Sulfide Materials Research Articles

The aluminum chemistry involved redox mechanisms in transition metal dichalcogenides

Transition metal dichalcogenides (TMDs) featured an open framework structure and versatile electronic properties are attractive for their higher capacitance when used as cathodes for aluminum-ion batteries (AIBs). However, the inexhaustive understanding of cell chemistry involving complicated charge transfer stalls the deployment of this type AIBs electrode materials. Here the sulfide materials of MS2 (M = Fe, Ni, Co) served as emblematic conversion-type electrodes are taken as models to shed light on the regularity among the Al storage mechanisms in TMDs cathodes. To explain such chemistry, we therefore interrogate the redox mechanisms between MS2 (M = Fe, Ni, Co) from a broad range of experimental and mechanistic characterization perspectives. Remarkably, as indicated by characterization results, the detailed Al insertion and removal processes occurring in MS2 (M = Fe, Ni, Co) cathodes are revealed, accompanied by the anionic-redox reaction of sulfide anion (S2−), whereas the valence state transitions of the metal element in CoS2 (Co2+∼Co3+) also occur simultaneously during the insertion/extraction of Al3+. Using theoretical calculations, we further clarify the essential reasons for the mechanistic discrepancy, and discuss the energy storage regularity in TMDs. These foundations not only contribute to a profound understanding for the charge storage mechanisms in TMDs but also expand the palette of property boosting electrode materials for practical AIBs.

Effect of Co/Ni ratio on electrocatalytic oxygen evaluation reaction of hydrothermally derived CoNi2S4 in alkaline medium

Bimetallic sulfide materials are considered as suitable candidates for improving the oxygen evaluation reaction (OER) performance. Here, CoNi2S4 materials are developed by an effective hydrothermal approach and employing anhydrous Na2S.xH2O as sulfur precursor. Altering the molar concentrations of Co and Ni precursors affects the morphologies, Co, Ni contents, Co3+ and Ni3+ centers. CoNi2S4–1 with lower concentrations possesses higher Co3+, Ni3+ and Co3+/Co2+ ratios boosting the OER performance. In addition, CoNi2S4–1 demonstrates a potential of 1.60 V vs. RHE to generate a 10 mA cm−2 with a lower Tafel slope, better mass activity and stability in an alkaline solution.

Facile Synthesis of Needle-like Copper Sulfide Structures as an Effective Electrochemical Sensor Material for Neurotransmitter Detection in Biological Samples.

Electrochemical sensors, due to their excellent and unique features, are of high interest nowadays for the detection and monitoring of several biological compounds. In such a case, serotonin (SRN), an important neurotransmitter, was herein studied for its detection in biological fluids since its presence is more crucial to be monitored and detected in clinical and medical applications. Several study strategies have been used to determine the chemical and physical properties. The crystalline size of the constructed copper sulfide (Cu2S) material was measured to be 25.92 nm. The Cu2S was fabricated over the working surface and further analyzed for several sensor parameters to be optimized. The charge transfer resistance of the copper sulfide-modified glassy carbon electrode (Cu2S/GCE) was determined to be about 277.0 Ω. With the linear range from about 0.029 μM to 607.6 μM for SRN, the limit of detection (LOD) was calculated as 3.2 nM, with a good sensitivity of 13.23 μA μM-1 cm2. The sensor experienced excellent repeatability, reproducibility, and long-term stability. The fabricated electrode was selective with the presence of different interfering compounds. The real sample analysis, as determined with the regular addition method with human serum and urine samples, revealed a good recovery percentage. Thus, the employed fabricated electrode material will be highly effective in sensing other analytes of choice.

Sulfur vacancies-induced electron delocalization effect of cobalt sulfide for enhanced catalytic activation of peracetic acid and norfloxacin degradation

Antibiotics have attracted widespread attention due to their potential risks to human health and environment. In this study, a heterogeneous advanced oxidation process (AOP) of peracetic acid (PAA) activation by cobalt material was developed to degrade a typical antibiotic, norfloxacin (NOR). Cobalt sulfide materials with sulfur vacancies (CoSx) were synthesized through a two-step hydrothermal process. The optimized material (CoSx-2) could efficiently activate PAA system, achieving 91.8% NOR degradation in 5 min. The Co(II)/Co(III) species in CoSx was key to activating PAA, as Co(II) initiated the reaction and Co(III) activation caused the production of CH3C(=O)OO• species. Moreover, the presence of sulfur vacancies (VS) led to the generation of hydroxyl radicals (•OH) and singlet oxygen (1O2) via chain reactions with CH3C(=O)OO•. Density functional theory (DFT) calculations reveal the contribution of VS to enhanced catalytic PAA activation, as the lower work function (5.76 eV), higher adsorption energy (-3.43 eV), bridge effect of delocalized electrons and shifted d-band center are achieved to reduce the energy barrier for electron transfer during catalytic reaction. In addition, DFT calculation on Fukui index further explains that 18 N and 21 N are reactive sites of NOR for electrophilic attack, leading to primary degradation pathways of C–N cleavage, defluorination, dealkylation and hydroxylation. This study gives a new perspective on the regulation of material structure for efficient activation of PAA and promotes the practical application of heterogenous PAA-based AOPs for emerging contaminants removal in water treatment process.

The effects of chlorine-containing species on cinnabar: A density functional theory investigation into the surface adsorption reactivity of mercury sulfide

First-principles computations can be used to noninvasively probe semiconductor surfaces and describe mechanisms and transformations that occur on those surfaces. One such material of interest is the chalcogenide mercury sulfide (HgS), also known as cinnabar. Cinnabar (α-HgS) and its synthetic counterpart (vermilion) have been used as bright red pigments since antiquity and are important sulfide materials in the field of art conservation. However, it has been known since Roman times that these pigments can darken when exposed to light. It has been hypothesized that Cl2 and other chlorine-containing materials are involved in the photodegradation of cinnabar surfaces. Here we use first-principles density functional theory (DFT) to probe the adsorption reactivity of Cl-containing adsorbates on HgS surfaces, as DFT yields information at the atomistic level and can link changes in surface structure to changes in electronic states. Specifically, we model single adsorbates interacting with corrugated and flat HgS surfaces to probe the initial step in the photodegradation mechanism. This allows us to not only assess the strength of adsorption and any corresponding adsorbate dissociations, but also link these adsorption and dissociation events to key changes in the electronic band structure that may act as spectroscopic identifiers in the degradation pathway of chalcogenide semiconductors that contain photoreactive metals.

N-Type Thermoelectric AgBiPbS3 with Nanoprecipitates and Low Thermal Conductivity.

Thermoelectric sulfide materials are of particular interest due to the earth-abundant and cost-effective nature of sulfur. Here, we report a new n-type degenerate semiconductor sulfide, AgBiPbS3, which adopts a Fm3̅m structure with a narrow band gap of ∼0.32 eV. Despite the homogeneous distribution of elements at the scale of micrometer, Ag2S nanoprecipitates with dimensions of several nanometers were detected throughout the matrix. AgBiPbS3 exhibits a low room-temperature lattice thermal conductivity of 0.88 W m-1 K-1, owing to the intrinsic low lattice thermal conductivity of Ag2S and the effective scattering of phonons at nanoprecipitate boundaries. Moreover, compared to AgBiS2, AgBiPbS3 demonstrates a significantly improved weighted mobility of >16 cm2 V-1 s-1 at 300 K, leading to an enhanced PF of 1.6 μW cm-1 K-2 at 300 K. The superior electrical transport in AgBiPbS3 can be attributed to the high valley degeneracy of the L point (the conduction band minimum), which is contributed by the Pb s and Pb p orbitals. Further, Ga doping is found to be effective in modulating the Fermi levels of AgBiPbS3, leading to further enhancement of PF with a PFave of 2.7 μW cm-1 K-2 in the temperature range of 300-823 K. Consequently, a relatively high ZTave of 0.22 and a peak ZT of ∼0.4 at 823 K have been achieved in 3% Ga-doped AgBiPbS3, highlighting the potential of AgBiPbS3 as an n-type thermoelectric sulfide.

Improving Photocurrent in Sb2Se3 Thin‐Film Solar Cells Through Sb2S3 Electron Reflector Layer: A Simulation Study

AbstractIn this paper, antimony sulfide (Sb2S3) material is utilized as an electron reflector layer (ERL) in antimony selenide (Sb2Se3) solar cells. The primary objective of this simulation study is to mitigate recombination at the back contact and improve cell performance. It is demonstrated that incorporating Sb2S3 ERL into a traditional Sb2Se3 cell yields enhancements in both the short‐circuit current density (Jsc) and carrier collection rate. This enhancement is assigned to the reduced interface recombination rate at the back electrical contact. The strong electric field at the p+‐Sb2S3/p‐Sb2Se3 electrical contact creates a barrier with a height of 0.34 eV in the conduction band that hinders the electron carriers' access to the back contact. This barrier effectively improves cell efficiency. The use of this method has demonstrated a significant improvement in the external quantum efficiency (EQE) at longer wavelengths, specifically ranging from ≈800 to 1100 nm. Using this method, the Sb2Se3 active layer thickness is reduced to 1 µm, which reduces the fabrication cost. After optimizing the device, the cell efficiency enhances from 9.2% to 13.1%, resulting in a significant improvement compared to traditional Sb2Se3 solar cells without an ERL, thanks to the incorporation of a suitable Sb2S3 ERL.

Construction of one-dimensional hierarchical MoS2/Ni3S2 composites with enhanced interfacial polarization and improved wideband microwave absorption

The construction of one-dimensional (1D) sulfides has attracted extensive attention for improving microwave absorption (MA) performance owing to the anisotropic conductive networks. However, the synthesis of conductive 1D hierarchical materials with unique interfacial polarization and excellent MA properties remains challenging. In this study, cable-like MoS2/Ni3S2 was synthesized by a one-step hydrothermal strategy. The complex permittivity of the binary composites could be improved by tuning the thickness of the MoS2 coating. Importantly, the construction of heterogeneous contacts by MoS2 and Ni3S2 contributed to enhanced polarization loss, and the charge distribution was validated by electron holography. The wide efficient absorption bandwidth can reach above 4.8 GHz at a thin thickness. These new discoveries shed light on novel structures for 1D sulfide materials and the design of functional core-shell composites for microwave absorption.

Enhanced structural properties of electrochemically synthesised NiFeS using 500 keV carbon C++ ions irradiation

ABSTRACT An electrochemical approach was used to synthesise nickel iron sulphide (NiFeS) materials in this work. The prepared NiFeS underwent a thorough investigation, which included analyses of its optical, electrical, structural, morphological, elemental, and functional group properties. Cubic crystal formations with prominent peaks were visible from the structural pattern. Nanoflakes and pebbles were visible, and their elements were determined through elemental dispersive X-ray diffractometer (EDX) spectrum. The film’s crystallinity increased after incorporating carbon ions and its optical properties improved, with energy band gap values ranging from 1.50 eV to 1.15 eV as the peaks became more distinct. The materials produced could be utilised in the production of solar cells and optoelectronic devices. The electrical conductivity diminishes with increasing thickness. Carbon ion radiation increases carrier concentration, which increases electrical conductivity.

Cobalt nickel sulfide anchored on graphene for high performance all-solid-state asymmetric supercapacitors

Transition metal sulfide materials exhibit huge potential in high performance supercapacitors due to high theoretical capacitance and activity. Herein, a facile hydrothermal method has been developed to prepare CoNiS/graphene composite. Due to the porous and stable sandwich like structure and effective ion/electron transfer path, the optimized CoNiS-10GO electrode delivers a large specific capacitance of 746.7 C g−1 at 1 A g−1 and with a 69.3 % initial capacitance retention even at 20 A g−1. Moreover, the prepared asymmetric supercapacitor using CoNiS-10GO as positive electrode and porous carbon as negative electrode shows a large energy density of 37.3 Wh kg−1 and good electrochemical stabilization in PVA/KOH sol electrolyte. Therefore, this research provides a simple, convenient approach for preparation of transition metal sulfides with high performance for supercapacitors.

High Entropy Sulfide Nanoparticles as Lithium Polysulfide Redox Catalysts.

The polysulfide shuttle contributes to capacity loss in lithium-sulfur batteries, which limits their practical utilization. Materials that catalyze the complex redox reactions responsible for the polysulfide shuttle are emerging, but foundational knowledge that enables catalyst development remains limited with only a small number of catalysts identified. Here, we employ a rigorous electrochemical approach to show quantitatively that the lithium polysulfide redox reaction is catalyzed by nanoparticles of a high entropy sulfide material, Zn0.30Co0.31Cu0.19In0.13Ga0.06S. When 2% by weight of the high entropy sulfide is added to the lithium sulfur cathode composite, the capacity and Coulombic efficiency of the resulting battery are improved at both moderate (0.2 C) and high (1 C) charge/discharge rates. Surface analysis of the high entropy sulfide nanoparticles using X-ray photoelectron spectroscopy provides important insights into how the material evolves during the cycling process. The Zn0.30Co0.31Cu0.19In0.13Ga0.06S nanoparticle catalyst outperformed the constituent metal sulfides, pointing to the role that the high-entropy "cocktail effect" can play in the development of advanced electrocatalytic materials for improved lithium sulfur battery performance.

Leaching of nitrogen, phosphorus and other solutes from a controlled drainage cultivated peatland in Ruukki, Finland

Cultivated peatlands are important for grass production in Northern Europe, but the potential impact of nutrients leaching to surface waters is a major concern. Due to a lack of data on nitrogen (N), phosphorus (P) and organic carbon leaching, a monitoring programme was established at Ruukki (Siikajoki, Finland), an agricultural, subsurface drained peat site with a peat thickness of 20–80 cm. Concentrations and loading of N, P, and total organic carbon (TOC) were monitored, along with other water quality parameters for the field discharge, in 2018–2021. We observed N leaching from subsurface discharge to be 25 kg N ha−1 year−1 (range 11–40 kg N ha−1 year−1, 74 % as nitrate NO3-N). The least N leaching was recorded from plots of thinner peat topsoil and those with grass cover, while the majority of N leaching originated from thicker peat plots (bare or under barley) in spring. Leaching of N strongly decreased during periods of thick grass cover. Significant N leaching also occurred during the mild winter of 2019–2020, characterized by alternating freeze and thaw periods. Annual P loading from subsurface drainage was 0.30 kg P ha−1 (0.20–0.43 kg P ha−1), low compared to that of average cultivated soils in Finland. It was estimated that 13 % of the total N leaching and 50 % of the total P leaching occurred in surface runoff. Leaching of TOC was significant at 87 kg ha−1 year−1 (31–137 kg ha−1 year−1). Leaching of dissolved P and TOC increased with peat thickness. Abundant loading of sulfur and acidity indicates the oxidation of sulfidic material in the subsoil. Leaching concentrations correlated with discharge quantity, suggesting that mobilization processes during the dry periods resulted in leaching during high discharge periods. The results show the importance of avoiding bare peat soil for NO3-N leaching reduction, even during wintertime in cultivated peatlands.

Influence of Water Table and Peat Thickness on Dissolved Organic Carbon of Tropical Peat Soil with Sulfidic Substratum from Central Kalimantan, Indonesia

Peatlands are important due to their high carbon storage, their role in suppressing climate change processes, and their importance for local and global communities’ livelihood. Large amounts of organic carbon pools in peatlands can be released into the environment as gaseous emitted carbon and lost through waterways (fluvial). The carbon released through the water stream consists of organic and inorganic forms and is partly in the form of CO2 and CH4 gases. The organic form consists of dissolved organic carbon (DOC) and particulate organic carbon, where DOC is the most dominant organic carbon in water sourced from peatlands. This research's objectives were to study the DOC concentration of peat water resulting from the hydrological condition's difference and the peat thickness overlaying the sulfidic substratum. The study was carried out in the Pangkoh area of Pulang Pisau district of Central Kalimantan. Peat water is taken on PVC pipes installed on each plot representing different peat thicknesses (deep, moderate, and shallow peat) at a depth of 25, 50, 100, 150, 200, and 250 cm from the soil surface. The water sampling was conducted on the peak wet season, during the transition from wet season to dry season and during the peak dry season. The results showed that DOC was influenced by peat thickness, depth of sulfidic material, and groundwater level. The release of DOC is higher from the deep peat than from the thin and moderate peat. The difference in DOC concentration between peat thickness is also related to the electrical conductivity of the peat water. The results showed a negative correlation between electrical conductivity and DOC concentration. The negative correlation was significant in the observation of the rainy and dry seasons, while in the transitional season, it was not significant.

Improve physical properties of zirconium doped strontium sulphide for optoelectronic purpose

The electrochemical deposition was used to synthesize zirconium-doped strontium sulphide materials at varying dopant concentrations of 0.01 to 0.03 mol. The surface micrograph of the zirconium doped films is well structured on the surface of the FTO used for the synthesis without any crack or lattice strain. The spectrum is polycrystalline with a cubic structure and a prominent peak at (111) orientation for SrS film. At the introduction of the zirconium dopant 0.01 mol, the peak intensity increases with a prominent peak at (211) which indicate acceptance of zirconium dopant in the precursor and as the dopant concentration rises the peak intensity decreases which depicts that a higher concentration of zirconium reduces the peak intensity of the films. The Williamson-Hall plot's slope increases as the dopant concentration increases. The materials exhibit a thickness increase of 121.32 to 126.13 nm and a decrease in film resistivity from 1.12 × 109 to 1.32 × 109 O.m, which further led to an increase in conductivity from 7.57 × 108 to 8.26 × 108 S/m. The bandgap energy of SrS is 1.50 eV while SrS-doped zirconium is 1.35 eV–2.52 eV.

Elucidating the Effect of Dry-Room Atmospheres on the Performance of Sulfidic Sheet-Type Separators for All-Solid-State Batteries

Electrifying the automotive sector requires energy storage systems with high energy and power density, intrinsic safety, and long durability.[1] Lithium-based all-solid-state batteries (ASSBs) are considered promising next-generation energy storage devices, as they possibly meet these requirements by replacing organic liquid electrolytes with non-flammable solid electrolytes (SEs) and by enabling the application of novel high energy density anode concepts.[2, 3] Among the SE material classes being pursued for use in ASSBs, sulfidic systems are considered particularly advantageous, as they possess high ionic conductivities and low Young’s moduli, enabling easier processing and densification compared to oxidic systems.[4] However, a rarely addressed key bottleneck to commercializing ASSBs with sulfidic SEs is the requirement on the environmental conditions during handling, processing, and assembly of the battery components, which will be dictated by the instability of sulfidic SEs towards humidity.[5] On the laboratory scale, this issue has been avoided by handling the sulfidic ASSB materials, components, and cells in argon-filled gloveboxes, but for the commercial production of ASSBs their manufacturing would preferably be done in a dry-room atmosphere.[6] However, very few studies exist that examine whether the dew points of typical dry-rooms are sufficient to handle and/or store ASSB components based on sulfidic SEs.[7,8] In this contribution, we will examine the dry-room compatibility of scalable sulfidic composite (Li6PS5Cl/HNBR) sheet-type separators,[9] investigating the influence of the exposure time to a dry-room atmosphere with a dew point of -48°C on the stability of the SE and on its electrochemical properties. Using X-ray diffraction (XRD) combined with Rietveld refinement and scanning electron microscopy (SEM), the influence on the morphology and the formation of degradation products upon reaction with the small concentration of water in a dry-room will be investigated. The results show that only long exposure times (> 96 h) lead to a significant hydrolysis-induced change in the XRD diffractograms, which indicates the formation of degradation products such as Li2S, LiCl, and Li3PO4.By means of potential electrochemical impedance spectroscopy (PEIS), the impact of different exposure times on the Li+-ion conductivity of the sheet-type Li6PS5Cl/HNBR separators and the activation energy for the Li+-ion transport are investigated (cf. figure 1). While short exposure times (< 12 h) have a minor influence on the Li+-ion conductivity (lowering it from 0.3 mS/cm to 0.25 mS/cm) and a negligible effect on the activation energy, longer exposure times (> 48 h) lead to a ≈ 10-fold loss of ionic conductivity (to ≈ 0.03 mS/cm) and a drastic increase in activation energy.Besides measuring the loss of ionic conductivity, the separator sheets are also used for assembling LiNi0.6Co0.2Mn0.2O2|LiIn half-cells, which are investigated using galvanostatic cycling. An analysis of the capacity profiles shows that an increased exposure of the separators to the dry-room atmosphere leads to a significant IR-drop, to lower initial discharge capacity, and enhanced capacity fading over several charge/discharge cycles. Further insights into these degradation phenomena will be gained by analyzing the dQ/dV plots, the mean (dis)charge voltage, and the full-cell impedance of the half-cells.Based on our findings, it can be concluded that moderate exposure times in a dry-room of up to 12 h have only a negligible effect on the chemical integrity and performance of sulfidic Li6PS5Cl/HNBR separators sheets. This opens the route of defining viable storage and processing times of sulfidic ASSBs cell components in industrial dry-room environments.[1] Y. Ding, Z. P. Cano, A. Yu, J. Lu, Z. Chen, Electrochemical Energy Reviews, 2, 1 – 28, (2019).[2] J. Janek and W. G. Zeier, Nature Energy, 1, 16141, (2016).[3] P. Oh, J. Yun, J. H. Choi, K. S. Saqib, T. J. Embleton, S. Park, C. Lee, J. Ali, K. Ko, J. Cho, Angew. Chem. Int. Ed., 61, e202201249, (2022).[4] A. Sakuda, A. Hayashi, M. Tatsumisago, Scientific Reports, 3, 2261, (2013).[5] H. Muramatsu, A. Hayashi, T. Ohtomo, S. Hama, M. Tatsumisago, Solid State Ionics, 182, 116 – 119, (2011).[6] D. H. S. Tan, Y. S. Meng, J. Jang, Joule, 6, 1755-1769, (2022).[7] Y.-T. Chen, M. A. T. Marple, D. H. S. Tan, S.-Y. Ham, B. Sayahpour, W.-K. Li, H. Yang, J. B. Lee, H. J. Hah, E. A. Wu, J.M. Doux, J. Jang, P. Ridley, A. Cronk, G. Deysher, Z. Chen, Y. S. Meng, J. Mater. Chem. A , 10, 7155-7164, (2022).[8] C. Singer, H.-C. Töpper, T. Kutsch, R. Schuster, R. Koerver, R. Daub, ACS Appl. Mater. Interfaces, 14, 24245–24254, (2022).[9] C. Sedlmeier, T. Kutsch, R. Schuster, L. Hartmann, R. Bublitz, M. Tominac, M. Bohn, H. A. Gasteiger, J. Electrochem. Soc., 169, 070508, (2022). Figure 1

Constraints of in-situ S-isotopic compositions of pyrite on the genesis of the Bayinqinggeli sandstone-hosted uranium deposit, Ordos Basin, Northern China

Sandstone-hosted uranium deposits are formed by redox interactions between oxidized ore-forming fluids and sufficient reductants, such as sulfide and organic materials within hosting strata, or hydrocarbon-bearing fluids from deep reservoirs. Origin and role of reducing agents are very important for deciphering uranium mineralization processes to guide prospecting, but are hard to be addressed due to rare occurrences, small size, and complex microstructures of minerals at the mineralization stage. The Mesozoic Ordos Basin in the North China Carton is an intracontinental basin, in which many giant sandstone-hosted roll-front uranium deposits form an uranium metallogenic belt. Among these, the Bayinqinggeli uranium deposit has two orebodies that are hosted in sandstones of the Jurassic lower Zhiluo Formation. Adjacent to orebodies, sandstones are variably modified to form oxidized and reduced zones. Pyrite grains from the oxidized zone are replaced by iron oxides, but those from the orebodies and reduced zone are better preserved and widespread. These pyrite grains have three generations based on their morphologies and structures. The early two generations, framboidal Py1 and concentric Py2, occur in the reduced zone and orebodies and formed before the uranium mineralization. They have large variable δ34S values ranging from −51.33‰ to +49.39‰ and −36.88‰ to +21.61‰, respectively. The pre-ore pyrite grains from the orebodies were partially dissolved by later oxidized ore-forming fluids and may act as a reducing agent during the uranium mineralization. The third generation of pyrite, subhedral to euhedral pyrite (Py3) or rims surrounding Py1 and Py2, coexists with uranium minerals, coffinite and pitchblende, and has dominantly negative δ34S values (-51.63‰ to +2.44‰), suggesting the microbial sulfate reduction origin and ruling out the deep hydrocarbon-bearing (CH4) hydrothermal fluids. Therefore, reduced hydrocarbon-bearing hydrothermal fluids outside ore-bearing zones were not necessary for the formation of the giant Bayinqinggeli uranium deposit. Instead, the deposit is more likely to have been formed by the continuous reduction of oxidized ore-forming fluids with the organic and inorganic reductants (e.g., carbonaceous debris and Fe2+-bearing minerals) within the lower Zhiluo Formation.

Constructing a CdS QDs/silica gel composite with high photosensitivity and prolonged recyclable operability for enhanced visible-light-driven NADH regeneration

Visible-light-driven nicotinamide adenine dinucleotide (NADH) regeneration is one of the most effective measures, and cadmium sulfide (CdS) materials are typically used as low-cost photocatalysts. The CdS photocatalysts, however, still suffer from low regeneration efficiency and poor cycle stability. In this work, the CdS quantum dots (QDs) less than 10 nm embedded onto silica gel (CdS QDs/Silica gel) were constructed for visible-light-driven NADH regeneration by a successive ionic layer adsorption reaction and ball milling method. Results demonstrate that the photosensitivity of the CdS QDs/Silica gel composite was 31 times higher than that of the bulk CdS. Moreover, the conduction band (CB) edge of the CdS QDs/Silica gel composite is −1.34 eV, which is more negative 0.5 eV than that of the bulk CdS. The obtained CdS QDs/Silica gel composites showed the highest NADH regeneration yields of 68.8% under visible-light (LED, 420 nm) illumination and can be reused for over 40 cycles. Finally, the bioactivity of NADH toward enzyme catalysis is further confirmed by the hydrogenation of benzaldehyde to benzyl alcohol catalyzed with an alcohol dehydrogenase as enzyme catalysis.

Vacancy engineering in transition metal sulfide and oxide composite material for thermal batteries of high specific capacity

As a thermal battery cathode material, WS2 has high decomposition temperature and large specific capacity, but its low voltage problem has been rarely reported. In this work, we first prepared WS2 containing sulfur vacancies and then used it as a precursor to prepare a mixture of sulfur-vacancy and oxygen-vacancy double-doped WO3 with WS2 (WS2-x-WO3-x). WO3 was attached to the surface of WS2, which made the samples easier to be pressed into tablets. The presence of vacancies was confirmed by x-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR). The discharge results show that the discharge time of WS2-x-WO3-x is 52% higher than that of WS2. This work provides a beginning for further applying transition metal sulfide and oxide composite material for high capacity thermal batteries.

Enhanced degradation of reactive black 5 via persulfate activation by natural bornite: influencing parameters, mechanism and degradation pathway

ABSTRACT Reactive black 5 (RBk5) is a refractory azo dye that constitutes a serious threat to the environment and humans. Herein, natural bornite (Nbo) was utilized to activate persulfate (PDS) for the RBk5 removal. The particle size of the Nbo catalyst was optimized and the RBk5 degradation rate constant that responded positively to the particle size of the Nbo catalyst was exhibited. Then, the operational factors affecting RBk5 removal were comprehensively investigated. With the addition of 1.5 g L−1 Nbo and 1.5 mM PDS, 99.05% of the RBk5 (20 mg L−1) was removed in 150 min compared with 0.46% removal with PDS only, which was caused by the additional reactive oxygen species (ROS) produced by the synergistic action of Fe-Cu bimetallic metal and reductive sulfur species. The Nbo catalyst presented high stability and reusability toward RBk5 removal. Identification of reactive oxygen species revealed that SO 4 ⋅ − , ·OH, O 2 ⋅ − and 1O2 collectively participated in RBk5 removal. Additionally, a possible degradation pathway for RBk5 was proposed, including cleavage of the azo, C–S and S–O bonds, hydroxylation, hydrolyzation, direct oxidation and other pathways. This work developed a highly effective and low-cost natural mineral-based bimetallic sulfide material for PDS activation for the degradation of contaminants and environmental remediation.

Advancing broadband light structuring through single-size nanostructured all-dielectric meta-devices

Traditional optical components and most artificially engineered structures (metamaterials) used for light manipulation are usually designed for narrow bandwidth and limited functionalities. Furthermore, bulkiness and inefficiency limit their application for integrated devices. Metasurfaces, the ultracompact counterpart of bulky metamaterials, exhibit an unprecedented ability to manipulate incident electromagnetic waves at a micron scale. Metasurfaces have emerged as promising candidates for light structuring and its potential applications, ranging from high-capacity data communication to particle manipulation. Despite significant advancement in metasurfaces, realizing high-performance metadevices exhibiting a broadband light manipulation capability is still challenging due to the material's intrinsic nature and lack of a more straightforward design methodology. Here, we demonstrated a broadband single-cell driven all-dielectric metadevice platform to realize high-performance phase modulation for light structuring over the broad visible spectrum475−650nm. The building block consists of an intelligently optimized nanoantenna made of unique zinc sulfide material that employs the PB phase to realize single-layered broadband metadevices for structured light generation, ensuring a decent average transmission efficiency ηavg=79.9% over the intended band. To prove the concept, we designed numerous metadevices for structured light generation and numerically investigated each under the illumination of selected visible wavelengths. We envisioned that the presented work could accelerate real-life applications such as high-resolution color imaging, optical communication and sensing, quantum information processing, and micromanipulation.