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[Display omitted] • Heterostructures of the three-dimensional spindle shape were successfully synthesized. • Bimetallic sulfides driven by topological sulfidation of bimetallic MOFs. • DFT reveals electronic coupling at the atomic/orbital level. • Heterogeneous interfaces provide efficient electron tuning engineering. Rational design and preparation of a multiphase electrocatalyst for hydrogen evolution reaction (HER) has become a hot research topic, while applicable and pH versatility of vanadium tetrasulfide (VS 4) and heptairon octasulfide (Fe 7 S 8) composites have rarely been reported. Here, the facile topological sulfide self-template sacrifice method using FeV bimetallic MOFs is designed to obtain Fe 7 S 8 coupled with VS 4 heterostructures, enhancing the electron precipitation in the catalysts and attracts electrons to migrate. According to DFT simulations, the electronic coupling at the atomic orbital level and the modulation of interfacial electrons among various interfaces play a crucial role in enhancing the intermediate state process of the hydrogen evolution reaction (HER) across the entire pH range, promoting the optimal d-band centroid value (ε d). Reassuringly, the prepared 3D Fe 7 S 8 /VS 4 electrodes possessed excellent performances of η 10 = 53 mV, η 10 = 135 mV and η 10 = 38 mV in a conventional three-electrode configuration in a 1 M KOH, 1 M Na 2 SO 4 , and 0.5 M H 2 SO 4 , and the stabilized currents can all be maintained for 48 h. This innovative design of in situ heterostructured materials constructed from dual transition metal sulfides provides inspiring ideas for the preparation of all-pH catalysts. [ABSTRACT FROM AUTHOR]

Reference electrodes which demonstrate long-term potential stability are essential for many continuous monitoring applications and are commonly based on Ag‖AgCl electrodes; however, these electrodes are susceptible to poisoning from aqueous sulphide species which are commonly present in wastewater and natural groundwater. This work presents a sulphide resistant solid-state reference electrode (SSRE) based on a composite material using suspended KCl electrolyte and sacrificial AgCl in a cross-linked polyvinyl acetate polymer matrix. Sulphidation of the sacrificial AgCl produces a stable Ag2S precipitate and prevents further ingress of the poisoning sulphide species through the composite material. A novel SSRE using this material is compared to a control SSRE without suspended AgCl and a typical liquid filled reference electrode. These three reference electrodes are studied using electrochemical impedance spectroscopy (EIS), and their application is also studied in potentiometric pH sensing and cyclic voltammetry (CV). The long-term sulphide resistance of the two SSREs is also studied with potentiometry, and cross-sections of these electrodes were examined using micro X-ray fluorescence (μXRF). Both SSREs demonstrated higher impedance than the liquid reference electrode but were similar to other SSREs reported in the literature. This impedance did not result a meaningful difference in potentiometric pH sensing or CV experiments done using typical scan rates. The KCl/AgCl SSRE exhibited remarkable sulphide resistance, with all samples demonstrating a stable potential without maintenance after ca. 120 days of continuous immersion in 1 g L−1 Na2S solution, whereas KCl SSRE samples all demonstrated significant drift before this time. μXRF sulphur maps revealed that suspended AgCl prevented sulphide ingress, thus protecting the embedded Ag‖AgCl electrode. This work presents a reference electrode that could enable long-term monitoring in challenging sulphide solutions, and also highlights a novel approach for preventing reference electrode poisoning which could be more widely explored. [ABSTRACT FROM AUTHOR]

Australia has large reserves of limonite and clay-based laterites that are currently underutilized. This review summarizes the latest nickel laterite upgrading studies reported in the literature which use physical beneficiation – only studies reported after the most recent review in 2015 included – as well as high-temperature methods involving oxidation/reduction roasting (with and without additives), sulphidation, and other high-temperature methods. The focus of this review is on upgrading limonite ores, but studies using other types of laterites are also discussed for comparative purposes. Oxidative roasting has proven to be ineffective but producing a magnetic phase by reduction roasting then magnetically separating it from gangue minerals has produced nickel grades and recoveries of up to 14% and 99% respectively with limonite ores. The choice of reductant has negligible effect although hydrogen reduction is predicted to occur at slightly lower temperatures and recoveries are slightly lower compared with carbon-based reductants. The addition of sulfurous compounds improves agglomeration of ferronickel particles, increases the nickel grade and recovery. The highest recovery of 97.91% (grade 13.62%) was reported when sulfur was used as an additive during the roasting of a limonite ore with coal and limestone at 1400°C for 6 h. The results show reduction roasting followed by magnetic separation is effective for upgrading nickel ores, but challenges with this technology are the potentially high reagent usage and temperatures required. The economic feasibility for processing limonite ores via this route is not clear and should be investigated further. [ABSTRACT FROM AUTHOR]

As a kind of anode material with high theoretical sodium storage capacity for sodium-ion batteries (SIBs), MoS2 has been widely studied. However, its low conductivity and large volume change hamper its application in SIBs. Herein, MoS2 microspheres were first synthesized through the sulfidation of molybdenyl acetylacetonate via a solvothermal method and then successfully covered with a few layers of MXene nanosheets using the electrostatic assembly method. The ratio of MoS2 to MXene was also investigated. The obtained MXene@MoS2 composite has a large specific surface area due to its porous and non-stacked structure, which benefits the enhancement of ion and electron diffusion kinetics in SIBs. Therefore, the MXene@MoS2 composite has a specific capacity of 257.8 mA h g−1 after 1000 cycles at a current density of 1 A g−1 with a capacity retention of 95.7% and excellent rate performance (220.8 mA h g−1 at 5 A g−1). [ABSTRACT FROM AUTHOR]

Various green materials like biochar and Fe0 (nano-scale zerovalent iron, nZVI) have been applied to remediate aqueous Cr(VI) contamination, but few studies have tried to further improve the performance of nZVI and/or biochar composites with different sulfidation methods. Here, we modified a hybrid material of nZVI@biochar with Na2S and pyrite (FeS2), applied it to remove aqueous Cr(VI) under different experimental conditions, and revealed key factors influencing Cr(VI) removal performance. The results show that pyrite loading is an effective sulfidation method to increase the Fe and S contents in composites. FeSx-nZVI@BC (1:1) had a Cr(VI) removal efficiency of ~95% with 5 mg/L Cr(VI) loaded, which was much higher than other hybrid composites. The Cr(VI) removal efficiency of FeSx-nZVI@BC showed a decreasing trend under pH conditions that increased from pH 3 to pH 9. The presence of dissolved oxygen and aqueous Cu2+ and Cd2+ could significantly suppress the removal of aqueous Cr(VI), while humic acids at different concentrations did not suppress Cr(VI) removal. After the reaction, it was observed with an energy-dispersive spectrometer (SEM-EDS) that most Cr in the solid phase was closely associated with pyrite minerals. X-ray photoelectron spectroscopy (XPS) spectra, together with the Fe2+-quenching method, confirmed that Fe (Fe2+ or Fe0) acted as the main electron donor, contributing to ~90% of the Cr(VI) reduction. Our study indicates that pyrite loading could further improve the performance of remediation materials and that the pyrite-loaded nZVI@BC composite is a green material with strong potential to be applied in the remediation of water contaminated by Cr(VI). [ABSTRACT FROM AUTHOR]

In this work, the binder-free Fe-doped cobalt LDH/nickel foam (CoFe LDH/NF) electrode was prepared using the hydrothermal method. To achieve higher electrocatalyst activity of CoFe LDH/NF, sulfurization was conducted using the hydrothermal method, while the phosphidation was performed through a chemical vapor deposition (CVD) technique. The CoFeS/NF and CoFeP/NF electrodes exhibited significantly higher electrocatalytic activity than CoFe LDH/NF electrode. The CoFeP/NF electrode with a specific surface area of 6.8 m2 g−1 had lower overpotentials of 120 and 236 mV for hydrogen (HER) and oxygen (OER) evolution reactions, respectively. Additionally, the CoFeP/NF electrode exhibited a low potential of 1.32 V vs. RHE at a current density of 10 mA cm−2 for urea oxidation reaction (UOR). The CoFeP/NF electrode demonstrated low overpotentials of 224 and 273 mV in a seawater solution for HER and OER, respectively. The density functional theory (DFT) calculations confirmed the experimental results in which the CoFeP/NF material had promising electrocatalytic activity for renewable energy applications. • CoFe LDH/nickel foam electrode was sulfurized and phosphorized for water splitting. • Sheet-like morphology of CoFeP and CoFeS materials was similar to CoFe LDH. • CoFeP/NF showed higher water splitting performance than the CoFeS/NF electrode. [ABSTRACT FROM AUTHOR]

The Huangjindong gold deposit in northeastern Hunan is one of the most representative gold deposits in the Jiangnan Orogenic Belt. The orebodies are mainly hosted in the Neoproterozoic Lengjiaxi Group, which comprises carbonaceous slates. Abundant carbonaceous material (CM) can be found in the host rocks and ore-bearing quartz veins, but its geological characteristics and genesis, as well as its association with gold mineralization, are still unclear. Systematic petrographic observation demonstrated two types of CM in host rocks and ores, i.e., CM1 and CM2. Among them, CM1 is the predominant type and mainly occurs in the layered carbonaceous slates, while CM2 is mostly present in quartz veins and mineralized host rocks. Laser Raman spectroscopic analyses of CM1 were performed at higher temperatures (376–504 °C), and CM2 was generated at similar temperatures (255–435 °C) to gold mineralization. Combined with previous studies, we can conclude that CM1 was produced by Neoproterozoic to early Paleozoic metamorphism before gold mineralization, while CM2 is of hydrothermal origin. Geochemical modeling indicates that CM1 could promote gold precipitation through reduction, as well as facilitate structure deformation and metal absorption as previously proposed. However, hydrothermal CM2 is favorable for gold mineralization because it triggers sulfidation, similar to other Fe-bearing minerals (such as siderite) in the host rocks. Consequently, both types of CM in the Huangjindong deposit are favorable for gold mineralization and carbonaceous slates could be important gold-bearing units for future ore prospecting in the Jiangnan Orogen as well as other places in South China. [ABSTRACT FROM AUTHOR]

Self-doped CuS nanoparticles (NPs) were successfully synthesized via microwave-assisted polyol process to act as co-catalysts to TiO2 nanofiber (NF)-based photoanodes to achieve higher photocurrents on visible light-assisted water electrolysis. The strategy adopted to perform the copper cation sulfidation in polyol allowed us to overcome the challenges associated with the copper cation reactivity and particle size control. The impregnation of the CuS NPs on TiO2 NFs synthesized via hydrothermal corrosion of a metallic Ti support resulted in composites with increased visible and near-infrared light absorption compared to the pristine support. This allows an improved overall efficiency of water oxidation (and consequently hydrogen generation at the Pt counter electrode) in passive electrolyte (pH = 7) even at 0 V bias. These low-cost and easy-to-achieve composite materials represent a promising alternative to those involving highly toxic co-catalysts. [ABSTRACT FROM AUTHOR]

Ternary metal sulfides having layered morphology are considered as potential active materials for various applications. Herein, Nb3VS6 is synthesized topochemically for the first time using a Nb–V–HDA complex having a lamellar structure by employing H2S gas as the sulfidation agent. Nb3VS6, as an anode for SIBs, exhibited a specific capacity of 101.15 mA h g−1 at 0.5 A g−1, along with excellent cycling stability with 100% capacity retention after 2500 cycles. [ABSTRACT FROM AUTHOR]

The microstructure and composition of the scales formed are examined after being exposed to atmosphere containing 2.0% SO2 + 5.0% O2 for 60 min in the temperature range of 900–1200 °C. The composition of the scale post‐oxidation primarily varies with temperature rather than silicon content. FeS exhibits a melting temperature of 950 °C, whereas FeSi2O4 melts at 1150 °C. Two mechanisms for FeS formation are proposed. Eutectoid transformation of molten FeS occurs during subsequent cooling, resulting in lamellar FeS + Fe–S–O compounds. Above 1150 °C, the melt of Fe2SiO4 further increases the Fe diffusion rate. This dual‐liquefaction mechanism involving FeS and Fe2SiO4 accounts for the anomalous oxidative mass gain observed in Fe–Si alloys exposed to a sulfur‐containing atmosphere. [ABSTRACT FROM AUTHOR]

Inorganic semiconductor gas sensors, being widely utilized in gas‐sensing applications, face significant challenges in attaining mechanical flexibility and humidity resistance in wearable sensing fields. Herein, a highly flexible, breathable, and hydrophobic all‐inorganic self‐supporting nanofiber (NF) gas sensor is developed using electrospinning combined with thermal sulfidation approach. This innovative sensor features a bilayer configuration, with an amorphous SiO2 nanofiber substrate layer and an interwoven SiO2 and SnO2–SnS2 nanofiber active layer. The relatively low elastic modulus of the amorphous SiO2 nanofibers, combined with the three‐dimensional network interwoven structure, endow the SnO2–SnS2–SiO2/SiO2 sensor with superior mechanical flexibility. The sensor exhibits excellent sensitivity, selectivity, moisture resistance, and cycling stability (>10 000 cycles at 140° bending) to both high and low concentration NO2. Notably, an excellent flexible detecting capability of the sensor to NO2, an asthma‐related biomarker, is demonstrated at ultralow concentrations (≈25 ppb) in simulated exhaled breath environments. The enhanced moisture resistance is attributed to the effective inhibition of hydrogen bond formation from H2O molecules by the Sn─S bonds formed through sulfidation of SnO2 nanofibers. This work represents a substantial advancement in the universal fabrication of flexible, breathable and moisture‐resistant inorganic semiconductor sensors for wearable breath sensing applications. [ABSTRACT FROM AUTHOR]

Sedimentological and rock magnetic analysis was performed on 67 turbidite samples recovered from Lithostratigraphic units I–III at IODP Site U1520 with the aim to characterise the sedimentary processes and post-depositional diagenesis within a Quaternary sequence in the Hikurangi Trough, New Zealand. Lithostratigraphic Unit I was rapidly emplaced with frequent turbidite deposition with high sedimentation rate (∼1.9 m/kyr). In contrast, in units II–III, the turbidites were finer grained and more thinly bedded, and were deposited at less than half the deposition rate of Unit I. The turbidites were classified into three clusters based on the magnetic properties. Clusters 1 and 2 are characterised by a high coercivity and SIRM/χ, but low to moderate Bcr/Bc. The recognition of gyroremanent magnetisation acquisition in their clusters indicates the diagenetic sulfidization. Cluster 3 was represented by low coercivity and SIRM/χ, but high Bcr/Bc, indicating lack of sulfidization. Restricted occurrence of Cluster 3 in Unit I may be ascribed to the high sedimentation rate, which prevents sulfidization at the sulfate–methane transition zone. Degree of sulfidization might be related with sedimentary features of turbidites in the trough, such as grain size, bed thickness and depositional rate. [ABSTRACT FROM AUTHOR]

Intermediate sulfidation epithermal deposits represent significant reservoirs of precious metals, playing a crucial role in global mining operations. The Anatolian Peninsula, predominantly characterized by relatively young (Tertiary) lithologies, hosts numerous occurrences of epithermal base and precious metal mineralization. Within the realm of research in Northeastern Anatolia, several hydrothermal alteration zones have emerged as indicators of concealed epithermal mineralization, with the Bahçecik mineralization standing out as a recent focal point. The Bahçecik mineralization represents an intermediate sulfidation epithermal Au-Ag system, hosted by Late Cretaceous andesitic rocks, as well as Eocene dacitic lava and tuffs. Employing U-Pb LA-ICP-MS zircon dating of the dacitic host rocks, the mineralization is estimated to have occurred during the Lutetian epoch (43.61 ± 0.35 Ma) or later. The genesis of the Bahçecik deposit is believed to be linked to postcollisional regional extensional tectonics, primarily controlling its structural arrangement. Comprising pyrite, chalcopyrite, low-Fe sphalerite, galena, tetrahedrite/tennantite, enargite-luzonite, and gold-silver minerals, the deposit is accompanied by prominent gangue minerals such as Mn- and Ca-carbonates, quartz, and barite. Microprobe measurements have identified a majority of Au-Ag minerals (krennerite, buckhornite, and nagyagite) closely associated with sulphide minerals. Fluid inclusion data reveal that mineralization and fluid transportation occurred at temperatures ranging from 153 to 327°C, with solutions exhibiting salinity levels consistent with those of intermediate sulfidation deposits (1.7–7.3 wt.% NaCl). This study unequivocally classifies the Bahçecik mineralization as an intermediate sulfidation deposit, contrary to the conclusions drawn in previous research. Moreover, our investigation has unveiled the presence of a substantial ore resource, totalling 7.84 million tons, featuring 1.76 g/t Au and 2.24 g/t Ag. As an intermediate-type deposit, it shares characteristics with other subtypes within the epithermal class, bridging the realms of both high and low sulfidation systems. [ABSTRACT FROM AUTHOR]

Nano zero-valent iron (nZVI) and sulfidation-modified nZVI (S-nZVI) were synthesized and used to remove hexavalent chromium (Cr(VI)) in wastewater. Characterization of the products showed that the sulfidation process significantly changed the morphology of nZVI, with enhanced crystallinity. The effects of S/Fe ratio, pH value, and reaction temperature on Cr(VI) removal were studied. A S/Fe ratio of 0.5 was the most appropriate parameter, with a removal efficiency of 98% in the condition of pH = 2. The effects of anions (Cl−, NO3−, CO32−, and SO42−) and cations (Ca2+ and Mg2+) on the Cr(VI) removal efficiency were investigated, and the relevant mechanisms were discussed. The Cr(VI) removal efficiency of S-nZVI was significantly greater than that of nZVI, mainly owing to the existence of FeS layers that could protect Fe0 cores and prompt electron transfer. The aging and cycling experiments showed that S-nZVI could maintain its reactivity when facing the corrosion of water, and showed cycling stability. Thus, S-nZVI is an effective and feasible agent for the remediation of Cr(VI)-contained wastewater.

The mechanism of interaction between ZnO and Sb2S3 in the temperature range of 500-700°С was studied. The methods of differential thermal analysis, X-ray diffraction, diffuse reflectance spectroscopy and IR transmission spectroscopy, as well as thermodynamic calculations established the exchangeable acid-base reaction mechanism with the removal of the most volatile of the products – Sb2O3. The final and only product of interaction in the system is ZnS of cubic modification (sphalerite) without phase impurities. Condensate mainly contains Antimony oxides of various compositions. In the same way, it is possible to remove oxygen-containing impurities (mainly ZnO) from zinc sulfide obtained by the method of self-propagating high-temperature synthesis.

The development of lithium–sulfur (Li─S) batteries has been hampered by the shuttling effect of lithium polysulfides (LiPSs). An effective method to address this issue is to use an electrocatalyst to accelerate the catalytic conversion of LiPSs. In this study, heterogeneous MnP‐MnO2 nanoparticles are uniformly synthesized and embedded in porous carbon (MnP‐MnO2/C) as core catalysts to improve the reaction kinetics of LiPSs. In situ characterization and density functional theory (DFT) calculations confirm that the MnP‐MnO2 heterostructure undergo surface sulfidation during the charge/discharge process, forming the MnS2 phase. Surface sulfidation of the MnP‐MnO2 heterostructure catalyst significantly accelerated the SRR and Li2S activation, effectively inhibiting the LiPSs shuttling effect. Consequently, the MnP‐MnO2/C@S cathode achieves outstanding rate performance (10 C, 500 mAh g−1) and ultrahigh cycling stability (0.017% decay rate per cycle for 2000 cycles at 5 C). A pouch cell with MnP‐MnO2/C@S cathode delivers a high energy density of 429 Wh kg−1. This study may provide a new approach to investigating the surface sulfidation of electrocatalysts, which is valuable for advancing high‐energy‐density Li−S batteries. [ABSTRACT FROM AUTHOR]

Sulphidation of nZVI (S-nZVI) has shown to significantly improve the arsenic removal capacity of nZVI, concurrently modifying the sequestration mechanism. However, to better apply S-nZVI for groundwater arsenic remediation, the impact of groundwater coexisting ions on the efficacy of arsenic uptake by S-nZVI needs to be investigated. This present study evaluates the potential of S-nZVI to remove arsenic in the presence of typical groundwater coexisting ions such as Cl−, HA, HCO3−, PO43− and SO42− through batch adsorption experiments. Individually, PO43− and HA had a dominant inhibition effect, while SO42− promoted As(III) removal by S-nZVI. Conversely, for As(V) removal, HCO3− and SO42− impeded the removal process. X-ray spectroscopic investigation suggests that the coexisting ions can either compete with arsenic for the adsorption sites, influence the S-nZVI corrosion rates and/or generate distinct corrosion products, thereby interfering with arsenic removal by S-nZVI. To investigate the cumulative effects of these ions, a 25–1 Fractional Factorial Design of experiments was employed, wherein the concentration of all the ions were varied simultaneously in an optimized manner, and their impact on arsenic removal by S-nZVI was observed. Our results shows that when these ions are present concurrently, PO43−, SO42− and HA still exerted a dominant influence on As(III) removal, whereas HCO3− was the main ions affecting As(V) removal, although the combined influence of the ions was not merely a summation of their individual effects. Overall, the finding of our study might provide valuable insight for predicting the actual performance of S-nZVI in field-scale applications for the remediation of arsenic-contaminated groundwater. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) landfills are a significant source of methane (CH4) emissions in the United States, contributing to global warming. Current landfill gas (LFG) management methods, like the landfill cover system and LFG collection system, do not entirely prevent LFG release. Biocovers have the potential to reduce CH4 emissions through microbial oxidation. However, LFG also contains carbon dioxide (CO2) and trace hydrogen sulfide (H2S) depending on waste composition, temperature, moisture content, and age of waste. An innovative biogeochemical cover (BGCC) was developed to tackle these concerns. This cover comprises a biochar-based biocover layer overlaid with a basic oxygen furnace (BOF) steel slag layer. The biochar-based biocover layer oxidizes CH4 emissions, while the BOF slag layer reduces CO2 and H2S through carbonation and sulfidation reaction mechanisms. The BGCC system's field performance remains unexamined. Therefore, a large-scale tank setup simulating near-field conditions was developed to evaluate the BGCC system's ability to mitigate CH4, CO2, and H2S from LFG simultaneously. Synthetic LFG was passed through the BGCC in five distinct phases, each designed to simulate the varying gas compositions and flux rates typical of MSW landfill. Gas profiles along the depth were monitored during each phase, and gas removal efficiency was measured. After testing, biocover and BOF slag samples were extracted to analyze physico-chemical properties. Batch tests were also conducted on samples extracted from the biocover and BOF slag layers to determine potential CH4 oxidation rates and residual CO2 sequestration capacity. The results showed that the BGCC system's CH4 removal efficiency decreased with higher CH4 flux rates, achieving its highest removal (74.7–79.7%) at moderate influx rates (23.9–25.5 g CH4/m2-day) and reducing to its lowest removal (27.4%) at the highest influx rate (57.5 g CH4/m2-day). Complete H2S removal occurred during Phase 3 in the biocover layer of BGCC system. CH4 oxidation rates were highest near the upper (277.9 µg CH4/g-day) and lowest in the deeper region of the biocover layer. In the tank experiment, CO2 breakthrough occurred after 156 days due to drying of the BOF slag layer, with an average residual carbonation capacity of 46 gCO2/kg slag after moisture adjustment. Overall, the BGCC system effectively mitigated LFG emissions, including CH4, CO2, and H2S, at moderate flux rates, showing promise as a comprehensive solution for LFG management. [ABSTRACT FROM AUTHOR]

Two accretionary sediment sequences from Sites 1245 and 1252 recovered during Ocean Drilling Program (ODP) Leg 204 at southern Hydrate Ridge were investigated to explore the response of geochemical partitioning of iron and sulfur isotopic composition of authigenic pyrite to non-steady-state depositional and diagenetic scenarios. Five iron species were characterized by a modified sequential extraction procedure that covers almost all iron-bearing minerals in sediment cores, including: (1) iron-bearing carbonates, mainly siderite; (2) ferric (hydr)oxides, probably ferrihydrite and/or lepidocrocite; (3) magnetite; (4) iron-bearing silicates; and (5) pyrite. Highly reactive iron has been accumulated for a long-term steady-state history and its pyritization, to varying degrees, is limited by availability of dissolved sulfide. This causes pyrite and siderite occurred in the same sedimentary layer and shows an inverse relationship between their concentrations. From this, their proportions to highly reactive iron can be chosen for evaluating the degree of sulfidization. A significant change in sulfur isotopic composition of pyrite (-42.4 to +16.8‰ VCDT) indicates that the steady-state conditions are dramatically limited, where the d34S values higher than -20‰ may result from an upward shift of SMT zone close to the seafloor or a sudden, massive depositional event. To explain the downcore sulfidization effects and pyrite d34S values, we developed two categories of conceptual scenarios based on variations in sedimentation rate and methane flux. The geochemical features similar to those derived from each scenario were searched in the sediment columns and the non-steady-state events behind the scenarios were proved to be consistent with the real observations. Thus, iron species and pyrite d34S values can be regarded as a proxy to differentiate different non-steady-state depositional and diagenetic controls on the sedimentary record. [ABSTRACT FROM AUTHOR]

The characteristics and hazards of acid coal mine drainage (ACMD) were introduced, and the treatment methods of ACMD were described. Techniques that could be used for source prevention and process containment were analyzed. The widely used terminal treatment technologies at present were summarized, such as the active treatment technology based on neutralization, sulfidation, adsorption and membrane technology, and the passive treatment technology based on chemical, biological and chemical-biological combined method. It was summarized and concluded that the multi-technology combination process was the main trend of engineering application and an effective way for large-scale collaborative treatment of ACMD. Finally, the development prospect of ACMD treatment method was prospected. [ABSTRACT FROM AUTHOR]

The recycling and recovery of value-added secondary raw materials such as spent Zn/C batteries is crucial to reduce the environmental impact of wastes and to achieve cost-effective and sustainable processing technologies. The aim of this work is to fabricate reduced graphene oxide (rGO)-based sorbents with a desulfurization capability using recycled graphite from spent Zn/C batteries as raw material. Recycled graphite was obtained from a black mass recovered from the dismantling of spent batteries by a hydrometallurgical process. Graphene oxide (GO) obtained by the Tour's method was comparable to that obtained from pure graphite. rGO-based sorbents were prepared by doping obtained GO with NiO and ZnO precursors by a hydrothermal route with a final annealing step. Recycled graphite along with the obtained GO, intermediate (rGO-NiO-ZnO) and final composites (rGO-NiO-ZnO-400) were characterized by Wavelength Dispersive X-ray Fluorescence (WDXRF) and X-ray diffraction (XRD) that corroborated the removal of metal impurities from the starting material as well as the presence of NiO- and ZnO-doped reduced graphene oxide. The performance of the prepared composites was evaluated by sulfidation tests under different conditions. The results revealed that the proposed rGO-NiO-ZnO composite present a desulfurization capability similar to that of commercial sorbents which constitutes a competitive alternative to syngas cleaning. [ABSTRACT FROM AUTHOR]

Cerussite is an essential lead oxide mineral with increasing economic importance as lead sulfide resources deplete. This study utilizes density functional theory (DFT) to investigate the structural and electronic properties of the sulfurized cerussite (110) surface. The results show that when the cerussite crystal cleaves along the (110) plane, only the surface layer atoms undergo relaxation to reconstruct the surface, while the atoms located deeper have almost no impact on the reconstructed surface structure. The Pb atoms on the cerussite (110) surface react with the sulfurizing agent to form a PbS deposition layer with a structure similar to galena. This PbS deposition layer is tightly adsorbed onto the lead oxide layer through Pb-S bonds formed by S and subsurface lead oxide structure Pb atoms. The chemical reactivity of Pb atoms in the PbS layer on the sulfurized cerussite (110) surface is more potent than that of Pb atoms on the galena surface; additionally, the Pb atoms closer to the lead oxide layer exhibit slightly higher chemical reactivity than those farther away. This study provides insight into sulfurized cerussite surfaces' structure and properties at an atomic level and assists in explaining the floating behavior of cerussite. [ABSTRACT FROM AUTHOR]

Triethanolamine (TEA) is a promising eco-friendly alternative to inorganic ammonia for enhancing surface sulfidization and flotation recovery of smithsonite. Micro-flotation experiments revealed an enhancement in smithsonite recovery to 95.21% with TEA modification, comparable to the results obtained using ammonia. The mechanisms behind the ability of TEA to enhance the sulfidization process were investigated through surface analysis and molecular dynamics simulations. TEA modification increased the content of sulfidization products, the proportion of crucial S22− in adsorbed products, and the thickness and size of the sulfidization product layer. The complexation of TEA with Zn sites formed positively charged Zn–TEA complexes that adsorb onto the smithsonite surface. These complexes promoted negatively charged HS− adsorption, creating a multi-layered adsorption structure. Moreover, TEA modification reduced the total energy required for the sulfidization. These findings open up new possibilities for using eco-friendly reagents in mineral processing, highlighting the potential of TEA in green mineral processing practices. [ABSTRACT FROM AUTHOR]

High‐entropy alloys (HEAs) are promising new materials considered for application in high temperature environments. In this work, the sulfidation behavior of an Al–Co–Cr–Ni–Si HEA at different elevated temperatures and various sulfur vapor partial pressures is investigated. Thermogravimetric studies indicate that the sulfidation kinetics are in accordance with the parabolic rate law. The corrosion rate has a strong temperature dependence, whereas the influence of sulfur vapor pressure is practically nonexistent. Changes in temperature also do not seem to affect the sulfidation mechanism as evidenced by the Arrhenius correlation determined between the obtained parabolic rate constants and temperature. Combined SEM–EDS and XRD studies reveal the formation of a thick multilayer scale on the studied alloy, where the outermost relatively compact part is built of Co0.5NiS2 and CrAl2S4 while the inner, rather porous part also contains metallic inclusions, including Si near the scale/substrate interface. [ABSTRACT FROM AUTHOR]

Zhengminghuaite, ideally Cu6Fe3As4S12, is a new Cu-Fe arsenosulfosalt found in the Zimudang Carlin-type gold deposit in southwestern Guizhou, China. It occurs as irregular, commonly fractured grains of several to a few tens of micrometers in the brecciated gold ores and is paragenetically associated with the late ore-stage mineral assemblage, including realgar, orpiment, pyrite, chalcopyrite, arsenopyrite, aktashite, christite, quartz, and calcite. Zhengminghuaite is opaque with a metallic luster and a conchoidal or uneven fracture. The Vickers microhardness (VHN10) is 219 kg/mm2 (range 192–247 kg/mm2), and the calculated density is 4.77(5) g/cm3. In reflected light, zhengminghuaite is whitish gray with weak bireflectance (whitish gray to pinkish tinted gray), very weak anisotropy, and no internal reflection. Electron microprobe analyses give the empirical formula (Cu5.92Hg0.08)Σ6.00 (Fe1.59Hg1.07Zn0.37)Σ3.03(As3.94Sb0.02)Σ3.96S11.93 on the basis of total cations = 13, with the simplified formula Cu6(Fe,Hg,Zn)3(As,Sb)4S12. Zhengminghuaite is trigonal, with space group R3. Unit-cell parameters determined from the single-crystal X-ray diffraction data are as follows: a = 13.5373(17) Å, c = 9.2354(13) Å, and V = 1465.7(4) Å3 (Z = 3). The eight strongest lines in the X-ray diffraction pattern are [d (Å) (I, %) (hkl)]: 3.0785 (67) (003), 3.0670 (100) (1 3 1), 2.6586 (89) (1 3 2), 1.8825 (97) (134), 1.8773 (82) (520), 1.6060 (89) (13 5), 1.6028 (81) (523), and 1.6012 (83) (26 1). The crystal structure of zhengminghuaite belongs to the nowackiite group and can be described as formed by (0001) layers composed of corner-sharing FeS4 and CuS4 tetrahedra that delimit two triangular cavities. Zhengminghuaite is the Fe-dominant analog at the divalent cations site of nowackiite (Cu6Zn3As4S12) and aktashite (Cu6Hg3As4S12). Paragenetic relationships indicate that zhengminghuaite and associated Hg- and Tl-sulfosalts precipitated in response to the increase in sulfidation state and decrease in temperature of the late-ore stage hydrothermal fluid. [ABSTRACT FROM AUTHOR]

Tailoring the morphological features of nanomaterials is of great importance for varied applications in energy storage, environment remediation etc. but is hampered by different parameters. Herein, a novel step by step synthesis approach is reported to elucidate different morphology of MoS2 heterostructures. A solvothermal method is employed to synthesize molybdenum glycerate (MoG) solid spheres (SS) followed by subsequent sulphidation. Continuous sulphidation of 3 hours and 8 hours produces flowers and ball-in-ball MoS2 heterostructures respectively. FESEM micrographs show the formation of MoG SS and different MoS2 heterostructures. XRD, Raman and UV measurements confirm the phase transition from 2H (semiconductor) to 1T (metallic) phase in 8 hours sulphidated ball-in-ball heterostructure. The formation of ball-in-ball morphology is attributed to the Kirkendall effect. The findings could potentially be extended to the idea of phase transitions and their applications. [ABSTRACT FROM AUTHOR]

The lanthanum sulfide γ-La 2 S 3 with cubic Th 3 P 4 structure has emerged as a promising long-wave infrared transparent material. However, the γ-La 2 S 3 is only stable at high temperatures (>1300 °C). In this work, a novel method to lower the stabilization temperature is reported. Bivalent Ba ions are incorporated into the La 2 S 3 crystal structure and the stabilization temperature of the γ-La 2 S 3 decreased to less than 850 °C. The Ba2+-doped γ-La 2 S 3 (γ-La 2 S 3 : Ba2+) was successfully developed using the coprecipitation reaction method and sulfidation with CS 2. The high phase purity, good thermal stability, and lowest oxide sulfide impurities were obtained by Ba/La = 0.1 (in mole, abbreviated as n Ba/La = 0.1). The first-principles calculation shows that the theoretical E g of the prepared γ-La 2 S 3 : Ba2+ was 2.94 eV, which matched well with the experimental data. The energy band structure and density of states of the synthesized γ-La 2 S 3 : Ba2+ powder indicated that it was an indirect semiconductor which could be employed as a raw material for preparing infrared transparent optical ceramics. [ABSTRACT FROM AUTHOR]

Thioethers are critical in the fields of pharmaceuticals and organic synthesis, but most of the methods for synthesis alkyl thioethers employ foul-smelling thiols as starting materials or generate them as by-products. Additionally, most thiols are air-sensitive and are easily oxidized to produce disulfides under atmospheric conditions; thus, a novel method for synthesizing thioethers is necessary. This paper reports a simple, effective, green method for synthesizing dialkyl or alkyl aryl thioether derivatives using odorless, stable, low-cost ROCS2K as a thiol surrogate. This transformation offers a broad substrate scope and good functional group tolerance with excellent selectivity. The reaction likely proceeds via xanthate intermediates, which can be readily generated via the nucleophilic substitution of alkyl halides or aryl halides with ROCS2K under transition-metal-free and base-free conditions. [ABSTRACT FROM AUTHOR]

The present case study involves a thorough and methodical metallurgical analysis of a failed water wall tube to identify sulfidation corrosion as the cause of failure. The investigation into the failure of the water wall tube was conducted through various methods, including visual observation, chemical analysis, examinations using optical and scanning electron microscopy, fractography and surface analysis via SEM–EDS, x-ray diffraction analysis of deposits and reaction products, and evaluation of mechanical properties. The water wall tube exhibited failure in the form of an elliptical puncture, with no significant thinning at the location of the puncture. The chemical composition, mechanical properties, and microstructure of the failed water wall tube were in accordance with the specified standards for SA 210 grade C steel. The microstructure of the tube consisted of a ferrite–pearlite structure and showed no anomalies related to microstructure. The experimental results revealed that the tube failed due to sulfidation corrosion on its outer surface. This sulfidation reaction was initiated by sulfur from pyrite (FeS2) in the coal-ash deposits on the outer surface. Moreover, the buildup of ash deposits caused localized overheating, which accelerated the sulfidation reaction, followed by an oxidation reaction. [ABSTRACT FROM AUTHOR]

Sulfidation and naphthenic acid corrosion are well-known damage mechanisms, hence, there are many ways to deal with them. These mechanisms are common in refineries and petrochemical industry due to the treatment of sour crude oils. The industrial manager usually takes advantages from the use of sour crude oils from an economic point of view, but at the same time he/she has to cope with sulfidation and naphthenic acid corrosion because of their implication on safety. A recent study, which is based on the use of a bayesian network for the management of the previous mentioned corrosion mechanisms and the dynamic updating of the Residual Useful Lifetime (RUL), has been improved. The new approach integrates the estimated RUL in the risk evaluation, giving a dynamic update of the position of the equipment in the risk matrix by introducing the performance coefficients (KPI - Key Performance Indicators) belonging to the Asset Integrity. The approach has been applied to the pre-heating section of an atmospheric distillation unit of the Milazzo Refinery. The parameters that have been taken into consideration are the material metallurgy, the characteristics of feedstock, the temperature and the number of inspections carried out during a reference period. An attempt has been made to link the approach to the integrity operating windows (IOW), which have been already implemented in a homemade software by the I&T department of the refinery. [ABSTRACT FROM AUTHOR]

The Val-d'Or vein field (VVF), located in the southern Abitibi subprovince (Québec, Canada), is host to ~ 47 Moz gold and is therefore an example of a greenstone-hosted orogenic gold district. Gold is contained in quartz-tourmaline-carbonate veins that cut As-poor intermediate to mafic volcanic and intrusive rocks, including dioritic, granodioritic and gabbroic sills, dikes, stocks, and plutons. Five investigated orebodies (Goldex, Triangle, Plug #4, Pascalis Gold Trend, Beaufor) host gold in vein- and wallrock-hosted pyrite-rich sulfide aggregates (> 95 vol%) that show a porous core domain (Py1), with abundant inclusions of carbonate, silicate, and Fe-oxides up to several tens of µm in size. A homogeneous pyrite rim domain (Py2) surrounds Py1 and contains most of the gold as native gold and polymetallic (Au-Ag-Te-Bi) inclusions, primarily calaverite and petzite. The two pyrites show different Au and As contents (Py1 = Au ≤ 30 ppm; As ≤ 67 ppm; Py2 = Au ≤ 1250 ppm; As ≤ 550 ppm). Pyrite shows a ubiquitous shift in δ34S values of up to + 3.0‰ from Py1 (δ34S = − 0.4‰ to 5.8‰, n = 32) to Py2 (δ34S = 0.0‰ to 6.3‰, n = 59) and records a small, slightly negative Δ33S signature between – 0.20‰ and 0.01‰. The δ34S shift suggests that removal of reduced sulfur species from auriferous hydrothermal fluids causes the formation of inclusion-hosted gold in Py2 by a decrease in the fluid sulfur fugacity (fS2) through wallrock sulfidation of Fe-oxides. The shift also correlates with locally enriched Co and Ni concentrations in Py1 (< 1 wt%), compared to lower, oscillatory zoned concentrations (< 0.1 wt%) in Py2, respectively, indicating an overall decrease in fluid oxygen fugacity (fO2). Contemporaneously, a decrease in fluid tellurium fugacity (fTe2) drives polymetallic inclusion-hosted gold formation in Py2, initially as calaverite followed by increasingly Ag-bearing petzite and hessite. The multiple sulfur isotopes and trace element compositions recorded in pyrite in the VVF indicate that a homogeneous fluid reservoir introduced gold-sulfide complexes. Even if considered a localized process at the ore-shoot scale, fluid-wallrock sulfidation reactions can lead to a coupled decrease in fS2, fO2, and fTe2 of auriferous hydrothermal fluids in a greenstone-hosted As-poor gold district. [ABSTRACT FROM AUTHOR]

Heterojunction structures improve the intrinsic activity of electrocatalysts by enhancing the charge transfer between the catalyst and the electrode. In this paper, the NiS/FeS2 heterostructured electrocatalyst is fabricated by a simple sulfidation method using an interface engineering strategy to adjust the surface electron density of the electrocatalyst. As expected, NiS/FeS2 electrocatalyst exhibits superior activity and durable oxygen evolution reaction (OER) stability, requiring only a low overpotential of 183 mV to achieve a current density of 10 mA·cm−2 and can be stable for more than 80 h, superior to NiS, FeS2 electrocatalyst individually, and precious RuO2. Notably, NiS/FeS2 is also a good bifunctional electrocatalyst with good overall water splitting performance, and it only requires a voltage 1.56 V to obtain a current density of 10 mA·cm−2 for more than 12 h. Remarkably, the NiS/FeS2 hybridization facilitates the formation of coral-like structures, increasing the electrochemical surface area (ECSA) and enhancing the charge transfer efficiency, thus leading to excellent electrocatalytic performance. This work proposes a constructive strategy for designing efficient electrocatalysts based on interface engineering, and lays a foundation for designing a new class of electrocatalysts. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) still confront the challenges of capacity fading and inferior fast‐charging capability for sodium storage. The rational design of heterostructures enables a new approach to conquer these drawbacks. In this work, a hierarchical structure consisting of SnS2 nanosheets and FeS2 microrods with triphasic heterostructures is proposed by the facile secondary growth and sulfidation process. The introduction of tin sources regulates the proportion of pyrite and marcasite phases, thereby achieving the triphasic heterostructures comprising pyrite, marcasite FeS2, and SnS2. When served as anode material for sodium‐ion batteries, the optimized sample exhibits a high reversible capacity (901 mAh g−1) and durable cycling performances (827 mAh g−1 after 200 cycles at 1 A g−1 and 742 mAh g−1 after 700 cycles at 5 A g−1). Paring with the commercial Na3V2(PO3)3 cathodes, the full‐cell also delivers extraordinary cyclic stability with a high capacity of 618 mAh g−1 (based on the weight of anode material) after 200 cycles at 1 A g−1 (98.7% capacity retention). The hierarchical structure with adjustably triphasic heterogeneous interfaces alleviates the volumetric expansion and interfacial passivation of active material, while modulating the energy band structure and inducing the build‐in electric fields to boost Na+/electrons transport rate. [ABSTRACT FROM AUTHOR]

Sulphidation of a CuNi alloy of Cu : Ni ratio 81 : 19 led to an exponential activity enhancement in the alkaline methanol oxidation reaction (MOR) by four fold due to an order of magnitude increase in the number of active Cu and Ni sites and improved charge transfer properties. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) are increasingly being used in medical, electronic, energy, and agricultural applications due to their unique properties that often arise due to the high surface area-to-volume ratio. However, this characteristic along with the high reactivity of NPs make these materials highly dynamic in environmental settings. Thus, several transformations can take place when these materials enter the environment that determines their transport, toxicity, and fate of them in our environment. These transformations, and more specifically oxidative dissolution and sulfidation, are directly impacted by the characteristics that a NP has in addition to the surrounding environmental conditions. Therefore, this review aims to summarize how NP characteristics (size, coatings, etc.) and other important environmentally relevant conditions (oxic/anoxic waters, natural organic matter, etc.) impact the oxidative dissolution and sulfidation of several metal and metal oxide NPs. The impact of these factors is crucial to understanding and predicting the environmental risks of these materials in a wide range of applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous lamellar GO/Ni 2 ZnS 4 @NiCo 2 S 4 was prepared using simple ZIF-8@ZIF-9 templating method. • The core–shell structure of graphene trimetallic sulfides was synthesized for the first time. • GO/Ni 2 ZnS 4 @NiCo 2 S 4 inherits the high specific surface area of the ZIF template and the high pseudocapacitance of the sulfide. • High specific capacity of 2284F/g were achieved at the current density of 1 A/g. Metal-organic frameworks (MOFs) have emerged as promising active electrode materials in supercapacitors for its controllable porous structure and excellent physio-chemical properties. However, the poor conductivities keep it from achieving its full capacitance potential, which greatly limits its practical application. Here, a facile pathway is reported to fabricate the GO/Ni 2 ZnS 4 @NiCo 2 S 4 composite with large specific surface area and favorable electrical conductivity. Thanks to the novel tremella-like core–shell structure and high-efficient synergistic effects among multi-components, the designed GO/Ni 2 ZnS 4 @NiCo 2 S 4 electrode shows a high specific capacitance of 2284 F/g at 1 A/g. Furthermore, the asymmetric supercapacitor fabricated by coupling GO/Ni 2 ZnS 4 @NiCo 2 S 4 positive electrode with biological carbon negative electrode achieves a remarkable energy density of 120 Wh kg−1 at a power density of 750 W kg−1. [ABSTRACT FROM AUTHOR]

The heavy metals present in the sludge can undergo a reaction with sulfur, leading to their conversion into metal sulfides through hydrothermal sulfidation. Sulfur ions, possessing a strong sulfidation capability, can operate within a wider pH range at elevated temperatures. The high temperature environment promotes the sulfidation process of zinc within heavy metal-laden sludge. Increasing the temperature of microwave hydrothermal sulfidation and extending the sulfidation duration for heavy metal-containing sludge can enhance the growth of crystal size in the artificially synthesized zinc sulfide. Zinc sulfide predominantly takes the form of ZnS, which facilitates the subsequent flotation recovery of zinc. [ABSTRACT FROM AUTHOR]

The Evevpenta ore occurrence is situated in the northeastern part of the Central Kamchatka volcanic belt (Kamchatka Peninsula, Russia), and lies among andesitic volcanic complexes of the Neogene age. The ore bodies are veins, zones of quartz streaks, and hydrothermal breccias, accompanied by aureoles of argillization which transition into propylites at the periphery. The formation of noble-metal mineralization occurred through two phases: the hypogene (hydrothermal) phase and the hypergene phase. For the hypogene phase we have identified two mineral associations related to noble-metal mineralization: the Central area contains gold—telluride–quartz mineralization, while the Northern area hosts telluride–sulfide–quartz mineralization. The hypergene mineral association with native gold occurs within the Central area only. Based on data relating to the material composition of the ores we show that the Evevpenta ore occurrence is a typical member of epithermal reduction-alkaline or low sulfidation deposits. [ABSTRACT FROM AUTHOR]

High sulphidation (HS) mineralization and associated advanced argillic alteration have been intersected by three drill holes below the Grasberg porphyry Cu-Au deposit, known as the Gajah Tidur prospect. The prospect is located between 1,500-2,750 m level, in Grasberg District, Papua, Indonesia. The holes are of KL98-10-21, KL98-10-22, and GRD39-08 which intersected 3.4 Ma Gajah Tidur monzonite, Grasberg Igneous Complex, the wall rocks of Kembelangan, and New Guinea Limestone Group. This research aims to determine the characteristics of high sulphidation mineralization associated with advanced argillic alteration at Gajah Tidur. Petrographic, XRD, SEM, fluid inclusion, and XRF (geochemical) analyses were applied to identify the mineralogy, geochemistry, and ore fluid properties. The major element plots show a differentiated intrusion. The alteration consists of potassic materials composed of biotite and K-feldspar, overprinted by phyllic and advanced argillic ones typified by alunite, pyrophyllite, and kaolinite. The high sulphidation mineralization characterized by pyrite-covellite, chalcopyrite-chalcocite, enargite, and digenite is also present. Fluid inclusion homogenization temperature of mineralized quartz vein ranges from 393 to 542°C, indicating a magmatic fluid origin predominantly. Two distinct porphyry systems, consisting of the Gajah Tidur Cu-Mo and the Main Grasberg Cu-Au porphyry systems are emplaced at the Gajah Tidur level. Advanced argillic is less intense compared to a pervasive phyllic alteration, overprinting the stockwork and surrounding rocks, emplaced at the upper part of quartz stockwork. It is possibly associated with a late stage of Gajah Tidur porphyry hydrothermal fluids which became cooler and highly acidic. Similar to other porphyry systems such as Oyu Tolgoi in Mongolia, the Gajah Tidur porphyry did not have its hydrothermal fluid ascent to the surface to form lithocap. Instead, the ascending fluids cooled at shallower depths resulting in the formation of advanced argillic alteration. [ABSTRACT FROM AUTHOR]

The mechanism of interaction between ZnO and Sb2S3 in the temperature range of 500-700°С was studied. The methods of differential thermal analysis, X-ray diffraction, diffuse reflectance spectroscopy and IR transmission spectroscopy, as well as thermodynamic calculations established the exchangeable acid-base reaction mechanism with the removal of the most volatile of the products – Sb2O3. The final and only product of interaction in the system is ZnS of cubic modification (sphalerite) without phase impurities. Condensate mainly contains Antimony oxides of various compositions. In the same way, it is possible to remove oxygen-containing impurities (mainly ZnO) from zinc sulfide obtained by the method of self-propagating high-temperature synthesis. [ABSTRACT FROM AUTHOR]

This paper presents tests related to the reactivity of commercial Hi-Fuel sorbent toward H2S (H2S/N2 mixture) in a packed bed at 300 °C. The sorbent used for breakthrough test was characterized before and after test by ESEM-EDX, FTIR-ATR, Raman, and elemental analyses. Testing reveals that the commercial sorbent contains two compounds reacting with H2S: ZnO and ZnCO3. According to thermodynamical studies, the reactivity of ZnCO3 at 300 °C is privileged (KR = 9.5 × 108) than ZnO (KR = 6.6× 106). In addition, the reaction of H2S with ZnCO3 induces a volume decrease, which promotes the movement of gas through the newly formed layer. The properties of this sorbent thus hold a good potential for the desulfurization process of gases polluted with H2S. We observed that the maximum sulfidation rate was reached on the surface of the sorbent and showed a maximum conversion of 27%. [ABSTRACT FROM AUTHOR]

For the emerging Sb2(S,Se)3 solar cells, most high‐efficiency devices employ a standard structure based on the heterojunction of weak n‐type Sb2(S,Se)3 and heavily n‐doped cadmium sulfide (CdS), and the sunlight is incident from the n‐type CdS side in either superstrate or substrate structure. The weak carrier extraction ability of the n–n heterojunction as well as the parasitic absorption and toxicity from CdS further limit the efficiency improvement and practical applications. Herein, for the first time, a strategy of treating manganese sulfide (MnS) with thioacetamide to enhance its p‐type conductivity is demonstrated, and a solar cell with inverted structure is constructed by forming a heterojunction with n‐type Sb2(S,Se)3. This inverted structure well overcomes the light absorption loss and toxicity elements in the standard structure. This post‐treatment effectively passivates the sulfur vacancy defects of MnS and in turn enables greater band bending in the heterojunctions for suppressed nonradiative recombination. Ultimately, the hole extraction ability of MnS shows essential improvement and enables a power conversion efficiency of 5.22% for the inverted Sb2(S,Se)3 solar cell. This study provides a proof‐of‐concept device structure for the preparation of high‐efficiency Sb2(S,Se)3 solar cells and offers new perspectives to achieve effective intrinsic doping of metal chalcogenides. [ABSTRACT FROM AUTHOR]

The development of cost-effective and highly efficient bifunctional catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media plays a crucial role in advancing renewable energy conversion technologies. In this study, we successfully constructed a three-dimensional (3D) composite on nickel foam (NF) by coupling NiFe-LDH nanosheets with NiCoS nanoparticles decorated NiCo-LDH nanosheets, resulting in a NiCo-LDH@NiCoS@NiFe-LDH hierarchical heterostructure. The resulting composite exhibits abundant heterogeneous interfaces and a well-defined nanosheet array structure, allowing for numerous exposed surface active sites and open channels. The strong synergistic effect among its various components allows the heterogeneous structure to effectively optimize the electronic structures of the metal active sites. Consequently, the NiCo-LDH@NiCoS@NiFe-LDH composite demonstrated remarkable catalytic activity towards OER, achieving current densities of 50 and 100 mA cm−2 at overpotentials as low as 209 and 224 mV, respectively. This result manifests a substantial improvement over recently developed electrocatalysts based on earth-abundant elements. Additionally, the NiCo-LDH@NiCoS@NiFe-LDH composite can efficiently catalyze HER in an alkaline medium, with a low overpotential of 93 mV at 10 mA cm−2 in 1 M KOH solution. Moreover, the electrolytic cell utilizing NiCo-LDH@NiCoS@NiFe-LDH as the electrodes could realize overall water splitting with an ultralow cell voltage of 1.55 V at 10 mA cm−2, and excellent electrochemical stability. These findings underscore the potential for developing high-performance bifunctional electrocatalysts with significant implications for large-scale commercial applications of renewable energy technologies. • A 3D hierarchical heterostructure of NiCo-LDH@NiCoS@NiFe-LDH was constructed on NF. • The composite shows well-defined nanosheet array structure with rich heterointerface. • It delivers an efficient bifunctional electrocatalyst for OER and HER in 1 M KOH. • Overall water splitting requires an ultralow cell voltage of 1.55 V at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Loss of copper minerals in the tailings of the rougher and scavenger circuits poses a significant challenge in copper processing plants, diminishing the circuit's efficiency. Part I of this paper identified the causes of copper mineral loss in the scavenger circuit tailings of the Sungun copper concentration plant, situated in northwestern Iran. Changes in feed composition, particularly the ratio of copper oxide to sulfide minerals, along with alterations in the mineralogical properties of the input feed to the scavenger circuit, emerged as pivotal factors contributing to the loss of copper minerals into the tailings. In line with these findings, the objective of the present paper (part II) is to optimize the scavenger circuit by proposing a solution to mitigate the loss of copper minerals to the tailings. Samples were collected from the feed, concentrate, and final tailings, as well as from each cell of the scavenger circuit, followed by comminution and flotation tests on each sample. The results indicate that redirecting the scavenger circuit tailings to the input of the rougher cells, owing to their higher copper grade compared to the tailings of the rougher circuit, can enhance the circuit's recovery by more than 4%. Additionally, employing a combination of sulfide and oxide collectors, along with sulfidation to float the copper oxide minerals in the scavenger circuit, resulted in an overall recovery increase exceeding 11%. Furthermore, adjusting the size of the air bubbles to capture fine copper mineral particles from the scavenger circuit cells proved to be an effective strategy for boosting recovery. Moreover, modifying the grinding circuit to liberate the minerals present in the scavenger circuit feed, predominantly the concentrate of the scavenger circuit itself, led to a recovery increase of approximately 5%. Considering the mineralogical characteristics of the scavenger circuit feed, derived from the tailings of the cleaner cells, implementing changes in the operating conditions of the cleaner circuit—such as employing hybrid bubbles (Nano and coarse bubbles) and utilizing sulfide and oxide collectors—significantly impacted the recovery of fine copper mineral particles and copper oxide minerals to the cleaner concentrate, thereby enhancing the scavenger circuit's performance. [ABSTRACT FROM AUTHOR]

Hemimorphite is important-supplementary resource for the commercial zinc production, but it easy loses into tailings due to extreme difficulty for its surface sulfidization. Adding active metal ions after sulfidization have been widely proposed for enhancing hemimorphite floatability, but its desired efficiency in flotation practice has not yet been completely achieved caused by the instability of sulfide layer. Whereas pre-adsorption of active metal ions to modify the hemimorphite surface has strong potential to make up for this shortcoming. Herein, the feasibility and appropriate environment of free Pb2+ for modifying the pure hemimorphite surface was evaluated. Subsequently, the performance of Pb2+ adsorption for enhancing sulfidization stability and floatability of hemimorphite were investigated. The X-ray photoelectron spectroscopy results indicated that the Pb2+ adsorption on hemimorphite surface was achieved through the Pb ions displacement for Zn ions, and it was bond to oxygen-containing groups on hemimorphite surface. Such adsorption was strengthened with the increasing of solution pH, owing to the abundant Pb hydroxyl species precipitated on mineral under alkaline conditions, in term of the results of visual MINTEQ modeling and time-of-flight secondary-ion mass spectrometry. In addition, the X-ray photoelectron spectroscopy results showed dominant Pb hydroxyl species further reacted with sulfur during subsequent sulfidization to generate much more S species than that of without Pb2+ pre-modification. Meanwhile, such sulfide layer composed by Pb2+ on the mineral surface presented much higher stability than Zn-S species, which was verified via adsorption and desorption tests. As a result, the sulfidization and flotation recovery of hemimorphite increased after Pb2+ pre-adsorption. [ABSTRACT FROM AUTHOR]

Various green materials like biochar and Fe0 (nano-scale zerovalent iron, nZVI) have been applied to remediate aqueous Cr(VI) contamination, but few studies have tried to further improve the performance of nZVI and/or biochar composites with different sulfidation methods. Here, we modified a hybrid material of nZVI@biochar with Na2S and pyrite (FeS2), applied it to remove aqueous Cr(VI) under different experimental conditions, and revealed key factors influencing Cr(VI) removal performance. The results show that pyrite loading is an effective sulfidation method to increase the Fe and S contents in composites. FeSx-nZVI@BC (1:1) had a Cr(VI) removal efficiency of ~95% with 5 mg/L Cr(VI) loaded, which was much higher than other hybrid composites. The Cr(VI) removal efficiency of FeSx-nZVI@BC showed a decreasing trend under pH conditions that increased from pH 3 to pH 9. The presence of dissolved oxygen and aqueous Cu2+ and Cd2+ could significantly suppress the removal of aqueous Cr(VI), while humic acids at different concentrations did not suppress Cr(VI) removal. After the reaction, it was observed with an energy-dispersive spectrometer (SEM-EDS) that most Cr in the solid phase was closely associated with pyrite minerals. X-ray photoelectron spectroscopy (XPS) spectra, together with the Fe2+-quenching method, confirmed that Fe (Fe2+ or Fe0) acted as the main electron donor, contributing to ~90% of the Cr(VI) reduction. Our study indicates that pyrite loading could further improve the performance of remediation materials and that the pyrite-loaded nZVI@BC composite is a green material with strong potential to be applied in the remediation of water contaminated by Cr(VI).

Due to its large capacity and relatively high conductivity, cobalt sulfide has been considered an excellent electrode material for lithium-ion batteries, but its extreme volume change during charging and discharging and lower conductivity than graphite limits its development. In this work, composite nanosheets of MXene and N-doped carbon-confined cobalt sulfide nanosheets (CoS@NC/MXene) were synthesized by growing the Co metal–organic framework of ZIF-67 onto MXene sheets, followed by sulfidation treatment. Different from normal ZIF-67 generally prepared in methanol, this work fabricates ZIF-67 in aqueous solution, which induces ZIF-67 to undergo some degree of hydrolysis and form more dispersed Co layered hydroxides mounted onto MXene. Also, the MXene incorporation imparts better water stability to ZIF-67(Co) and helps maintain its morphology during the sulfidation. CoS@NC/MXene has a conductive network supported by MXene and enhanced by NC, as well as a 3D hierarchical porous structure offered by the rational combination of its components. These favorable characteristics allow CoS@NC/MXene to deliver a capacity of 691 mA h g−1 at 200 mA g−1 in the 100th cycle and retain the specific capacity of 382 mA h g−1 at a higher current density of 8000 mA g−1. [ABSTRACT FROM AUTHOR]