Unique Nanostructure Research Articles

Facile fabrication of single-walled carbon nanotubes@cerium oxide composite sensing platform for ultrasensitive electrochemical analysis of methyl parathion

We proposed a simple and feasible strategy to fabricate the nano-structured cerium oxide (CeO2) nanoparticles decorated single-walled carbon nanotubes networks (SWCNT@CeO2), which was utilized to fabricate the SWCNT@CeO2/GCE sensor for detecting methyl parathion (MP) with high sensitivity. SWCNT possessed the unique one-dimensional hollow nanostructure with excellent conductivity performance, which boosted the charge diffusion rate. CeO2 with good biocompatibility and high catalytic capacity could achieve the adsorption of MP molecules on the surface of sensing electrode due to the affinity of CeO2 nanoparticles towards the phosphate groups of MP. Furthermore, SWCNT could effectively make up for the inherent disadvantage of CeO2 nanoparticles in the term of electrical conductivity. The fabricated SWCNT@CeO2/GCE sensor achieved the ultrasensitive MP electrochemical analysis property (LOD: 9.12 nM). The satisfactory repeatability, reproducibility, anti-interference abilities were obtained at the fabricated sensor. Regarding the electrochemical detection of MP in real food samples, both satisfactory recovery rates of 87.68–107.31% and low RSD of 1.09–2.65% suggested the favorable application prospect of SWCNT@CeO2/GCE sensor in the field of pesticide residue analysis.

GO based nanocomposite hydrogel enabled high performance wearable all-solid supercapacitor based on hierarchical structure electrodes derived from ZIF-67

The flexible and wearable supercapacitors have attracted wide interest because of their widespread application in smart electronic devices with rapid charging and discharging. As an important part of supercapacitor, the electrode materials with a hollow structure, especially those with hierarchical structures that provide an array of continuous hollow cages, are considered promising. Because of its porous shell which is rich in redox reaction sites for supercapacitors. In this work, we fabricated a ZIF-67 derived hollow Co3O4 growth on the surface of 1D NiCo2O4 to assemble into a beaded structure. In this case, NiCo precursor acted as a structure-directing agent to grow a ZIF-67, a promising electroactive material of electrochemical capacitors to provide capacitance after calcination. Combined with the grapheneoxide (GO) based high conductivity hydrogel as the solid electrolyte, the capacitance of the flexible supercapacitor exhibited a high specific capacitance of 90F g−1 at 0.5 A/g, and it was sturdy and durable. There was no significant loss of capacitance while suffering from bending and pressing. The outstanding electrochemical properties of the all-solid supercapacitor can be attributed to the unique nanostructure of the electrode that created more reactive active sites, increased the diffusion pathway for electrolyte ions, along with the high conductivity of the hydrogel electrolyte.

Microstructure and EMW absorption properties of PDCs-SiCN(Ti) ceramics with adjustable SiC nanowires and TiC nanocrystallines

Herein, a novel type of ceramic material exhibiting tunable electromagnetic properties was synthesized using the polymer-derived ceramics (PDCs) method. The precursor employed in this process was a tetrabutyl titanate-modified polysilazane, which ultimately led to the formation of PDCs-SiCN(Ti) ceramics. High-temperature annealing (1400 °C-1500 °C) was used to prepare PDCs-SiCN(Ti) ceramics, which exhibited a unique dual nanostructure comprising SiC nanowires and TiC nanocrystals and served as effective nanoabsorbents. The SiC and TiC contents are closely related to the annealing temperature and induced Ti content. After annealing at 1500 °C, the PDCs-SiCN(Ti) ceramics with the typical A + B + C electromagnetic absorbing structure exhibited excellent electromagnetic wave (EMW) absorption properties. The PDCs-SiCN(Ti) ceramics, with a Ti content of 5 wt%, demonstrated an effective absorption bandwidth (EAB) of 3.8 GHz, which encompassed 90.5 % of the X band, despite having a relatively thin impedance matching thickness of only 2.1 mm. The outstanding EMW attenuation capability of the PDC-SiCN(Ti) ceramics can be ascribed to their large specific surface area and defects combined with the high permittivity of dispersed TiC nanocrystals, which facilitates multiple reflections of EMW within the SiCN matrix. Therefore, this work provides a controllable preparation method for PDCs-SiCN(Ti) ceramics with various microwave absorbing phases.

Highly Active Coreactant-Capped and Water-Stable 3D@2D Core-Shell Perovskite Quantum Dots as a Novel and Strong Self-Enhanced Electrochemiluminescence Probe.

Self-enhanced electrochemiluminescence (ECL) probes have attracted more and more attention in analytical chemistry for their significant simplification of the ECL sensing operation while improving the ECL sensing sensitivity. However, the development and applications of self-enhanced ECL probes are still in their infancy and mainly suffer from the requirement of a complicated synthesis strategy and relatively low self-enhanced ECL activity. In this work, we took advantage of the recently emerged perovskite quantum dots (PQDs) with high optical quantum yields and easy surface engineering to develop a new type of PQD-based self-enhanced ECL system. The long alkyl chain (C18) diethanolamine (i.e., N-octadecyldiethanolamine (ODA)) with high ECL coreactant activity was selected as a capping ligand to synthesize an ODA-capped PQD self-enhanced ECL probe. The preparation of the coreactant-capped PQDs is as simple as for the ordinary oleylamine (OAm)-capped PQDs, and the obtained ODA-capped PQDs exhibit very strong self-enhanced ECL activity, 82.5 times higher than that of traditional OAm-capped PQDs. Furthermore, the prepared ODA-PQDs have a unique nanostructure (ODA-CsPbBr3@CsPb2Br5), with the highly emissive 3D CsPbBr3 PQD as the core and the water-stable 2D CsPb2Br5 as the shell, which allows ODA-PQDs to be very stable in aqueous media. It is envisioned that the prepared ODA-3D@2D PQDs with the easy preparation method, strong self-enhanced ECL, and excellent water stability have promising applications in ECL sensing.

Fatigue Properties at Elevated Temperatures of Secondary Tempered Nanostructured Bainite: A Study of Deformation Mechanisms

Nanostructured bainitic steel obtained through austempering or bainitic transformation of high Si steels consists of bainitic ferrite and carbon‐enriched retained austenite. Secondary tempering of those microstructures tailors their mechanical properties through its unique nanostructure and austenite stability. Herein, fatigue and tensile properties of a nanobainitic steel in different secondary tempering conditions are presented and the results are discussed based on the deformation mechanisms taking place due to the microstructure evolution during secondary tempering. Influence of secondary tempering and elevated testing temperature on tensile and fatigue properties at room temperature and 250 °C is presented. Based on the present deformation, mechanism results are discussed supported by microstructure evolution results obtained through dilatometry, X‐ray diffraction, and microscopy. Depending on secondary tempering temperature, main influencing mechanisms are martensite formation after secondary tempering during cooling, transformation‐induced plasticity effect, and precipitation hardening obtained by secondary tempering.

“Two in one”: A novel DNA cascade amplification strategy for trace detection of dual targets

According to the characteristics of DNA programming, the cascaded nucleic acid amplification technology with larger output can overcome the problem of insufficient sensitivity of single nucleic acid amplification technology, and it combines the advantages of two or even multiple nucleic acid amplification technologies at the same time. In this work, a novel cascade signal amplification strategy with strand displacement amplification (SDA) and cascade hybridization chain reaction (HCR) was proposed for trace detection of hAAG and VEGF165. HAAG-induced SDA produced a large amount of S2 to open H2 on Polystyrene (PS) nanospheres, thereby triggering cascade HCR to form DNA dendritic nanostructures with rich fluorescence (FL) signal probes (565 nm). It could realize the amplification of FL signals for the detection of hAAG. Moreover, many doxorubicin (Dox) were loaded into the GC bases of DNA dendritic nanostructures, and its FL signal was effectively shielded. VEGF165 specifically bound to its aptamer to form G-quadruplex structures, which released Dox to produce a high FL signal (590 nm) for detection of VEGF165. This work developed a unique multifunctional DNA dendritic nanostructure fluorescence probe, and cleverly designed a new “On-off” switch strategy for sensitive trace detection of cancer markers.

Anti-perovskite Co4N nanowhisker rooted on nickel foam to activate peroxymonosulfate for robust degradation of p-nitrophenol via non-radical dominant pathway

The fabrication of metal-nitrogen functional centers that possess features of easy recovery and high performance for degrading organic pollutants through activating peroxymonosulfate (PMS) represents a significant challenge. In this study, we present the synthesis of an anti-perovskite Co4N architecture in a granular nanowhisker form rooted on three-dimensional nickel foam (Co4N/NF) using a hydrothermal method followed by thermal nitridation with ammonia from urea pyrolysis. The resulting Co4N/NF exhibits exceptional efficiency in degrading p-nitrophenol (PNP), achieving a degradation efficiency of 97.8 % and a rate constant of 0.204 min−1 within 20 min. The unique nanostructure of granular nanowhisker Co4N on NF provides abundant surface sites for activating PMS and enhances mass/electron transport, contributing to its excellent degradation capabilities. Additionally, the Co4N/NF material exhibits outstanding stability, easy separation and recovery features, maintaining a degradation efficiency of 90.2 % within 20 min even after five cycles. This study lays the groundwork for developing advanced anti-perovskite nitrides on a 3D substrate to activate PMS for environmental contaminant remediation.

Bi2WO6/TiO2-based visible light-driven photoelectrochemical enzyme biosensor for glucose measurement.

Nowadays, the frequent occurrence of food adulteration makes glucose detection particularly important in food safety and quality management. The quality and taste of honey are closely related to the glucose content. However, due to the drawbacks of expensive equipment, complex operating procedures, and time-consuming processes, the application scope of traditional glucose detection methods is limited. Hence, this study developed a photoelectric chemical (PEC) sensor, which is composed of a photoactive material of bismuth tungstate (Bi2WO6) with titanium dioxide (TiO2) and glucose oxidase (GOD), for simple and rapid detection of glucose. Notably, the composites' absorption prominently increased in the visible light region, and the photo-generated electron-hole pairs were efficiently separated by virtue of the unique nanostructure system, thus playing a crucial role in facilitating PEC activity. In the presence of dissolved oxygen, the photocurrent intensity was enhanced by H2O2 generated from glucose under electro-oxidation specifically catalyzed by GOD fixed on the modified electrode. When the working potential was 0.3V, the changes of photocurrent response indicated that the PEC enzyme biosensor providesalow detection limit (3.8µM), and a wide linear range (0.008-8mM). This method has better selectivity in honey samples and broad application prospects in clinical diagnosis for future.

Fabrication and piezoelectric analysis based on nanogrid architecture composed of ZnO ultrathin nanosheets grown on fiber paper substrates for wearable energy harvesting

In this work, three-dimensional (3D) nanogrid architecture composed of two-dimensional (2D) ZnO ultrathin nanosheets (ZUNSs) is grown on fiber paper substrates by a two-step low-temperature hydrothermal process, and a flexible piezoelectric nanogenerator (PENG) is also developed based on the as-grown ZUNS-paper. Piezoelectric signals were also measured under compressive forces that can harvest energy up to 30 nA and 120 mV. In order to exploit the piezoelectric properties of the unique ZnO nanostructure, a series of simulation experiments based on ZUNSs were conducted systematically through the finite element method (FEM, COMSOL). The size-dependent simulation analysis (including thickness, length, and height) under two different force modes manifests that the ZUNSs possess tremendous merits for optimizing the output performance of piezoelectric nanogenerators, especially in the case of lateral bending. Besides, the anisotropic electricity generation has been investigated and analyzed within the ZUNSs via applying force with various orientations. Our results may provide guidance for the design and performance optimization of wearable self-powered micro/nanoelectric devices.

Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply.

Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.

A novel fluorescent aptasensor based on H-shaped DNA nanostructure and hollow carbon-doped nitrogen nanospheres for sensitive detection of AFB1

The existence of aflatoxin B1 (AFB1) in food has a high carcinogenic effect on humans and animals. In this study, a fluorescent aptasensor for AFB1 detection was studied by designing a unique H-shaped DNA nanostructure and using novel hollow carbon-doped nitrogen nanospheres (HCNS) as the quenching material. The two DNA strands were hybridized to form the skeleton of the H-shaped DNA nanostructure, and the signal probe (S1-FAM) was paired with complementary bases to form the complete H-shaped DNA nanostructure. When AFB1 was absent, the S1-FAM was replaced by AFB1-Apt and was adsorbed by HCNS to generate a fluorescence resonance energy transfer effect (FRET), causing the signal to turn off. In the presence of AFB1, AFB1 specifically bound to AFB1-Apt to form a complex, which led to the stable formation of the S1-FAM into the H-shaped DNA nanostructure, resulting in the signal turn-on. Under the optimal conditions, an excellent linear relationship (R2 = 0.992) was observed between LgCAFB1 and fluorescent intensity ratio in the range of 0.05–500 ng/mL, and the detection limit was 0.023 ng/mL. The designed aptasensor platform was applied to analyze the spiked AFB1 in peanut, corn flour, wheat flour, wine, and black tea with recoveries ranging from 93.6% to 107.2%.

Tensile nanostructured hierarchically porous non-precious transition metal-based electrocatalyst for durable anion exchange membrane-based water electrolysis

Electrochemical water electrolysis is a promising method for sustainable hydrogen production while transiting towards hydrogen economy. Among many, the Anion Exchange Membrane (AEM) based water electrolyzer is an emerging yet potentially affordable technology on maturity for producing large-scale hydrogen accommodating the usage of Non-Platinum Group Metal (non-PGM) based inexpensive electrocatalysts. Herein, we demonstrate the excellent performance of a bifunctional Nickel Copper Phosphide-Nickel sulphide (NCP-NS) electrocatalyst with a unique tensile nanostructure obtained via a facile, controlled ambient galvanic displacement route. An AEM electrolyzer with a larger active area of 10 cm2 stacked with the symmetric NCP-NS electrodes and a membrane demonstrates scalability with a requirement of a mere 1.66 V to reach a current density of 10 mA cm−2. The nickel-copper phosphide boosts the kinetics of charge transfer between the electrode and electrolyte interface, while a unique combination of a few nickel sulphide phases present in the catalyst provides sufficiently appropriate active sites for the overall water electrolysis. For the first time, we report a room temperature performance of ∼ 230 mA cm−2 at 2 V for a non-PGM-based bifunctional electrocatalyst with exceptional durability for over 300 h of operation in an AEM water electrolyser with a retention rate of 95 %-97 % at a current density range of 80–800 mA cm−2.

Superaerophobic/Superhydrophilic Multidimensional Electrode System for High-Current-Density Water Electrolysis.

Water electrolysis is emerging as a promising renewable-energy technology for the green production of hydrogen, which is a representative and reliable clean energy source. From economical and industrial perspectives, the development of earth-abundant non-noble metal-based and bifunctional catalysts, which can simultaneously exhibit high catalytic activities and stabilities for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is critical; however, to date, these types of catalysts have not been constructed, particularly, for high-current-density water electrolysis at the industrial level. This study developed a heterostructured zero-dimensional (0D)-one-dimensional (1D) PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF)-Ni3S2 as a self-supported catalytic electrode via interface and morphology engineering. This unique heterodimensional nanostructure of the PBSCF-Ni3S2 system demonstrates superaerophobic/superhydrophilic features and maximizes the exposure of the highly active heterointerface, endowing the PBSCF-Ni3S2 electrode with outstanding electrocatalytic performances in both HER and OER and exceptional operational stability during the overall water electrolysis at high current densities (500 h at 500 mA cm-2). This study provides important insights into the development of catalytic electrodes for efficient and stable large-scale hydrogen production systems.

Carbon Nanotube Composites with Bimetallic Transition Metal Selenides as Efficient Electrocatalysts for Oxygen Evolution Reaction

Hydrogen fuel is a clean and versatile energy carrier that can be used for various applications, including transportation, power generation, and industrial processes. Electrocatalytic water splitting could be the most beneficial and facile approach for producing hydrogen. In this work, transition metal selenide composites with carbon nanotubes (CNTs) have been investigated for electrocatalytic water splitting. The synthesis process involved the facile one-step hydrothermal growth of transition metal nanoparticles over the CNTs and acted as an efficient electrode toward electrochemical water splitting. Scanning electron microscopy and XRD patterns reveal that nanoparticles were firmly anchored on the CNTs, resulting in the formation of composites. The electrochemical measurements reveal that CNT composite with nickel–cobalt selenides (NiCo-Se/CNTs@NF) display remarkable oxygen evolution reaction (OER) activity in basic media, which is an important part of hydrogen production. It demonstrates the lowest overpotential (η10mAcm−2) of 0.560 V vs. RHE, a reduced Tafel slope of 163 mV/dec, and lower charge transfer impedance for the OER process. The multi-metallic selenide composite with CNTs demonstrating unique nanostructure and synergistic effects offers a promising platform for enhancing electrocatalytic OER performance and opens up new avenues for efficient energy conversion and storage applications.

A H2O2 Oxidation Approach to Ti3C2/TiO2 for Efficient Photocatalytic Removal of Distinct Organic Pollutants in Water.

To develop versatile photocatalysts for efficient degradation of distinct organic pollutants in water is a continuous pursuit in environment remediation. Herein, we directly oxidize Ti3C2 MXene with hydrogen peroxide to produce C-doped anatase TiO2 nanowires with aggregates maintaining a layered architecture of the MXene. The Ti3C2 MXene provides a titanium source for TiO2, a carbon source for in situ C-doping, and templates for nanowire aggregates. Under UV light illumination, the optimized Ti3C2/TiO2 exhibits a reaction rate constant 1.5 times that of the benchmark P25 TiO2 nanoparticles, toward photocatalytic degradations of trace phenol in water. The mechanism study suggests that photogenerated holes play key roles on the phenol degradation, either directly oxidizing phenol molecules or in an indirect way through oxidizing first the surface hydroxyl groups. The unreacted Ti3C2 MXene, although with trace amounts, is supposed to facilitate electron transfer, which inhibits charge recombination. The unique nanostructure of layered aggregates of nanowires, abundant surface oxygen vacancies arising from the carbon doping, and probably the Ti3C2/TiO2 heterojunction guarantee the high photocatalytic efficiency toward removals of organic pollutants in water. The photocatalyst also exhibits an activity superior to, or at least comparable to, the benchmark P25 TiO2 toward photodegradations for typical persistent organic pollutants of phenol, dye molecule of rhodamine B, antibiotic of tetracycline, pharmaceutical wastewater of ofloxacin, and pesticide of N,N-dimethylformamide, when evaluated in total organic carbon removal.

Fabrication of multifunctional silk nanofibril/hyaluronic acid scaffold for spinal cord repair

Bioactive scaffolds accurately mimicking the structure and composition of the extracellular matrix have garnered significant interest in tissue engineering. In this study, we developed a platform utilizing natural silk nanofibrils, hyaluronic acid, and basic fibroblast growth factor for the purpose of promoting spinal cord regeneration by creating an optimal microenvironment. The bioactive scaffold exhibited notable characteristics such as high porosity and hydrophilicity, attributed to its unique nanostructure, high connectivity, and polysaccharide composition. Furthermore, the pore size of the scaffold can be adjusted within the range of 90 μm to 120 μm by varying the content of hyaluronic acid. In vitro, human umbilical vein endothelial cells were seeded into the scaffold, demonstrating enhanced cell viability. The scaffold facilitated cell proliferation and migration. In vivo experiments on rats indicated that the scaffold had a beneficial impact on spinal cord regeneration, creating a conducive environment for motor function recovery of the rats. This effect may be attributed to the scaffold's ability to stimulate axon growth and neuronal survival, as well as inhibit the formation of glial scars, as evidenced by the decreased expression of growth associated protein-43, microtubule-associated protein 2, and neurofilament-200. This study presents a promising method to develop a feasible bioscaffold for the treatment of spinal cord injury.

Rational Construction of 3D Self-Supported MOF-Derived Cobalt Phosphide-Based Hollow Nanowall Arrays for Efficient Overall Water Splitting At large Current Density.

Developing efficient nonprecious bifunctional electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) in the same electrolyte with a low overpotential and large current density presents an appealing yet challenging goal for large-scale water electrolysis. Herein, a unique 3D self-branched hierarchical nanostructure composed of ultra-small cobalt phosphide (CoP) nanoparticles embedded into N, P-codoped carbon nanotubes knitted hollow nanowall arrays (CoPʘNPCNTs HNWAs) on carbon textiles (CTs) through a carbonization-phosphatization process is presented. Benefiting from the uniform protrusion distributions of CoP nanoparticles, the optimum CoPʘNPCNTs HNWAs composites with high abundant porosity exhibit superior electrocatalytic activity and excellent stability for OER in alkaline conditions, as well as for HER in both acidic and alkaline electrolytes, even under large current densities. Furthermore, the assembled CoPʘNPCNTs/CTs||CoPʘNPCNTs/CTs electrolyzer demonstrates exceptional performance, requiring an ultralow cell voltage of 1.50V to deliver the current density of 10mAcm-2 for overall water splitting (OWS) with favorable stability, even achieving a large current density of 200mAcm-2 at a low cell voltage of 1.78V. Density functional theory (DFT) calculation further reveals that all the C atoms between N and P atoms in CoPʘNPCNTs/CTs act as the most efficient active sites, significantly enhancing the electrocatalytic properties. This strategy, utilizing 2D MOF arrays as a structural and compositional material to create multifunctional composites/hybrids, opens new avenues for the exploration of highly efficient and robust non-noble-metal catalysts for energy-conversion reactions.

Machine learning-coupled vertical graphene triboelectric pressure sensors array as artificial tactile receptor for finger action recognition

Wearable pressure sensors have been emerging for recording human biomechanical information during movement and action behavior. When combined with advanced signals processing and analysis methods, these sensors may offer the opportunities of recognizing patterns in specific human actions. In this study, we proposed a machine learning-coupled vertical graphene triboelectric pressure sensors array (ML-vGTEPS array), which could serve as artificial finger tactile receptors for sensing pressure patterns generated by specific finger actions. By utilizing the vertical graphene (vG) with excellent electrical properties and unique nanostructure as the key friction layer, the triboelectric sensor exhibited high sensitivity and broad sensing range. Ten sets of triboelectric sensors are integrated and designed as wearable devices on fingers, which could transmit multi-channel tactile signals under different finger actions with minimal crosstalk. Taking the tracking technical actions of playing table tennis as an example, 16 types of finger tactile signals generated during specific table tennis technical actions were obtained using a self-designed acquisition hardware. Action recognition with high accuracy (98.1%) was achieved by a fully connected neural network (FCNN) deep learning model, serving as validation for the ML-vGTEPS Array in action monitoring and recognition. The exemplary recognition results demonstrated the potential of the ML-vGTEPS Array as a high-performance technique for human-machine interface, intelligent athletic training, telemedicine, and applications in virtual reality/augmented reality.

Biporous silica nanostructure-induced nanovortex in microfluidics for nucleic acid enrichment, isolation, and PCR-free detection

Efficient pathogen enrichment and nucleic acid isolation are critical for accurate and sensitive diagnosis of infectious diseases, especially those with low pathogen levels. Our study introduces a biporous silica nanofilms-embedded sample preparation chip for pathogen and nucleic acid enrichment/isolation. This chip features unique biporous nanostructures comprising large and small pore layers. Computational simulations confirm that these nanostructures enhance the surface area and promote the formation of nanovortex, resulting in improved capture efficiency. Notably, the chip demonstrates a 100-fold lower limit of detection compared to conventional methods used for nucleic acid detection. Clinical validations using patient samples corroborate the superior sensitivity of the chip when combined with the luminescence resonance energy transfer assay. The enhanced sample preparation efficiency of the chip, along with the facile and straightforward synthesis of the biporous nanostructures, offers a promising solution for polymer chain reaction-free detection of nucleic acids.

Three-Dimensional Porous Indium Single-Atom Catalysts with Improved Accessibility for CO2 Reduction to Formate.

Single-atom catalysts (SACs) present substantial potential in electrocatalytic CO2 reduction reactions; however, inferior accessibility of single-atom sites to CO2 limits the overall CO2RR performances. Herein, we propose to improve the accessibility between In sites and CO2 through the construction of a three-dimensional (3D) porous indium single-atom catalyst (In1/NC-3D). The NaCl template-mediated synthesis strategy generates the unique 3D porous nanostructure of In1/NC-3D. Multiple characterizations validate that In1/NC-3D exhibits increased exposure of active sites and enhanced CO2 transport/adsorption capacity compared to the bulk In1/NC, thus improving accessibility of active sites to CO2. As a result, the In1/NC-3D presents superior CO2RR performance to the bulk In1/NC, with a partial current density of formate of 67.24 mA cm-2 at -1.41 V, relative to a reversible hydrogen electrode (vs RHE). The CO2RR performances with high formate selectivity at a large current density also outperform most reported In-based SACs. Importantly, the In1/NC-3D is demonstrated to maintain an FEformate of >82% at -66.83 mA·cm-2 over 21 h. This work highlights the design of a 3D porous single-atom catalyst for efficient CO2RR, promoting the development of advanced catalysts toward advanced energy conversion.