Subsequent Sulfidation Research Articles

Facile Synthesis of CuxS Electrocatalysts for CO2 Conversion into Formate and Study of Relations Between Cu and S with the Selectivity

AbstractThe conversion of CO2 into formate (HCOO−), a techno‐economically feasible product, can be achieved using earth‐abundant CuxS electrocatalysts, but questions remain regarding how catalyst structure, composition, and reaction environment influence product selectivity. A novel synthesis method based on electrodeposition of Cu foam and its subsequent sulfidation via immersion in sulfur saturated toluene solution resulted in CuxS foams. Catalytic activity studies found that HCOO− selectivity is dependent on electrochemical activation at higher overpotentials. To understand the effects of activation, determine the active forms of the catalysts, and identify the role of sulfur, the electrodes are carefully characterized as well as gaseous and sulfur dissolved in electrolyte. This included study of the effects of intentional addition of solution sulfur species, identification of the sulfur loss, determination of the electrode composition and relating sulfur speciation to observed product selectivity. It is found that residual sulfur stabilizes Cu+ during electrolysis at potentials favoring HCOO− production, in contrast to pristine Cu that undergoes complete reduction and shows poor HCOO− selectivity. Sulfur in both the catalyst and dissolved in electrolyte are of dynamic nature, and surface residues of SO42− species are identified in all activated catalysts which correspond with enhanced HCOO− production.

Hidden deep sulfide cumulates beneath the Jinchuan Ni−Cu−platinum-group element deposit (China) inferred from Ni−Cu isotopes

The mechanisms that concentrated metals in the world’s single largest nickel−copper−platinum-group element (Ni−Cu−PGE) sulfide deposit, the Jinchuan deposit in northwestern China, remain enigmatic. Nickel and Cu isotopes are novel isotopic systems that may fill this knowledge gap as they are major constituents of sulfide melt, the main carrier of economically important metals. Sulfide ores in the Jinchuan deposit are characterized by systematically high δ60/58Ni and δ65Cu values, which are positively correlated (r2 = 0.84), and show well-defined correlations with PGEs, S, Ni, and Cu contents, and Ni/Pd, Cu/Pd, and Pd/Ir ratios. The isotopic signatures can be best explained by the early segregation of sulfide melt at depth prior to ascent of the parental magmas, storing isotopically light Ni and Cu in deep magma chambers. Subsequent sulfide melt segregation and fractionation in shallow portions of the magmatic conduit generated the currently explored sulfide ores, with heavy and positively correlated Ni−Cu isotopic signatures. Therefore, hidden deep orebodies are promising targets for further exploration beneath the Jinchuan deposit.

The influence of NaCl on xanthate adsorption on chalcopyrite surface and chalcopyrite flotation

Due to freshwater scarcity, mineral flotation plants have been using alternative water resources including seawater together with water recycling, resulting in the accumulation of salts in process water. However, how salts affect the adsorption of xanthates on the surfaces of sulphide minerals and subsequent sulphide mineral flotation is unclear. To address the knowledge gap, this study investigated how NaCl affected the adsorption of potassium amyl xanthate (PAX) on chalcopyrite surface and chalcopyrite flotation. Cyclic voltammetry (CV) tests identified that NaCl increased the oxidation of PAX and its adsorption on chalcopyrite surface due to elevated ionic strength and electrical conductivity of water, facilitating charge transfer among PAX, chalcopyrite surface and oxygen. NaCl also increased chalcopyrite surface oxidation to produce more CuS, facilitating the formation of copper-xanthate complexes. Flotation tests identified that the increased adsorption of PAX by NaCl was only translated into improved true flotation of chalcopyrite at a low PAX concentration such as 50 ppm in NaCl solutions with low and medium concentrations (0.1 and 0.7 M, respectively). At a high PAX concentration such as 150 ppm, the coexistence of high concentrations of PAX and NaCl led to strong froth destabilisation, resulting in a dramatic reduction in water recovery and true flotation recovery of chalcopyrite. The findings from this study will be able to guide the flotation plants to maximise mineral flotation by choosing collector dosage based on the ionic strength of process water.

Efficient electrocatalysts for OER: Amorphous cerium-doped cobalt sulfide with enhanced performance and durability

Developing highly efficient electrocatalysts is essential for advancing the oxygen evolution reaction (OER), a key step in water splitting. In this study, a novel approach for the synthesis of an amorphous sulfide structure has been presented. First, a cerium-doped zeolitic imidazolate framework-67 (Ce-ZIF-67) using a co-precipitation method, followed by a multi-step transformation process. This process includes oxidation to form cerium-doped cobalt oxide (Ce-CO) and a subsequent sulfidation step to produce an amorphous cerium-doped cobalt sulfide (Ce-CS) structure. The introduction of cerium and the formation of an amorphous sulfide structure result in a significantly enhanced OER performance due to increased atomic disorder, improved electron mobility, and an expanded active surface area. Remarkably, the Ce-CS structure achieved a reduction in overpotential from 352 mV for Ce-CO to 291 mV at 100 mA cm−2 in 1.0 M KOH, alongside a Tafel slope reduction from 86.2 mA decade−1 to 67.2 mV decade−1. These enhancements underline the importance of cerium doping and amorphization in optimizing electrocatalytic efficiency. Furthermore, the Ce-CS catalyst demonstrated exceptional durability, with no observable degradation in performance or structural integrity after 10 h of continuous operation. This work presents a pioneering strategy for designing and synthesizing highly effective OER electrocatalysts, contributing a significant advancement to the field.

Highly efficient and durable water electrolysis via ligand modulated interfacial assembly

Herein, we report a robust ligand-modulated interfacial assembly strategy for controllable metal doping to yield high-efficiency and durable bifunctional electrocatalysts of FeCoS-embedded hollow N-doped carbon (denoted H-FeCoS/NC) for electrocatalytic overall water splitting (EOWS). Specifically, the hollow Co-based layered double hydroxide (Co-LDH) is employed to render interfacial assembly of CoFe-PBA with tunable composition, morphology, and interface on Co-LDH, regulated by inorganic ligand. Subsequent sulfidation produces H-FeCoS/NC, manifesting outstanding OER/HER activities owing to favourable ligand-modulated Fe-doping, large specific surface area, well-dispersed FeCoS nanoparticles. DFT calculation reveals that ligand-modulated Fe-doping effectively promotes charge transfer, optimizes the intermediates/electrocatalyst interaction, and reduces OER/HER energy barriers, thus boosting the EOWS performance. The H-FeCoS/NC-assembled electrolyzer delivers a low cell voltage of 1.52 V and stably operates for 1000 h in alkaline medium, surpassing most non-noble-metal-based electrocatalysts. This work highlights a facile interfacial assembly route to engineer highly active electrocatalysts for high-performance and durable energy conversion and storage.

Platinum-Group Elements and Nb-Ta geochemistry of the Deccan basalts from Kumbharli and other Ghat sections and the Koyna Seismic Zone, Maharashtra (India): Crustal contamination and implication for sulfide saturation of the magma

The Deccan basalts from Kumbharli, Nadlapur, Bijaynagar, Hazarmacchi, and Surli Ghat sections (surface samples) and the Koyna borehole-7 (KBH-7, sub-surface samples) from Maharashtra (western India) demonstrate a two-stage crystallization process. Olivine and chromite were crystallized earlier in a shallow crustal magma chamber while clinopyroxene and plagioclase phenocrysts were crystallized in the sub-volcanic conduits forming the crystal mush, and carried to the surface by the evolved Fe-Ti-rich ascending basaltic magma. The high modal abundance of plagioclase at the top and clinopyroxene at the bottom part of the Kumbharli Ghat section is responsible for an increase in Sr and a decrease in Sc content towards the upper flows. The surface and sub-surface basalt samples contain Pd = 5–31 ppb, Pt = 4–15 ppb, Ir = 1–4 ppb, Ru = 1–3 ppb, and Rh = 3–5 ppb. Negative relations of Pd/Ir, Pd/Ru, and Pd/Rh with MgO from both sets of samples indicate partitioning of Ir, Ru, and Rh to early fractionated cumulus chromite (or olivine). Magnetite is a late crystallizing phase from the evolved Fe-Ti-rich basaltic magma. With an increasing modal abundance of magnetite, there is an increase of FeO total , TiO 2 , and V with Pd indicating fractionation of Pd by magnetite. Geochemical characters show that the surface basalt samples are less contaminated compared to the sub-surface KBH-7 basalts. High Nb (6.8–13.6 ppm) and low Ta (0.2–0.37 ppm) content and elevated Nb/Ta ratios of the surface samples from the ghat sections indicate the possible interaction of the basaltic magma with the carbonate metasomatized subcontinental lithospheric mantle (SCLM). On the other hand, a high degree of partial melting with limited crustal contamination can also elevate the Nb/Ta ratios of the basalts from the ghat sections. Deccan basalts from the study areas do not bear the signature of sulfide supersaturation and subsequent immiscible sulfide segregation. This is evidenced by their high chalcophile element concentrations (Ni = 79–103 ppm, Cu = 121–259 ppm) and ratios like Cu/Zr (≥ 1), Ni/MgO (13.7–21.8) with low Cu/Pd (2140–29938) compared to other Ni-Cu (PGE) sulfide mineralized continental flood basalts. The lack of crustal sulfur in the various contaminants is perhaps the main reason for this sulfide-undersaturated character of the Deccan basalts of the current study.

In-Situ Sulfuration of CoAl Metal-Organic Framework for Enhanced Supercapacitor Properties.

Designing efficient electrode materials is necessary for supercapacitors but remains highly challenging. Herein, cobalt sulfide with crystalline/amorphous heterophase (denoted as Co(Al)S) derived from an Al metal-organic framework was constructed by ion exchange/acid etching and subsequent sulfidation strategy. It was found that rational sulfidation by adjusting the sulfur source concentration to a suitable level was favorable to form a 3D nanosheet-interconnected network architecture with a large specific surface area, which promoted ion/electron transport and charge separation. Benefiting from the features of the unique network structure and heterophase accompanied by aluminum, nitrogen and carbon coordinated in amorphous phase, the optimal Co(Al)S(10) exhibited a high specific capacity (1791.8 C g-1 at 1 A g-1), an outstanding rate capability and an excellent cycling stability. Furthermore, the as-assembled Co(Al)S//AC device afforded an energy density of 72.3 Wh kg-1 at a power density of 750 W kg-1, verifying that the Co(Al)S was a promising material for energy storage devices. The developed scheme is expected to promote the application of MOF-derived electrode materials in electrochemical energy storage and conversion fields.

Amorphous and crystalline Sb2S3 nanoparticles embedded in N/S co-doped carbon as anodes for potassium-ion batteries

Antimony trisulfide (Sb2S3) has emerged as a promising anode candidate for potassium-ion batteries (PIBs) owing to its low cost and high theoretical specific capacity. However, its large volume expansion upon K+ storage and sluggish kinetics result in poor cycling performance and rate capability. To address these challenges, rational structural design is highly desirable. Herein, we report the synthesis of amorphous and crystalline Sb2S3 nanoparticles embedded in N/S co-doped carbon composites (a-Sb2S3@NSC and c-Sb2S3@NSC) via a facile organic coating combined with subsequent carbonization and sulfidation processes. When used as a PIBs anode material, a-Sb2S3@NSC exhibits a high discharge specific capacity of 415.6 mAh g−1 after 50 cycles at 200 mA g−1 and a stable rate capability (224.8 mAh g−1 at 2 A g−1), which remarkably outperforms that of the c-Sb2S3@NSC with inferior specific capacity (311.5 mAh g−1) and poor rate capability (67.7 mAh g−1). The amorphous structure of Sb2S3 nanoparticles in a-Sb2S3@NSC provides abundant defects and structural disorder, which reduces the entropy energy and activation barrier associated with K+ incorporation, effectively facilitating the transport and storage of K+. Moreover, the synergistic interactions between amorphous Sb2S3 nanoparticles and N/S co-doped carbon can effectively improve the electron/ion reaction kinetics and buffer volume variations, thus leading to superior potassium storage performances.

Application of geological and short wavelength infrared (SWIR) spectroscopy mapping in the Mailong gold deposit, East Kunlun: Implications for exploration targeting

Widespread regolith cover makes it difficult to identify the anomalous size of their mineralogical or geochemical footprint at the surface in gold exploration. Short wavelength infrared (SWIR) spectroscopy with effective identification of clays and other hydrous minerals shows potential application in gold exploration. The detailed geological and short wavelength infrared (SWIR) spectroscopy mapping was conducted in the newly-discovered orogenic-type Mailong gold deposit (13.06 t @ 6.29 g/t Au), East Kunlun, to determine alteration stage and mineral assemblages and discuss the potential values of SWIR spectral in gold exploration.In the Mailong area, magmatic rocks consist of granodiorite, biotite granodiorite, plagiogranite and mafic dikes, and the gold mineralization shows a close spatial and temporal relationship with mafic dikes. The earliest chloritization (chlorite-quartz) is widely distributed in granodiorite, biotite granodiorite and plagiogranite. The following potassic alteration (hydrothermal K-feldspar and quartz) is developed along high-angle fault/fracture, which cut through granodiorite, biotite granodiorite and plagiogranite. The subsequent sulfide alteration (chlorite-muscovite-sulfide-carbonate) overprints the former potassic and chloritization alteration, and shows spatial association with mafic dikes. Native gold occurs in fracture arsenopyrite or associated with minerals such as pyrite, and chalcopyrite during the early sulfide stage. Supergene alteration is characterized by limonite and malachite. At Mailong, the SWIR data indicate that the most abundant alteration minerals (chlorite, white micas and ankerite) mainly occurred in the northern area. White mica Al-OH absorption occurs at longer wavelengths (Pos2200 = 2202.5 ∼ 2203 nm) and higher Illite crystallinity (IC = 1.2 ∼ 3.1) probably reflecting a higher temperature and pH conduit at the bottom of ZK0001 and ZK0801. The sharp shift of IC values near the bottom reflects the control of fault. This area is also situated at the V-shaped intersections of the three granitic intrusions and structural transection, indicating more of a possible hydrothermal fluid channel than a mineralization center. Low-grade Au mineralization (Au = 0.1 ∼ 0.5 g/t) is mainly distributed within hydrothermal channels with higher Pos2200 (mainly 2022.5 ∼ 2203 nm) and IC values (mainly 1.2 ∼ 3.1), while high-grade Au endowment associated with mafic dikes has low Pos2200 (mainly 2201 ∼ 2202.5 nm) and IC values (mainly 0.43 ∼ 1.2). Meanwhile, an equation of distance = -15*IC + 31 (R2 = 0.47) can be summarized for low-grade orebodies vectoring. Integrating geological mapping and spectral data, target areas for high-grade ore bodies can be outlined using the criteria of white mica, shorter wavelength of Al-OH absorption position (Pos2200 = 2201 ∼ 2202.5 nm), lower IC values (IC = 0.43 ∼ 1.2), and chlorite Fe-OH absorption position Pos2250 (>2247 nm) along with occurrences of mafic dikes. This study demonstrates that utilizing the detailed SWIR identification in conjunction with accurate geological mapping has great potential for greenfield exploration of orogenic gold deposits.

Interface engineering of 2D NiFe LDH/NiFeS heterostructure for highly efficient 5-hydroxymethylfurfural electrooxidation

The electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to valuable chemicals is an efficient way to upgrade biomass molecules and replace traditional catalytic synthesis. It is crucial to develop efficient and low-cost earth-abundant electrocatalysts to enhance catalytic performance of HMF oxidation. Herein, a new type of two-dimensional (2D) hybrid arrays consisting of NiFe layered double hydroxides (LDH) nanosheets and bimetallic sulfide (NiFeS) is constructed via interface engineering for efficient electrocatalytic oxidation of HMF to 2,5-furandicarboxylic acid (FDCA). The preparation process of 2D NiFe LDH/NiFeS with ultrathin heterostructure involves in anchoring a Co-based metal-organic framework (Co MOF) as template onto the carbon cloth (CC) via in-situ growth, formation of NiFe LDH on the surface of Co MOF and subsequent partial sulfidation. The electrocatalyst of NiFe LDH/NiFeS exhibits outstanding performance towards HMF oxidation, about 98.5% yield for FDCA and 97.2% Faraday efficiency (FE) in the alkaline electrolyte with 10 mmol/L HMF, as well as excellent stability retaining 90.1% FE for FDCA after six cycles test. Moreover, even at an HMF concentration of 100 mmol/L, the yield and FE for FDCA remain high at 83.6% and 93.6%, respectively. These findings highlight that 2D heterostructure containing abundant interfaces between NiFe LDH nanosheets and NiFeS can enhance the intrinsic activity of LDH and thus promote the oxidation reaction kinetics. Additionally, the synergistic effect of the bimetallic NiFe compounds also improved the selectivity of HMF conversion to FDCA. Our present work demonstrates that constructing 2D ultrathin heterostructure of NiFe LDH/NiFeS is a facile strategy via interface engineering to enhance the intrinsic activity of LDH electrocatalysts, which would open new avenues toward low-cost and advanced 2D nanocatalysts for sustainable energy conversion and electrochemical valorization of biomass derivatives.

Methane production from sugarcane vinasse: The alkalinizing potential of fermentative-sulfidogenic processes in two-stage anaerobic digestion

The two-stage anaerobic digestion (2st-AD) of sugarcane vinasse is widely studied and well-known for improving the energy recovery potential in sugarcane biorefineries. Maintaining enhanced substrate acidification in a separate (first stage) reactor directly improves the performance of methanogenesis (second stage). However, problems derived from the presence of sulfate (SO42−) and the subsequent sulfide formation in the second stage are not prevented in conventional 2st-AD systems. In addition, high costs related to reactor alkalinization still represent significant drawbacks in that configuration. The energy recovery potential via methanogenesis was assessed from acidified sugarcane vinasse samples collected from different dark fermentative systems, namely: V1 (subjected to NaOH+NaHCO3 dosing), V2 (subjected to NaOH dosing) and V3 (subjected to no pH control). Despite the harmfulness of sulfide, the enhanced production of acetate from the incomplete oxidation of organic matter in sulfidogenesis can benefit methanogens. The highest methane yield (296.3 NmL-CH4 g-COD−1) and global energy recovery potential (354,603 GWh per season) were obtained from the lactate and SO42−rich vinasse (V2). Nevertheless, from a technological perspective, the methanogenesis of vinasses subjected to the fermentative-sulfidogenic process (V1) provided a higher quality biogas due to a higher calorific power (26.4-27.0 MJ Nm−3) and decreased H2S content in the biogas. Finally, the fermentative-sulfidogenic process as an alkalinizing strategy was demonstrated to be the best economic approach for scaling up the 2st-AD of sugarcane vinasse, overcoming the main economic drawback of this configuration.

Co-ZIF-derived dual Co and Co3S4 nanoparticles encapsulated in N-doped carbon matrix for efficient photocatalytic CO2 reduction

In this study, a novel N-doped carbon-coated dual Co and Co3S4 nanoparticles composite (Co-Co3S4@NC) has been developed by pyrolysis of an ideal flower-like Co-ZIF precursor followed via subsequent hydrothermal sulfidation. Under visible-light irradiation, the Co-Co3S4@NC exhibits outstanding performances for CO2 reduction with H2O vapor into CO (23.14 μmol g−1 h−1) and CH4 (0.62 μmol g−1 h−1) in a continuous flow system, significantly outperforming the single Co@NC photocatalyst. The experimental results demonstrate that the energy band structure in Co-Co3S4@NC can provide a more favorable reduction potential for the effective reduction of CO2. Moreover, the presence of Co3S4 is beneficial for the rapid separation and transfer of charges, thereby enhancing the utilization of photogenerated charge carriers. Thanks to its unique composition, Co-Co3S4@NC possesses abundant active sites for chemisorption and activation of CO2, which facilitates CO2 photoreduction. The reaction mechanism is revealed in detail by analyzing the key intermediate species obtained through in situ DRIFTS. The current work offers a facile route for the construction of MOF-derived composites for promising photocatalytic reactions.

Evolution of skarn to quartz-vein mineralization: Insights from the Tongshanling Cu–Pb–Zn deposit, South China

The Tongshanling Cu–Pb–Zn deposit, situated within the Qin-Hang intra-continental porphyry-skarn metallogenic belt in South China, presents a valuable case study of intrusion-related ore systems. This deposit is characterized by skarn mineralization closely associated with subsequent quartz-vein sulfide mineralization. While considerable research has been devoted to understanding the origin and evolution of the intrusions and mineralization processes, limited attention has been given to elucidating the relationship between the skarn and quartz-vein mineralization, along with the physicochemical conditions governing their formation. Here, we conducted a comprehensive mineralogical and isotopic investigation of sulfides, and a thorough analysis of fluid inclusion assemblages. We aimed to discern disparities in the sources of ore-forming materials, formation temperature, sulfide fugacity, and precipitation-alteration mechanisms of hydrothermal fluids for these two distinct orebodies. Although same sulfide species including arsenopyrite, pyrite, chalcopyrite, and sphalerite, some silicate minerals such as garnet, chlorite, and epidote are exclusive to the skarn orebodies and absent in the quartz veins.The homogeneous temperatures of fluid inclusions in the skarn orebody, ranging from the early to late stages of evolution, decrease from ∼310 to ∼290 °C. Simultaneously, salinity varies from 5.5 to 3.1 wt% NaCl eqv. In the quartz vein mineral body, the temperature reduction is more pronounced, decreasing from ∼270 to 186 °C, with salinity ranging from 3.6 to 1.4 wt% NaCl eqv. Sphalerite geothermometer indicates that peak hydrothermal fluid temperature in the skarn orebodies (∼300–340 °C) was relatively higher than that in the quartz-vein orebodies (<300 °C). Nevertheless, temperatures in both hydrothermal fluid systems declined as mineral precipitation proceeded, corresponding to a decrease in sulfur fugacity. The final stage of sphalerite represents the lowest temperature, salinity and sulfur fugacity with associated quartz displaying the lowest salinity across the entire hydrothermal fluid spectrum at the Tongshanling deposit, suggestive of meteoric water incorporation. This study delves into the multifaceted history of mineralization at the Tongshanling deposit, providing a fresh perspective on the origin and evolutionary relationships of Cu-polymetallic deposits associated with intrusions, particularly those involving multiple stages of mineralization in skarns and quartz veins, contributing to a better understanding of similar deposits worldwide.

Flexible Self-Supporting MOF-Based Bean Pod Cube Hollow Nanofibers for Ultralong Cycling and High Rate Na Storage.

Sodium-ion batteries (SIBs) have garnered significant attention due to their potential as an emerging energy storage solution. Tin sulfide (SnS) has emerged as a promising anode material for SIBs due to its impressive theoretical specific capacity of 1022 mA h g-1 and excellent electrical conductivity. However, its practical application has been hindered by issues such as large volume expansion, which adversely affects cycling stability and rate performance during the charge/discharge processes. In this study, a novel approach to address these issues by synthesizing the bean pod cube hollow metal-organic framework (MOF)-SnSx/NC@N-doped carbon nanofibers through a process involving electrospinning, PDA coating, and calcination. The Sn-MOF serves as a self-sacrificing template, facilitating the simultaneous dissociation of MOF and polymerization of dopamine, leading to the creation of hollow intermediates that retain tin components. Subsequent sulfidation results in the integration of the hollow MOF-SnSx/NC nanoparticles within 3D nitrogen-doped carbon nanofibers, forming the distinctive bean pod cube composite structure. This unique configuration effectively shortens the diffusion path and mitigates volume expansion for sodium ions, ultimately yielding an exceptional high rate performance of 130 mA h g-1 (10 A g-1) and an ultralong cycling performance of 328 mA h g-1 even after 3500 cycles (2 A g-1) as the anode for SIBs.

The organic–inorganic dual anchoring strategy based on organic chelators and lacunary polyoxometalates for the preparation of efficient CoWS hydrodesulfurization catalysts

Designing catalysts with bimetallic intimate synergistic effects to enhance catalytic activity has always been a focused problem for hydrodesulfurization (HDS) systems. Efficient HDS catalysts with abundant CoWS active phases were prepared through novel organic–inorganic ligand dual anchoring strategy based on the organic chelating agents and lacunary polyoxometalates (POMs). Citric acid (CA) chelating agent and Co2+ promoter are pre-coordinated in the impregnating solution, the trivacant Keggin [SiW9O34]10- (SiW9) POMs attract the promoter through the nucleophilic oxygen groups at the vacant sites to form the CA-Co@SiW9 “sandwich-like” structure, which allows the organic chelator-promoter-active center to be intimate interaction in a single molecule, thus achieving atomic-scale Co-W proximity on the precursor. In the subsequent sulfidation process, CA delayed the reduction temperature of cobalt species, enabling more Co promoter to be anchored at the edge sites of WS2 clusters to form abundant CoWS active phases, which fully exerted the bimetallic intimate synergism in the HDS reaction. Furthermore, the carbon deposits generated from CA carbonation acted as secondary support weakening the interaction of active metals with Al2O3 support and increasing the sulfidation degree as well as the dispersion of active metals. As a result, the S-Co(CA)W/Al2O3 catalyst achieves a remarkable turnover frequencies (TOF) value of 1.24 × 10-3 s−1 in HDS reaction of dibenzothiophene (DBT). This dual anchoring method based on POMs inorganic ligand and organic chelator ligand provides a new idea for designing novel HDS catalysts.

Vanished evaporites, halokinetic structure, and Zn-Pb mineralization in the world-class Angouran deposit, northwestern Iran

The Angouran deposit (19.3 Mt at 23.4% Zn and 4% Pb) is the second-largest Zn-Pb deposit in Iran. The deposit is hosted in a Neoproterozoic−Cambrian marble-schist sequence within a breccia pipe in a domal structure, with sulfide mineralization under low-temperature hydrothermal conditions (&amp;lt;200 ºC). The features of the ore-hosting breccias are similar to known halokinetic diapir breccias in the world but evaporite minerals are subtle. The common types of breccia clasts in the Angouran breccia pipe include a matrix-supported angular clast (float breccia) with highly variable sizes and orientations and exotic volcanic clasts. The volcanic clasts were derived from the underlying Miocene volcanic rocks, evidenced by the consistent petrography and zircon U-Pb ages dated at 20−19 Ma. Abundant smithsonite pseudomorphs after anhydrite and anhydrite inclusions within sphalerite and pre-ore marcasite in the breccia matrix indicate that the breccia pipe contains abundant anhydrite prior to the Zn-Pb mineralization. The enrichment of evaporite is also supported by the occurrence of considerable double-terminated quartz crystals that contain spherical and tabular carbonate inclusions and anomalously high Li, Na, and K concentrations, relatively high B concentration, and high δ18O values (up to 28.3‰). These observations suggest the Angouran deposit formed in a former halokinetic diapir breccia pipe. The halokinetic diapirism was possibly triggered by thrust loading of the marble-schist sequence over the Miocene evaporite beds during the Arabia-Eurasia continental collision. Halokinetic structures elsewhere in the Angouran region warrant this consideration. Most of the evaporite minerals in the breccia pipe were dissolved and replaced before and/or during subsequent Zn-Pb sulfide and smithsonite mineralization events. This study provides a good example for the identification of vanished evaporites, halokinetic structure, and associated Mississippi Valley-type mineralization.

Interface ion-exchange strategy of MXene@FeIn2S4 hetero-structure for super sodium ion half/full batteries

Herein, a well-designed hierarchical architecture of bimetallic transition sulfide FeIn2S4 nanoparticles anchoring on the Ti3C2 MXene flakes has been prepared by cation exchange and subsequent high-temperature sulfidation processes. The introduction of MXene substrate with excellent conductivity not only accelerates the migration rate of Na+ to achieve fast reaction dynamics but provides abundant deposition sites for the FeIn2S4 nanoparticles. In addition, this hierarchical structure of MXene@FeIn2S4 can effectively restrain the accumulation of MXene to guarantee the maximized exposure of redox active sites into the electrolyte, and simultaneously relieve the volume expansion in the repeated discharging/charging processes. The MXene@FeIn2S4 displays outstanding rate capability (448.2 mAh g−1 at 5 A g−1) and stable long cycling performance (428.1 mAh g−1 at 2 A g−1 after 200 cycles). Moreover, the Nay-In6S7 phase detected by ex-situ XRD and XPS characterization may be regarded as a “buffer” to maintain the stability of the Fe-based components and enhance the reversibility of the electrochemical reaction. This work confirms the practicability of constructing the hierarchical structure bimetallic sulfides with the promising electrochemical performance.

Synthesis of prussian blue analogue derived porous Mo2C/Co9S8/N-doped carbon composite for electrochemical hydrogen storage application

The Prussian blue analogue Co3[Co(CN)6]2 (Co-CoPBA) nanoparticles with three-dimensional cubic structure and uniform size were prepared via precipitation method. Using Co-CoPBA as the precursor, the porous Co9S8/N-doped carbon (Co9S8–CN) nanostructure was formed after heat treatment and sulfidation processes. To further improve the electrocatalytic activity of the composite, Mo2C was introduced within the porous Co9S8–CN. The Mo2C/Co9S8–CN materials containing different contents of Mo2C were prepared via high-temperature calcination and subsequent sulfidation. Ultimately, for electrochemical hydrogen storage, the porous Co9S8–CN exhibited higher discharge capacity than conventional Co9S8 prepared by hydrothermal method. The special porous structure and large specific surface area derived from Co-CoPBA provided more electrochemical active sites. The conductivity of Co9S8 was enhanced due to the existence of N-doped carbon. Additionally, the electrochemical performance further enhanced owing to the excellent electrocatalytic activity of the embedded Mo2C species. The Mo2C/Co9S8–CN2 electrode showed an optimum discharge capacity of 647.4 mAh/g. Moreover, the high-rate dischargeability (HRD), corrosion resistance and kinetic properties were also improved after Mo2C loading. Consequently, Mo2C/Co9S8–CN can be used as a potential electrochemical hydrogen storage material.

Construction of 3D interconnected NiCo2S4/bio-carbon coated Ni foam as binder-free electrode for high-performance supercapacitor

Although transition metal hydroxides/sulfides are considered as promising potential electrode materials for supercapacitors due to their excellent electrochemical activity, the low electrical conductivity, easy agglomeration of nanomaterials and poor rate performance seriously hinder their practical applications. Herein, we construct 3D interconnected binder-free electrode NiCo2S4/bio-carbon coated nickel foam (NiCo2S4/GRCNF) by growing NiCo2S4 nanosheets on the surface of low-cost and highly conductive GRCNF substrate via a simple hydrothermal reaction followed with subsequent sulfidation. As suggested by systematic characterizations, the advantages of obtained NiCo2S4/GRCNF include that the ultrathin 3D interconnected network of NiCo2S4 can furnish massive electrochemically active sites for faradic reaction, and the highly conductive GRCNF substrate promotes electron transfer and meanwhile prevents the aggregation of NiCo2S4 nanosheets. With a high specific capacitance of 7.71 F cm−2 at 3 mA cm−2, NiCo2S4/GRCNF has a huge application advantage over the contrast samples Ni-Co LDH/NF (3.29 F cm−2) and Ni-Co LDH/GRCNF (5.97 F cm−2). In addition, NiCo2S4/GRCNF shows a much higher rate performance (82.1%) than Ni-Co LDH/NF (44.5%) and Ni-Co LDH/GRCNF (66.4%). Furthermore, hybrid supercapacitor NiCo2S4/GRCNF//GNPC which is assembled with NiCo2S4/GRCNF as the anode possesses an impressive energy density of 0.429 mWh cm−2 at a power density of 7.023 mW cm−2 and good cycling stability (82.3% over 5000 cycles). The outstanding electrochemical performance of NiCo2S4/GRCNF suggests that the reported strategy provides new inspiration for the design and preparation of new binder-free composite electrodes for electrochemical energy storage.

Recovered cobalt-nickel sulfide from spent lithium-ion batteries as an advanced anode material toward sodium-ion batteries

Explosive growth of the electric vehicle market has led to a substantial accumulation of spent lithium-ion batteries (LIBs), causing significant environmental pollution and the wastage of precious metal resources. Thus, we developed a simple hydrothermal method to convert the spent LiNi0.8Co0.1Mn0.1O2 (NMC-811) cathode into CoNi-MOF. After the subsequent sulfidation process, waxberry-like Co0.11Ni0.89S@N-doped carbon composites (Co0.11Ni0.89S@NC), as a bimetallic sulfide solid solution, can be successfully synthesized to serve as high-performance anode materials for sodium-ion batteries (SIBs). The waxberry-like structure and strong S-C bonds between the carbon matrix and transition metal sulfides ensure the structural stability of the material during the cycle. Besides, the coexistence of Co and Ni in the bimetallic sulfide solid solution generates abundant lattice defects and modifies the electronic structures that significantly improve the charge transfer ability and Na+ diffusivity. The as-prepared Co0.11Ni0.89S@NC exhibits a high specific capacity of 622 mAh g−1 at 200 mA g−1, outstanding rate capacity of 370 mAh g−1 at 5000 mA g−1 and good cycling stability (330 mAh g−1 after 1500 cycles at 5000 mA g−1). This study presents a promising approach for the recycling of spent LIBs into high-performance anodes for SIBs, thus achieving the transformation of waste into valuable resources.