low-cost, easy-to-process, highly efficient and ethanol/water tolerant perovskites NCs indicate their promising application prospect in multifunctional photoelectric devices.

Practical Application of Li-Rich Materials in Halide All-Solid-State Batteries and Interfacial Reactions between Cathodes and Electrolytes

Benefiting from the advanced solid-state electrolytes (SSEs), conventional cathodes have been widely applied in all-solid-state lithium batteries (ASSLBs). However, Li-rich Mn-based (LRM) cathodes, which possess enhanced discharge capacities beyond 250 mA h g-1, have not yet been studied in ASSLBs. In this work, the practical application of LRM cathodes in ASSLBs using a high-voltage-stability halide SSE (Li3InCl6, LIC) is reported for the first time. Furthermore, we decipher that the active oxygen released from LRM cathodes at a high operation voltage seriously oxidizes the LIC electrolytes, thus resulting in the large interfacial resistance between cathodes and electrolytes and hindering their industrialized application in ASSLBs. Therefore, surface chemistry engineering of LRM cathodes with an ionic conductive coating material of LiNbO3 (LNO) is employed to stabilize the LRM/LIC interface. Consequently, the LRM-based ASSLBs deliver a high specific capacity of 221 mA h g-1 at 0.1 C and a decent cycle life of 100 cycles. This contribution gives insights into studying the interfacial issues between LRM cathodes and halide electrolytes and sheds light on the application of LRM cathode materials in ASSLBs.

Tuning the surface chemistry of 2D MXenes for optimizing the micellization of bio-targeted carriers

Using nanocarriers to deliver drugs to cancer cells is an effective way to treat cancer. However, this method faces several challenges, including the instability of nanocarriers, and the appropriate method for the synthesis of nanocarriers. In this regard, in this work, the effect of the two-dimensional MXene in increasing the stability of riboflavin-targeted PLGA-PEG nanocarriers for delivering doxorubicin (Dox) has been investigated using molecular dynamics simulation. In this study, the role of surface chemistry engineering of MXene in optimizing Dox-loaded micelles has been studied. On the other hand, the effect of the microfluidic method on the synthesis of nanocarriers has been investigated. According to the obtained results, the use of MXene has outstandingly increased the stability of Dox-loaded nanocarriers. MXene increases the attraction energy between micelles from −600 Kj/mol to −1700 Kj/mol. But the use of hydrophilic functional groups in the MXene has reduced the stability of nanocarriers. The molecular analysis approves the greater stability of nanocarriers synthesized by the microfluidic method in comparison to non-microfluidic method. Finally, this could lead to the widespread use of microfluidic synthesis as well as MXene in the synthesis of nanocarriers.

Front Cover: Carbon Neutralization, Volume 1, Issue 2, September 2022

Front cover image: Transition metal layered oxide materials are considered one of the most promising sodium ion batteries cathodes (SIBs), however, poor air stability, complicated interfacial reaction, and irreversible phase translation of layered oxide cathodes pose problems for the long-term cycle as well as rate performance. Surface chemistry engineering could relieve those mentioned above problems. In article number 10.1002/cnl2.19, the effects, processes, and types of surface modification methods used in layered oxide cathodes for SIBs have been comprehensively summarized. Additionally, an innovative concept of interface conversion reaction with bulk penetration doping integration is proposed to attempt to solve interface and bulk issues simultaneously and then implement high-performance cathodes for SIBs.

Surface chemistry engineering of layered oxide cathodes for sodium‐ion batteries

AbstractSodium‐ion batteries (SIBs) have attracted extensive attention to be applied in large‐scale energy storage due to their low cost and abundant storage resources. Among cathode materials for SIBs, layered oxide cathodes are considered one of the most promising candidates for practical application owing to their high theoretical capacities, simple synthesis routes, and environmental friendliness. However, poor air stability, complicated interfacial reaction, and irreversible phase translation of layered oxide cathodes pose problems for the long‐term cycle as well as rate performance. In this review, the recent achievements and progress in surface engineering chemistry strategies to improve the electrochemical performance of SIBs have been summarized including mechanical mixing, in‐situ coating methods, and designing unique interfacial structures. Moreover, inspired by previous studies, we propose an innovative concept of interface conversion reaction with bulk penetration doping integration, which is expected to deal with both interfacial and intrinsic issues synchronously through heat treatment. It could not only eliminate residual sodium compounds on the surface and improve air stability but also suppress the dissolution and the migration of transition metal and the phase transformation. The insights that came up in this review can be considered as a guide for surface engineering on layered oxide cathode for SIBs.

Low‐Dimensional Electrocatalysts for Acidic Oxygen Evolution: Intrinsic Activity, High Current Density Operation, and Long‐Term Stability

AbstractProduction of green hydrogen (H2) by water electrolysis is important for achieving the global mission of carbon neutrality. For this, acidic water electrolysis with a higher current density operation and energy conversion efficiency compared with alkaline water electrolysis has attracted much attention. The four‐electron‐transfer oxygen evolution reaction (OER) limits the overall efficiency of water electrolysis devices. In recent years, low‐dimensional OER catalysts have been extensively explored to increase the overall efficiency of such devices, but most of them work well only at low current density and show unsatisfied long‐term stability. In this review, recent progress in acidic OER is discussed and three aspects including intrinsic activity, high current density operation, and long‐term stability are focused upon. Strategies to improve these aspects including surface chemistry engineering, constructing porous structure, and protecting the active sites’ are comprehensively reviewed. Finally, prospects for developing high‐performance catalysts with high current density operation and long‐term stability for industrial applications are proposed.

Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives.

The presence of surface ligands not only plays a key role in keeping the colloidal integrity and non-defective surface of metal halide perovskite quantum dots (PQDs), but also serves as a knob to tune their optoelectronic properties for a variety of exciting applications including solar cells and light-emitting diodes. However, these indispensable surface ligands may also deteriorate the stability and key properties of PQDs due to their highly dynamic binding and insulating nature. To address these issues, a number of innovative surface chemistry engineering approaches have been developed in the past few years. Based on an in-depth fundamental understanding of the surface atomistic structure and surface defect formation mechanism in the tiny nanoparticles, a critical overview focusing on the surface chemistry engineering of PQDs including advanced colloidal synthesis, in-situ surface passivation, and solution-phase/solid-state ligand exchange is presented, after which their unprecedented achievements in photovoltaics and other optoelectronics are presented. The practical hurdles and future directions are critically discussed to inspire more rational design of PQD surface chemistry toward practical applications.

Salt-Resistive Photothermal Materials and Microstructures for Interfacial Solar Desalination

Solar interfacial evaporation, featured by high energy transfer efficiency, low cost, and environmental compatibility, has been widely regarded as a promising technology for solar desalination. However, the interplay between energy transfer and water transport in the same channels suggests that the tradeoff between high efficiency and long-term stability inherently exists in conventional photothermal nanomaterials. We summarize state-of-the-art research on various anti-salt clogging photothermal microstructures as long-term stable interfacial solar evaporators for solar desalination. The review starts with an overview of the current status and the fundamental limit of photothermal materials for solar desalination. Four representative strategies are analyzed in detail with the most recent experimental demonstrations, including fluid convection enhancement, surface wettability engineering, energy-mass-path decoupling, and surface chemistry engineering. Finally, this article focuses on the challenges in anti-salt clogging solar interfacial evaporators and potential point-of-use applications in the future.

Structurally stabilized lithium-metal anode via surface chemistry engineering

Dendrite-free lithium (Li) has been the primary issue for the practical application of metallic Li anode. Repeated Li plating/stripping is known to inevitably lead to severe volume changes and gradual Li dendrite growth, eventually resulting in irreversible Li (called dead-Li) as an unexpected feature. In order to avoid the dead-Li, a lithiophilic surface is highly desirable and a nanoarchitectured host for metallic Li is also required. Herein, cobalt-embedded, mesoporous, nitrogen-doped graphite (N-doped graphite) is strategically proposed as a new innovative Li-metal storage host. After tuning the surface chemistry, the material shows high Li ion affinity as well as a highly lithiophilic surface, which is attributed to the low formation energy of N-doped graphite, strongly supported by density functional theory calculations. As a result, the desirable anode shows excellent electrochemical performance with high Li-metal reversible capacity and even stable long-term cyclability with no dead-Li formation. Our findings pave the way to optimize the Li-metal host up to the limit of the theoretical capacity.

Composition and surface chemistry engineering of graphene grafting chitosan for stimuli-responsive cancer therapy: An in-silico study

Graphene-based drug delivery studies have been utilized in pharmaceutical science, primarily a molecular investigation of cancer therapy. The energetic interactions between drugs and graphene nanosheets are one of the critical components of cancer treatment studies. In the present work, Graphene-based nanosheets, including; carboxylated graphene (CGRA), Silicon-doped graphene (SiGRA) and Phosphorus-doped graphene (PGRA) were utilized as carriers for Doxorubicin/Paclitaxel co-delivery. Furthermore, these nanosheets were modified by pH- and thermal-sensitive co-polymer, named trimethyl chitosan (TMC)- b- N, N- dimethyl acrylamide (DMAA). TMC-DMAA co-polymer benefits from remarkable features leading to its pH- and temperature-sensitivity for drug loading and stimuli-responsive release purposes. First, the TMC-DMAA co-polymer, as well as functionalized graphene molecules, have been optimized at acidic and neutral conditions. Then, the loading and release of drugs in the normal and cancerous conditions were investigated by molecular dynamics tools, respectively. Finally, the validation test clarified the accuracy and precision of the simulation systems. The results indicated that TMC-DMAA functionalized graphene nanocarrier could retain drug molecules from unwanted interactions in normal tissues while causing the drug release in a pH and temperature-sensitive manner at the tumor microenvironment. Moreover, P-doped and Si-doped modification increased the capacity of drug loading on graphene nanosheets. By investigating molecular insight, shedding the light of anti-cancer drug loading and release achieved. The results of this study would help future studies about cancer drug delivery research. • DOX and PAX co-delivery by functionalized graphene nanocarriers studied by molecular dynamics simulation. • Van der Waals and electrostatic interactions and hydrogen bonds work throughout the combination. • Effect of dimethyl acrylamide -trimethyl chitosan on the drug release kinetics is obtained via molecular dynamics. • Drug release from the carboxylated graphene is controlled by the modifying polymer at various pH conditions. • P-doped and Si-doped graphene increased the capacity of loading at normal condition.

Ligand-Length Modification in CsPbBr3 Perovskite Nanocrystals and Bilayers with PbS Quantum Dots for Improved Photodetection Performance.

Nanocrystals surface chemistry engineering offers a direct approach to tune charge carrier dynamics in nanocrystals-based photodetectors. For this purpose, we have investigated the effects of altering the surface chemistry of thin films of CsPbBr3 perovskite nanocrystals produced by the doctor blading technique, via solid state ligand-exchange using 3-mercaptopropionic acid (MPA). The electrical and electro-optical properties of photovoltaic and photoconductor devices were improved after the MPA ligand exchange, mainly because of a mobility increase up to 5 × 10−3 . The same technology was developed to build a tandem photovoltaic device based on a bilayer of PbS quantum dots (QDs) and CsPbBr3 perovskite nanocrystals. Here, the ligand exchange was successfully carried out in a single step after the deposition of these two layers. The photodetector device showed responsivities around 40 and 20 mA/W at visible and near infrared wavelengths, respectively. This strategy can be of interest for future visible-NIR cameras, optical sensors, or receivers in photonic devices for future Internet-of-Things technology.

Engineering the surface active sites of actiniae-like hierarchical Fe3O4/Co3O4 nanoheterojunction for efficient oxygen reduction reaction

For the purpose of revealing the interplay between nanostructure, chemical composition and electrocatalytic oxygen reduction reaction (ORR) activity, actiniae-like hierarchical Fe3O4/Co3O4 nanoheterojunctions with controlled porosity and textural parameters are flexibly constructed through a solvothermal quasi-reverse-emulsion approach. The electrocatalysts possess high specific surface area (302–810 m2 g−1), optimized multipore size distribution as well as pore volume. The actiniae nanoheterojunctions exhibit excellent electrocatalytic ORR activity, outstanding long-term stability and methanol tolerance in alkaline solution. Correlation analysis demonstrates that the electrocatalytic ORR activity of a porous nanoheterojunction is not merely directly proportional to its specific surface area. It is also governed by suitable surface chemistry engineering of the electrocatalyst material. This work provides the validity and generality of our strategy to derive high ORR activity from nonprecious transitional metal oxides.

Morphology and surface chemistry engineering toward pH-universal catalysts for hydrogen evolution at high current density

Large-scale implementation of electrochemical hydrogen production requires several fundamental issues to be solved, including understanding the mechanism and developing inexpensive electrocatalysts that work well at high current densities. Here we address these challenges by exploring the roles of morphology and surface chemistry, and develop inexpensive and efficient electrocatalysts for hydrogen evolution. Three model electrocatalysts are flat platinum foil, molybdenum disulfide microspheres, and molybdenum disulfide microspheres modified by molybdenum carbide nanoparticles. The last catalyst is highly active for hydrogen evolution independent of pH, with low overpotentials of 227 mV in acidic medium and 220 mV in alkaline medium at a high current density of 1000 mA cm−2, because of enhanced transfer of mass (reactants and hydrogen bubbles) and fast reaction kinetics due to surface oxygen groups formed on molybdenum carbide during hydrogen evolution. Our work may guide rational design of electrocatalysts that work well at high current densities.

Nanoporous photonic crystals with tailored surface chemistry for ionic copper sensing

We present a study on optical and surface chemistry engineering of nanoporous photonic crystals as sensing platforms for detection of ionic copper.

Geometric and Electronic Structure of Closed Graphene Edges

We report theoretical and experimental results on single and multiple looped graphene sheets. Experimental images of stable closed-edge structures in few-layer graphene samples obtained by high-resolution transmission electron microscopy (HRTEM) are compared with first- principles density functional theory calculations. We demonstrate that the electronic structure of a graphene nanoribbon is not significantly perturbed upon closing. By contrast, a significant modulation of the electronic structure is observed for closed-edge graphene structures deposited on a planar graphene substrate. This effect is due to an enhanced reactivity of the looped (coalesced) edges observed experimentally. The coexistence of different degrees of curvature in the graphene sheet induced by folding indicates that these materials could be used for surface chemistry engineering.