Theoretical Validation of Non-Noble Cu Sites Integrated on SnO2 Nanoflowers for Enhanced Gas Sensing of Ethanethiol at Room Temperature.

Ethanethiol (EtSH), being highly toxic, flammable, and explosive, poses significant risks to human health and safety and is capable of causing fires and explosions. Room-temperature detection using chemiresistive gas sensors is essential for managing these risks. However, the gas-sensing performance of conventional metal-oxide sensing materials may be limited by their weak interaction with EtSH at room temperature. Herein, SnO2 nanoflowers assembled with non-noble Cu-site-enriched porous nanosheets were designed and prepared by an in situ self-template pyrolysis synthesis strategy to enable highly sensitive and selective room-temperature detection of EtSH. By regulating the number of non-noble Cu sites, these nanoflowers achieved efficient EtSH sensing with a Ra/Rg value of 11.0 at 50 ppb, ensuring high selectivity, reproducibility, and stability at room temperature. Moreover, a comparative analysis of the room-temperature gas-sensing performance of SnO2 nanoflowers with non-noble Fe- or Ni-site-enriched nanosheets highlights the benefits of non-noble Cu sites for EtSH detection. Density functional theory (DFT) analysis reveals that non-noble Cu sites have a unique affinity for EtSH, offering preferential binding over other gases and explaining the outstanding sensing performance of non-noble Cu-site-enriched nanosheet-assembled SnO2 nanoflowers. The structural and interface engineering of the sensing materials presented in this work provides a promising approach for offering efficient and durable gas sensors operable at room temperature.

Serum levels of neurotensin, pannexin-1, and sestrin-2 and the correlations with sleep quality or/and cognitive function in the patients with chronic insomnia disorder.

Objectives: To examine serum concentrations of neurotensin, pannexin-1 and sestrin-2, and their correlations with subjective and objective sleep quality and cognitive function in the patients with chronic insomnia disorder (CID). Methods: Sixty-five CID patients were enrolled continuously and fifty-six good sleepers in the same period were served as healthy controls (HCs). Serum levels of neurotensin, pannexin-1 and sestrin-2 were measured by enzyme-linked immunosorbent assays. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI) and polysomnography, and mood was evaluated by 17-item Hamilton Depression Rating Scale. General cognitive function was assessed with the Chinese-Beijing Version of Montreal Cognitive Assessment and spatial memory was evaluated by Blue Velvet Arena Test (BVAT). Results: Relative to the HCs, the CID sufferers had higher levels of neurotensin (t=5.210, p<0.001) and pannexin-1 (Z=-4.169, p<0.001), and lower level of sestrin-2 (Z=-2.438, p=0.015). In terms of objective sleep measures, pannexin-1 was positively associated with total sleep time (r=0.562, p=0.002) and sleep efficiency (r=0.588, p=0.001), and negatively with wake time after sleep onset (r=-0.590, p=0.001) and wake time (r=-0.590, p=0.001); sestrin-2 was positively associated with percentage of rapid eye movement sleep (r=0.442, p=0.016) and negatively with non-rapid eye movement sleep stage 2 in the percentage (r=-0.394, p=0.034). Adjusted for sex, age and HAMD, pannexin-1 was still associated with the above objective sleep measures, but sestrin-2 was only negatively with wake time (r=-0.446, p=0.022). However, these biomarkers showed no significant correlations with subjective sleep quality (PSQI score). Serum concentrations of neurotensin and pannexin-1 were positively associated with the mean erroneous distance in the BVAT. Adjusted for sex, age and depression, neurotensin was negatively associated with MoCA score (r=-0.257, p=0.044), pannexin-1 was positively associated with the mean erroneous distance in the BVAT (r=0.270, p=0.033). Conclusions: The CID patients had increased neurotensin and pannexin-1 and decreased sestrin-2 in the serum levels, indicating neuron dysfunction, which could be related to poor sleep quality and cognitive dysfunction measured objectively.

In-situ precipitation zero-valent Co on Co2VO4 to activate oxygen vacancies and enhance bimetallic ions redox for efficient detection toward Hg(II).

Despite the widespread utilization of variable valence metals in electrochemistry, it is still a formidable challenge to enhance the valence conversion efficiency to achieve excellent catalytic activity without introducing heterophase elements. Herein, the in-situ precipitation of Co particles on Co2VO4 not only enhanced the concentration of oxygen vacancies (Ov) but also generated a greater number of low-valence metals, thereby enabling efficient reduction towards Hg(II). The electroanalysis results demonstrate that the sensitivity of Co/Co2VO4 towards Hg(II) was measured at an impressive value of 1987.74 µA µM-1 cm-2, significantly surpassing previously reported results. Further research reveals that Ov acted as the main adsorption site to capture Hg(II). The redox reactions of Co2+/Co3+ and V3+/V4+ played a synergistic role in the reduction of Hg(II), accompanied by the continuous supply of electrons from zero-valent Co to expedite the valence cycle. The Co/Co2VO4/GCE presented remarkable selectivity towards Hg(II), with excellent stability, reproducibility, and anti-interference capability. The electrode also exhibited minimal sensitivity fluctuations towards Hg(II) in real water samples, underscoring its practicality for environmental applications. This study elucidates the mechanism underlying the surface redox reaction of metal oxides facilitated by zero-valent metals, providing us with new strategies for further design of efficient and practical sensors.

Melatonin improves maternal sleep deprivation-induced learning and memory impairment, inflammation, and synaptic dysfunction in murine male adult offspring.

INTRODUCTION: Maternal sleep deprivation (MSD), which induces inflammation and synaptic dysfunction in the hippocampus, has been associated with learning and memory impairment in offspring. Melatonin (Mel) has been shown to have anti-inflammatory, antioxidant, and neuroprotective function. However, the beneficial effect of Mel on MSD-induced cognitive impairment and its mechanisms are unknown. METHODS: In the present study, adult offspring suffered from MSD were injected with Mel (20 mg/kg) once a day during postnatal days 61-88. The cognitive function was evaluated by the Morris water maze test. Levels of proinflammatory cytokines were examined by enzyme-linked immunosorbent assay. The mRNA and protein levels of synaptic plasticity associated proteins were examined using reverse transcription-polymerase chain reaction and western blotting. RESULTS: The results showed that MSD impaired learning and memory in the offspring mice. MSD increased the levels of interleukin (IL)-1creIL-6, and tumor necrosis factor-α and decreased the expression levels of brain-derived neurotrophic factor, tyrosine kinase receptor B, postsynaptic density protein-95, and synaptophysin in the hippocampus. Furthermore, Mel attenuated cognitive impairment and restored markers of inflammation and synaptic plasticity to control levels. CONCLUSIONS: These findings indicated that Mel could ameliorate learning and memory impairment induced by MSD, and these beneficial effects were related to improvement in inflammation and synaptic dysfunction.

Changed nocturnal levels of stress-related hormones couple with sleep-wake states in the patients with chronic insomnia disorder: A clinical pilot study.

OBJECTIVES: To explore the relationship between nocturnal levels of stress-related hormones and different sleep-wake states in chronic insomnia disorder (CID) patients. METHODS: Thirty-three CID patients and 34 good sleepers were enrolled and completed assessment of sleep log, Pittsburgh Sleep Quality Index and Insomnia Severity Index. During a-overnight polysomnography monitoring, the patients' vein bleeds were continually collected at different time points (pre-sleep, deep-sleep, 5-min or 30-min waking, and morning waking-up). The control subjects' bleeds were collected only at 22:00 and morning waking-up. The serum hormones were detected using enzyme-linked immunosorbent assay. RESULTS: Compared with at pre-sleep, the level of cortisol was significantly higher at morning waking-up respectively in two-group subjects (Ps < 0.001), with insignificant inter-group differences in cortisol, corticotropin releasing hormone and copeptin at the two time-points. In the patients, the nocturnal secretion curves of three hormones were similar, with the highest concentration at morning waking-up, followed by 30-min waking, 5-min waking, pre-sleep, and deep-sleep. The patients' cortisol (Z = 79.192, P < 0.001) and copeptin (Z = 12.333, P = 0.015) levels were statistically different at different time-points, with higher cortisol at morning waking-up relative to deep-sleep, pre-sleep and 5-min waking (Ps < 0.05), and at 30-min waking relative to deep-sleep and pre-sleep (Ps < 0.05), and higher copeptin at morning waking-up relative to deep-sleep (P < 0.05). CONCLUSIONS: In CID, the nocturnal wakes were instantaneously accompanied by high level, and deep sleep was accompanied by the lowest levels, of stress-related hormones, especially in cortisol, supporting the insomniac hypothesis of increased nocturnal pulse-release of cortisol.

Highly Accurate Determination of the Total Amount of Pb2+ and Pb(OH)+ in a Natural Water Environment Revealed by Dynamic Simulation and DFT Calculation: Benefit from the Electron Inverse Effect of Pt Nanoclusters over Defective g-C3N4.

Although utilizing nanomaterial-modified electrodes for lead ion detection has achieved great success, most of them are carried out under acidic conditions and ignore the variation of Pb(II) speciation at different pH conditions, leading to the potential inaccuracy of Pb(II) detection in a neutral natural water environment. Thus, designing a novel catalyst with high accuracy for the detection of various forms of the total amount of Pb(II) (Pb2+ and Pb(OH)+) in neutral waters is significant. Herein, Pt nanoclusters (Pt NCs) were elaborately constructed and stabilized on the Co single-atom-doped g-C3N4 with abundant N vacancies (Pt NCs/VN-C3N4), which achieved the ultrasensitive detection (102.16 µM µA-1) of Pb(II) in neutral conditions. The dynamic simulation and theoretical calculations reveal that the parallel deposition of Pb2+ and Pb(OH)+ occurs on the electrode surface modified by Pt NCs/VN-C3N4, and the current peaks of Pb(II) are cocontributed by Pb2+ and Pb(OH)+ species. An "electron inverse" phenomenon in Pt NCs/VN-C3N4 from the VN-C3N4 substrate to Pt NCs endows Pt NCs in an electron-rich state, serving as active centers to promote rapid and efficient reduction for both Pb2+ and Pb(OH)+, facilitating the accurate detection of the total amount of Pb(II) in all forms in the actual water environment.

Phosphorus-doped synergy of phase change in heterogeneous catalysts of NiS-NiS2 for efficient electrocatalysis of Pb(II).

A fundamental understanding of the electroanalytical activity of transition metal sulfide electrocatalysts, especially the origin of the electrocatalytic reactivity on the surface sites of heterostructures with multiple crystalline phases, is essential for the design of low-cost and highly efficient nonprecious metal electrocatalysts for further scientific and technological achievements. Herein, we injected P into NiS and occupied the S sites through a doping strategy. The redistributed electronic structure induced the construction of heterostructures, which significantly improved the structure and chemical state of electrochemically inert NiS. The phase-change mechanism between NiS and NiS2 synergistically catalyzes Pb(II), while the P and S sites jointly lose electrons. Moreover, the constructed heterojunction sensor shows the a sensitivity of 83.43 µA µM-1 to Pb(II) with a theoretical limit of detection of 48 nM, as well as excellent stability, reproducibility, and anti-interference ability. The accurate detection in real water further reveals the potential of this sensor for practical applications. This study provides a guiding strategy for improving electrochemically inert materials to design highly active electrocatalytic interfaces, which has important implications for the development of highly efficient electrode-sensitive materials similar to precious metals to achieve accurate electrical analysis.

In Situ Laser-Induced Breakdown Spectroscopy for Chromium Speciation Analysis Based on the Interactions of Oxygen-Containing Groups with Functionalized Co3O4-rGO: Evidence from Advanced Optical Techniques and Density Functional Theoretical Calculations under Electric Field.

Achieving accurate detection of different speciations of heavy metal ions (HMIs) in an aqueous solution is an urgent problem due to the different bioavailabilities and physiological toxicity. Herein, we nominated a novel strategy to detect HCrO4- and Cr(OH)2+ at a trace level via the electrochemical sensitive surface constructed by Co3O4-rGO modified with amino and carboxyl groups, which revealed that the interactions between distinct functional groups and different oxygen-containing groups of target ions are conducive to the susceptible and anti-interference detection. The detection sensitivities of 19.46 counts µg-1 L for HCrO4- and 13.44 counts µg-1 L for Cr(OH)2+ were obtained under optimal conditions, while the limits of detection were 0.10 and 0.12 µg L-1, respectively. Satisfactory anti-interference and actual water sample analysis results were obtained. A series of advanced optical techniques like X-ray photoelectron spectroscopy, X-ray absorption near-edge structure technology, and density functional theory calculations under an electric field demonstrated that chemical interactions between groups contribute more to the fixation of target ions than electrical attraction alone. The presence of oxygen-containing groups distinct from simple ionic forms was a critical factor in the selectivity and anti-interference detection. Furthermore, the valence cycle of Co(II)/(III) synergistically boosted the detection performance. This research provides a promising tactic from the microscopic perspective of groups' interactions to accomplish the precise speciation analysis of HMIs in the water environment.

Personality traits and peritoneal dialysis patients' prognosis.

Objective: Peritoneal dialysis (PD) requires high patient conscientiousness. Therefore, we aimed to investigate the relationship between conscientiousness score and prognosis in PD patients.Methods: The ten-item Big Five Personality Inventory's Chinese version was used to assess the conscientiousness score. Basic clinical information, prior medical history, hematological examination results, the occurrence of the first peritonitis and catheter-related infection, the start of hemodialysis, and the time of renal transplantation were collected. The patients were split into two groups, high and low conscientiousness groups, based on the mean value of the conscientiousness score. The differences in prognostic indicators were compared between groups, and the association between conscientiousness score and prognostic indicators in PD patients was assessed.Results: Enrolled PD patients were divided into low conscientiousness group 103 and high conscientiousness group 98. There were significant differences in serum albumin (p = 0.021) and iPTH (p = 0.045) between the two groups. Multivariate Cox regression analysis identified conscientiousness score as an independent risk factor for the development of first peritonitis (HR = 0.558, 95% CI 0.400-0.779, p = 0.001) and first catheter-related infection (HR = 0.544, 95% CI 0.308-0.962, p = 0.036) in PD patients. Conscientiousness score (HR = 2.377, 95% CI 1.109-5.095, p = 0.026) was independently associated with renal transplantation.Conclusion: Conscientiousness personality is closely related to the prognosis of PD patients.

Modulating paired Ir-O-Ir via electronic perturbations of correlated Ir single atoms to overcome catalytic selectivity.

Single-atom catalysts have been extensively utilized for electrocatalysis, in which electronic metal-support interactions are typically employed to stabilize single atoms. However, this neglects the metal-metal interactions of adjacent atoms, which are essential for the fine-tuning of selective sites. Herein, the high-loading of Ir single atoms (Ir SAs) (8.9 wt%) were adjacently accommodated into oxygen vacancy-rich Co3O4 nanosheets (Ir SAs/Co3O4). Electronic perturbations for both Ir single atoms and Co3O4 supports were observed under electronic metal-support and metal-metal interactions, thus generating Ir-O-Co/Ir units. Electrons were transferred from Co and Ir to O atoms, inducing the depletion of 3d/5d states in Co/Ir and the occupation of 2p states in O atoms to stabilize the Ir SAs. Moreover, the O atoms of Ir-O-Ir functioned as the main active sites for the electrocatalysis of As(iii), which reduced the energy barrier for the rate-determining step. This was due to the stronger electronic affinities for intermediates from reduction of As(iii), which were completely distinct from other coordinated O atoms of Co3O4 or IrO2. Consequently, the resultant Ir SAs/Co3O4 exhibited far more robust electrocatalytic activities than IrO2/Co3O4 and Co3O4 in the electrocatalysis of As(iii). Moreover, there was a strong orbital coupling effect between the coordinated O atoms of Ir SAs and the -OH of H3AsO3, thus exhibiting superior selectivity for As(iii) in contrast to other common heavy metal cations. This work offers useful insights into the rational design of intriguing SACs with high selectivity and stability for the electrocatalysis and electrochemical analysis of pollutants on an electronic level.

Revealing the solid-solution interface interference behaviors between Cu2+ and As(III) via partial peak area analysis of simulations and experiments.

The mutual interference in the sensing detection of heavy metal ions (HMIs) is considerably serious and complex. Besides, the co-existed ions may change the stripping peak intensity, shape and position of the target ion, which partly makes peak current analysis inaccurate. Herein, a promising approach of partial peak area analysis was proposed firstly to research the mutual interference. The interference between two species on their electrodeposition processes was investigated by simulating different kinetics parameters, including surface coverage, electro-adsorption, -desorption rate constant, etc. It was proved that the partial peak area is sensitive and regular to these interference kinetics parameters, which is favorable for distinctly identifying different interferences. Moreover, the applicability of the partial peak area analysis was verified on the experiments of Cu2+, As(III) interference at four sensing interfaces: glassy carbon electrode, gold electrode, Co3O4, and Fe2O3 nanoparticles modified electrodes. The interference behaviors between Cu2+ and As(III) relying on solid-solution interfaces were revealed and confirmed by physicochemical characterizations and kinetics simulations. This work proposes a new descriptor (partial peak area) to recognize the interference mechanism and provides a meaningful guidance for accurate detection of HMIs in actual water environment.

Interface catalytic regulation via electron rearrangement and hydroxyl radicals triggered by oxygen vacancies and heavy metal ions.

Although the enhanced intrinsic activities of some nano-metal oxides are obtained by manufacturing oxygen vacancies (OVs), the effect of multiple roles of OVs is ambiguous. Herein, an interface catalytic regulation via electron rearrangement and hydroxyl radicals (˙OH) was proposed with the designed ZrO2 hollow sphere rich in OVs (Vo-rich ZrO2). Surprisingly, it was shown that the catalytic ability of Vo-rich ZrO2 was 9.9 times higher than that of ZrO2 with little OVs in electrochemical catalytic reduction of Pb(ii). It was found that the generation of Zr2+ and Zr3+ caused by OVs results in the rearrangement of abundant free electrons to facilitate the catalytic reaction rates. The longer bond length between Vo-rich ZrO2 and reactants, and the lower adsorption energy are beneficial for reactants to desorb, improving the conversion rates. Besides, the produced ˙OH were captured which were induced by OVs and trace divalent heavy metal ions in in situ electron paramagnetic resonance (EPR) experiments, contributing to lowering the energy barriers. This study not only revealed the enhanced interface catalytic effect of electron rearrangement and generated ˙OH triggered by OVs, but also provided unique insights into interface catalytic regulation on nano-metal oxides simulated by OVs.

Generalizable Descriptors of Highly Sensitive Detection of As(III) over Transition-Metal Single Atoms: A Combined Density Function Theory and Gradient Boosting Regression Approach.

Traditional nanomodified electrodes have made great achievements in electrochemical stripping voltammetry of sensing materials for As(III) detection. Moreover, the intermediate states are complicated to probe because of the ultrashort lifetime and complex reaction conditions of the electron transfer process in electroanalysis, which seriously hinder the identification of the actual active site. Herein, the intrinsic interaction of highly sensitive analytical behavior of nanomaterials is elucidated from the perspective of electronic structure through density functional theory (DFT) and gradient boosting regression (GBR). It is revealed that the atomic radius, d-band center (εd), and the largest coordinative TM-N bond length play a crucial role in regulating the arsenic reduction reaction (ARR) performance by the established ARR process for 27 sets of transition-metal single atoms supported on N-doped graphene. Furthermore, the database composed of filtered intrinsic electronic structural properties and the calculated descriptors of the central metal atom in TM-N4-Gra were also successfully extended to oxygen evolution reaction (OER) systems, which effectively verified the reliability of the whole approach. Generally, a multistep workflow is developed through GBR models combined with DFT for valid screening of sensing materials, which will effectively upgrade the traditional trial-and-error mode for electrochemical interface designing.

Coordination engineering strategy of iron single-atom catalysts boosts anti-Cu(II) interference detection of As(III) with a high sensitivity.

Mutual interference issues between heavy metal ions tremendously affect the detection reliability and accuracy in water quality analysis, especially the serious interference of Cu(II) on the detection of As(III) is greatly hard to overcome, which needs to be solved urgently. Herein, iron single-atom catalysts with different coordination structures of FeN2C2 and FeN3P are constructed to selectively catalyze the detection of As(III) in the coexistence of Cu(II). FeN3P achieves a high sensitivity of 3.90 µA ppb-1 toward As(III) in NH4Cl/NH3·H2O electrolyte (pH 8.0), completely avoiding Cu(II)-interference. Moreover, the turnover frequency (TOF) of FeN3P is an order of magnitude higher than that of FeN2C2. X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations demonstrate that an As-O bond of H3AsO3 is broken by the strong affinities between both P and O atoms and Fe and As atoms, and H3AsO3 are preferentially reduced by FeN3P during adsorptive process. Meanwhile, the low reaction energy barrier of the rate-determined step for As(III) reduction over FeN3P also accelerates the deposition of As(III) and enhances its response signals. The free-Cu(II) are difficult to adsorb on FeN3P and do not compete with As(III) for Fe active sites, which contributes to the excellent anti-Cu(II) interference capability.

General Strategies to Construct Highly Efficient Sensing Interfaces for Metal Ions Detection from the Perspective of Catalysis.

Constructing high-effective electrode sensing interfaces has been considered an effective method for electrochemical detection toward heavy metal ions (HMIs). However, most research has been devoted to enhancing the stripping currents of HMIs by simply improving the adsorptive capacity and conductivity of the electrode modified materials, while lacking theoretical guidelines in fabricating catalytic sensing interfaces. Besides, the understanding of detection mechanisms is quite unscientific from the perspective of catalysis. This perspective summarizes five general strategies in designing highly efficient sensing interfaces in the recent five years, including modulating crystal phases, orientations and planes, defect engineering, ionic valence state cycle engineering, adsorption in situ catalysis strategy, and construction of atomic level catalytic active sites. What's more, the catalytic mechanisms for improving the signals of HMIs, such as boosting the electron transfer rates and conversion rates, lowering the energy barriers, etc., are introduced and emphasized. This study has a great significance in directionally controlling functionalized electrochemical sensors to achieve excellent sensitivity and selectivity in detecting environmental pollutants from the view of catalysis, and it also brings enlightenments and guidance to develop new electroanalytical methods.

In-situ electronic structure redistribution tuning of single-atom Mn/g-C3N4 catalyst to trap atomic-scale lead(II) for highly stable and accurate electroanalysis.

Constructing catalysts with simple structures, uniform effective sites, and excellent performance is crucial for understanding the reaction mechanism of target pollutants. Herein, the single-atom catalyst of Mn-intercalated graphitic carbon nitride (Mn/g-C3N4) was prepared. It was found that the intercalated Mn atoms acted as strong electron donors to effectively tune the electronic structure distribution of the in-situ N atoms, providing a large number of negative potential atomic-scale sites for catalytic reactions. In the detection, the in-situ N atom established an electron bridge for the transient electrostatic trapping of free Pb(II), which induced Pb-N-Mn coordination bonding. Even in g-C3N4-loaded Mn nanoparticles, the N atom was again confirmed to be the interaction site for coupling with Pb. And the MnII-N4-C/MnIV-N4-C cycle actively participated in the electrocatalysis of Pb(II) was confirmed. Moreover, Mn/g-C3N4 achieved highly stable and accurate detection for Pb(II) with a sensitivity of 2714.47 µA·µM-1·cm-2. And excellent reproducibility and specific detection of real water samples made the electrode practical. This study contributes to understanding the changes in the electronic structure of chemically inert substrates after single-atom intercalation and the interaction between contaminants and the microstructure of sensitive materials, providing a guiding strategy for designing highly active electrocatalytic interfaces for accurate electroanalysis.

Sensing Material-Dependent Interference of Multiple Heavy Metal Ions: Experimental and Simulated Thermodynamics Study on Cu(II), Cd(II), and As(III) Electroanalysis.

Interference among multiple heavy metal ions (HMIs) is a significant problem that must be solved in electroanalysis, which extremely restricts the practical popularization of electrochemical sensors. However, due to the limited exploration of the intrinsic mechanism, it is still difficult to confirm the influencing factors. In this work, a series of experimental and theoretical electroanalysis models have been established to investigate the electroanalysis results of Cu(II), Cd(II), As(III), and their mixtures, which were based on the simple structure and stable coordination of nickel single-atom catalysts. X-ray absorption spectroscopy and density functional theory calculations were used to reveal the underlying detection mechanism of the 50-fold boosting effect of Cu(II) on As(III) while Cd(II) inhibits As(III). Combining the application of the thermodynamic model and Fourier transform infrared reflection, the specific interaction of the nanomaterials and HMIs on the interface is considered to be the fundamental source of the interference. This work opens up a new way of thinking about utilizing the unique modes of interplay between nanomaterials and HMIs to achieve anti-interference intelligent electrodes in stripping analysis.

Enhanced electrochemical sensing performance for trace Hg(II) by high activity of Co3+ on Co3O4-NP/N-RGO surface.

Constructing a highly sensitive and selective electrochemical interface is of great significance for the effective detection of Hg2+ in water and biological samples. Herein, Co3O4 nanopolyhedron (NP) anchored on nitrogen-doped reduced graphene oxide (N-RGO) is utilized as the electrode material for the detection of Hg2+ in the range of 0.1 µM-1.0 µM, with high sensitivity (1899.70 µA µM-1 cm-2) and low detection limits (0.03 µM) in natural water. Moreover, the Co3O4-NP/N-RGO modified electrode possesses reasonable anti-interference ability for Hg2+ in the presence of inorganic ions and glucose, which is the basis of its good response to trace Hg2+ in serum. Besides, combined with X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations, the electron transfer tendency is revealed. Additionally, combined with the electron state density of Co-p, it is speculated that Co3+ is an optimum active site for catalytic reaction. The above results elucidate an electrochemically sensitive interface is constructed to realize the efficient detection of Hg2+, which provides some theoretical guidance for the development of electrochemical sensors.

Engineering Electron-Rich Sites on CoSe2-x Nanosheets for the Enhanced Electroanalysis of As(III): A Study on the Electronic Structure via X-ray Absorption Fine Structure Spectroscopy and Density Functional Theory Calculation.

Vacancy and doping engineering are promising pathways to improve the electrocatalytic ability of nanomaterials for detecting heavy metal ions. However, the effects of the electronic structure and the local coordination on the catalytic performance are still ambiguous. Herein, cubic selenium vacancy-rich CoSe2 (c-CoSe2-x) and P-doped orthorhombic CoSe2-x (o-CoSe2-x|P) were designed via vacancy and doping engineering. An o-CoSe2-x|P-modified glass carbon electrode (o-CoSe2-x|P/GCE) acquired a high sensitivity of 1.11 µA ppb-1 toward As(III), which is about 40 times higher than that of c-CoSe2-x, outperforming most of the reported nanomaterial-modified glass carbon electrodes. Besides, o-CoSe2-x|P/GCE displayed good selectivity toward As(III) compared with other divalent heavy metal cations, which also exhibited excellent stability, repeatability, and practicality. X-ray absorption fine structure spectroscopy and density functional theory calculation demonstrate that electrons transferred from Co and Se to P sites through Co-P and Se-P bonds in o-CoSe2-x|P. P sites obtained plentiful electrons to form active centers, which also had a strong orbital coupling with As(III). In the detection process, As(III) was bonded with P and reduced by the electron-rich sites in o-CoSe2-x|P, thus acquiring a reinforced electrochemical sensitivity. This work provides an in-depth understanding of the influence of the intrinsic physicochemical properties of sensitive materials on the behavior of electroanalysis, thus offering a direct guideline for creating active sites on sensing interfaces.

Highly Sensitive and Stable Determination of As(III) under Near-Neutral Conditions: Benefit from the Synergetic Catalysis of Pt Single Atoms and Active S Atoms over Pt1/MoS2.

Designing new catalysts with high activity and stability is crucial for the effective analysis of environmental pollutants under mild conditions. Here, we developed a superior catalyst of Pt single atoms anchored on MoS2 (Pt1/MoS2) to catalyze the determination of As(III). A detection sensitivity of 3.31 µA ppb-1 was obtained in acetate buffer solution at pH 6.0, which is the highest compared with those obtained by other Pt-based nanomaterials currently reported. Pt1/MoS2 exhibited excellent electrochemical stability during the detection process of As(III), even in the coexistence of Cu(II), Pb(II), and Hg(II). X-ray absorption fine structure spectroscopy and theoretical calculations revealed that Pt single atoms were stably fixed by four S atoms and activated the adjacent S atoms. Then, Pt and S atoms synergistically interacted with O and As atoms, respectively, and transferred some electrons to H3AsO3, which change the rate-determining step of H3AsO3 reduction and reduce reaction energy barriers, thereby promoting rapid and efficient accumulation for As(0). Compared with Pt nanoparticles, the weaker interaction between arsenic species and Pt1/MoS2 enabled the effortless regeneration and cyclic utilization of active centers, which is more favorable for the oxidation of As(0). This work provides inspiration for developing highly efficient sensing platforms from the perspective of atomic-level catalysis and affords references to explore the detection mechanism of such contaminants.