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Materials Research at the Hong Kong University of Science and Technology

The Hong Kong University of Science and Technology (HKUST) was established in 1991 as the first research-focused university in Hong Kong to advance learning and knowledge, particularly in science, technology, engineering, management, and business studies, and at the postgraduate level. HKUST has developed significantly in the past 35 years, ranking itself as one of the best among young universities.

Colloidal Quantum Dots

Colloidal quantum dots (QDs) are exceptional photocatalysts due to their unique photophysical properties, tunable surface chemistry, and structural diversity. These properties enable novel photocatalytic organic transformations, overcoming limitations of traditional catalysts. This review highlights recent QD-driven advancements and discusses future research directions in photocatalysis. More details can be found in article number 2409096 by Haipeng Lu and co-workers.

Stretchable Interconnects for Wearable Bioelectronics

As wearable telemedicine advances, stretchable interconnects becomes vital in skin-compatible devices for reliable health signals. Article number 2408456 by Hnin Yin Yin Nyein and co-workers explores various materials and fabrication methods for stretchable interconnects, highlighting their electrical and mechanical traits along with their geometric versatility. The review also showcases successful rigid-soft interfaces, while addressing unresolved challenges and outlining future directions for practical wearable applications.

Materials Research at the Hong Kong University of Science and Technology

The campus in Hong Kong is situated on a hillside that overlooks Clear Water Bay, offering breathtaking views of the bay and the South China Sea. At the heart of the campus, the Red Bird sundial stands as a prominent sculpture of the university. This piece is inspired by one of humanity's earliest scientific achievements: the sundial. Constructed from steel, the sundial is gracefully placed on a paved podium with broad steps, surrounded by a flowing water pool. The podium features a carved mural celebrating 39 notable Chinese contributions to science and technology. Completed on October 8, 1991, the Red Bird sundial, titled “Circle of Time,” has become an enduring symbol of HKUST.

Promotion of C─C Coupling in electrochemical reduction of CO2 to valuable C2+ products is reviewed from microcosmic to macroscopic. The discussed advances and outstanding challenges in the strategies of efficient catalyst design, the influence of local environment in electrolyte, and the design of potential industrial flow cells provided the guidelines for future research in promoted C─C coupling from foundation to application.

The electrochemical CO2 reduction reaction (CO2RR) to valuable C2+ products emerges as a promising strategy for converting intermittent renewable energy into high-energy-density fuels and feedstock. Leveraging its substantial commercial potential and compatibility with existing energy infrastructure, the electrochemical conversion of CO2 into multicarbon hydrocarbons and oxygenates (C2+) holds great industrial promise. However, the process is hampered by complex multielectron-proton transfer reactions and difficulties in reactant activation, posing significant thermodynamic and kinetic barriers to the commercialization of C2+ production. Addressing these barriers necessitates a comprehensive approach encompassing multiple facets, including the effective control of C─C coupling in industrial electrolyzers using efficient catalysts in optimized local environments. This review delves into the advancements and outstanding challenges spanning from the microcosmic to macroscopic scales, including the design of nanocatalysts, optimization of the microenvironment, and the development of macroscopic electrolyzers. By elucidating the influence of the local electrolyte environment, and exploring the design of potential industrial flow cells, guidelines are provided for future research aimed at promoting C─C coupling, thereby bridging microscopic insights and macroscopic applications in the field of CO2 electroreduction.

This review focuses on low-dimensional perovskite materials and discusses their applications in light-emitting diodes (LEDs). Special attention is given to the introduction of perovskite quantum wires and nanorods, two unique types of one-dimensional (1D) materials, and their interesting optoelectronic properties. Moreover, the applications of low-dimensional perovskite materials can extend beyond LEDs to others, such as photodetectors and memristors.

Perovskite materials, celebrated for their exceptional optoelectronic properties, have seen extensive application in the field of light-emitting diodes (LEDs), where research is as abundant as the proverbial “carloads of books.” In this review, the research of perovskite materials is delved into from a dimensional perspective, with a focus on the exemplary performance of low-dimensional perovskite materials in LEDs. This discussion predominantly revolves around perovskite quantum wires and perovskite nanorods. Perovskite quantum wires are versatile in their growth, compatible with both solution-based and vapor-phase growth, and can be deposited over large areas—even on spherical substrates—to achieve commendable electroluminescence (EL). Perovskite nanorods, on the other hand, boast a suite of superior characteristics, such as polarization properties and tunability of the transition dipole moment, endowing them with the great potential to enhance light extraction efficiency. Furthermore, zero-dimensional (0D) perovskite materials like nanocrystals (NCs) are also the subject of widespread research and application. This review reflects on and synthesizes the unique qualities of the aforementioned materials while exploring their vital roles in the development of high-efficiency perovskite LEDs (PeLEDs).

Implantable devices significantly enhance healthcare but are limited by battery life. Ultrasound power transfer technology offers a promising solution for sustainable operation. This review addresses gaps in current research, particularly in sound field analysis and energy efficiency optimization. It proposes an energy flow diagram, discusses development stages, and explores the potential advancements in ultrasound-based healthcare solutions.

Implantable medical devices (IMDs), like pacemakers regulating heart rhythm or deep brain stimulators treating neurological disorders, revolutionize healthcare. However, limited battery life necessitates frequent surgeries for replacements. Ultrasound power transfer (UPT) emerges as a promising solution for sustainable IMD operation. Current research prioritizes implantable materials, with less emphasis on sound field analysis and maximizing energy transfer during wireless power delivery. This review addresses this gap. A comprehensive analysis of UPT technology, examining cutting-edge system designs, particularly in power supply and efficiency is provided. The review critically examines existing efficiency models, summarizing the key parameters influencing energy transmission in UPT systems. For the first time, an energy flow diagram of a general UPT system is proposed to offer insights into the overall functioning. Additionally, the review explores the development stages of UPT technology, showcasing representative designs and applications. The remaining challenges, future directions, and exciting opportunities associated with UPT are discussed. By highlighting the importance of sustainable IMDs with advanced functions like biosensing and closed-loop drug delivery, as well as UPT's potential, this review aims to inspire further research and advancements in this promising field.

This review explores the evolution of AIE materials in bacterial research, highlighting their journey from initial studies of visualizing the unseen bacterial world to uncovering the underlying interaction and antibacterial mechanism. Recent advancements highlight the versatility and potential of AIE materials across a multitude of bacterial applications, showcasing their significant impact in various scientific fields.

Bacteria share a longstanding and complex relationship with humans, playing a role in protecting gut health and sustaining the ecosystem to cause infectious diseases and antibiotic resistance. Luminogenic materials that share aggregation-induced emission (AIE) characteristics have emerged as a versatile toolbox for bacterial studies through fluorescence visualization. Numerous research efforts highlight the superiority of AIE materials in this field. Recent advances in AIE materials in bacterial studies are categorized into four areas: understanding bacterial interactions, antibacterial strategies, diverse applications, and synergistic applications with bacteria. Initial research focuses on visualizing the unseen bacteria and progresses into developing strategies involving electrostatic interactions, amphiphilic AIE luminogens (AIEgens), and various AIE materials to enhance bacterial affinity. Recent progress in antibacterial strategies includes using photodynamic and photothermal therapies, bacterial toxicity studies, and combined therapies. Diverse applications from environmental disinfection to disease treatment, utilizing AIE materials in antibacterial coatings, bacterial sensors, wound healing materials, etc., are also provided. Finally, synergistic applications combining AIE materials with bacteria to achieve enhanced outcomes are explored. This review summarizes the developmental trend of AIE materials in bacterial studies and is expected to provide future research directions in advancing bacterial methodologies.

The development of all-solid-state lithium-sulfur batteries offers higher specific energies and lower costs compared to state-of-the-art Li-ion batteries. However, a lack of mechanistic understanding hinders advancement. This review analyzes key electrode parameters, evaluates progress in enhancing ion/electron percolation, and addresses electrochemical-mechanical degradation, offering future research directions.

The development of all-solid-state lithium-sulfur batteries (ASSLSBs) toward large-scale electrochemical energy storage is driven by the higher specific energies and lower cost in comparison with the state-of-the-art Li-ion batteries. Yet, insufficient mechanistic understanding and quantitative parameters of the key components in sulfur-based cathode hinders the advancement of the ASSLSB technologies. This review offers a comprehensive analysis of electrode parameters, including specific capacity, voltage, S mass loading and S content toward establishing the specific energy (Wh kg−1) and energy density (Wh L−1) of the ASSLSBs. Additionally, this work critically evaluates the progress in enhancing lithium ion and electron percolation and mitigating electrochemical-mechanical degradation in sulfur-based cathodes. Last, a critical outlook on potential future research directions is provided to guide the rational design of high-performance sulfur-based cathodes toward practical ASSLSBs.

Stretchable interconnects are one of the fundamental components in achieving robust wearable devices, but their importance is often overlooked. This review highlights their importance and provides insightful information on various materials, configurations, and manufacturing approaches being studied for interconnects. Their practical potentials for wearable bioelectronics are also discussed for future research opportunities.

Since wearable technologies for telemedicine have emerged to tackle global health concerns, the demand for well-attested wearable healthcare devices with high user comfort also arises. Skin-wearables for health monitoring require mechanical flexibility and stretchability for not only high compatibility with the skin's dynamic nature but also a robust collection of fine health signals from within. Stretchable electrical interconnects, which determine the device's overall integrity, are one of the fundamental units being understated in wearable bioelectronics. In this review, a broad class of materials and engineering methodologies recently researched and developed are presented, and their respective attributes, limitations, and opportunities in designing stretchable interconnects for wearable bioelectronics are offered. Specifically, the electrical and mechanical characteristics of various materials (metals, polymers, carbons, and their composites) are highlighted, along with their compatibility with diverse geometric configurations. Detailed insights into fabrication techniques that are compatible with soft substrates are also provided. Importantly, successful examples of establishing reliable interfacial connections between soft and rigid elements using novel interconnects are reviewed. Lastly, some perspectives and prospects of remaining research challenges and potential pathways for practical utilization of interconnects in wearables are laid out.

Colloidal quantum dots (QDs) have gained significant attention as photocatalysts in organic transformations in recent years. This review highlights QDs’ distinctive features, including the quantum size effect, compositional and structural diversity, tunable surface chemistry, and photophysics. Recent advancements in using QDs as photocatalysts for organic transformations are further summarized and an outlook in this field is provided.

Colloidal quantum dots (QDs) have emerged as a versatile photocatalyst for a wide range of photocatalytic transformations owing to its high absorption coefficient, large surface-to-volume ratio, high stability, and efficient charge and energy transfer dynamics. The past decades have witnessed a rapid development of QDs for artificial photocatalysis. In this review, the unique characteristics of QDs are focused on, including quantum size effect, compositional and structural diversity, tunable surface chemistry, and photophysics, that can be utilized for photocatalytic transformations. The recent advancements in photocatalytic organic transformations enabled by QDs photocatalysts are summarized. The unique opportunities of QDs are highlighted to tackle organic reactions that are previously unattainable with small molecule photocatalysts. Lastly, an outlook is provided for future directions in this field.

This review summarizes the current status of microenvironment regulation of catalytic reaction interface, flow electrolyzers design, and the flow electrolyzers derived stepwise approaches for COxRR to alcohol, aiming to provide new insights into the production of alcohols via COxRR.

The electrocatalytic reduction of COx (including CO2 and CO) into value-added fuels and chemicals, particularly multi-carbon (C2+) alcohols, presents a significant opportunity to close the manmade carbon cycle and support sustainable energy systems. The catalytic performance of electrochemical reduction reactions of CO2 and CO (COxRR) is strongly correlated with the local microenvironments, the flow electrolyzer, and the catalysis approaches with flow electrolyzers, which contribute to the kinetic and thermodynamic landscape of the reaction, ultimately determining the efficiency and selectivity of the COxRR toward desired reduction products. However, controllable microenvironment construction, rationally designed flow electrolyzers, and matchable flow electrolyzers derived catalysis approaches chosen for improving COxRR-to-alcohol performance still face challenges. Building upon the foundation laid by previous research, this review article will provide an in-depth summary of the regulation of the catalytic reaction interface microenvironment, the design of flow electrolyzers, and the development of derived stepwise catalysis approaches with the flow electrolyzers, which provide a comprehensive and strategic approach to enhancing the COxRR process for alcohol production, offering valuable insights and innovative solutions that can significantly impact the field of COxRR conversion to alcohol and contribute to the development of more sustainable chemical production methods.

Radiative cooling controls surface optical properties for solar and thermal radiation, offering solutions for global warming and energy savings. Despite significant advances, key challenges remain: optimizing optical efficiency, maintaining aesthetics, preventing overcooling, enhancing durability, and enabling scalable production. This review explores advanced solutions in material design and fabrication to guide future research and industrial applications.

Radiative cooling is achieved by controlling surface optical behavior toward solar and thermal radiation, offering promising solutions for mitigating global warming, promoting energy saving, and enhancing environmental protection. Despite significant efforts to develop optical surfaces in various forms, five primary challenges remain for practical applications: enhancing optical efficiency, maintaining appearance, managing overcooling, improving durability, and enabling scalable manufacturing. However, a comprehensive review bridging these gaps is currently lacking. This work begins by introducing the optical fundamentals of radiative cooling and its potential applications. It then explores the challenges and discusses advanced solutions through structural design, material selection, and fabrication processes. It aims to provide guidance for future research and industrial development of radiative cooling technology.

Polymeric charge transporters hold immense potential for inverted perovskite solar cells due to their tunable structures, high conductivity, and inherent flexibility. This review comprehensively explores recent advancements in these polymeric materials, while also delving into the remaining challenges and proposing practical design strategies for their future optimization.

Inverted perovskite solar cells (PSCs) hold exceptional promise as next-generation photovoltaic technology, where both perovskite absorbers and charge-transporting materials (CTMs) play critical roles in cell performance. In recent years, polymeric CTMs have played an important role in developing efficient, stable, and large-area inverted PSCs due to their unique properties of high conductivity, tunable structures, and mechanical flexibility. This review provides a comprehensive overview of polymeric CTMs used in inverted PSCs, encompassing polymeric hole transport materials (HTMs) and electron transport materials (ETMs). the relationship between their molecular structures, modification strategies are systematically summarized and analyzed for adjusting energy levels, and improving charge extraction, enabling a deep understanding of these widely used materials. The review also explores effective strategies for designing even more efficient polymeric CTMs. Finally, an outlook is proposed on the exciting research of novel polymeric CTMs, paving the way for their commercialized applications in PSCs.

CART cell therapy has proven effective for blood cancers but struggles with solid tumors due to diverse antigens and complex environments. Recent efforts focus on improving CAR design and validation platforms. Advances in protein engineering, machine learning, and organoid systems aim to enhance CAR-T therapy against solid tumors. Some solid tumors, like neuroblastoma, have responded well in trials.

Cancer immunotherapy, specifically Chimeric Antigen Receptor (CAR)-T cell therapy, represents a significant breakthrough in treating cancers. Despite its success in hematological cancers, CAR-T exhibits limited efficacy in solid tumors, which account for more than 90% of all cancers. Solid tumors commonly present unique challenges, including antigen heterogeneity and complex tumor microenvironment (TME). To address these, efforts are being made through improvements in CAR design and the development of advanced validation platforms. While efficacy is limited, some solid tumor types, such as neuroblastoma and gastrointestinal cancers, have shown responsiveness to CAR-T therapy in recent clinical trials. In this review, it is first examined both experimental and computational strategies, such as protein engineering coupled with machine learning, developed to enhance T cell specificity. The challenges and methods associated with T cell delivery and in vivo reprogramming in solid tumors is discussed. It is also explored the advancements in engineered organoid systems, which are emerging as high-fidelity in vitro models that closely mimic the complex human TME and serve as a validation platform for CAR discovery. Collectively, these innovative engineering strategies offer the potential to revolutionize the next generation of CAR-T therapy, ultimately paving the way for more effective treatments in solid tumors.

This review addresses challenges and recent advances in fast-charging solid-state batteries, focusing on solid electrolyte and electrode materials, as well as interfacial chemistries. The role of multiscale modeling and simulation in understanding Li+ transport and interfacial phenomena is emphasized, providing insights into materials, strategies, and future prospects for high-performance, fast-charging solid-state batteries.

The ability to rapidly charge batteries is crucial for widespread electrification across a number of key sectors, including transportation, grid storage, and portable electronics. Nevertheless, conventional Li-ion batteries with organic liquid electrolytes face significant technical challenges in achieving rapid charging rates without sacrificing electrochemical efficiency and safety. Solid-state batteries (SSBs) offer intrinsic stability and safety over their liquid counterparts, which can potentially bring exciting opportunities for fast charging applications. Yet realizing fast-charging SSBs remains challenging due to several fundamental obstacles, including slow Li+ transport within solid electrolytes, sluggish kinetics with the electrodes, poor electrode/electrolyte interfacial contact, as well as the growth of Li dendrites. This article examines fast-charging SSB challenges through a comprehensive review of materials and strategies for solid electrolytes (ceramics, polymers, and composites), electrodes, and their composites. In particular, methods to enhance ion transport through crystal structure engineering, compositional control, and microstructure optimization are analyzed. The review also addresses interface/interphase chemistry and Li+ transport mechanisms, providing insights to guide material design and interface optimization for next-generation fast-charging SSBs.

This review summarizes recent advanced catalysts applied in thermal catalysis, microwave-assisted catalysis, photocatalysis, electrocatalysis, and enzymatic catalysis reaction systems for the chemical recycling of plastic waste into valuable feedstocks.

Plastic products bring convenience to various aspects of the daily lives due to their lightweight, durability and versatility, but the massive accumulation of post-consumer plastic waste is posing significant environmental challenges. Catalytic methods can effectively convert plastic waste into value-added feedstocks, with catalysts playing an important role in regulating the yield and selectivity of products. This review explores the latest advancements in advanced catalysts applied in thermal catalysis, microwave-assisted catalysis, photocatalysis, electrocatalysis, and enzymatic catalysis reaction systems for the chemical recycling of plastic waste into valuable feedstocks. Specifically, the pathways and mechanisms involved in the plastics recycling process are analyzed and presented, and the strengths and weaknesses of various catalysts employed across different reaction systems are described. In addition, the structure-function relationship of these catalysts is discussed. Herein, it is provided insights into the design of novel catalysts applied for the chemical recycling of plastic waste and outline challenges and future opportunities in terms of developing advanced catalysts to tackle the “white pollution” crisis.

In this review, the recent development of deep-blue (≤465 nm) perovskite light-emitting diodes (PeLEDs) are summarized, using different perovskite nanomaterials, including nanocrystals (NCs), quantum dots (QDs), nanoplatelets (NPLs), quasi-2D thin film, 3D bulk thin film, as well as lead-free perovskite nanomaterials. The challenges, optimization, and the future of deep-blue PeLEDs are discussed.

In this review, the recent development of blue perovskite light-emitting diodes (PeLED) are summarized. On deep-blue (≤465 nm) perovskite nanomaterials of different structural forms are mainly focused, including nanocrystals (NCs), quantum dots (QDs), nanoplatelets (NPLs), quasi-2D thin film, 3D bulk thin film, as well as lead-free perovskite nanomaterials. The current challenges are also examined in producing efficient deep-blue PeLED, such as material and spectral instability, imbalance charge transport, Joule heat impact, and poor optoelectronic performance. Several strategies are further discussed to overcome these challenges and achieve efficient deep-blue PeLED for next-generation display technology.

Incorporating tris(trimethylsilyl)-based additives, this work addresses the elimination reaction of methyl trifluoroethyl carbonate (FEMC) to contrast a homogeneous robust polymer-rich cathode-electrolyte interphase. Using the optimized electrolyte, the LiCoO2 cathode can maintain 95% after 500 cycles with a high cut-off voltage of 4.6 V. This study establishes a foundational framework for employing linear fluorocarbonates in high voltage systems and provides innovative insights into CEI design and construction.

Stabilizing LiCoO2 (LCO) cathode at high voltages is still challenging in lithium-ion batteries (LIBs). Although fluorinated solvents are utilized in high-voltage systems for their superior oxidation resistance, linear fluorinated carbonates still undergo elimination reactions at high voltages, producing corrosive substances that compromise electrode materials. This study addresses the elimination reaction of methyl trifluoroethyl carbonate (FEMC) by incorporating tris(trimethylsilyl)-based additives, thereby constructing a homogeneous and robust polymer-rich cathode-electrolyte interphase (CEI). With the incorporation of tris(trimethylsilyl)phosphite in the optimized electrolyte, the capacity of the coin cell with LCO as the cathode can maintain 95% after 500 cycles with a high cut-off voltage of 4.6 V. This study establishes a foundational framework for employing linear fluorocarbonates in high-voltage systems and provides innovative insights into CEI design and construction.