Ordered Mesoporous Crystalline Frameworks Toward Promising Energy Applications

Ultrathin Mesoporous Sandwiched Junctions with Monolayered Mesopores for Ultrahigh-Rate Sodium-Ion Storage

Rational nanostructural design for anode materials plays a crucial role in sodium-ion batteries (SIBs). Two-dimensional (2D) mesostructured composites capable of ideal diffusion kinetics and electronic conductivity are promising materials; however, difficulties remain in actual synthesis. Herein, we present a sequential monomicelle assembly strategy to synthesize uniform monolayered mesoporous TiO2-reduced graphene oxide sandwiched junctions (meso-TiO2/rGO sandwich), which enables superior pseudocapacitive sodium-ion storage. Such a sandwich structure has an ultrathin thickness, monolayered TiO2 mesopores at both sides of the rGO, a high surface area, and a uniform mesopore size. The combination of ultrathin 2D morphology, excellent mesoporosity, and electrical conductivity gives rise to comprehensive electrolyte access, reduced Na+ diffusion lengths, and promoted charge transfer. Remarkably, the sandwich anode exhibits a high reversible capacity, great rate capability, and cycling stability. Our study exemplifies the significance of constructing hybrid materials as an effective strategy for fast electrochemical sodium-ion storage.

Commodity Thermoplastic Elastomer-Enabled Templated Synthesis of Large-Pore Ordered Mesoporous Materials

Fabrication of ordered mesoporous materials (OMMs) has predominantly relied on templating-based methods. However, these methods are constrained by several limitations, especially the limited pore sizes attainable with commercially available surfactants used as structure-directing agents. To unlock the full potential of the OMMs, it is essential to develop synthetic strategies that facilitate the production of large-pore OMMs using scalable processes and cost-effective precursors. This work demonstrates the use of thermoplastic elastomer (TPE)-derived carbon replicas for synthesizing ordered mesoporous silica (OMS) and metal oxides (OMMOs) via precursor infiltration and template removal. The nanostructural evolution of the resulting inorganic materials was systematically investigated. Specifically, using tetraethyl orthosilicate (TEOS) as a silica precursor, this method can produce an OMS with relatively large pores. To establish the generalizability of this process, the fabrication approach was extended to other commercially available TPEs with varied chemical compositions and molecular weights while consistently resulting in ordered structures. Additionally, this synthetic strategy can be successfully applied to the production of OMMOs, including tin and titanium oxide matrix chemistries, yielding pore sizes of 16.0 and 19.2 nm, respectively. By developing a general method and using low-cost precursors, this work presents a scalable approach for fabricating large-pore OMMs with tunable pore textures and matrix chemistries.

Electrochemical Sensing Mechanisms and Interfacial Design Strategies of Mesoporous Nanochannel Membranes in Biosensing Applications

Precise and rapid detection of key biomolecules is crucial for early clinical diagnosis. These critical biomolecules and biomarkers are typically present at low concentrations within complex environments, presenting significant challenges for their accurate and reliable detection. Nowadays, electrochemical sensors based on nanochannel membranes have attracted significant attention due to their high sensitivity, simplicity, rapid response, and label-free point-of-care detection capabilities. The confined arena provided by the nanochannels for target recognition and interactions facilitates detection and signal amplification, leading to enhanced detection performance. The nanochannel membranes also can act as filters to repel the interferents and enable target detection in more complex environments. Thus, sensors based on nanochannel membranes are considered promising platforms for biosensing applications. However, challenges such as uncontrollable structures and unstable performance in some materials limit their applications and theoretical advancements. To investigate the relationship between architecture and sensing performance and to achieve reliable and efficient performance, it is essential to construct sensors with precise nanostructures possessing stable properties. With the development of nanomaterials technology, mesoporous nanochannel membranes with robust, controllable, and ordered mesostructures, along with tunable surface properties and tailored ion transport dynamics, have emerged as promising candidates for achieving reliable and efficient biosensing performance. Additionally, investigating the sensing mechanisms and key influencing factors will provide valuable insights into optimizing sensor architecture and enhancing the efficiency and reliability of biosensing technologies. In this Account, we highlight substantial advancements in mesoporous nanochannel membranes, which are mainly based on the research work published by our group. In the first section, we explore the underlying mechanisms of the sensing processes, including the solid-liquid interfacial interactions and nanoconfinement effects (i.e., electrostatic interactions, hydrophilic/hydrophobic interactions, and steric hindrance effects). We also delve into the key parameters including geometry, materials, recognition elements, and external factors related to mesoporous nanochannel membranes and their impacts on sensing mechanisms and performance. In particular, we point out that mesoporous nanochannel membranes with three-dimensional interconnected networks can facilitate ion penetration and lead to an increased number of binding sites, contributing to high sensitivity. Additionally, composite or multilevel mesoporous nanochannel membranes, particularly when integrated with external stimuli such as pH, light, and heat, can introduce unexpected properties, enhancing the sensing performance. These understandings provide valuable insights into the fundamental principles and influencing factors pertinent to the research and design of intelligent, high-quality sensors or nanofluidic devices. Furthermore, we conduct an analysis of integrating various biosensing mechanisms and strategies, which offers significant opportunities for biomedical monitoring, disease diagnosis, and the pharmaceutical industry. Finally, we describe future research directions and their potential for commercial adoption. Nanochannel sensors with novel structures, properties, and functional porous materials may lead to new trends in biomedical applications, including self-powered and wearable sensors for disease monitoring. We believe that this Account holds implications for promoting interdisciplinary endeavors encompassing chemistry and materials science and nanotechnology as well as analysis, biosensing, and biomedical science.

Defect-Modulated MOF Nanochannels for the Quasi-Solid-State Electrolyte of a Dendrite-Free Lithium Metal Battery

Efficient and selective Li+ transport within the nanochannel is essential for high-performance solid-state electrolytes (SSEs) in lithium metal batteries. Introducing Li+ hopping sites into SSEs shows great potential for promoting Li+ transport; however, it typically reduces the Li+ transport nanochannel size, consequently increasing the energy barrier for Li+ transport. Herein, we present a molecular defect strategy for MOFs to introduce Li+ hopping sites and increase the nanochannel size simultaneously as quasi-solid-state electrolytes (QSSEs). Compared with the defect-free Li@UiO-66-based QSSE, the optimized Li@UiO-66-D2-based QSSE exhibits a remarkable 343% enhancement in Li+ conductivity and improved Li+ selectivity. Furthermore, the 9 cm × 6 cm Li|Li@UiO-66-D2|LFP pouch cell exhibits excellent cycling performance with high capacity retention. An in-depth mechanism study has unveiled the significant impact of both hopping sites and nanochannel size on Li+ transport, emphasizing the importance of a molecular defect strategy in enhancing the overall Li+ transport performance of MOF-based QSSEs.

Stabilizing Hydrogen Radicals in Two-Dimensional Cobalt-Copper Mesoporous Nanoplates for Complete Nitrate Reduction Electrocatalysis to Ammonia

Ambient electrochemical reduction of waste nitrate (NO3 -) represents an alternative green route for sustainable ammonia (NH3) electrosynthesis in water. Despites some encouraged achievements, sluggish eight electron and nine proton reduction routes that involve multi-step hydrogenation pathways have severely hindered their NH3 Faradaic efficiency (FENH3) and yield rate. Herein, we develop a robust two-dimensional mesoporous cobalt-copper (meso-CoCu) nanoplate electrocatalyst that delivers excellent performance of complete NO3 - reduction reaction (NO3RR), including superior FENH3 of 98.8 %, high NH3 yield rate of 3.39 mol h-1 g-1 and energy efficiency of 49.8 %, and good cycling stability. Mechanism investigations unveil that active hydrogen (*H) radicals produced from water splitting on Co sites spillover to adjacent Cu sites and further stabilize within confined mesopores, which kinetically promote its coupling hydrogenation reactions of nitrogen intermediates and thus facilitate complete NO3RR for favorable NH3 electrosynthesis. Moreover, meso-CoCu nanoplates perform well as a bifunctional electrocatalyst in the two-electrode coupling system that concurrently synthesizes NH3 from NO3 - at cathode and 2,5-furanedicarboxylic acid from 5-hydroxymethylfurfural at anode. This work in stabilizing *H radicals in mesoporous microenvironment provides some insights applied to various hydrogenation reactions for selective electrosynthesis of high value-added chemicals in water.

Construction of Compartmentalized Meso/Micro Spaces in Hierarchically Porous MOFs with Long-Chain Functional Ligands Inspired by Biological Signal Amplification

The creation of spatially coupled meso-/microenvironments with biomimetic compartmentalized functionalities is of great significance to achieve efficient signal transduction and amplification. Herein, using a soft-template strategy, UiO-67-type hierarchically mesoporous metal-organic frameworks (HMMOFs) were constructed to satisfy the requirements of such an artificial system. The key to the successful synthesis of HMUiO-67 is rooted in the utilization of the preformed cerium-oxo clusters as metal precursors, aligning the growth of MOF crystals with the mild conditions required for the self-assembly of the soft template. The adoption of long-chain functional 2,2'-bipyridine-5,5'-dicarboxylic acid ligands not only resulted in larger microporous sizes, facilitating the transport of various cascade reaction intermediates, but also provided anchorages for the introduction of enzyme-mimicking active sites. A cascade amplification system was designed based on the developed HMUiO-67, in which enzyme cascade reactions were initiated and relayed by a target analyte in the separate but coupled meso/micro spaces. As a proof of concept, natural acetylcholinesterase (AChE) and Cu-based laccase mimetics were integrated into HMMOFs, establishing a spatially coupled nanoreactor. The activity of AChE was triggered by the target analyte of carbaryl, while the amplified products of AChE catalysis mediated the activity of biomimetic enzyme in the closely proximate microporous spaces, producing further amplification of detectable signal. This enabled the entire cascade system to respond to minimal carbaryl with a limit of detection as low as approximately 2 nM. Such a model of cascade amplification is expected to set a conceptual guideline for the rational design of various bioreactors, serving as a sensitive response system for quantifying numerous target analytes.

A Review of Anode Materials for Dual-Ion Batteries

Distinct from "rocking-chair" lithium-ion batteries (LIBs), the unique anionic intercalation chemistry on the cathode side of dual-ion batteries (DIBs) endows them with intrinsic advantages of low cost, high voltage, and eco-friendly, which is attracting widespread attention, and is expected to achieve the next generation of large-scale energy storage applications. Although the electrochemical reactions on the anode side of DIBs are similar to that of LIBs, in fact, to match the rapid insertion kinetics of anions on the cathode side and consider the compatibility with electrolyte system which also serves as an active material, the anode materials play a very important role, and there is an urgent demand for rational structural design and performance optimization. A review and summarization of previous studies will facilitate the exploration and optimization of DIBs in the future. Here, we summarize the development process and working mechanism of DIBs and exhaustively categorize the latest research of DIBs anode materials and their applications in different battery systems. Moreover, the structural design, reaction mechanism and electrochemical performance of anode materials are briefly discussed. Finally, the fundamental challenges, potential strategies and perspectives are also put forward. It is hoped that this review could shed some light for researchers to explore more superior anode materials and advanced systems to further promote the development of DIBs.

Mesoporous Metal Nanomaterials: Developments and Electrocatalytic Applications

Mesoporous metal nanomaterials (MPMNs) are pivotal in nanotechnology, especially in electrochemical applications, due to their unique structure. Unlike traditional nanomaterials, MPMNs possess hierarchical and mesoporous characteristics, providing more active sites for improved mass and electron transfer. This distinctive composition offers dual benefits, enhancing activity, stability, and selectivity for specific reactions. The intricate architecture, featuring interconnected pores, amplifies surface area, ensuring efficient use of active sites and boosting reactivity in electrocatalytic processes. Additionally, the mesoporous nature promotes superior diffusion kinetics, facilitating better transport of reactants and products. This intricate interplay of structural elements contributes not only to the increased efficiency of electrochemical reactions but also to the extended durability of MPMNs during prolonged usage. This concept focus on the synthesis and design strategies of MPMNs, aligning with the dynamic requirements of diverse electrocatalytic applications. The synergy resulting from these advancements not only accentuates the intrinsic properties of MPMNs but also broadens their scope for practical implementation in emerging fields of electrochemistry.