Nanoarchitectures for Mesoporous Metals

Nucleation and growth of zinc-templated mesoporous selenium nanoparticles and potential non-thermal effects during their microwave-assisted synthesis

The effects of 5.8-GHz microwave (MW) irradiation on the synthesis of mesoporous selenium nanoparticles (mSeNPs) in aqueous medium by reduction of selenite ions with ascorbic acid, using zinc nanoparticles as a hard template and cetyltrimethylammonium bromide (CTAB) as a micellar template, are examined for the first time with a particular emphasis on MW-particle interactions and the NPs morphology. This MW-assisted synthesis is compared to 2.45 GHz MW heating method and conventional hydrothermal method at around 100 °C to produce the nanoparticles of different morphology and particle size distributions. The NPs morphology is tailored by varying the temperature ramp characteristics and the MW irradiation time. Under mild synthesis conditions only spherical particles are formed. Enhancing temperature ramp rate in the presence of CTAB micelles increases the metal-semiconductor hybrid particles growth rate and promotes the formation of nanorods and branched shapes. The effect is MW frequency dependent and non-thermal to some extent. Multi-step mechanism of mSeNPs formation is proposed based on derivative UV-Vis spectrophotometry and scanning electron microscopy (SEM) data. Both the stability of the chemical composition at a single particle level and the high efficiency of zinc template removal are determined by single particle microwave plasma optical emission spectrometry (SP-MWP-OES). After Zn template removal mSeNPs can be loaded with antifungal carbamate agent, hence the application as a nanopesticide is suggested.

Research Progress on Ni-Based Electrocatalysts for the Electrochemical Reduction of Nitrogen to Ammonia

The electrochemical nitrogen reduction reaction (NRR) to synthesize ammonia (NH3) is considered as a promising method due to its approvable advantages of zero-pollution emission, feasible reaction proceedings, good safety and easy management. The multiple efforts have been devoted to the exploration of earth-abundant-element-based nanomaterials as high-efficiency electrocatalysts for realizing their industrial applications. Among these, the Ni-based nanomaterials is prioritized as an attractive non-noble-metal electrocatalysts for catalyzing NRR because they are earth-abundance and exceedingly easy to synthesize as well as also delivers the potential of high electrocatalytic activity and durability. In this review, after briefly elucidating the underlying mechanisms of NRR during the electrochemical process, we systematically sum up the recent research progress in representative Ni-based electrocatalysts, including monometallic Ni-based nanomaterials, bimetallic Ni-based nanomaterials, polymetallic Ni-based nanomaterials, etc. In particular, we discuss the effects of physicochemical properties, such as phases, crystallinity, morphology, composition, defects, heteroatom doping, and strain engineering, on the comprehensive performance of the abovementioned electrocatalysts, with the aim of establishing the nanostructure-function relationships of the electrocatalysts. In addition, the promising directions of Ni-based electrocatalysts for NRR are also pointed out and highlighted. The generic approach in this review may expand the frontiers of NRR and provides the inspiration for developing high-efficiently Ni-based electrocatalysts.

Versatile synthesis of uniform mesoporous superparticles from stable monomicelle units

Superstructures with architectural complexity and unique functionalities are promising for a variety of practical applications in many fields, including mechanics, sensing, photonics, catalysis, drug delivery and energy storage/conversion. In the past five years, a number of attempts have been made to build superparticles based on amphiphilic polymeric micelle units, but most have failed owing to their inherent poor stability. Determining how to stabilize micelles and control their superassembly is critical to obtaining the desired mesoporous superparticles. Here we provide a detailed procedure for the preparation of ultrastable polymeric monomicelle building units, the creation of a library of ultrasmall organic-inorganic nanohybrids, the modular superassembly of monomicelles into hierarchical superstructures and creation of novel multilevel mesoporous superstructures. The protocol enables precise control of the number of monomicelle units and the derived mesopores for superparticles. We show that ultrafine nanohybrids display enhanced mechanical antipressure performance compared with pristine polymeric micelles, and describe the functional characterization of mesoporous superstructures that exhibit excellent oxygen reduction reactivity. Except for the time (4.5 d) needed for the preparation of the triblock polystyrene-block-poly(4-vinylpyridine)-block-poly(ethylene oxide) PS-PVP-PEO or the polystyrene-block-poly(acrylic acid)-block-poly(ethylene oxide) (PS-PAA-PEO) copolymer, the synthesis of the ultrastable monomicelle, ultrafine organic-inorganic nanohybrids, hierarchical superstructures and mesoporous superparticles require ~6, 30, 8 and 24 h, respectively. The time needed for all characterizations and applications are 18 and 10 h, respectively.

Mesoporous High-Entropy Alloy Films

High-entropy alloys (HEAs) are promising materials for electrochemical energy applications due to their excellent catalytic performance and durability. However, the controlled synthesis of HEAs with a well-defined structure and a uniform composition distribution remains a challenge. Herein, a soft template-assisted electrodeposition technique is used to fabricate a mesoporous HEA (m-HEA) film with a uniform composition distribution of Pt, Pd, Rh, Ru, and Cu, providing a suitable platform for investigating structure-performance relationships. Electrochemical deposition enables the uniform nucleation and grain growth of m-HEA, which can be deposited onto many conductive substrates. The m-HEA film exhibits an enhanced mass activity of 4.2 A mgPt-1 toward methanol oxidation reaction (MOR), which is 7.2-fold and 35-fold higher than a mesoporous Pt film and commercial Pt black, respectively. Experimental characterization indicates that structural defects and a low work function of the m-HEA film offer sufficient active sites and fast electron-transfer kinetics. Furthermore, theoretical calculations demonstrate that the variety of favorable adsorption sites on multimetallic elements of HEA reduces the barriers for dehydration pathways and *CO species removal, ensuring optimal performance for complex MOR reactions. This work provides an effective approach to designing a variety of HEA catalysts with well-controlled porous structures for targeted electrocatalytic applications.

Enhanced Ocular Delivery of Beva via Ultra-Small Polymeric Micelles for Noninvasive Anti-VEGF Therapy

Pathological ocular neovascularization resulting from retinal ischemia constitutes a major cause of vision loss. Current anti-VEGF therapies rely on burdensome intravitreal injections of Bevacizumab (Beva). Herein ultrasmall polymeric micelles encapsulating Beva (P@Beva) are developed for noninvasive topical delivery to posterior eye tissues. Beva is efficiently loaded into 11 nm micelles fabricated via self-assembly of hyperbranched amphiphilic copolymers. The neutral, brush-like micelles demonstrate excellent drug encapsulation and colloidal stability. In vitro, P@Beva enhances intracellular delivery of Beva in ocular cells versus free drug. Ex vivo corneal and conjunctival-sclera-choroidal tissues transport after eye drops are improved 23-fold and 7.9-fold, respectively. Anti-angiogenic bioactivity is retained with P@Beva eliciting greater inhibition of endothelial tube formation and choroid sprouting over Beva alone. Remarkably, in an oxygen-induced retinopathy (OIR) model, topical P@Beva matching efficacy of intravitreal Beva injection, is the clinical standard. Comprehensive biocompatibility verifies safety. Overall, this pioneering protein delivery platform holds promise to shift paradigms from invasive intravitreal injections toward simplified, noninvasive administration of biotherapeutics targeting posterior eye diseases.

2D PtRhPb Mesoporous Nanosheets with Surface-Clean Active Sites for Complete Ethanol Oxidation Electrocatalysis

The development of active and selective metal electrocatalysts for complete ethanol oxidation reaction (EOR) into desired C1 products is extremely promising for practical application of direct ethanol fuel cells. Despite some encouraging achievements, their activity and selectivity remain unsatisfactory. In this work, it is reported that 2D PtRhPb mesoporous nanosheets (MNSs) with anisotropic structure and surface-clean metal site perform perfectly for complete EOR electrocatalysis in both three-electrode and two-electrode systems. Different to the traditional routes, a selective etching strategy is developed to produce surface-clean mesopores while retaining parent anisotropy quasi-single-crystalline structure without the mesopore-forming surfactants. This method also allows the general synthesis of surface-clean mesoporous metals with other compositions and structures. When being performed for alkaline EOR electrocatalysis, the best PtRhPb MNSs deliver remarkably high activity (7.8 A mg-1) and superior C1 product selectivity (70% of Faradaic efficiency), both of which are much better than reported electrocatalysts. High performance is assigned to multiple structural and compositional synergies that not only stabilized key OHads intermediate by surface-clean mesopores but also separated the chemisorption of two carbons in ethanol by adjacent Pt and Rh sites, which facilitate the oxidation cleavage of stable C─C bond for complete EOR electrocatalysis.

Enzymatic Mesoporous Metal Nanocavities for Concurrent Electrocatalysis of Nitrate to Ammonia Coupled with Polyethylene Terephthalate Upcycling

Electrochemical upcycling of waste pollutants into high value-added fuels and/or chemicals is recognized as a green and sustainable solution that can address the resource utilization on earth. Despite great efforts, their progress has seriously been hindered by the lack of high-performance electrocatalysts. In this work, bimetallic PdCu mesoporous nanocavities (MCs) are reported as a new bifunctional enzymatic electrocatalyst that realizes concurrent electrocatalytic upcycling of nitrate wastewater and polyethylene terephthalate (PET) plastic waste. Abundant metal mesopores and open nanocavities of PdCu MCs provide the enzymatic confinement of key intermediates for the deeper electroreduction of nitrate and accelerate the transport of reactants/products within/out of electrocatalyst, thus affording high ammonia Faradic efficiency (FENH3) of 96.6% and yield rate of 5.6 mg h-1 mg-1 at the cathode. Meanwhile, PdCu MC nanozymes trigger the selective electrooxidation of PET-derived ethylene glycol (EG) into glycolic acid (GA) and formic acid with high FEs of >90% by a facile regulation of potentials at the anode. Moreover, concurrent electrosynthesis of value-added NH3 and GA is disclosed in the two-electrode coupling system, further confirming the high efficiency of bifunctional PdCu MC nanozymes in producing value-added fuels and chemicals from waste pollutants in a sustainable manner.

Ir-Doped CuPd Single-Crystalline Mesoporous Nanotetrahedrons for Ethylene Glycol Oxidation Electrocatalysis: Enhanced Selective Cleavage of C-C Bond

The development of highly efficient electrocatalysts for complete oxidation of ethylene glycol (EG) in direct EG fuel cells is of decisive importance to hold higher energy efficiency. Despite some achievements, their progress, especially electrocatalytic selectivity to complete oxidated C1 products, is remarkably slower than expected. In this work, we developed a facile aqueous synthesis of Ir-doped CuPd single-crystalline mesoporous nanotetrahedrons (Ir-CuPd SMTs) as high-performance electrocatalyst for promoting oxidation cleavage of C-C bond in alkaline EG oxidation reaction (EGOR) electrocatalysis. The synthesis relied on precise reduction/co-nucleation and epitaxial growth of Ir, Cu and Pd precursors with cetyltrimethylammonium chloride as the mesopore-forming surfactant and extra Br- as the facet-selective agent under ambient conditions. The products featured concave nanotetrahedron morphology enclosed by well-defined (111) facets, single-crystalline and mesoporous structure radiated from the center, and uniform elemental composition without any phase separation. Ir-CuPd SMTs disclosed remarkably enhanced electrocatalytic activity and excellent stability as well as superior selectivity of C1 products for alkaline EGOR electrocatalysis. Detailed mechanism studies demonstrated that performance improvement came from structural and compositional synergies, which kinetically accelerated transports of electrons/reactants within active sites of penetrated mesopores and facilitated oxidation cleavage of high-energy-barrier C-C bond of EG for desired C1 products. More interestingly, Ir-CuPd SMTs performed well in coupled electrocatalysis of anode EGOR and cathode nitrate reduction, highlighting its high potential as bifunctional electrocatalyst in various applications.

Ordered Mesoporous Crystalline Frameworks Toward Promising Energy Applications

Ordered mesoporous crystalline frameworks (MCFs), which possess both functional frameworks and well-defined porosity, receive considerable attention because of their unique properties including high surface areas, large pore sizes, tailored porous structures, and compositions. Construction of novel crystalline mesoporous architectures that allows for rich accessible active sites and efficient mass transfer is envisaged to offer ample opportunities for potential energy-related applications. In this review, the rational synthesis, unique structures, and energy applications of MCFs are the main focus. After summarizing the synthetic approaches, an emphasis is placed on the delicate control of crystallites, mesophases, and nano-architectures by concluding basic principles and showing representative examples. Afterward, the currently fabricated components of MCFs such as metals, metal oxides, metal sulfides, and metal-organic frameworks are described in sequence. Further, typical applications of MCFs in rechargeable batteries, supercapacitors, electrocatalysis, and photocatalysis are highlighted. This review ends with the possible development and synthetic challenges of MCFs as well as a future prospect for high-efficiency energy applications, which underscores a pathway for developing advanced materials.

Hofmann-Type Cyanide Bridged Coordination Polymers for Advanced Functional Nanomaterials

Since the discovery of Hofmann clathrates of inorganic cyanide bridged coordination polymers (Hofmann-type CN-CPs), extensive research is done to understand their behavior during spin transitions caused by guest molecules or external stimuli. Lately, research on their nanoscale architectures for sensors and switching devices is of interest. Their potential is reported for producing advanced functional inorganic materials in two-dimensional (2D) morphology using a scalable solid-state thermal treatment method. For instance, but not restricted to, alloys, carbides, chalcogenides, oxides, etc. Simultaneously, their in situ crystallization at graphene oxide (GO) nanosheet surfaces, followed by a subsequent self-assembly to build layered lamellar structures, is reported providing hybrid materials with a variety of uses. Hence, an overview of the most recent developments is presented here in the synthesis of nanoscale structures, including thin films and powders, using Hofmann-type CN-CPs. Also thoroughly demonstrated are the most recent synthetic ideas with the modest control over the size and shape of nanoscale particles. Additionally, in order to create new functional hybrid materials for electrical and energy applications, their thermal decomposition in various environments and hybridization with GO and other guest molecules is examined. This review article also conveyed their spin transition, astounding innovative versatile adhesives, and structure features.

Facile one-step synthesis of mesoporous Pt-based alloy nanospheres for ethanol electrooxidation

Mesoporous Pt-based alloy nanospheres were prepared via a one-step soft-template strategy. The regulation of electronic structure, lattice contraction and abundant active sites endowed the mesoporous Pt-based catalysts with remarkable electrochemical activity towards ethanol oxidation reaction.

Two-dimensional mesoporous metals: a new era for designing functional electrocatalysts

Two-dimensional (2D) mesoporous metals contribute a unique class of electrocatalyst materials for electrochemical applications. The penetrated mesopores of 2D mesoporous metals expose abundant accessible undercoordinated metal sites, while their 2D nanostructures accelerate the transport of electrons and reactants. Therefore, 2D mesoporous metals have exhibited add-in structural functions with great potential in electrocatalysis that not only enhance electrocatalytic activity and stability but also optimize electrocatalytic selectivity. In this Perspective, we summarize recent progress in the design, synthesis, and electrocatalytic performance of 2D mesoporous metals. Four main strategies for synthesizing 2D mesoporous metals, named the CO (and CO container) induced route, halide ion-oriented route, interfacial growth route, and metal oxide atomic reconstruction route, are presented in detail. Moreover, electrocatalytic applications in several important reactions are summarized to highlight the add-in structural functions of 2D mesoporous metals in enhancing electrochemical activity, stability, and selectivity. Finally, current challenges and future directions are discussed in this area. This Perspective offers some important insights into both fundamental investigations and practical applications of novel high-performance functional electrocatalysts.

Electrochemical simultaneous determination of hydroquinone, catechol, bisphenol A, and bisphenol S using a novel mesoporous nickel-modified carbon sensor

The widespread occurrence of endocrine disruptor compounds in wastewater has garnered significant attention owing to their toxicity, even at low concentrations, and their persistence in the water body. Among various analytical techniques, electrochemical sensors become popular for the environmental monitoring of water pollutants due to their low cost, rapid detection, high sensitivity, and selectivity. In this study, the mesoporous Ni (MNi) material was synthesized with an innovative method using Pluronic™ F-127 as a soft template and applied as a modifier for the simultaneous electrochemical sensing of hydroquinone (HQ), catechol (CC), bisphenol A (BPA), and bisphenol S (BPS). MNi with high porosity efficiently enhanced the redox-active surface area and conductivity of the glassy carbon electrode contributing to a significantly improved sensitivity in the detection of target chemicals. The pore size and surface area of MNi were estimated based on atomic force microscopy and Brunauer Emmett and Teller techniques to be ∼14.2 nm and 31.1 m2 g-1, respectively. The limit of detection for HQ, CC, BPA, and BPS was determined to be 5.3, 5.7, 5.6, and 61.5 nM, respectively. The electrochemical sensor presented in this study holds promise as a platform for developing portable and miniaturized tools offering the rapid and sensitive detection of these hazardous phenolic compounds in environmental water samples.

Monitoring of Pore Orientation by in Operando Grazing Incidence Small-Angle X-ray Scattering during Templated Electrodeposition of Mesoporous Pt Films

We have used in operando grazing incidence small-angle X-ray scattering (GISAXS) to monitor structural changes during templated electrodeposition of mesoporous platinum films on gold electrodes from a ternary lyotropic liquid crystalline mixture of aqueous hexachloroplatinic acid and the diblock copolymer surfactant Brij56. While the cylindrical micelles of the lyotropic liquid crystal (LLC) in the hexagonal phase have a center-to-center distance of 7.5 nm with a preferential alignment parallel to the electrode surface, the electrodeposited platinum films contain highly ordered mesopores arranged in a 2D hexagonal structure, with a center-to-center distance of about 8.5 nm and a preferential orientation perpendicular to the electrode surface. The progression of structural changes of the LLC template and the deposited mesoporous Pt could be monitored for the first time in operando by GISAXS: within the first 14 s of deposition, a nucleation burst of Pt coincides with a loss of preferential alignment of the LLC. Initially, the morphology of the 2-dimensionally nucleated Pt replicates the Au substrate. During the following 5 to 7 min, the growth morphology of the Pt film changes, and vertically aligned mesopores form. Our results indicate mutual interaction between the species involved in the electrodeposition and the LLC template, leading to a partial loss of horizontal orientation of the LLC during Pt nucleation before vertical rearrangement of the micelles to the electrode surface. The vertically aligned mesopores in the Pt and the possibility to produce freestanding films make these materials interesting in fields such as electrocatalysis, energy harvesting, and nanofluidics.

Abundant Exterior/Interior Active Sites Enable Three-Dimensional PdPtBiTe Dumbbells C-C Cleavage Electrocatalysts for Actual Alcohol Fuel Cells

Developing high-activity electrocatalysts is of great significance for the commercialization of direct alcohol fuel cells (DAFCs), but it still faces challenges. Herein, three-dimensional (3D) porous PdPtBiTe dumbbells (DBs) were successfully fabricated via the visible photoassisted method. The alloying effect, defect-rich surface/interface and nanoscale cavity, and open pores make the 3D PdPtBiTe DBs a comprehensive and remarkable electrocatalyst for the C1-C3 alcohol (ethanol, ethylene glycol, glycerol, and methanol) oxidation reaction (EOR, EGOR, GOR, and MOR, respectively) in an alkaline electrolyte, and the results of in situ Fourier transform infrared spectra revealed a superior C-C bond cleavage ability. The 3D PdPtBiTe DBs exhibit ultrahigh EOR, EGOR, GOR, and MOR mass activities of 25.4, 23.2, 16.8, and 18.3 A mgPd + Pt-1, respectively, considerably surpassing those of the commercial Pt/C and Pd/C. Moreover, the mass peak power densities of 3D PdPtBiTe DBs in actual ethanol, ethylene glycol, glycerol, or methanol fuel cells increase to 409.5, 501.5, 558.0, or 601.3 mW mgPd + Pt-1 in O2, respectively. This study provides a new class of multimetallic nanomaterials as state-of-the-art multifunctional anode electrocatalysts for actual DAFCs.

Mesoporous multimetallic nanospheres with exposed highly entropic alloy sites

Multimetallic alloys (MMAs) with various compositions enrich the materials library with increasing diversity and have received much attention in catalysis applications. However, precisely shaping MMAs in mesoporous nanostructures and mapping the distributions of multiple elements remain big challenge due to the different reduction kinetics of various metal precursors and the complexity of crystal growth. Here we design a one-pot wet-chemical reduction approach to synthesize core-shell motif PtPdRhRuCu mesoporous nanospheres (PtPdRhRuCu MMNs) using a diblock copolymer as the soft template. The PtPdRhRuCu MMNs feature adjustable compositions and exposed porous structures rich in highly entropic alloy sites. The formation processes of the mesoporous structures and the reduction and growth kinetics of different metal precursors of PtPdRhRuCu MMNs are revealed. The PtPdRhRuCu MMNs exhibit robust electrocatalytic hydrogen evolution reaction (HER) activities and low overpotentials of 10, 13, and 28 mV at a current density of 10 mA cm-2 in alkaline (1.0 M KOH), acidic (0.5 M H2SO4), and neutral (1.0 M phosphate buffer solution (PBS)) electrolytes, respectively. The accelerated kinetics of the HER in PtPdRhRuCu MMNs are derived from multiple compositions with synergistic interactions among various metal sites and mesoporous structures with excellent mass/electron transportation characteristics.

Nanoarchitectonics of Metallene Materials for Electrocatalysis

Controlling the synthesis of metal nanostructures is one approach for catalyst engineering and performance optimization in electrocatalysis. As an emerging class of unconventional electrocatalysts, two-dimensional (2D) metallene electrocatalysts with ultrathin sheet-like morphology have gained ever-growing attention and exhibited superior performance in electrocatalysis owing to their distinctive properties originating from structural anisotropy, rich surface chemistry, and efficient mass diffusion capability. Many significant advances in synthetic methods and electrocatalytic applications for 2D metallenes have been obtained in recent years. Therefore, an in-depth review summarizing the progress in developing 2D metallenes for electrochemical applications is highly needed. Unlike most reported reviews on the 2D metallenes, this review starts by introducing the preparation of 2D metallenes based on the classification of the metals (e.g., noble metals, and non-noble metals) instead of synthetic methods. Some typical strategies for preparing each kind of metal are enumerated in detail. Then, the utilization of 2D metallenes in electrocatalytic applications, especially in the electrocatalytic conversion reactions, including the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, fuel oxidation reaction, CO₂ reduction reaction, and N₂ reduction reaction, are comprehensively discussed. Finally, current challenges and opportunities for future research on metallenes in electrochemical energy conversion are proposed.

Stepwise Monomicelle Assembly for Highly Ordered Mesoporous TiO2 Membranes with Precisely Tailored Mesophase and Porosity

Mesoporous materials with crystalline frameworks have been acknowledged as very attractive materials in various applications. Nevertheless, due to the cracking issue during crystallization and incompatible hydrolysis and assembly, the precise control for crystalline mesoscale membranes is quite infertile. Herein, we presented an ingenious stepwise monomicelle assembly route for the syntheses of highly ordered mesoporous crystalline TiO₂ membranes with delicately controlled mesophase, mesoporosity, and thickness. Such a process involves the preparation of monomicelle hydrogels and follows self-assembly by stepwise solvent evaporation, which enables the sensitive hydrolysis of TiO₂ oligomers and dilatory micelle assembly to be united. In consequence, the fabricated mesoporous TiO₂ membranes exhibit a broad flexibility, including tunable ordered mesophases (worm-like, hexagonal p6mm to body-centered cubic Im3̅m), controlled mesopore sizes (3.0-8.0 nm), and anatase grain sizes (2.3-8.4 nm). Besides, such mesostructured crystalline TiO₂ membranes can be extended to diverse substrates (Ti, Ag, Si, FTO) with tailored thickness. The great mesoporosity of the in situ fabricated mesoscopic membranes also affords excellent pseudocapacitive behavior for sodium ion storage. This study underscores a novel pathway for balancing the interaction of precursors and micelles, which could have implications for synthesizing crystalline mesostructures in higher controllability.

Prussian blue nanozymes coated with Pluronic attenuate inflammatory osteoarthritis by blocking c-Jun N-terminal kinase phosphorylation

Osteoarthritis (OA) is a degenerative joint disorder associated with inflammation, functional disability, and high socioeconomic costs. The development of effective therapies against inflammatory OA has been limited owing to its complex and multifactorial nature. The efficacy of Prussian blue nanozymes coated with Pluronic (PPBzymes), US Food and Drug Administration-approved components, and their mechanisms of action have been described in this study, and PPBzymes have been characterized as a new OA therapeutic. Spherical PPBzymes were developed via nucleation and stabilization of Prussian blue inside Pluronic micelles. A uniformly distributed diameter of approximately 204 nm was obtained, which was maintained after storage in an aqueous solution and biological buffer. This indicates that PPBzymes are stable and could have biomedical applications. In vitro data revealed that PPBzymes promote cartilage generation and reduce cartilage degradation. Moreover, intra-articular injections with PPBzymes into mouse joints revealed their long-term stability and effective uptake into the cartilage matrix. Furthermore, intra-articular PPBzymes injections attenuated cartilage degradation without exhibiting cytotoxicity toward the synovial membrane, lungs, and liver. Notably, based on proteome microarray data, PPBzymes specifically block the JNK phosphorylation, which modulates inflammatory OA pathogenesis. These findings indicate that PPBzymes might represent a biocompatible and effective nanotherapeutic for obstructing JNK phosphorylation.

Controllable Preparation of Gold Nanocrystals with Different Porous Structures for SERS Sensing

Porous Au nanocrystals (Au NCs) have been widely used in catalysis, sensing, and biomedicine due to their excellent localized surface plasma resonance effect and a large number of active sites exposed by three-dimensional internal channels. Here, we developed a ligand-induced one-step method for the controllable preparation of mesoporous, microporous, and hierarchical porous Au NCs with internal 3D connecting channels. At 25 °C, using glutathione (GTH) as both a ligand and reducing agent combined with the Au precursor to form GTH-Au(I), and under the action of the reducing agent ascorbic acid, the Au precursor is reduced in situ to form a dandelion-like microporous structure assembled by Au rods. When cetyltrimethylammonium bromide (C₁₆TAB) and GTH are used as ligands, mesoporous Au NCs formed. When increasing the reaction temperature to 80 °C, hierarchical porous Au NCs with both microporous and mesoporous structures will be synthesized. We systematically explored the effect of reaction parameters on porous Au NCs and proposed possible reaction mechanisms. Furthermore, we compared the SERS-enhancing effect of Au NCs with three different pore structures. With hierarchical porous Au NCs as the SERS base, the detection limit for rhodamine 6G (R6G) reached 10^-10 M.

Au-Loaded Superparamagnetic Mesoporous Bimetallic CoFeB Nanovehicles for Sensitive Autoantibody Detection

Construction of a well-defined mesoporous nanostructure is crucial for applying nonnoble metals in catalysis and biomedicine owing to their highly exposed active sites and accessible surfaces. However, it remains a great challenge to controllably synthesize superparamagnetic CoFe-based mesoporous nanospheres with tunable compositions and exposed large pores, which are sought for immobilization or adsorption of guest molecules for magnetic capture, isolation, preconcentration, and purification. Herein, a facile assembly strategy of a block copolymer was developed to fabricate a mesoporous CoFeB amorphous alloy with abundant metallic Co/Fe atoms, which served as an ideal scaffold for well-dispersed loading of Au nanoparticles (∼3.1 nm) via the galvanic replacement reaction. The prepared Au-CoFeB possessed high saturation magnetization as well as uniform and large open mesopores (∼12.5 nm), which provided ample accessibility to biomolecules, such as nucleic acids, enzymes, proteins, and antibodies. Through this distinctive combination of superparamagnetism (CoFeB) and biofavorability (Au), the resulting Au-CoFeB was employed as a dispersible nanovehicle for the direct capture and isolation of p53 autoantibody from serum samples. Highly sensitive detection of the autoantibody was achieved with a limit of detection of 0.006 U/mL, which was 50 times lower than that of the conventional p53-ELISA kit-based detection system. Our assay is capable of quantifying differential expression patterns for detecting p53 autoantibodies in ovarian cancer patients. This assay provides a rapid, inexpensive, and portable platform with the potential to detect a wide range of clinically relevant protein biomarkers.

A Comparison between Porous to Fully Dense Electrodeposited CuNi Films: Insights on Electrochemical Performance

Nanostructuring of metals is nowadays considered as a promising strategy towards the development of materials with enhanced electrochemical performance. Porous and fully dense CuNi films were electrodeposited on a Cu plate by electrodeposition in view of their application as electrocatalytic materials for the hydrogen evolution reaction (HER). Porous CuNi film were synthesized using the hydrogen bubble template electrodeposition method in an acidic electrolyte, while fully dense CuNi were electrodeposited from a citrate-sulphate bath with the addition of saccharine as a grain refiner. The prepared films were characterized chemically and morphologically by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The Rietveld analysis of the XRD data illustrates that both CuNi films have a nanosized crystallite size. Contact angle measurements reveal that the porous CuNi film exhibits remarkable superhydrophobic behavior, and fully dense CuNi film shows hydrophilicity. This is predominately ascribed to the surface roughness of the two films. The HER activity of the two prepared CuNi films were investigated in 1 M KOH solution at room temperature by polarization measurements and electrochemical impedance spectroscopy (EIS) technique. Porous CuNi exhibits an enhanced catalysis for HER with respect to fully dense CuNi. The HER kinetics for porous film is processed by the Volmer-Heyrovsky reaction, whereas the fully dense counterpart is Volmer-limited. This study presents a clear comparison of HER behavior between porous and fully dense CuNi films.

WITHDRAWN: Prussian blue nanozymes coated with pluronic attenuate inflammatory osteoarthritis by blocking c-Jun N-terminal kinase phosphorylation

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Hierarchical Design in Nanoporous Metals

Hierarchically porous metals possess intriguing high accessibility of matter molecules and unique continuous metallic frameworks, as well as a high level of exposed active atoms. High rates of diffusion and fast energy transfer have been important and challenging goals of hierarchical design and porosity control with nanostructured metals. This review aims to summarize recent important progress toward the development of hierarchically porous metals, with special emphasis on synthetic strategies, hierarchical design in structure-function and corresponding applications. The current challenges and future prospects in this field are also discussed.

NiFe2O4@B,N,F-tridoped CeO2 (NFTDNC): a mesoporous nanocatalyst in the synthesis of pyrazolopyranopyrimidine and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives and as an adsorbent

Mesoporous materials, due to their unique textural and structural features and successful applications in different scientific areas, engrossed our curiosity to form a mesoporous nanostructure. A facile method for the formation of nickel ferrite immobilized over B,N,F tridoped mesoporous cerium oxide (CeO₂) nanostructures (NFTDNC) was designed and communicated in this report. It was characterized by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction study (PXRD), scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HR-TEM), field emission gun-scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM), photoluminescence (PL), Brunauer-Emmett-Teller (BET), energy dispersive X-ray analysis (EDX) and elemental mapping, UV-visible spectroscopy (UV-VIS) and Fourier transform infrared spectroscopy (FT-IR). The applications of the mesoporous nanomaterial (NFTDNC) as an adaptable heterogeneous nanocatalyst and as a phenomenal adsorbent for methyl orange (MO) dye were established. It catalyzed the formation of pyrazolopyranopyrimidine and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones derivatives for the five runs. The recycled catalyst exhibited agglomeration in structural features confirmed by PXRD and HR-TEM studies. NFTDNC as an adsorbent fitted the Freundlich isotherm for the adsorption of MO dye. Moreover, it followed the linear pseudo-second-order kinetics rate equation (R² ≥ 0.98914). MO was adsorbed completely in 60 min with the NFTDNC mesoporous nanostructure.

Recent advances in nanoarchitectures of monocrystalline coordination polymers through confined assembly

Various kinds of monocrystalline coordination polymers are available thanks to the rapid development of related synthetic strategies. The intrinsic properties of coordination polymers have been carefully investigated on the basis of the available monocrystalline samples. Regarding the great potential of coordination polymers in various fields, it becomes important to tailor the properties of coordination polymers to meet practical requirements, which sometimes cannot be achieved through molecular/crystal engineering. Nanoarchitectonics offer unique opportunities to manipulate the properties of materials through integration of the monocrystalline building blocks with other components. Recently, nanoarchitectonics has started to play a significant role in the field of coordination polymers. In this short review, we summarize recent advances in nanoarchitectures based on monocrystalline coordination polymers that are formed through confined assembly. We first discuss the crystallization of coordination polymer single crystals inside confined liquid networks or on substrates through assembly of nodes and ligands. Then, we discuss assembly of preformed coordination polymer single crystals inside confined liquid networks or on substrates. In each part, we discuss the properties of the coordination polymer single crystals as well as their performance in energy, environmental, and biomedical applications.

Noble-Metal-Based Hollow Mesoporous Nanoparticles: Synthesis Strategies and Applications

As second-generation mesoporous materials, mesoporous noble metals (NMs) are of significant interest for their wide applications in catalysis, sensing, bioimaging, and biotherapy owing to their structural and metallic features. The introduction of interior hollow cavity into NM-based mesoporous nanoparticles (MNs), which subtly integrate hierarchical hollow and mesoporous structure into one nanoparticle, produces a new type of hollow MNs (HMNs). Benefiting from their higher active surface, better electron/mass transfer, optimum electronic structure, and nanoconfinement space, NM-based HMNs exhibit their high efficiency in enhancing catalytic activity and stability and tuning catalytic selectivity. In this review, recent progress in the design, synthesis, and catalytic applications of NM-based HMNs is summarized, including the findings of the groups. Five main strategies for synthesizing NM-based HMNs, namely silica-assisted surfactant-templated nucleation, surfactant-templated sequential nucleation, soft "dual"-template, Kirkendall effect in synergistic template, and galvanic-replacement-assisted surfactant template, are described in detail. In addition, the applications in ethanol oxidation electrocatalysis and hydrogenation reactions are discussed to highlight the high activity, enhanced stability, and optimal selectivity of NM-based HMNs in (electro)catalysis. Finally, the further outlook that may lead the directions of synthesis and applications of NM-based HMNs is prospected.

Soft Template-Based Synthesis of Mesoporous Phosphorus- and Boron-Codoped NiFe-Based Alloys for Efficient Oxygen Evolution Reaction

Controlling the morphology, composition, and crystalline phase of mesoporous nonnoble metal catalysts is essential for improving their performance. Herein, well-defined P- and B-codoped NiFe alloy mesoporous nanospheres (NiFeB-P MNs) with an adjustable Ni/Fe ratio and large mesopores (11 nm) are synthesized via soft-template-based chemical reduction and a subsequent phosphine-vapor-based phosphidation process. Earth-abundant NiFe-based materials are considered promising electrocatalysts for the oxygen evolution reaction (OER) because of their low cost and high intrinsic catalytic activity. The resulting NiFeB-P MNs exhibit a low OER overpotential of 252 mV at 10 mA cm^-2 , which is significantly smaller than that of B-doped NiFe MNs (274 mV) and commercial RuO₂ (269 mV) in alkaline electrolytes. Thus, this work highlights the practicality of designing mesoporous nonnoble metal structures and the importance of incorporating P in metallic-B-based alloys to modify their electronic structure for enhancing their intrinsic activity.

Constructing Unique Mesoporous Carbon Superstructures via Monomicelle Interface Confined Assembly

Constructing hierarchical three-dimensional (3D) mesostructures with unique pore structure, controllable morphology, highly accessible surface area, and appealing functionality remains a great challenge in materials science. Here, we report a monomicelle interface confined assembly approach to fabricate an unprecedented type of 3D mesoporous N-doped carbon superstructure for the first time. In this hierarchical structure, a large hollow locates in the center (∼300 nm in diameter), and an ultrathin monolayer of spherical mesopores (∼22 nm) uniformly distributes on the hollow shells. Meanwhile, a small hole (4.0-4.5 nm) is also created on the interior surface of each small spherical mesopore, enabling the superstructure to be totally interconnected. Vitally, such interconnected porous supraparticles exhibit ultrahigh accessible surface area (685 m² g^-1) and good underwater aerophilicity due to the abundant spherical mesopores. Additionally, the number (70-150) of spherical mesopores, particle size (22 and 42 nm), and shell thickness (4.0-26 nm) of the supraparticles can all be accurately manipulated. Besides this spherical morphology, other configurations involving 3D hollow nanovesicles and 2D nanosheets were also obtained. Finally, we manifest the mesoporous carbon superstructure as an advanced electrocatalytic material with a half-wave potential of 0.82 V (vs RHE), equivalent to the value of the commercial Pt/C electrode, and notable durability for oxygen reduction reaction (ORR).

Mesoporous Gold Nanostructures: Synthesis and Beyond

Mesoporous metal nanostructures have offered multiple advantages that cannot be realized elsewhere. These materials have been attracting more research attention in catalysis and electrocatalysis owing to their functional structures and compositions. Of the various mesoporous metals available, mesoporous gold (mesoAu) nanostructures are of special interest in surface-enhanced Raman scattering (SERS) and related applications because of their strong electromagnetic field (localized surface plasmon resonance). In the last few decades, various synthesis strategies have been developed to prepare mesoAu nanostructures with controllable morphologies that exhibit fascinating physicochemical properties and increase applications in SERS, catalysis, and electrocatalysis. In this Perspective, we systematically summarize recent advances in synthesis and applications of mesoAu nanostructures. Four synthesis strategies, including dealloying, nanocasting, electrochemical deposition, and intermediate template, are discussed in detail. Moreover, physicochemical properties and promising applications of mesoAu nanostructures are presented. Finally, we describe current challenges and give a general outlook to explore further directions in synthesis and applications of mesoAu nanostructures.

Recent advances in fuel cell reaction electrocatalysis based on porous noble metal nanocatalysts

As the center of fuel cells, electrocatalysts play a crucial role in determining the conversion efficiency from chemical energy to electrical energy. Therefore, the development of advanced electrocatalysts with both high activity and stability is significant but challenging. Active site, mass transport, and charge transfer are three central factors influencing the catalytic performance of electrocatalysts. Endowed with rich available surface active sites, facilitated electron transfer and mass diffusion channels, and highly active components, porous noble metal nanomaterials are widely considered as promising electrocatalysts toward fuel cell-related reactions. The past decade has witnessed great achievements in the design and fabrication of advanced porous noble metal nanocatalysts in the field of electrocatalytic fuel oxidation reaction (FOR) and oxygen reduction reaction (ORR). Herein, the recent research advances regarding porous noble metal nanocatalysts for fuel cell-related reactions are reviewed. In the discussions, the inherent structural features of porous noble metal nanostructures for electrocatalytic reactions, advanced synthetic strategies for the fabrication of porous noble metal nanostructures, and the structure-performance relationships are also provided.

A General Concurrent Template Strategy for Ordered Mesoporous Intermetallic Nanoparticles with Controllable Catalytic Performance

We report a general concurrent template strategy for precise synthesis of mesoporous Pt-/Pd-based intermetallic nanoparticles with desired morphology and ordered mesostructure. The concurrent template not only supplies a mesoporous metal seed for re-crystallization growth of atomically ordered intermetallic phases with unique atomic stoichiometry but also provides a nanoconfinement environment for nanocasting synthesis of mesoporous nanoparticles with ordered mesostructure and rhombic dodecahedral morphology under elevated temperature. Using the selective hydrogenation of 3-nitrophenylacetylene as a proof-of-concept catalytic reaction, mesoporous intermetallic PtSn nanoparticles exhibited remarkably controllable intermetallic phase-dependent catalytic selectivity and excellent catalytic stability. This work provides a very powerful strategy for precise preparation of ordered mesoporous intermetallic nanocrystals for application in selective catalysis and fuel cell electrocatalysis.

Degradable mesoporous semimetal antimony nanospheres for near-infrared II multimodal theranostics

Metallic and semimetallic mesoporous frameworks are of great importance owing to their unique properties and broad applications. However, semimetallic mesoporous structures cannot be obtained by the traditional template-mediated strategies due to the inevitable hydrolytic reaction of semimetal compounds. Therefore, it is yet challenging to fabricate mesoporous semimetal nanostructures, not even mention controlling their pore sizes. Here we develop a facile and robust selective etching route to synthesize monodispersed mesoporous antimony nanospheres (MSbNSs). The pore sizes of MSbNSs are tunable by carefully controlling the partial oxidation of Sb nuclei and the selective etching of the as-formed Sb₂O₃. MSbNSs show a wide absorption from visible to second near-infrared (NIR-II) region. Moreover, PEGylated MSbNSs are degradable and the degradation mechanism is further explained. The NIR-II photothermal performance of MSbNSs is promising with a high photothermal conversion efficiency of ~44% and intensive NIR-II photoacoustic signal. MSbNSs show potential as multifunctional nanomedicines for NIR-II photoacoustic imaging guided synergistic photothermal/chemo therapy in vivo. Our selective etching process would contribute to the development of various semimetallic mesoporous structures and efficient multimodal nanoplatforms for theranostics.

Nanostructured SiO2 material: synthesis advances and applications in rubber reinforcement

Silica is a commercially significant material due to its extensive use in widespread applications and products. Synthetic amorphous silica (SAS) is a form of SiO₂ that is intentionally manufactured and has been produced and marketed for decades without significant changes in its physico-chemical properties. The industrial production of nanostructured SiO₂ is nowadays challenged by the expensive raw material use and high energy consumption. The search for non-petroleum-based fillers such as nanostructured SiO₂, which are environmentally friendly, cheap, abundant, renewable, and efficient, has been initiated nowadays. Therefore, a large number of research activities have been carried out so far for the preparation of SAS from potential alternate precursors, i.e., synthetic chemicals, biogenic, and mineral ore resources. Reinforcement of rubbers with nanostructured SiO₂ fillers is a process of great practical and technological importance for improving their mechanical, dynamic, and thermal properties. The efficiencies of SiO₂ reinforcement correlate with different factors such as filler structure, surface area, rubber–filler interactions, and filler–filler interactions with their effects. This review paper discusses the recent synthesis advances of nanostructured SiO₂ from synthetic chemicals, biogenic and mineral ore resources, their physical characteristics, and applications in rubber reinforcement, overcoming challenges. Finally, summary and future work recommendations have been mentioned well for future researchers.

This review discusses recent advances in the synthesis of nanostructured SiO₂ from synthetic chemicals, and biogenic and mineral ore resources, its physical characteristics, and its applications in rubber reinforcement.

Investigation of emission behaviour of perovskite nanocrystals using nano to microspheres of TiO2

The encapsulation of MAPbBr3 perovskites nanocrystals into the pores of TiO2 microspheres (m-TiO2) remarkably enhances the stability and PLQY to 95%.

Mesoporosity-Enabled Selectivity of Mesoporous Palladium-Based Nanocrystals Catalysts in Semihydrogenation of Alkynes

We reported mesoporosity engineering as a general strategy to promote semihydrogenation selectivity of palladium (Pd)-based nanobundles catalysts. The best mesoporous PdP displayed full conversion, remarkable activity, excellent selectivity, and high stability in semihydrogenation of 1-phenyl-1-propyne, all of which are remarkably better than commercial Lindlar catalysts. Mechanistic investigations ascribed high semihydrogenation selectivity to continuous crystalline framework and penetrated mesoporous channel of catalysts that weakened the adsorption and interaction capacity of alkenes and thus inhibited over-hydrogenation of alkenes to industrially unfavorable alkanes. Density functional theory calculations further demonstrated that convex crystalline mesoporosity of nanobundles catalysts electronically optimized the coordination environment of Pd active sites and energetically changed hydrogenation trends, resulting in a superior semihydrogenation selectivity to targeted alkenes.

Interfacial Assembly and Applications of Functional Mesoporous Materials

Functional mesoporous materials have gained tremendous attention due to their distinctive properties and potential applications. In recent decades, the self-assembly of micelles and framework precursors into mesostructures on the liquid-solid, liquid-liquid, and gas-liquid interface has been explored in the construction of functional mesoporous materials with diverse compositions, morphologies, mesostructures, and pore sizes. Compared with the one-phase solution synthetic approach, the introduction of a two-phase interface in the synthetic system changes self-assembly behaviors between micelles and framework species, leading to the possibility for the on-demand fabrication of unique mesoporous architectures. In addition, controlling the interfacial tension is critical to manipulate the self-assembly process for precise synthesis. In particular, recent breakthroughs based on the concept of the "monomicelles" assembly mechanism are very promising and interesting for the synthesis of functional mesoporous materials with the precise control. In this review, we highlight the synthetic strategies, principles, and interface engineering at the macroscale, microscale, and nanoscale for oriented interfacial assembly of functional mesoporous materials over the past 10 years. The potential applications in various fields, including adsorption, separation, sensors, catalysis, energy storage, solar cells, and biomedicine, are discussed. Finally, we also propose the remaining challenges, possible directions, and opportunities in this field for the future outlook.

Magnetic mesoporous embolic microspheres in transcatheter arterial chemoembolization for liver cancer

Transcatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug loading, and imaging properties have not yet been constructed. Herein, we report a new magnetic mesoporous embolic microsphere that can simultaneously be loaded with doxorubicin (Dox), block vessels, and be observed by magnetic resonance imaging (MRI). The microspheres were prepared by decorating magnetic polystyrene/Fe₃O₄ particles with mesoporous organosilica microparticles (denoted as PS/Fe₃O₄@MONs). The PS/Fe₃O₄@MONs were uniformly spherical and large (50 µm), with a high specific surface area, uniform mesopores, and a Dox loading capacity of 460.8 µg mg^-1. Dox-loaded PS/Fe₃O₄@MONs (PS/Fe₃O₄@MON@Dox) effectively inhibited liver cancer cell growth. A VX2 rabbit liver tumor model was constructed to study the efficacy of TACE with PS/Fe₃O₄@MON@Dox. In vivo, PS/Fe₃O₄@MON@Dox could be smoothly delivered through an arterial catheter to achieve chemoembolization. Moreover, PS/Fe₃O₄@MON@Dox and residual tumor parenchyma could be distinguished on MRI, which is of great significance for evaluating the efficacy of TACE. Histopathology showed that PS/Fe₃O₄@MON@Dox could be deposited in the tumor vessels, completely blocking the blood supply. Overall, PS/Fe₃O₄@MON@Dox showed good drug loading, embolization and imaging performance as well as potential for use in TACE. STATEMENT OF SIGNIFICANCE: Transcatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug-loading, and imaging properties have not yet been constructed. In this work, we prepared magnetic mesoporous microspheres as a new embolic agent that can simultaneously load doxorubicin (Dox), block blood vessels and enable magnetic resonance imaging. Overall, this new embolic microsphere-mediated TACE strategy for liver cancer showed good therapeutic effects, and the PS/Fe₃O₄@MON@Dox embolic microspheres provide a new avenue for improving the efficacy of TACE for liver cancer and postoperative evaluation.

General Synthesis of Ultrafine Monodispersed Hybrid Nanoparticles from Highly Stable Monomicelles

Ultrafine nanoparticles with organic-inorganic hybridization have essential roles in myriad applications. Over the past three decades, although various efforts on the formation of organic or inorganic ultrasmall nanoparticles have been made, ultrafine organic-inorganic hybrid nanoparticles have scarcely been achieved. Herein, a family of ultrasmall hybrid nanoparticles with a monodisperse, uniform size is synthesized by a facile thermo-kinetics-mediated copolymer monomicelle approach. These thermo-kinetics-mediated monomicelles with amphiphilic ABC triblock copolymers are structurally robust due to their solidified polystyrene core, endowing them with ultrahigh thermodynamic stability, which is difficult to achieve using Pluronic surfactant-based micelles (e.g., F127). This great stability combined with a core-shell-corona structure makes the monodispersed monomicelles a robust template for the precise synthesis of ultrasmall hybrid nanoparticles with a highly uniform size. As a demonstration, the obtained micelles/SiO₂ hybrid nanoparticles display ultrafine sizes, excellent uniformity, monodispersity, and tunable structural parameters (diameters: 24-47 nm and thin shell thickness: 2.0-4.0 nm). Notably, this approach is universal for creating a variety of multifunctional ultrasmall hybrid nanostructures, involving organic/organic micelle/polymers (polydopamine) nanoparticles, organic/inorganic micelle/metal oxides (ZnO, TiO₂ , Fe₂ O₃ ), micelle/hydroxides (Co(OH)₂ ), micelle/noble metals (Ag), and micelle/TiO₂ /SiO₂ hybrid composites. As a proof of concept, the ultrasmall micelle/SiO₂ hybrid nanoparticles demonstrate superior toughness as biomimetic materials.

Porous Noble Metal Electrocatalysts: Synthesis, Performance, and Development

Active sites (intrinsic activity, quantity, and distribution), electron transfer, and mass diffusion are three important factors affecting the performance of electrocatalysts. Composed of highly active components which are built into various network structures, porous noble metal is an inherently promising electrocatalysts. In recent years, great efforts have been made to explore new efficient synthesis methods and establish structural-performance relationships in the field of porous noble metal electrocatalysis. In this review, the very recent progress in strategies for preparing porous noble metal, including innovation and deeper understanding of traditional methods is summarized. A discussion of relationship between porous noble metal structure and electrocatalytic performance, such as accessibility of active sites, connectivity of skeleton structures, channels dimensions, and hierarchical structures, is provided.

Mesoporous NiCo alloy/reduced graphene oxide nanocomposites as efficient hydrogen evolution catalysts

Water electrolysis is a clean and efficient route for producing high-purity hydrogen. Developing highly efficient, stable and inexpensive electrocatalysts to replace Pt is currently a major challenge for the widespread application of water splitting. Herein, we report a facile and novel strategy for the synthesis of mesoporous NiCo alloy nanoparticle/reduced graphene oxide (MNiCo/rGO) composites via electroless deposition technique. Owing to the synergistic interaction of Ni and Co, the mesoporous structure of NiCo alloy, and the optimized combination of the mesoporous NiCo with rGO, the obtained optimal MNi₆₃Co₃₇/rGO₅ catalyst exhibits outstanding electrocatalytic performance for hydrogen evolution reaction (HER) with a low overpotential of 115 mV to reach the current density of 10 mA cm^-2, and a small Tafel slope of 45 mV dec^-1, as well as a high durability in alkaline solution. These remarkable merits make it a favorable alternative to noble metal Pt-based catalysts for HER, thereby further promoting the development of non-noble metal electrocatalysts.

Ultrathin and Wavy PdB Alloy Nanowires with Controlled Surface Defects for Enhanced Ethanol Oxidation Electrocatalysis

Engineering crystalline structures/defects and elemental compositions is synthetically critical to optimize surface features of noble metal nanocrystals and thus improve their catalytic performances in various reactions. In this manuscript, we report a facile one-step aqueous synthesis of one-dimensional (1D) noble metal-metalloid alloy nanowires (NWs) with an ultrathin and wavy morphology, controlled crystalline defects, and binary PdB compositions as a highly efficient catalyst toward the electrochemical ethanol oxidation reaction (EOR). We show that the utilization of hexadecylpyridinium chloride as functional surfactant is of great importance to confine in-the-columnar epitaxial nucleation of anisotropic ultrathin PdB NWs, while the attachment growth precisely controls their surface crystalline defects with a wavy morphology. Meanwhile, this strategy is synthetically universal and can be readily extended to engineer an ultrathin wavy morphology and crystalline defect of ternary PdMB (M = Cu and Pt) alloy NWs. Owing to multiple structural and compositional merits, resultant PdB alloy NWs synergistically expose more electrocatalytically active sites and also kinetically accelerate the removal of CO-related poisons, remarkably improving electrocatalytic EOR activity and stability compared to their counterpart catalysts. Besides, wavy PdB alloy NWs are also electrochemically more active for electrocatalytic oxidation of other alcohols (methanol, glycerol, and glucose). The findings reported here thus shed a bright light on rational design of the high-performance metal alloy catalysts for their potential applications in fine chemical synthesis, fuel cells, and beyond.