Electron Transfer Ability Research Articles

Rapid room-temperature synthesis of disposable Co nanoparticles modified 3D N-doped porous carbon electrode device for efficient electrochemical detection of veterinary drug and pesticide residue

In this work, Co-based metal-organic framework (ZIF-67) coupled polyimide (ZIF-67/PI) film was fastly and effectively transformed into flexible Co nanoparticles modified 3D N-doped porous carbon (Co@3D NPC) electrode device using simple laser ablation technique at room temperature. Compared with 3D NPC electrode device that derived from pure polyimide film, Co@3D NPC exhibited significantly enhanced electron transfer ability, physical adsorption ability and electrochemically active surface area. By adjusting the laser power and ZIF-67 concentration, the surface morphology and electrochemical property of the Co@3D NPC electrode devices can be easily controlled. Furthermore, the fabricated flexible Co@/3D NPC electrode device exhibited exceptional electrochemical activity for the sensitive detection of clozapine and albendazole, two kinds of common veterinary drug and pesticide. The detection sensitivity of Co@/3D NPC electrode device reached to 410.47 μA μM−1 cm−2 and 580.33 μA μM−1 cm−2, with detection limits as low as 2.8 nM and 2.5 nM for clozapine and albendazole, respectively. Besides, the Co@/3D NPC electrode device demonstrated excellent stability and accuracy. Given the advantages of laser ablation technology, including its low cost, scalability, and high stability, the reported Co@/3D NPC electrode device holds significant potential for practical applications in the field of electrochemical analysis.

Hierarchically porous architecture of metal–organic framework-derived and S induced electron localization of Fe single atom sites for boosted ORR

Metal-organic frameworks (MOFs), with their high specific surface area, excellent stability and high electron transfer ability, are ideal supports for accommodating single metal atoms. However, the low utilisation of single-atom active sites limits the improvement of oxygen reduction reaction (ORR) performance.In this work, NH2-MIL-53(Al), a MOF possessing a mesoporous cage architecture, is used as the precursor to prepare N-doped carbon supports (denoted herein as N-HPC) with a well-defined mesoporous structure through pyrolysis. Thiourea was further employed for S doping and impregnated with a FePc, and heated again to yield Fe@S/N-HPC catalysts rich in accessible FeNx single atom sites. The porous structure is more accessible to Fe center atoms by exposing the active sites, provide easy electron conductivity and facilitate mass transport of ORR-intermediates. The prepared hierarchically porous architecture of NH2-MIL-53(Al)-derived and S induced electron localization of Fe SAs sites exhibit excellent ORR performance in alkaline (E1/2 = 0.88 V) medium.

Carbonized polyacrylonitrile-coated three-dimensional porous TiP2O7 as a high-rate capability anode for lithium-ion batteries

TiP2O7 is a hopeful anode material for lithium-ion batteries (LIBs) due to its three-dimensional (3D) open skeletons, excellent ion transfer kinetics, and good structural stability. However, the inferior intrinsic electronic conductivity degrades seriously the electrochemical performance of LIBs. Herein, a strategy of carbonized polyacrylonitrile-coated TiP2O7 (TPO/cPAN) with 3D porous structures was proposed to enhance Li+-storage capability. The TPO/cPAN modified with 30 wt% polyacrylonitrile and calcined at 800 ℃ delivers superior long-term cycling stability at 0.5 A g−1 and excellent rate capacities of 558.7, 523.8, 477.5, 409.8, and 303.4 mAh g−1 at 0.1, 0.2, 0.4, 0.8, and 1.6 A g−1, respectively. Structural characterizations and electrochemical analysis reveal that the pyrolytic N-doped carbon layer markedly ameliorates the electron transferability and protects the electrode from organic electrolyte erosion. Meanwhile, the design of 3D porous structures and the generation of rich oxygen defects facilitate Li+ transport and pseudocapacitance energy storage. The work provides a novel pathway for optimizing the electron/ion migration of polyanionic electrode materials.

Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets.

Possessing excellent electronic properties and high chemical stability, semiconducting n-type two-dimensional (2D) tin dioxide (SnO2) nanosheets have been featured in sensing and electrocatalysis applications recently. Derived from non-layered crystal structures, 2D SnO2 has abundant unsaturated dangling bonds existing at the surface, providing interfacial activity. How the surface chemistry alters the electronic properties of 2D SnO2 nanomaterials remains unexplored. In this study, we synthesised ultra-thin 2D SnO2 nanosheets using a liquid metal (LM) touch printing technique and investigated experimentally and theoretically how the interactions of organic solvents composed of alkyl and hydroxyl groups with the surface of LM-derived 2D SnO2 modulate the electronic properties. It was found that alkane solvents can physically absorb onto the SnO2 surface with no impact on the material conductivity. Alcohol-based solvents on the other hand interact with the SnO2 surface via chemical absorptions primarily, in which oxygen atoms of hydroxyl groups in the alcohols form bonds with the surface atoms of SnO2. The binding stability is determined by the length and configuration of the hydrocarbon chain in alcohols. As representative long-chain alcohols, 1-octanol and 1-pentanol attach onto the SnO2 surface strongly, lowering the binding energy of Sn4+ and reducing the electron transfer ability of SnO2 nanosheets. Consequently, the electronic properties, i.e. conductivity and electronic mobility of SnO2 nanosheet-based electronic devices are decreased significantly.

A Poly(L-Arginine)-Based Electrochemical Sensor for Simultaneous Determination of Uric Acid, Tryptophan, and Hypoxanthine

This study presents the development of an efficient and cost-effective voltammetric sensor for the individual and simultaneous determination of uric acid (UA), tryptophan (Try) and hypoxanthine (HX), the three important biomarkers in the human body. The sensor consists of glassy carbon electrode (GCE) modified with the conducting layer of poly(L-Arginine) (p-Arg) prepared by the electropolymerisation of L-Arginine using cyclic voltammetry. p-Arg modified GCE (p-Arg/GCE) provided well-resolved and improved electrooxidation responses for UA, Try, and HX due to the greater electrocatalytic activity and fast electron transfer ability of the polymer layer. The fabricated sensor was characterised using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Atomic Force Microscopy (AFM), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Electrochemical Impedance Spectroscopy (EIS) and electroactive surface area calculations. Under optimal analytical conditions, determination of the three analytes was possible over wide linear ranges with the limit of detection of 1.97 × 10−8 M, 4.43 × 10−8 M, and 8.44 × 10−9 M, respectively for UA, Try, and HX. Practical utility of the sensor was successfully verified in synthetic urine and blood serum samples and determination of Try and HX was carried out in dietary supplements and commercially available samples of tea and coffee, respectively.

Synthesis and applications of metal nanoparticles (Au, Ag)@C-graphene oxide and carbon nanotubes hybrid nanoarchitectures

In this work, we made an effort to use dopamine hydrochloride and the solid state method to anchor the gold and silver metallic nanoparticles over the graphene oxide-carbon nanotubes to improve the metal nanoparticles' interaction with the support materials. Because the hybrid nanoarchitectures of graphene-CNT provide enhanced electron transfer ability, which facilitates the catalytic activity more quickly and enhances the rate. Additionally, carbon nanotubes–graphene oxide-metal nanoparticles based hybrid catalyst was developed in a similar fashion. The formation of metallic nanoparticles in a size range of 3–15 nm is visible in the micrographs. These particles developed as nano-islands. The excess reductant formed as polydopamine acts as a stabilizer, and further, we utilise this polydoapmine into carbon by the calcination process. It results that carbonous materials will enhance the interaction between metal and support (CNT/GO). This leads to improved catalytic activity towards the reduction of 4-nitrophenol and catalytic decolorization of methylene blue at room temperature. The suggested technique for synthesizing metal nanoparticles over carbon nanostructures is simple and environmentally friendly.

A universal synthesis strategy of Pd-based trimetallic nanowires for efficient alcohol electrooxidation.

Trimetallic nanowires (NWs) have drawn much attention in efficient alcohol oxidation reaction (AOR) due to their unique features, including high atomic utilization efficiency and fast electron transfer ability. However, a universal strategy to synthesize Pd-based trimetallic NWs with high catalytic performance is still lacking. Herein, we develop a universal method for facile synthesis of PdBiM (M = Pt, Ru, Ir, Co, Cu) NWs with excellent AOR activities. By taking PdBiPt NWs as an example, the formation mechanism was investigated, and it is found that introduction of bismuth (Bi) plays an important role in facilitating the formation of the NW structure. Moreover, the PdBiPt NWs deliver an outstanding performance toward both the ethanol oxidation reaction (EOR) and the methanol oxidation reaction (MOR). Density functional theory (DFT) calculations together with experimental results disclose that the moderate electronic structure of trimetallic PdBiPt NWs can optimize the adsorption of OHads and weaken the adsorption of COads, thereby leading to the substantially enhanced AOR performance. We believe that this work can inspire the design of multimetallic NWs as high-performance catalysts.

Rare earth oxide based electrocatalysts: synthesis, properties and applications.

As an important strategic resource, rare earths (REs) constitute 17 elements in the periodic table, namely 15 lanthanides (Ln) (La-Lu, atomic numbers from 57 to 71), scandium (Sc, atomic number 21) and yttrium (Y, atomic number 39). In the field of catalysis, the localization and incomplete filling of 4f electrons endow REs with unique physical and chemical properties, including rich electronic energy level structures, variable coordination numbers, etc., making them have great potential in electrocatalysis. Among various RE catalytic materials, rare earth oxide (REO)-based electrocatalysts exhibit excellent performances in electrocatalytic reactions due to their simple preparation process and strong structural variability. At the same time, the electronic orbital structure of REs exhibits excellent electron transfer ability, which can reduce the band gap and energy barrier values of rate-determining steps, further accelerating the electron transfer in the electrocatalytic reaction process; however, there is a lack of systematic review of recent advances in REO-based electrocatalysis. This review systematically summarizes the synthesis, properties and applications of REO-based nanocatalysts and discusses their applications in electrocatalysis in detail. It includes the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), methanol oxidation reaction (MOR), nitrogen reduction reaction (NRR) and other electrocatalytic reactions and further discusses the catalytic mechanism of REs in the above reactions. This review provides a timely and comprehensive summary of the current progress in the application of RE-based nanomaterials in electrocatalytic reactions and provides reasonable prospects for future electrocatalytic applications of REO-based materials.

Metal-doped M-NH4-PW catalyst with enhanced electron transfer for formaldehyde-propylene condensation to 4-methyl-1,3-dioxane

Recognizing and modifying the acid property-dependent catalytic characteristics of catalysts are of great importance for Prins condensation reaction. Herein, a series of metal-doped M-NH4-PW catalysts (M=Pt, Fe, Ir, Ru) are successfully synthesized for Prins condensation reaction of formaldehyde and propylene to produce 4-methyl-1,3-dioxane. Our findings demonstrate that the catalytic performance of M-NH4-PW catalysts is influenced by the chemical nature of metal site properties with different electron transfer abilities. Specifically, the new Lewis acid decorated by Pt metal on 4-H site is more favorable for the selective adsorption of formaldehyde and activation of its CO bond. Additionally, the synergistic effect between Pt metal sites and nearby O in [PW12O40]3− promotes the formation of CC bonds between protonated formaldehyde and propylene. Consequently, the Pt-NH4-PW catalyst exhibits high conversion (> 80 %) and simultaneous selectivity towards 4-methyl-1,3-dioxane selectivity (65 %). This strategy may provide valuable insights for developing efficient multifunctional catalysts for Prins condensation reactions.

Defective Auδ−-Ov interfacial sites boost C-H bond activation for enhanced selective oxidation of amino alcohols to amino acids

Designing efficient active sites to facilitate the oxidation of hydroxyl group to carboxylic acid under the influence of nitrogen-containing functional groups is worth exploring, but it is rarely investigated. Herein, we construct defective Au-ZrO2 interfacial structures by tuning the calcination temperature of ZrO2 support to boost the oxidation of amino alcohols to amino acids. Interestingly, the modification of calcination temperature induces the escape of saturated coordination oxygen atoms in ZrO2 support, leaving behind abundant surface oxygen vacancy (Ov). The as-formed Auδ−-Ov interfacial site displays the unique synergistic adsorption effect and electron transfer ability. Specifically, the Ov site voluntarily adsorbs the –NH2 group of amino alcohol, thus ensuring that the electron-rich Auδ− nearby Ov site adsorbs the hydroxyl groups and activates the C-H bond activation of NH2CH2CH2O* intermediates. Consequently, Au/ZrO2-600 catalyst with more defective Auδ−-Ov interfacial sites exhibits 98.8 % product yield for the oxidation of diethanolamine to iminodiacetic acid at only 30 °C. The catalyst system is further extended to the oxidation of other amino alcohols, involving monoethanolamine and triethanolamine, to their corresponding amino acids with excellent catalytic performance.

ZIF-67-derived FeCoNi-LDH with a 3D nanoflower hierarchical structure for highly efficient oxidation of 5-Hydroxymethylfurfural and coupling seawater splitting hydrogen production

To achieve clean and sustainable energy development, the thermodynamically favourable electrocatalytic oxidation reaction of biomass derivatives can be combined with electrolysis for hydrogen production. This process simultaneously generates high-value 2,5-furandicarboxylic acid and green energy (i.e., hydrogen). The present thesis focuses on the synthesis of a novel Fe-Co-Ni nanosheet catalyst foam using impregnation methods and one-pot hydrothermal techniques. Subsequently, the 3D nanoflower FeCoNi-S@NF catalysts are subsequently prepared by sulfurizing the FeCoNi-LDH@NF precursors. These catalysts were then employed for electrolytic seawater hydrogen production coupled with the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMFOR). This strategy is expected to address the slow kinetics of the oxygen evolution reaction (OER). The 3D nanoflower structure of the FeCoNi-S@NF catalyst enhances the exposure of catalytically active sites, while sulfur doping further improves the electron transfer ability. At a low reaction potential of 1.45 V vs. RHE, FeCoNi-S@NF exhibited remarkable performance with a 95.68 % conversion rate for 5-hydroxymethylfurfural (HMF), a 94.83 % yield for 2,5-furandicarboxylic acid (FDCA), and a Faraday efficiency of 94.71 %. Furthermore, FeCoNi-S@NF exhibits a remarkable response in terms of hydrogen evolution in seawater. By utilizing HMFOR as the anodic reaction and low-cost seawater as the cathodic electrolyte for the hydrogen evolution reaction (HER), simultaneous biomass upgrading and hydrogen production can be achieved. Incorporating HMFOR into a two-electrode system for the electrolytic seawater hydrogen production process significantly reduces the needed voltage (1.70 V@10 mA cm−2), thereby potentially decreasing the cost of this process.

Polymeric carbon nitrides/3D honeycomb poly(ionic liquid)s photoreactor with improved photo-electric property for efficient wastewater treatment

Here we report a strategy to synthesize efficient polymeric carbon nitrides/3D honeycomb poly(ionic liquid)s photoreactor. The initial parent polymeric carbon nitrides (PCN) were synthesized by sintering precursor formed by self-assembling molecules of cyanuric acid and melamine. Ionic liquids with polymerizable groups polymerized in situ with crosslinkers in a system dispersed in PCN to synthesize a photoreactor. Impressively, the obtained photoreactors have structurally stable nanoparticle morphology in a dry state and a transparent 3D network structure in a swelling state. Their successful formation, swelling ability and morphology were fully characterized by XRD, WAXS, FT-IR, SEM, XPS, TEM and N2 adsorption/desorption isotherm. UV–vis DRS, PL spectra, and photocurrent tests showed the improved photo-electric property of the photoreactor, which was attributed to the 3D network honeycomb structure improving the contact between the active centres in the reactor and the reaction substrate and the improving electron-hole separation efficiency of PCN by excellent electron transfer ability of poly(ionic liquid)s. These synthesized photoreactors could highly efficiently degrade the anionic dyes, such as methyl orange and acid blue 93, under a metal halide lamp or even natural sunlight.

Biochar with self-doped N to activate peroxymonosulfate for bisphenol-A degradation via electron transfer mechanism: The active edge graphitic N site

Environmental endocrine disruptors, represented by bisphenol A (BPA), have been widely detected in the environment, bringing potential health risks to human beings. Nitrogen-containing biocarbon catalyst can activate peroxymonosulfate (PMS) to degrade BPA in water, but its active sites remain opaque. Herein, in this work, nitrogen-containing biochar, i.e., CNedge, enriched with graphitic-N defects at the edges was prepared by one-pot co-pyrolysis of chitosan and potassium carbonate. The results showed that the CNedge/PMS system can effectively degrade 98% of BPA (50 mg/L). The electron transfer based non-radical oxidation mechanism was responsible for BPA degradation. Edge graphitic-N doping endows biochar with strong electron transfer ability. The catalyst had good recovery and reuse performance. This catalytic oxidation was also feasible for other refractory pollutants removal and worked well for treating practical wastewater. This work may provide valuable information in unraveling the N doping configuration-activity relationship during activating PMS by biochar.

Mixed-Dimensional Partial Dealloyed PtCuBi/C as High-Performance Electrocatalysts for Methanol Oxidation with Enhanced CO Tolerance.

Developing efficient electrocatalysts for methanol oxidation reaction (MOR) is crucial in advancing the commercialization of direct methanol fuel cells (DMFCs). Herein, carbon-supported 0D/2D PtCuBi/C (0D/2D PtCuBi/C) catalysts are fabricated through a solvothermal method, followed by a partial electrochemical dealloying process to form a novel mixed-dimensional electrochemically dealloyed PtCuBi/C (0D/2D D-PtCuBi/C) catalysts. Benefiting from distinctive mixed-dimensional structure and composition, the as-obtained 0D/2D D-PtCuBi/C catalysts possess abundant accessible active sites. The introduction of Cu as a water-activating element weakens the COads, and oxophilic metal Bi facilitates the OHads, thereby enhancing its tolerance to CO poisoning and promoting MOR activity. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS) collectively reveal the electron transfer from Cu and Bi to Pt, the electron-enrichment effect induced by dealloying, and the strong interactions among Pt-M (Cu, Pt, and Bi) multi-active sites, which improve the tuning of the electronic structure and enhancement of electron transfer ability. Impressively, the optimized 0D/2D D-PtCuBi/C catalysts exhibit the superior mass activity (MA) of 17.68 A mgPt -1 for MOR, which is 14.86 times higher than that of commercial Pt/C. This study offers a proposed strategy for Pt-based alloy catalysts, enabling their use as efficient anodic materials in fuel cell applications.

P-doped NiS2/Ni nanoheteroparticles embedded into N-doped carbon framework anchored on multi-walled carbon nanotubes as an efficient counter electrode for Pt-free dye-sensitized solar cells

Designing of inexpensive counter electrode (CE) material with robust electrochemical properties and perfect electrical conductivity is of great essential to improve the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Herein, the catalytic nickel nanoparticles are in-situ embedded into nitrogen-doped carbon framework (Ni-NC) by high-temperature carbonization. Next, the formed Ni-NC hybrid is subjected to simultaneous sulfurization/phosphorization treatment in the N2 atmosphere to acquire P–NiS2/Ni-NC. Finally, the acquired P–NiS2/Ni-NC hybrid is anchored on functional carboxylated multi-walled carbon nanotubes (MWCNTs) by ultrasonication to obtain P–NiS2/Ni-NC@MWCNTs. According to the electrochemical results, the P–NiS₂/Ni-NC@MWCNTs CE displays remarkable catalytic activities, great electron transfer ability, and high stability in the iodine/iodide electrolyte. DSSC assembled with P–NiS2/Ni-NC@MWCNTs CE yields an impressive PCE of 9.57 %, surpassing those of platinum (Pt) electrode (PCE = 7.84 %) and other corresponding counterparts. Such notable photovoltaic performance can be ascribed to the structural advantages and synergistic coupling effect of NiS2/Ni nanoheterostructure, P doping effect, and the support role of porous carbon network, which offer abundant catalytic active sites, high porosity, and exceptional electrical conductivity. Our work suggests a novel strategy to fabricate Pt-like CE materials based on transition metal sulfides/carbon-based nanostructures with excellent performances for large-scale energy conversion devices to reach the consumer market.

Efficient activation of peroxymonosulfate by molybdenum disulfide cocatalysis of Co and N co-doped porous carbon for degrading perfluorooctanoic acid: Synergistic effect of Co and N by molybdenum and its mechanism

In this study, precursor ultrathin molybdenum disulfide nanosheets and ZIF-67 was selected to prepare Co and N co-doped porous carbon by the support of Mo (MoS2/Co@NPC) to activate peroxymonosulfate (PMS) for perfluorooctanoic acid (PFOA) degradation. The morphology, crystal form and composition of MoS2/Co@NPC are studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other methods. In MoS2/Co@NPC/PMS process, PFOA was completely degraded in 180 min at pH 7, 0.3 g/L catalyst, 0.1 mM PMS and reaction temperature of 25 °C. The degradation efficiency was much higher than that in other systems. The oxidative species for PFOA degradation was studied using free radical quenching experiments and electron paramagnetic resonance (ESR) tests. SO−4 plays a major role in the degradation of PFOA, OH plays an auxiliary role, and 1O2 contributes the least. The effect of different types and positions of cobalt‑nitrogen and molybdenum atoms on the electrocatalytic activity was investigated by density functional theory (DFT) calculations. The co-doping of Co and N into carbon-based materials can synergistically enhance by Mo for the activation of PMS. The unsaturated S atoms on the surface of metal sulfides can trap protons to form H2S while exposing the reducing metal active site, which also accelerates the rate-limiting step of the Co3+/Co2+ conversion. The core-shell structure of Co@NPC doped with Mo has the characteristics of improving the electron transfer ability of carbon, promoting the mass transfer of reactants, and preventing cobalt metal agglomeration and metal dissolution. The degradation pathways of PFOA were investigated and three possible pathways were proposed. In addition to PFOA, MoS2/Co@NPC-800/PMS system can also remove contaminant in pharmaceutical wastewater, indicating that the process has potential application value in practical wastewater treatment.

Enhancing Oxygen Evolution Reaction Performance: Electrochemical Activation of the Biphasic CoNi/Zn(Fe,Al,Cr)2O4 via Controlled Aluminum Leaching Facilitated Surface Reconstruction

AbstractGiven that the oxygen evolution reaction (OER) faces challenges due to its sluggish kinetics, development of efficient and robust OER catalytic electrodes is critical for reducing the cost of hydrogen production through electrochemical water splitting. In this study, a biphasic CoNi/Zn(Fe,Al,Cr)2O4 coating, characterized by a densely organized stalagmite‐like microarray structure, is deposited on a commercial pure titanium plate, creating an exceptionally effective OER catalytic electrode. The formation of numerous metal/spinel oxide heterogeneous interfaces is demonstrated to enhance its electron transfer ability and conductivity. At high potentials, aluminum leaching and lattice oxygen consumption can facilitate deep surface reconstruction of highly active Fe‐doped CoNiOOH phase inducing electrochemical activation, further optimizing thermodynamic barrier of the fundamental reaction step. Ultimately, this electrode showcases exceptional OER catalytic performance (low overpotential of 248 and 335 mV to deliver the current density of 10 and 100 mA cm−2) compared to commercial IrO2 catalyst (overpotential of ≈310 mV at 10 mA cm−2). Moreover, it demonstrates high current stability sustaining a current density of 500 mA cm−2 for 100 h. This work deepens the comprehension of the surface reconstruction process in OER and, more broadly, introduces a new avenue for designing and enhancing the performance of catalytic materials.

A Portable Integrated Electrochemical Sensing System for On-Site Nitrite Detection in Food.

Ensuring an appropriate nitrite level in food is essential to keep the body healthy. However, it still remains a huge challenge to offer a portable and low-cost on-site food nitrite analysis without any expensive equipment. Herein, a portable integrated electrochemical sensing system (IESS) is developed to achieve rapid on-site nitrite detection in food, which is composed of a low-cost disposable microfluidic electrochemical patch for few-shot nitrite detection, and a reusable smartphone-assisted electronic device based on self-designed circuit board for signal processing and wireless transmission. The electrochemical patch based on MXene-Ti3C2Tx/multiwalled carbon nanotubes-cyanocobalamin (MXene/MWCNTs-VB12)-modified working electrode achieves high sensitivity of 10.533µA mm-1 and low nitrite detection limit of 4.22µm owing to strong electron transfer ability of hybrid MXene/MWCNTs conductive matrix and high nitrite selectivity of VB12 bionic enzyme-based ion-selective layer. Moreover, the portable IESS can rapidly collect pending testing samples through a microfluidic electrochemical patch within 1.0s to conduct immediate nitrite analysis, and then wirelessly transmit data from a signal-processing electronic device to a smartphone via Bluetooth module. Consequently, this proposed portable IESS demonstrates rapid on-site nitrite analysis and wireless data transmission within one palm-sized electronic device, which would pave a new avenue in food safety and personal bespoke therapy.

Hydrangea-like AuPtRu/ZnO-rGO Nanocomposites with Enhanced Peroxidase Mimiking Activity for Senitive Colorimetric Determination of H2O2.

In this study, a facile and cost-effective hydrothermal synthesis method was used to synthesize zinc oxide nanoflowers modified by reduced graphene oxide, and subsequently, trimetallic AuPtRu nanoparticles(AuPtRuNPs) were supported via the reduction method for high-sensitivity colorimetric detection of H2O2 in weakly acidic solutions. Compared to monometallic and bimetallic nanoparticles, trimetallic nanoparticles exhibit significant synergistic effects and enhanced catalytic activity. After providing a three-dimensional structure with multiple pores by zinc oxide and enhancing electron transfer ability by reduced graphene, the trimetallic nanocomposites (AuPtRu/ZnO-rGO) exhibited excellent peroxidase-mimicking activity, which can effectively catalyze 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue oxidation product (oxTMB) in the presence of H2O2. Compared to horseradish peroxidase (HRP), AuPtRu/ZnO-rGO demonstrated significantly enhanced catalytic velocity (Vmax = 6.16 × 10-8 M/s) and affinity (Km = 0.02) for H2O2. The study of the catalytic mechanism showed that trimetallic Au, Pt, and Ru could effectively catalyze H2O2 to produce hydroxyl radicals (•OH) to accelerate the oxidation of TMB and enhance the peroxidase-mimicking activity of the AuPtRu/ZnO-rGO nanocomposites. The results showed that the as-synthesized hydrangea-like AuPtRu/ZnO-rGO nanocomposites showed enhanced peroxidase-mimicking activity. It could be used for the colorimetric detection of H2O2 in the range 5-1000 μM with a LOD of 3.0 μM (S/N = 3), and the recoveries are 93.0-101.7%. In addition, the AuPtRu/ZnO-rGO nanocomposites have good applicability for sensitive colorimetric determination of H2O2 in milk, and it has broad application prospects as a multifunctional sensing platform in the food processing industry.

Electrocatalysis through interface and structural engineering of hollow/porous NiSe/CoSe2 nanotubes for overall water splitting

Nickel/cobalt-based selenides is considered as a promising electrocatalyst for overall water splitting ascribed to rapid electron transfer ability and long-term durability. However, the sluggish water dissociation kinetics and high Gibbs free energy seriously hinder its actual application. Herein, interface engineering is proposed to promote the formation of high-valence metal cations, thus activating the active center of electrocatalytic water dissociation and reducing the adsorption/desorption free energy of the intermediates significantly. In addition, a stable hollow mesoporous structure is constructed through structural engineering, which provides abundant accessible inner and outer surfaces, and the capillary phenomenon caused by the hollow structure promotes the adsorption of water molecules in the reaction center and the desorption of gases. Based on the coupling effect described above, the hollow/porous NiSe/CoSe2-100 nanotubes (denoted as NiSe/CoSe2-X HNTs, X is the weight of Se powder) demonstrate an overpotential of 117 and 225 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Meanwhile, the system of NiSe/CoSe2-100 HNTs//NiSe/CoSe2-100 HNTs requires a low voltage of 1.46 V to drive water splitting and the faraday efficiency is close to 100%. Overall, a new route is proposed for the construction of electrocatalysts with fast hydrolysis kinetics.