Plasmonic CsPbBr3–Au nanocomposite for excitation wavelength dependent photocatalytic CO2 reduction

The optoelectronic performance of CsPbBr_3 nanocrystal(NC) has been dramatically limited by the severe charge carrier recombination and its narrow light absorption range,which are anticipated to be resolved via coupling with plasmonic Au nanoparticle(NP).In view of this,CsPbBr_3-Au nanocomposite is fabricated and further employed as a concept model to study the electronic interaction between perovskite NC and Au NP for the first time.It has been found that the excitation-wavelength dependent carrier transfer behavior exists in CsPbBr_3-Au nanocomposite.Upon illumination with visible light(λ>420 nm),photo-generated electrons in CsPbBr_3 can inject into Au with an electron injection rate and efficiency of 2.84×10~9 s^-1 and 78%,respectively.The boosted charge separation is further translated into a 3.2-fold enhancement in CO_2 photocatalytic reduction activity compared with pristine CsPbBr_3.On the other hand,when solely exciting Au NP with longer wavelength light(λ>580 nm),the localized surface plasmon resonance(LSPR) induced hot electrons in Au NPs can transfer to CsPbBr_3 NC and further participate in photocatalytic reaction towards CO_2 reduction.The present study provides new insights into preparing plasmonic nanostructure to enhance the performance of perovskite based optoelectronic devices.     

Ag2S Quantum Dots Decorated on Porous Cubic-CdS Nanosheets-assembled Flowers for Photocatalytic CO2 Reduction

The production of renewable fossil fuels such as CH₄ and CO by photocatalytic CO₂ reduction has attracted more and more attention. However, single photocatalyst is less efficient for photocatalytic reduction of CO₂ due to the fast recombination of photogenerated electron pairs. Herein, we successfully prepare Cd S-Ag₂S composite by assembling the Ag₂S QDs cocatalyst on the surface of Cd S nanosheet-assembled flower through oil-bath solvother...     

The reactivity of O2 with copper cluster anions Cun-（n = 7-20）:Leveling effect of spin accommodation

The activation of molecular oxygen is an important step in metal-catalyzed oxidation reactions and a hot subject for the research of gas-phase metal clusters.It is known that the Ag and Au clusters readily react with O₂when they have open shell electronic structures.Distinct from this,here we observed Cu_n^-（n=7-20） clusters of both open and closed shells possess high reactivity with O₂with few exceptions.In a combination with ab initio calculations,we d...     

The reactivity of O2 with copper cluster anions Cun-（n = 7-20）:Leveling effect of spin accommodation

The activation of molecular oxygen is an important step in metal-catalyzed oxidation reactions and a hot subject for the research of gas-phase metal clusters.It is known that the Ag and Au clusters readily react with O₂when they have open shell electronic structures.Distinct from this,here we observed Cu_n^-（n=7-20） clusters of both open and closed shells possess high reactivity with O₂with few exceptions.In a combination with ab initio calculations,we d...     

Indium-organic framework CPP-3（In） derived Ag/In2O3 porous hexagonal tubes for H2S detection at low temperature

There is a great demand for high-performance hydrogen sulfide（H₂S） sensors with low operating temperatures. Ag/In₂O₃ hexagonal tubes with different proportions were prepared by the calcination of Ag+-impregnated indium-organic frameworks(CPP-3（In）), and the developed sensors exhibit enhanced gassensing performance toward H₂S. Gas sensing measurements indicate that the response of Ag/In₂O₃（2.5 wt%） sensor to 5 ppm H₂S ha...     

Double laminated reduced graphene/Cu2S/reduced graphene/graphene oxide nanofilms and their photoelectrochemical properties

In this work,an efficient photocatalytic material was prepared directly on Indium tin oxide（ITO）glass substrates by fabricating Cu₂ S and graphene oxide onto graphene for photoelectrochemical（PEC） water splitting.The double laminated reduced graphene/Cu₂S/reduced graphene/graphene oxide（RG/Cu₂S/RG/GO） nanofilms were characterized,and an enhanced photoelectrochemical response in the visible region was discovered.The photocurrent density of the nanofilms for PEC water splitting was measured to be up to 1.98 m A/cm²,which could be ascribed to the followings:（i） a higher efficiency of light-harvesting because of GO coupling with Cu₂ S that could broaden the absorbing solar spectrum and enhance the light utilization efficiency;（ii） a stepwise structure of band-edge levels in the Cu₂S/GO electrode was constructed;（iii） double laminated electron accelerator（RG） was used in the Cu₂S/GO materials to get better electron-injecting efficiency.     

The formation of crystalline lithium sulfide on electrocatalytic surfaces in lithium-sulfur batteries

Lithium-sulfur(Li-S)battery is highly regarded as a promising next-generation energy storage device but suffers from sluggish sulfur redox kinetics.Probing the behavior and mechanism of the sulfur species on electrocatalytic surface is the first step to rationally introduce polysulfide electrocatalysts for kinetic promotion in a working battery.Herein,crystalline lithium sulfide(Li₂S)is exclusively observed on electrocatalytic surface with uniform spherical morphology while Li₂S on non-electrocatalytic surface is amorphous and irregular.Further characterization indicates the crystalline Li₂S preferentially participates in the discharge/charge process to render reduced interfacial resistance,high sulfur utilization,and activated sulfur redox reactions.Consequently,crystalline Li₂S is proposed with thermodynamic and kinetic advantages to rati on alize the superior performances of Li-S batteries.The evoluti on of solid Li₂S on electrocatalytic surface not only addresses the polysulfide electrocatalysis strategy,but also inspires further investigation into the chemistry of energy-related processes.     

CuSx-mediated two reaction systems enable biomimetic photocatalysis in CO2 reduction with visible light

The performances of heterogeneous catalysts can be effectively improved by optimizing the catalysts via appropriate structure design.Herein,we show that the catalysis of cuprous sulfide can be boosted by constructing the hybrid structure with Cu₂S nanoparticles on amorphous CuSx matrix(Cu₂S/CuSx).In the photocatalytic CO₂ reduction under visible light irradiation,the Cu₂S/CuSx exhibited a CO production rate at 4.0μmol h-1 that is 12-fold higher than that of the general Cu₂S catalyst.Further characterizations reveal that the Cu₂S/CuSx has two reaction systems that realize the biomimetic catalysis,involving in the light reaction on the Cu₂S nanoparticle-CuSx matrix heterojunctions for proton/electron production,and the dark reaction on the defect-rich CuSx for CO₂ reduction.The CuSx matrix could efficiently activate CO₂ and stabilize the split hydrogen species to hinder undesired hydrogen evolution reaction,which benefits the proton-electron transfer to reduce CO₂,a key step for bridging the two reaction systems.     

Dramatically Enhanced Visible-light-responsive H_2 Evolution of Cd_(1-x)Zn_xS via the Synergistic Effect of Ni_2P and 1T/2H MoS_2 Cocatalysts

Photocatalytic hydrogen generation from water-splitting holds huge promise for resolving the current energy shortage and environmental issues.Nevertheless,it is still challenging so far to develop non-noble-metal photocatalysts which are efficient toward solar-powered hydrogen evolution reaction(HER).In this work,through an ultrasonic water-bath strategy combined with solvothermal and electrostatic assembly processes,we obtain homogeneous Cd_1-xZn_xS–Ni₂P–MoS₂ hybrid nano-spheres consisting of Cd_1-xZn_xS solid solutions decorated by Ni₂P and 1 T/2 H MoS₂ cocatalysts,which demonstrate excellent activity and stability for visible-light-responsive(λ>420 nm)H₂ production.Specifically,the Cd_1-xZn_xS-Ni₂P-MoS₂ nano-spheres with 2 wt%Ni₂P and 0.2 wt%MoS₂(CZ_0.7S–2 N–0.2 M)exhibit the optimal HER activity of 55.77 mmol·g^-1·h^-1,about 47 and 32 times more than that of CZ_0.7S and Pt–CZ_0.7S,respectively.The outstanding HER performance of Cd_1-xZn_xS–Ni₂P–MoS₂ can be ascribed to the presence of abundant HER active sites in Ni2 P nanoparticles and 1 T/2 H MoS₂ nanosheets as well as the effective transfer and separation of charge carriers.Moreover,the coupling sequence of cocatalysts in Cd_1-xZn_xS–Ni₂P–MoS₂ is found to be critical in the regulation of charge transfer pathways and thus the resultant photocatalytic efficiency.The results displayed here could facilitate the engineering of high-performance photocatalysts employing multi-component cocatalysts for sustainable solar-to-fuel conversion.     

Dual-functional marigold-like ZnxCd1-xS homojunction for selective glucose photoreforming with remarkable H2 coproduction

The global commitment to pivoting to sustainable energy and products calls for technology development to utilize solar energy for hydrogen(H₂) and value-added chemicals production by biomass photoreforming. Herein, a novel dual-functional marigold-like Zn_xCd_1-xS homojunction has been the production of lactic acid with high-yield and H₂ with high-efficiency by selective glucose photoreforming. The optimized Zn_0.3Cd_0.7S exhibits out...     

Cytidine-stabilized gold nanocluster as a fluorescence turn-on and turn-off probe for dual functional detection of Ag and Hg

In this study, we have developed a label-free, dual functional detection strategy for highly selective and sensitive determination of aqueous Ag⁺ and Hg²⁺ by using cytidine stabilized Au NCs and AuAg NCs as fluorescent turn-on and turn off probes, respectively. The Au NCs and AuAg NCs showed a remarkably rapid response and high selectivity for Ag⁺ and Hg²⁺ over other metal ions, and relevant detection limit of Ag⁺ and Hg²⁺ is ca. 10 nM and 30 nM, respectively. Importantly, the fluorescence enhanced Au NCs by doping Ag⁺ can be conveniently reusable for the detection of Hg²⁺ based on the corresponding fluorescence quenching. The sensing mechanism was based on the high-affinity metallophilic Hg²⁺–Ag⁺ interaction, which effectively quenched the fluorescence of AuAg NCs. Furthermore, these fluorescent nanoprobes could be readily applied to Ag⁺ and Hg²⁺ detection in environmental water samples, indicating their possibility to be utilized as a convenient, dual functional, rapid response, and label-free fluorescence sensor for related environmental and health monitoring.     

Catalytic gold nanoparticles for fluorescent detection of mercury(II) and lead(II) ions

In this study, we developed a fluorescence assay for the highly sensitive and selective detection of Hg²⁺ and Pb²⁺ ions using a gold nanoparticle (Au NP)-based probe. The Hg–Au and Pb–Au alloys that formed on the Au NP surfaces allowed the Au NPs to exhibit peroxidase-mimicking catalytic activity in the H₂O₂-mediated oxidation of Amplex UltraRed (AUR). The fluorescence of the AUR oxidation product increased upon increasing the concentration of either Hg²⁺ or Pb²⁺ ions. By controlling the pH values of 5 mM tris–acetate buffers at 7.0 and 9.0, this H₂O₂–AUR–Au NP probe detected Hg²⁺ and Pb²⁺ ions, respectively, both with limits of detection (signal-to-noise ratio: 3) of 4.0 nM. The fluorescence intensity of the AUR oxidation product was proportional to the concentrations of Hg²⁺ and Pb²⁺ ions over ranges 0.05–1 μM (R² = 0.993) and 0.05–5 μM (R² = 0.996), respectively. The H₂O₂–AUR–Au NP probe was highly selective for Hg²⁺ (>100-fold) and Pb²⁺ (>300-fold) ions in the presence of other tested metal ions. We validated the practicality of this simple, selective, and sensitive H₂O₂–AUR–Au NP probe through determination of the concentrations of Hg²⁺ and Pb²⁺ ions in a lake water sample and of Pb²⁺ ions in a blood sample. To the best of our knowledge, this system is the first example of Au NPs being used as enzyme-mimics for the fluorescence detection of Hg²⁺ and Pb²⁺ ions.     

Development of silver/gold nanocages onto indium tin oxide glass as a reagentless plasmonic mercury sensor

We demonstrate the utilization of silver/gold nanocages (Ag/Au NCs) deposited onto transparent indium tin oxide (ITO) film glass as the basis of a reagentless, simple and inexpensive mercury probe. The localized surface plasmon resonance (LSPR) peak wavelength was located at ∼800 nm. By utilizing the redox reaction between Hg²⁺ ions and Ag atoms that existed in Ag/Au NCs, the LSPR peak of Ag/Au NCs was blue-shifted. Thus, we develop an optical sensing probe for the detection of Hg²⁺ ions. The LSPR peak changes were lineally proportional to the concentration of Hg²⁺ ions over the range from 10 ppb to 0.5 ppm. The detection limit was ∼5 ppb. This plasmonic probe shows good selectivity and high sensitivity. The proposed optical probe is successfully applied to the sensing of Hg²⁺ in real samples.     

Selective removal of heavy metal ions using sol-gel immobilized and SPE-coated thiacrown ethers

Sorbent materials based on three thiacrown ethers, 1,4,7,10-tetrathiacyclododecane (12S4), 1,4,7,10,13-pentathiacyclopentadecane (15S5) and 1,4,7,10.13,16-hexathiacyclooctadecane (18S6) were prepared either by immobilizing the ligands into sol-gel (SG) matrix or coating on commercial solid phase extraction (SPE) column. SG sorbents were characterized by FT-IR, energy dispersive X-ray microanalysis (EDX) and thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG). A marked thermal stability of the ligands when immobilized in sol-gel matrix was noted. The competitive sorption characteristics of a mixture of eleven metal ions (Mg²⁺, Zn²⁺, Cd²⁺, Co²⁺, Mn²⁺, Ca²⁺, Cu²⁺, Ni²⁺, Ag⁺, V⁴⁺, Hg²⁺) using: (i) batch method with ligands trapped in SG matrices, and (ii) off-line SPE column containing coated ligands were studied using ICP-MS. The extraction of metals were optimized for key parameters such as pH, contact time/flow rate, particle size (for SG sorbents) and ligand concentration. Under the optimized conditions, all the immobilized thiacrown ethers exhibited highest selectivity toward Ag⁺, with lesser responses to Hg²⁺ while the extraction of other metal ions were negligible. Among the SG sorbents, 18S6-SG offer the highest capacity and the best selectivity over Hg²⁺. However, for practical applications such as for selective isolation and preconcentration of Ag⁺, the SPE type especially based on 18S6 is preferred as analysis time and recoveries are favorable. The sorbents can be repeatedly used three times as there was no significant deterioration in the metal uptake (%E > 90%) or interference from other metal ions. The optimized procedures were successfully applied for the separation and preconcentration of traces Ag⁺ in different water samples.     

Electrochemical aptamer sensor for highly sensitive detection of mercury ion with Au/Pt@carbon nanofiber‐modified electrode

In this paper, an electrochemical aptamer sensor was proposed for the highly sensitive detection of mercury ion (Hg²⁺). Carbon nanofiber (CNF) was prepared by electrospinning and high‐temperature carbonization, which was used for the loading of platinum nanoparticles (PtNPs) by the hydrothermal method. The Pt@CNF nanocomposite was modified on the surface of carbon ionic liquid electrode (CILE) to obtain Pt@CNF/CILE, which was further decorated by gold nanoparticles (AuNPs) through electrodeposition to get Au/Pt@CNF/CILE. Self‐assembling of the thiol‐based aptamer was further realized by the formation of Au‐S bond to get an electrochemical aptamer sensor (Aptamer/Au/Pt@CNF/CILE). Due to the specific binding of aptamer probe to Hg²⁺ with the formation of T‐Hg²⁺‐T structure, a highly sensitive quantitative detection of Hg²⁺ could be achieved by recording the changes of current signal after reacting with Hg²⁺ within the concentration range from 1.0 × 10^?15 mol/L to 1.0 × 10^?6 mol/L and the detection limit of 3.33 × 10^?16 mol/L (3σ). Real water samples were successfully analyzed by this method.     

Mo3S132− Intercalated Layered Double Hydroxide: Highly Selective Removal of Heavy Metals and Simultaneous Reduction of Ag+ Ions to Metallic Ag0 Ribbons

We demonstrate a new material by intercalating Mo₃S₁₃^2? into Mg/Al layered double hydroxide (abbr. Mo₃S₁₃-LDH), exhibiting excellent capture capability for toxic Hg²⁺ and noble metal silver (Ag). The as-prepared Mo₃S₁₃-LDH displays ultra-high selectivity of Ag⁺, Hg²⁺ and Cu²⁺ in the presence of various competitive ions, with the order of Ag⁺>Hg²⁺>Cu²⁺>Pb²⁺≥Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺. For Ag⁺ and Hg²⁺, extremely fast adsorption rates (≈90 % within 10 min, >99 % in 1 h) are observed. Much high selectivity is present for Ag⁺ and Cu²⁺, especially for trace amounts of Ag⁺ (≈1 ppm), achieving a large separation factor (SF_Ag/Cu) of ≈8000 at the large Cu/Ag ratio of 520. The overwhelming adsorption capacities for Ag⁺ (q_m^Ag=1073 mg g^?1) and Hg²⁺ (q_m^Hg=594 mg g^?1) place the Mo₃S₁₃-LDH at the top of performing sorbent materials. Most importantly, Mo₃S₁₃-LDH captures Ag⁺ via two paths: a) formation of Ag₂S due to Ag-S complexation and precipitation, and b) reduction of Ag⁺ to metallic silver (Ag⁰). The Mo₃S₁₃-LDH is a promising material to extract low-grade silver from copper-rich minerals and trap highly toxic Hg²⁺ from polluted water.     

Electrochemical Sensors Based on Au Nanoparticles Decorated Pyrene-Reduced Graphene Oxide for Hydrazine, 4-Nitrophenol and Hg2+ Detection in Water

Monitoring hazardous chemical compounds such as hydrazine (N₂H₄), 4-nitrophenol (4-NP) and Hg²⁺ in natural water resources is a crucial issue due to their toxic effects on human health and catastrophic impact on the environment. Electrochemical nanostructured platforms integrating hybrid nanocomposites based on graphene derivatives and inorganic nanoparticles (NPs) are of great interest for such a purpose. In this work, disposable screen-printed carbon electrodes (SPCEs) have been modified with a hybrid nanocomposite formed by reduced graphene oxide (RGO), functionalized by 1-pyrene carboxylic acid (PCA), and decorated by colloidal Au NPs. These hybrid platforms have been tested for the electrocatalytic detection of N₂H₄ and 4-NP by differential pulse voltammetry and have been modified with an electropolymerized film of Hg²⁺ ions imprinted polycurcumin for the electroanalytical detection of Hg²⁺ by DPV. LODs, lower and in line with the lowest ones reported for state-of-the-art electrochemical sensors, integrating similar Au-graphene < nanocomposites, have been estimated. Additionally, good repeatability, reproducibility, and storage stability have been assessed, as well as a high selectivity in the presence of a 100-fold higher concentration of interfering species. The applicability of the proposed platforms for the detection of the compounds in real complex matrices, such as tap and river water samples, has been effectively demonstrated.     

A ratiometric electrochemical biosensor for sensitive detection of Hg based on thymine–Hg–thymine structure

In this paper, a simple, selective and reusable electrochemical biosensor for the sensitive detection of mercury ions (Hg²⁺) has been developed based on thymine (T)-rich stem–loop (hairpin) DNA probe and a dual-signaling electrochemical ratiometric strategy. The assay strategy includes both “signal-on” and “signal-off” elements. The thiolated methylene blue (MB)-modified T-rich hairpin DNA capture probe (MB-P) firstly self-assembled on the gold electrode surface via Au–S bond. In the presence of Hg²⁺, the ferrocene (Fc)-labeled T-rich DNA probe (Fc-P) hybridized with MB-P via the Hg²⁺-mediated coordination of T–Hg²⁺–T base pairs. As a result, the hairpin MB-P was opened, the MB tags were away from the gold electrode surface and the Fc tags closed to the gold electrode surface. These conformation changes led to the decrease of the oxidation peak current of MB (I_MB), accompanied with the increase of that of Fc (I_Fc). The logarithmic value of I_Fc/I_MB is linear with the logarithm of Hg²⁺ concentration in the range from 0.5 nM to 5000 nM, and the detection limit of 0.08 nM is much lower than 10 nM (the US Environmental Protection Agency (EPA) limit of Hg²⁺ in drinking water). What is more, the developed DNA-based electrochemical biosensor could be regenerated by adding cysteine and Mg²⁺. This strategy provides a simple and rapid approach for the detection of Hg²⁺, and has promising application in the detection of Hg²⁺ in real environmental samples.     

Polythymine Oligonucleotide‐Modified Gold Electrode for Voltammetric Determination of Mercury(II) in Aqueous Solution

Polythymine oligonucleotide (PTO)‐modified gold electrode (PTO/Au) was developed for selective and sensitive Hg²⁺ detection in aqueous solutions. This modified electrode was prepared by self‐assembly of thiolated polythymine oligonucleotide (5′‐SH‐T₁₅‐3′) on the gold electrode via Au? S bonds, and then the surface was passivated with 1‐mercaptohexanol solution. The proposed electrode utilizes the specific binding interactions between Hg²⁺ and thymine to selectively capture Hg²⁺, thereby reducing the interference from coexistent ions. After exchanging the medium, electrochemical reduction at ?0.2 V for 60 s, voltammetric determination was performed by differential pulse voltammetry using 10 mM HEPES; pH 7.2, 1 M NaClO₄ as supporting electrolyte. This electrode showed increasing voltammetric response in the range of 0.21 nM Hg²⁺, with a relative standard deviation of 5.32% and a practical detection limit of 60 pM. Compared with the conventional stripping approach, the modified electrode exhibits good sensitivity and selectivity, and is expected to be a new type of green electrode.     

Determination of mercury species using thermal desorption analysis in AAS

Analytical aspects of the determination of inorganic mercury (Hg) species by thermal desorption followed by atomic absorption spectrometry (AAS) detection were investigated in this work. Characteristic Hg release curves of the following species were observed: Hg⁰, HgCl₂, HgO, HgSO₄, HgS, and the Hg bound to humic acids. Particular attention was dedicated to the thermal stability and change of bond of Hg⁰ in the following matrices: sand, kaolinite, granite, peat, power plant ash, and soil. The bond of elemental Hg in environmental materials was described on basis of this experiment. Contaminated soil samples from two locations in the Czech Republic were investigated by thermal desorption analysis. Afterwards, the contents of volatile and plant-available Hg in the studied samples were determined. The determination of Hg⁰ using the thermal method was related to the results of liquid sequential extraction. The development of Hg speciation and the stability of Hg were assessed on basis of the data obtained. Thus, the analytical procedure used is a suitable tool for the study of inorganic Hg species in contaminated soils.