Ultrafine Nanoparticles Research Articles

Bonded Interface Enabled Durable Solid‐state Lithium Metal Batteries with Ultra‐low Interfacial Resistance of 0.25 Ω cm2

AbstractThe solid‐state batteries (SSBs) with Li anode present one of the most promising energy storage systems due to their enhanced energy density and safety. However, interfacial problems between Li anode and solid‐state electrolyte hinder the advancement of SSBs. Among them, insufficient solid‐solid interfacial contact is the main issue, which causes large resistance and hinders Li+ diffusion, leading to current distribution unevenness and lithium dendrites growth. To meet these challenges, a silver/carbon interlayer composed of ultrafine Ag nanoparticles (≈5 nm) grown on COOH‐CNTs (nano‐Ag@COOH‐CNTs) is constructed. In which, nano‐Ag is designed to guide homogeneous Li deposition, while CNTs substrate bonds with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte by reactions between ─COOH groups and LLZTO alkaline surface, thus transforming loose physical solid‐solid contact to chemical bonding contact. In addition, nano‐Ag is immobilized by CNTs, avoiding the migration of Li+ implanted nano‐Ag during cycling. Therefore, nano‐Ag@COOH‐CNTs interlayer can boost Li+ transport at LLZTO/Li interface and inhibit Li dendrites, achieving an ultra‐low interfacial resistance of 0.25 Ω cm2, a high critical current density of 1.7 mA cm−2 and a long cycling over 2155 h at 0.5 mA cm−2. The modified SSBs with LiNi0.83Co0.12Mn0.05O2 cathode cycles stably over 500 cycles. Moreover, high‐loading SSBs operate stably for 85 cycles.

Synergistic effect of iron phthalocyanine and ultrafine cobalt nanoparticles for efficient CO2 electroreduction to syngas

Developing efficient electrocatalysts for CO2 electroreduction to syngas with a specific H2/CO ratio over a wide potential window is desperately required but still challenging. In this work, a series of dual-site catalysts composed of iron phthalocyanine (FePc) and ∼18 nm Cobalt nanoparticles (Co NPs) anchored on N-doped carbon matrix has been constructed from zeolitic imidazolate framework-67 (ZIF-67). Benefiting from the synergistic effect of FePc and Co NPs, the derived FePc/Co@N–C catalyst shows impressive capability for CO2 electrolysis to syngas. By varying the pyrolysis temperatures (600–800 °C) of ZIF-67 and the mass ratio of Co@N–C to FePc (1–3), an adjustable H2/CO ratio of 2–4 is obtained, and the value can be maintained stable within a potential window of −0.66 to −0.86 V vs. RHE in an H-type cell. Moreover, this electrocatalyst exhibits favorable stability without distinct performance decay. When conducted in a flow cell, an enhanced catalytic activity is demonstrated with an industrial current density (>100 mA cm−2) at −0.8 V vs. RHE and a steady H2/CO ratio of 2 from −0.4 to −0.6 V vs. RHE. This work provides a promising strategy of designing bifunctional electrocatalysts for syngas generation with stable H2/CO ratio across a wide potential range.

Ring-shaped cavity anchor Pt to derive Pt/WO3-x heterointerfaces for efficient hydrogen evolution in acidic water and seawater

Developing novelplatinum (Pt)-based hydrogen evolution reaction (HER) catalysts with high activity and stability is significant for the ever-broader applications of hydrogen energy. However, achieving precise modulation of the ultrafine Pt nanoparticles coordination environment in conventional catalysts is challenging. In this work, we developed a unique “ring-shaped cavity induced” strategy to anchor the Ptx through the ring-shaped cavity of polyoxometalates (POMs) Na33H7P8W48O184 (denoted as P8W48). The NayPtx[P8W48O184] (PtxP8W48) was in-situ converted into abundant Pt/WO3-x heterostructure with Pt (∼2 nm) and highly depressed Pt-O-W heterointerfaces. Pt/WO3-x nanoparticles supported on highly conductive rGO exhibit superior HER activity. The overpotentials of the catalyst are only 2.8 mV and 4.7 mV at 10 mA·cm−2 in acidic water and seawater, far superior to commercial 20 % Pt/C catalyst. Additionally, the catalyst can be stabilized at a current density of 30 mA·cm−2 for 180 h. This study provides a feasible strategy for rational design of Pt-based catalysts for renewable energy applications.

Ultrafine CoNi alloy nanoparticles anchored on surface-roughened halloysite nanotubes for highly efficient catalytic hydrogenation of 4-nitrophenol

The hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is an effective and cost-competitive procedure to change waste into valuables. With the purpose of designing efficient and green catalysts to convert 4-NP, we adopt halloysite nanotubes (HNTs), a resource-rich and eco-friendly clay mineral material, as CoNi alloy nanoparticles support in this study. The HNTs used have been increased the surface roughness (defined as rHNTs) through the etching process. Thereafter, a series of ultrafine CoNi alloy nanoparticles (1.2 ∼ 1.4 nm) anchored onto rHNTs (CoxNi1-x/rHNTs, where x represents the molar percentage of Co to total metal elements) are successfully synthesized via a simple one-pot approach. Benefitting from the positive synergy of Co and Ni bimetals and the powerful metal-support interaction, Co0.7Ni0.3/rHNTs catalyst (8.55 wt% total actual metal loading) exhibits the best catalytic performance for 4-NP degradation with a conversion efficiency of 99 % within 4 min at 298 K, and meanwhile a high turnover frequency (TOF) of 1.16 × 10-2 mmol mg−1 min−1 is achieved with the rate constant of 1.09 min−1. Of note, Co0.7Ni0.3/rHNTs also show excellent degradation performance towards two other nitrophenol isomers (2-nitrophenol and 3-nitrophenol).

Facile one-pot in-situ hydrothermal preparation of 0D/2D Mn3O4/CdS heterojunctions for improved photocatalytic H2 production and degradation of methylene blue

Developing heterojunction photocatalysts is a critical method to augment the photocatalytic activity of single semiconductors. However, the instability of their heterostructure poses a significant challenge. Herein, a unique 0D/2D Mn3O4/CdS p-n photocatalyst has been prepared by a simple one-pot in-situ hydrothermal approach for H2 production and methylene blue (MB) degradation. The optimized MC-0.18 (18 at% Mn) nanocomposite showed remarkable photocatalytic properties, producing a significantly higher H2 generation rate of 1291 μmol·g−1·h−1, which was 13.7 and 9.2 times higher than that of pristine CdS and ex-situ synthesized MC-0.18-ex photocatalysts, respectively. MC-0.18 displayed the highest reaction rate at 0.0435 min−1 for MB degradation, which was approximately 2.6 and 6.3 times higher than CdS and Mn3O4, respectively. Active species capture experiments and ESR identified •OH and •O2− as the main substances involved in MB degradation. Importantly, MC-0.18 demonstrated excellent stability and reusability in photocatalytic H2 production and MB degradation cycle tests. The formation of unique p-n heterostructures results in enhanced photoactivity due to the matched band alignment between ultrafine Mn3O4 nanoparticles and CdS nanosheets, leading to a high charge separation capacity. This study offers a facile route to design p-n heterojunctions that have remarkable charge transfer abilities to promote H2 production and degrade organic dyes.

Synthesis of ultrafine Fe-doped Ni3Se4 nanoparticles on tube-like N-doped carbon as a robust electrocatalyst for oxygen evolution reaction

Metal-organic frameworks (MOFs) present a wealth of possibilities for functional materials, courtesy of vast tunable compositions to tailor the physical and chemical properties of their derivatives. In this work, NiFe-BTC(H2SeO3) MOF precursors with varied Fe:Ni ratios are synthesized via a modified hydrogen-bonded organic framework (HOF)-templated strategy. The pre-introduced selenium source in the MOF framework provide the advantages of confined growth of FeNi-selenides during the calcination process. As a result, a highly active and stable, ultrafine Fe-doped Ni3Se4 nanoparticles (4.3 nm) loaded on hollow tube-like N-doped carbon is synthesized as an advanced electrocatalyst for oxgen evolution reaction (OER). Furthermore, the Fe:Ni ratio in catalyst also play a crucial role for efficient electrochemical OER applications. Remarkably, the optimized 2Fe-Ni3Se4@NC catalyst exhibited impressive OER activity with a low overpotential of 272 mV to achieve a current density of 10 cm mA-² and exceptional stability for 110 h at 20 mA cm−2 tested in a 1.0 M KOH solution. This proposed strategy presents a facile approach for the rational design of catalyst composition, and can be extended to prepare other energy conversion and storage materials.

Palladium nanoparticles immobilized on TiO2 nanosheets matrix for the valorization of furfural to produce tetrahydrofurfuryl alcohol

The development of highly dispersed and ultra-small sized metal nanocatalysts are crucial for the hydrogenation of biomass. In this work, the ultrafine palladium nanoparticles modified on the 2-dimensional TiO2 nanosheets (PdNPs-TiO2NSs) as a catalyst for the selective hydrogenation of furfural (FAL) to tetrahydrofurfuryl alcohol (THFA) was achieved. The as-prepared PdNPs-TiO2NSs catalyst was characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The spherical PdNPs were well dispersed on TiO2NSs surface with the average particle size of 1.6 ± 0.2 nm was confirmed by TEM measurements. The PdNPs-TiO2NSs catalyst showed the remarkable hydrogenation of FAL to THFA by 100 % of conversion with > 99 % of selectivity towards THFA at 140 °C and 20 bar hydrogen pressure in the 4 h reaction time. The stability and reusability test for PdNPs-TiO2NSs were found to be good even after three catalytic cycles with high catalytic activity.

Enhanced photocatalytic dehydrogenation of formic acid over ultrafine electron-deficient Pd nanoparticles immobilized on amine-functionalized mesoporous titanium dioxide

Formic acid (FA) has been increasingly favored by researchers as an ideal material for the chemical storage of hydrogen. However, the exploration of photocatalytic hydrogen evolution from FA is less extensive compared to conventional thermal catalytic FA decomposition. Therefore, constructing highly active photocatalysts for H2 release from FA presents a challenging issue. Herein, we employed a strategy that involves Pd nanoparticles (NPs) immobilized on amine-functionalized mesoporous titanium dioxide (TiO2–NH2) to promote hydrogen production from FA under full-spectrum light illumination. Impressively, the as-made 2 wt% Pd/TiO2–NH2 catalyst showed remarkable activity under full-spectrum light (Turnover frequency (TOF) of 1380.5 h−1 at 308 K, H2 selectivity: 100%). Characterization results indicated that the unique mesoporous structure of TiO2–NH2, the synergistic interaction of Pd NPs with –NH2, and the Mott-Schottky heterojunction are primarily responsible for the excellent photocatalytic performance of 2 wt% Pd/TiO2–NH2. This study modulates the metal-support interactions through surface engineering and proposes a novel and effective method for the construction of high-performance photocatalysts for H2 production from FA or other photoinduced reactions.

Green synthesis of ultrafine gold nanoparticles from sweet flag (Acorus calamus) for effective anti-leukemic, anti-urolithiatic and in silico docking studies

Gold nanoparticles (AuNPs) are emerging effective biomaterials which play a vital role in the biodiversity research area due to their biocompatibility, and less toxic nature. The AuNPs of various sizes and shapes have vibrant optical features that can be utilized for a variety of imaging and therapeutic applications. Acorus calamus (A. calamus) has been used in traditional medical systems as a general tonic for centuries. It is thought to have potential benefits in the treatment of digestive disorders and respiratory problems. In Kerala, newborns were given a nanogram of (A. calamus) rhizome paste to increase oral cleanliness and improve their health and immunity. This prompted us to produce AuNPs by A. calamus and to explore their concealed pharmacological properties. In this work, we used a simple sonication method to synthesise blue-coloured AuNPs using sweet flag (A. calamus) extract, which acted as a stabilising and reducing agent at ambient temperature. The formation and morphology of the AC-AuNPs was confirmed by XRD, TEM, EDX, FT-IR and UV–vis spectral techniques. Anti-leukemic and anti-urolithiatic activities of the AC-AuNPs were also investigated. The anti-leukemic results revealed cytomorphological changes like cancer cell membrane lyses and coiling in Human myelogenous leukemia cells (K562) and exhibited IC50 at a concentration of 41.45 µg/mL. Furthermore, in vitro DNA binding assay of AC-AuNPs with calf-thymus were conducted. The anti-urolithiatic activity of AC-AuNPs suggests a dose-dependent suppression of calcium oxalate method (COM) crystals nucleation and aggregation. These results suggest that AC-AuNPs have potent antileukemic and anti-urolithiatic activities. In silico docking results revealed that eugenol, α-asarone and calamenene possess good binding scores with myeloid cell surface antigen (CD33) and estrogen receptors, respectively. In vitro anticancer and DNA binding studies have endorsed the capping nature of AC-AuNPs by these phytoconstituents, which is validated by docking analysis.

Tailoring Stress-Relieved Structure for SnSe Toward High Performance Potassium Ion Batteries.

Metal chalcogenides as an ideal family of anode materials demonstrate a high theoretical specific capacity for potassium ion batteries (PIBs), but the huge volume variance and poor cyclic stability hinder their practical applications. In this study, a design of a stress self-adaptive structure with ultrafine SnSe nanoparticles embedded in carbon nanofiber (SnSe@CNF) via the electrospinning technology is presented. Such an architecture delivers a record high specific capacity (272 mAh g-1 at 50mA g-1) and high-rate performance (125 mAh g-1 at 1 A g-1) as a PIB anode. It is decoded that the fundamental understanding for this great performance is that the ultrafine SnSe particles enhance the full utilization of the active material and achieve stress relief as the stored strain energy from cycling is insufficient to drive crack propagation and thus alleviates the intrinsic chemo-mechanical degradation of metal chalcogenides.

Ultra-sensitive electrochemical sensor based on in situ grown ultrafine HKUST-1 nanoparticles @ graphite nanosheets and core-shell structured MoO3-polypyrrole nanowires for the detection of rutin in orange juice.

Rutin extracted from natural plants has important medical value, so developing accurate and sensitive quantitative detection methods is one of the most important tasks. In this work, HKUST-1@GN/MoO3-Ppy NWs were utilized to develop a high-performance rutin electrochemical sensor in virtue of its high conductivity and electrocatalytic activity. The morphology, crystal structure, and chemical element composition of the fabricated sensor composites were characterized by SEM, TEM, XPS, and XRD. Electrochemical techniques including EIS, CV, and DPV were used to investigatethe electrocatalytic properties of the prepared materials. The electrochemical test conditions were optimized to achieve efficient detection of rutin. The 2-electron 2-proton mechanism, consisting of several rapid and sequential phases, is postulated to occur during rutin oxidation. The results show that HKUST-1@GN/MoO3-Ppy NWs have the characteristics of large specific surface area, excellent conductivity, and outstanding electrocatalytic ability. There is a significant linear relationship between rutin concentration and the oxidation peak current of DPV. The linear range is 0.50-2000 nM, and the limit of detection is 0.27 nM (S/N = 3). In addition, the prepared electrode has been confirmed to be useful for rutin analysis in orange juice.

Thermal-driven Dispersion of Bismuth Nanoparticles among Carbon Matrix for Efficient Carbon Dioxide Reduction.

The poor electrocatalytic stability and rapid deactivation of metal electrocatalysts are always present in the electrocatalytic conversion of carbon dioxide (CO2) due to the harsh reduction condition. Herein, we demonstrate the controllable dispersion of ultrafine bismuth nanoparticles among the hollow carbon shell (Bi@C-700-4) simply by a thermal-driven diffusion process. The confinement effect of nitrogen-doped carbon matrix is able to low the surface energy of bismuth nanoparticles against the easy aggregation commonly observed for the thermal treatment. On the basis of the synergistic effect and confinement effect between bismuth nanoparticles and carbon matrix, the highly dispersed active sites render the obviously improved electrocatalytic activity and stability for carbon dioxide reduction into formate. The in-situ experimental observation on the reduction process and theoretical calculations reveal that the incorporation of bismuth nanoparticles with nitrogen-doped carbon matrix would promote the activation of CO2 and the easy formation of key intermediate (*OCHO), thus leading the enhanced electrocatalytic activity, with a Faradaic Efficiency (FE) of formate about 94.8% and the long-time stability. Furthermore, the coupling of an anode for 5-hydroxymethylfurfural oxidation reaction (HMFOR) in solar-driven system renders the high 2,5-furandicarboxylic acid (FDCA) yield of 81.2%, presenting the impressive solar-to-fuel conversion.

Thermal‐Driven Dispersion of Bismuth Nanoparticles among Carbon Matrix for Efficient Carbon Dioxide Reduction

AbstractThe poor electrocatalytic stability and rapid deactivation of metal electrocatalysts are always present in the electrocatalytic conversion of carbon dioxide (CO2) due to the harsh reduction condition. Herein, we demonstrate the controllable dispersion of ultrafine bismuth nanoparticles among the hollow carbon shell (Bi@C‐700‐4) simply by a thermal‐driven diffusion process. The confinement effect of nitrogen‐doped carbon matrix is able to low the surface energy of bismuth nanoparticles against the easy aggregation commonly observed for the thermal treatment. On the basis of the synergistic effect and confinement effect between bismuth nanoparticles and carbon matrix, the highly dispersed active sites render the obviously improved electrocatalytic activity and stability for CO2 reduction into formate. The in situ experimental observations on the reduction process and theoretical calculations reveal that the incorporation of bismuth nanoparticles with nitrogen‐doped carbon matrix would promote the activation of CO2 and the easy formation of key intermediate (*OCHO), thus leading the enhanced electrocatalytic activity, with a Faradaic Efficiency (FE) of formate about 94.8 % and the long‐time stability. Furthermore, the coupling of an anode for 5‐hydroxymethylfurfural oxidation reaction (HMFOR) in solar‐driven system renders the high 2,5‐furandicarboxylic acid (FDCA) yield of 81.2 %, presenting the impressive solar‐to‐fuel conversion.

Elaborate construction of honeycomb-like porous carbon with embedment of N-doped carbon nanotubes as efficient electrocatalyst for zinc-air battery

Devising the synthesis strategy and uncovering the evolution mechanism of carbon-based materials are critical to the development of efficient oxygen reduction reaction (ORR) electrocatalysts for renewable energy storage systems. This study reports a hierarchical ORR electrocatalyst, Co@N-CNTs/3DHC, which features ultrafine cobalt nanoparticles embedded in nitrogen-doped carbon nanotubes (Co@N-CNTs) and Co@N-CNTs firmly anchored in the nano-chambers of a three-dimensional honeycomb-like porous carbon (3DHC). The synthesis strategy of Co@N-CNTs/3DHC involves the initial construction of a precursor, followed by controllable pyrolysis step. Based on detailed analysis of both evolved gases and carbonized products of precursors, the evolution mechanism of Co@N-CNTs/3DHC is specifically proposed. Prompted by the electron reconfiguration, extensive reaction interface and fast mass-transfer pathway, the as-synthesized hierarchical Co@N-CNTs/3DHC displays superior ORR activity in alkaline media (0.88 V of half-wave potential) compared to commercial Pt/C. Impressively, zinc-air battery equipped with Co@N-CNTs/3DHC cathode presents outstanding discharge voltage and exceptional stability. This work highlights a unique perspective on the synthesis strategy and growth mechanism of Co@N-CNTs@3DHC toward creation of hierarchical 3D carbon-based composite for advanced electrochemical energy devices.

Coordination-induced amidated modified polyacrylonitrile loaded ultrafine palladium nanoparticles for thermocatalytic hydrogen evolution

A promising approach for powering hydrogen fuel cells (HFCs) involves the in-situ production of hydrogen from formic acid decomposition, with Pd-based catalysts recognized as effective for formic acid dehydrogenation. However, the immobilization of ultrafine palladium nanoparticles (Pd NPs) on catalytic supports presents a challenge and necessitates further investigation into their formation mechanism. We propose a coordination-induced strategy to understand the behavior of ultrafine Pd NPs formation based on multi-functional groups. To establish the structure–activity relationship for tunable Pd microenvironment and catalytic performance, we synthesized various polyacrylonitrile (PAN) carriers through hydrolysis and amidation modification. Molecular dynamics simulations confirmed that a stronger coordination-induced microenvironment facilitates the dispersion of Pd2+, suppressing aggregation and enhancing Pd loading. Our experimental results and density functional theory (DFT) calculations demonstrated that the catalytic activity of Pd@APAN(15_1%) with ultrafine Pd NPs (1.5 nm) exhibits over 10 times higher than that of Pd@PAN NPs with the turnover of frequency climbing from 112.6 h−1 to 1309.4 h−1 at 323 K. And Pd-imine and Pd-secondary amine moieties were verified to contribute to the creation of a favorable catalysis microenvironment. This study provides new insights into the design of modified supports with various groups to load well-dispersed and ultrafine Pd for highly efficient catalysts based on a coordination-induced strategy.

Highly Efficient One-pot Electrosynthesis of Oxime Ethers from NOx over Ultrafine MgO Nanoparticles Derived from Mg-based Metal-Organic Frameworks.

Oxime ethers are attractive compounds in medicinal scaffolds due to the biological and pharmaceutical properties, however, the crucial and widespread step of industrial oxime formation using explosive hydroxylamine (NH2OH) is insecure and troublesome. Herein, we present a convenient method of oxime ether synthesis in a one-pot tandem electrochemical system using magnesium based metal-organic framework-derived magnesium oxide anchoring in self-supporting carbon nanofiber membrane catalyst (MgO-SCM), the in situ produced NH2OH from nitrogen oxides electrocatalytic reduction coupled with aldehyde to produce 4-cyanobenzaldoxime with a selectivity of 93 % and Faraday efficiency up to 65.1 %, which further reacted with benzyl bromide to directly give oxime ether precipitate with a purity of 97 % by convenient filtering separation. The high efficiency was attributed to the ultrafine MgO nanoparticles in MgO-SCM, effectively inhibiting hydrogen evolution reaction and accelerating the production of NH2OH, which rapidly attacked carbonyl of aldehydes to form oximes, but hardly crossed the hydrogenation barrier of forming amines, thus leading to a high yield of oxime ether when coupling benzyl bromide nucleophilic reaction. This work highlights the importance of kinetic control in complex electrosynthetic organonitrogen system and demonstrates a green and safe alternative method for synthesis of organic nitrogen drug molecules.

Highly Efficient One‐pot Electrosynthesis of Oxime Ethers from NOx over Ultrafine MgO Nanoparticles Derived from Mg‐based Metal‐Organic Frameworks

AbstractOxime ethers are attractive compounds in medicinal scaffolds due to the biological and pharmaceutical properties, however, the crucial and widespread step of industrial oxime formation using explosive hydroxylamine (NH2OH) is insecure and troublesome. Herein, we present a convenient method of oxime ether synthesis in a one‐pot tandem electrochemical system using magnesium based metal‐organic framework‐derived magnesium oxide anchoring in self‐supporting carbon nanofiber membrane catalyst (MgO‐SCM), the in situ produced NH2OH from nitrogen oxides electrocatalytic reduction coupled with aldehyde to produce 4‐cyanobenzaldoxime with a selectivity of 93 % and Faraday efficiency up to 65.1 %, which further reacted with benzyl bromide to directly give oxime ether precipitate with a purity of 97 % by convenient filtering separation. The high efficiency was attributed to the ultrafine MgO nanoparticles in MgO‐SCM, effectively inhibiting hydrogen evolution reaction and accelerating the production of NH2OH, which rapidly attacked carbonyl of aldehydes to form oximes, but hardly crossed the hydrogenation barrier of forming amines, thus leading to a high yield of oxime ether when coupling benzyl bromide nucleophilic reaction. This work highlights the importance of kinetic control in complex electrosynthetic organonitrogen system and demonstrates a green and safe alternative method for synthesis of organic nitrogen drug molecules.

Production of ultrafine particles with nanometer size distribution via a bubble film bursting method

Producing particles smaller than 50 nm continues to be a challenge for commonly used atomization techniques. In the present study, an atomization method based on bubble film bursting was proposed to generate ultrafine nanoparticles. The atomization solution added with surfactant was converted to big bubble with thin film, and three needles were employed to puncture the bubbles to produce small droplets. Droplets formed ultrafine nanoparticles after being dried by a diffusion dryer. The results showed that the median diameter of particles generated by bubble film bursting could be as low as 30 nm. The thinness of the bubble film played a significant role in producing small droplets. Additionally, the size distribution of particles was influenced by the NaCl concentration and the distance of the needle to orifice, as they altered the thickness of the bubbles. The bubble film bursting atomization method offers the advantage of producing ultrafine particles and holds potential for application in various fields.

Electrochemical detection platform based on graphene-zinc oxide composite nanomaterials for 17β-estradiol determination in milk

This research presents the development of an innovative electrochemical detection platform using a graphene-zinc oxide (G-ZnO) nanocomposite for the quantification of 17β-estradiol in milk. The G-ZnO nanocomposite, synthesized via a facile one-pot method, exhibited a unique wrinkled structure with a high specific surface area of 143 m²/g. Characterization through SEM, TEM, and XRD confirmed the effective integration of ultrafine ZnO nanoparticles onto graphene sheets. The electrochemical performance of the G-ZnO modified glassy carbon electrode was evaluated, revealing a notably low detection limit of 8.3 nM for 17β-estradiol, a significant improvement over traditional sensors. The sensor demonstrated a wide linear range of 0.05–100 μM and exceptional reproducibility with less than 3.5 % RSD over repeated measurements. Recovery studies in spiked milk samples yielded highly accurate results, with recovery percentages ranging from 97.8 % to 104.6 %. These findings underscore the potential of G-ZnO nanocomposites in creating sensitive, efficient, and reliable sensors for healthcare and environmental applications.

Dual-type atomic Ru promoted bifunctional catalytic process realizing ultralow overpotential for Li-O2 batteries

Developing well-defined catalysts to ameliorate overpotential and cycling capability is imperative for high-performance Li-O2 batteries. However, conventional catalysts face fundamental challenges that ORR and OER with different rate-determining steps are catalyzed by the same active center, inevitably weakening the selectivity and activity. Herein, we report a cross-scale catalyst with ultrafine RuPt nanoparticles and surrounding RuPt pairs on porous carbon (RuPt NPs@RuPt-N-C). The planted Ru single atoms within Pt nanoparticles and carbon matrix contribute to a fresh bifunctional catalytic mechanism for enhancing ORR/OER catalytic kinetics. As a proof-of-concept application in Li-O2 batteries, this catalyst realizes extremely low overpotentials of only 0.43 V and superior cyclic stability of 209 cycles at 200 mA g−1. Experimental and computational results disclose that for Pt NPs@Pt-N-C without Ru functionalization, only Pt-N-C works as ORR/OER active centers. By contrast, for RuPt NPs@RuPt-N-C, due to downshifted d-band center and enhanced charge transfer with LiO2 intermediate, the Pt nanocrystals are fully activated by Ru atoms, making RuPt nanocrystals as preferable ORR kinetics promoter for the formation of easily-decomposed nanoflower Li2O2. Moreover, adjacent RuPt pairs with weakened O2 affinity can work as major OER center, contributing to accelerating the following Li2O2 decomposition. This work expands the frontier of cross-scale electrocatalysts with tailored bifunctional catalysis properties for other electrocatalytic fields.