Natural Molybdenite Research Articles

Enhanced visible light photo-Fenton catalysis by Fe-doping oligo-layer natural molybdenite with efficient carrier spatial-driven Fe3+/Fe2+ cycle.

Developing cost-effective and efficient photo-Fenton catalysts is crucial for advancing photo-Fenton technology. MoS2 is a representative transition metal disulfide with attractive photoresponsiveness, making it ideal for preparing composite photo-Fenton catalysts. In this study, natural molybdenite was innovatively utilized as a source of MoS2 (OM) to synthesize a low-cost and efficient Fe@MoS2 (OMF) composite photo-Fenton catalyst by comminution and adsorption, which was then applied to the remediation of antibiotic-contaminated water. The OMF composites exhibited significant catalytic activity, with a kinetic rate constant of 0.022 min-1, which was 3.1 times higher than that of the original OM (0.007 min-1), indicating a 3% increase. This was attributed to the synergistic effect of many photogenerated electrons and reversible Mo4+/Mo6+ redox pairs, which accelerated the regeneration of Fe2+. After three cyclic tests, the concentrations of dissolved Fe2+ and Mo2+ ions remained below 0.38 mg/L and 0.17 mg/L, respectively. This indicates the high reusability of the catalyst in cyclic experiments. Ultimately, the main active species, •OH and •O2 -, were generated during the photo-Fenton process, contributing significantly to TC degradation. This study may serve as a reference for the development and application of natural mineral composite photo-Fenton catalysts in the treatment of organic wastewater.

In situ precise determination of stable Mo isotope ratios in molybdenite by femtosecond LA-MC-ICP-MS

We developed a new method for in situ measurement of Mo stable isotope ratios using femtosecond laser ablation coupled with MC-ICP-MS. Additionally, experiments were conducted on nine natural molybdenite samples from different ore deposits in China.

Simultaneous tunable ion and phase hybridization in natural molybdenite for enhancing electromagnetic wave attenuation

Simultaneous tunable ion and phase hybridization in natural molybdenite for enhancing electromagnetic wave attenuation

Interfacial Mo-S-C Bond with High Reversibility for Advanced Alkali-Ion Capacitors: Strategies for High-Throughput Production.

The high-throughput scalable production of low-cost and high-performance electrode materials that work well under high power densities required in industrial application is full of challenges for the large-scale implementation of electrochemical technologies. Here, motivated by theoretical calculation that Mo-S-C heterojunction and sulfur vacancies can reduce the energy band gap, decrease the migration energy barrier, and improve the mechanical stability of MoS2 , the scalable preparation of inexpensive MoS2-x @CN is contrived by employing natural molybdenite as precursor, which is characteristic of high efficiency in synthesis process and energy conservation and the calculated costs are four orders of magnitude lower than MoS2 /C in previous work. More importantly, MoS2- x @CN electrode is endowed with impressive rate capability even at 5 A g-1 , and ultrastable cycling stability during almost 5000 cycles, which far outperform chemosynthesis MoS2 materials. Obtaining the full SIC cell assembled by MoS2- x @CN anode and carbon cathode, the energy/power output is high up to 265.3W h kg-1 at 250W kg-1 . These advantages indicate the huge potentials of the designed MoS2- x @CN and of mineral-based cost-effective and abundant resources as anode materials in high-performance AICs.

Sulfur-vacancy engineering of natural molybdenite for enhanced EMW absorption

The fine processing and functional application of natural minerals are crucial for allowing the comprehensive utilization of natural mineral resources. This paper reports the modification of natural molybdenite: S-vacancies are used to promote the attenuation of electromagnetic waves (EMWs) in molybdenite matrix composites, thus improving the EMW absorption performance of molybdenite. First, S-vacancies are constructed on the base plane of molybdenite (MoS(2-x)) via treatment with NaBH4. The generated S-vacancies are found to change the original electronic layout, reduce the energy gap, and increase the probability of charge transfer within molybdenite. Concomitantly, the introduction of S-vacancies increases the number of active sites for interfacial and defecs polarization in molybdenite. MoS(2-x)-1 shows a higher absorption performance, with a minimum reflection loss (RLmin) of − 34.35 dB (the absorbing layer thickness is 2.1 mm). The attenuation of EMWs by MoS(2-x) is attributed to a dielectric loss mechanism in which the polarization loss is dominant, and the increase in internal charge transfer promotes conductive loss. The findings of this study greatly expand the application scope of pure natural molybdenite and will facilitate the industrial production of high-performance EMW-absorbing materials and improve the comprehensive utilization of mineral resources.

Natural Molybdenite as a High‐Capacity Anode Material for Fast‐Charging Lithium‐Ion Capacitors

Lithium‐ion capacitor (LIC) is a promising energy storage device, which combines double advantages of high‐energy lithium‐ion batteries (LIBs) and high‐power supercapacitors. However, the reported anode materials for LICs are synthesized based on the high‐purity chemicals under complicated and time‐consuming conditions, which exhibit a prohibitive cost in practical application. Herein, natural molybdenite is employed as the precursor to construct a high‐capacity and low‐cost anode material of LICs. Specifically, molybdenite is exfoliated into thin‐layer MoS2 under the interaction of hydrazine hydrate and sodium hydroxide, and then coupled with reduced graphene oxide to form a MoS2@rGO composite. Resulting from high reactive activity and structural stability, the MoS2@rGO anode shows excellent lithium‐ion storage performance including high specific capacity (936 mAh g−1 at 100 mA g−1) and rate capability (446 mAh g−1 at 5000 mA g−1). By using MoS2@rGO as an anode and activated carbon as a cathode, the assembled LIC device provides a maximum energy density of 105 Wh kg−1. Even at a high power density of 25 000 W kg−1, the energy density is still up to 65 Wh kg−1. This work provides a reference for the commercial utilization of natural molybdenum resources in the energy storage field.

Promoting azo dye decomposition in natural molybdenite activated peroxymonosulfate process by low concentration of ferrous ions.

In this study, low concentration of ferrous ions (Fe2+) was added into natural molybdenite (MDN) activated peroxymonosulfate (PMS) process to degrade a typical azo dye, orange G (OG). It was found that the addition of Fe2+ promoted OG degradation and simultaneously reduced the leaching of toxic Mo ions significantly. Further, the utilization efficiency of MDN was improved immensely, which was estimated from reuse experiment. MDN mainly acted as the reductant to promote cycling of Fe3+/Fe2+ redox couple through reducible sulfur and Mo(IV) on its surface. Sulfate radicals (SO4•-), hydroxyl radical (•OH) and singlet oxygen (1O2) were verified as the main reactive oxygen species responsible for OG degradation by scavenging tests and electron paramagnetic resonance. Some experiment parameters, such as MDN dosage, Fe2+ concentration, PMS concentration, initial solution pH and coexisting anion, all affected OG degradation efficiency. In a word, this work provides a new method of enhancing PMS activation by MDN using low concentration of Fe2+ for degradation of organic pollutants in water.

Phase Transformation of 1T′-MoS2 Induced by Electrochemical Prelithiation for Lithium-Ion Storage

Two-dimensional (2D) MoS2 is one of the most representative materials of the transition metal dichalcogenide (TMD) family, which is mostly studied in the semiconductor 2H and metal 1T phases. However, the properties of the metalloid 1T′ phase remain unclear because of its immature preparation process and thermodynamic instability (metastable state). Herein, this study used theoretical calculations to discover the relationship and conditions for MoS2 to transition between the 2H, 1T, and 1T′ phases. Meanwhile, charge and discharge voltages and current density were controlled by ion insertion technology, and then 1T′-MoS2 with large size and definite morphology (the whole process was called “phase transition engineering”) was prepared. The prepared 1T′-MoS2 was used as the anode material for lithium-ion batteries. Compared with 2H-MoS2, the cyclic stability and specific capacity of 1T′-MoS2 were greatly improved. In addition, phase transformation of natural molybdenite (2H-MoS2) by phase transition engineering also yielded promising electrochemical properties. Consequently, phase transition engineering not only provided an opportunity for the phase transformation of TMDs of natural sulfide metals such as molybdenite but also offered an effective method to investigate the properties of 2D metastable polymorphic materials.

Efficient organic contaminant and Cr (VI) synchronous removing by one-step modified molybdenite cathode microbial fuel cells.

As a novel technique with a wide range of applications, microbial fuel cell (MFC) could simultaneously remove organic contaminants and heavy metals in complex wastewater, despite striking differences in physicochemical properties of these contaminant. But its wastewater treatment efficiency is restricted by its lower generation performance. However, approaches for the modification of MFCs' cathode with appropriate catalyst could effectively overcome this limitation. Herein, a new-type efficient cathode catalyst was invented through modifying natural molybdenite via one-step oxidation method. In this case, molybdenite had many changes in morphology (wave-shaped bending, fragmentation and decrescent diameter) during oxidation modification process, and oxidation-modified molybdenite could provide much more active sites for the cathode. After applying this novel cathode catalyst, the electric generation capacity of MFC system increased by 5.08 times, and its simultaneous degradation efficiency of methyl blue (MB) and Cr (VI) increased by 3.35 times (compared with graphite cathode MFC). This study provides a novel low-carbon and environmentally friendly way to prepare high efficiency cathode catalyst materials and provides a new idea of simultaneous purification for organic and metallic pollutants from complex wastewater.

Rational Design of Nature Molybdenite with La2O3 Catalysts for Improved Energy‐Storage Behaviors

AbstractNatural molybdenite (MoS2) displays large interlayer distance and rich electrochemical activities, but suffers from the complex preparation process with serious pollution. MoS2, as the low‐cost resources, have captured numerous attentions as first‐hand energy‐storage materials. However, they are still limited by the shuttling of polysulfide and side reactions. Through the in situ solution deposition and thermochemical methods, molybdenite@La2O3 is successfully prepared with the formation of MoSLa bonds in the interfaces. La2O3, as the important catalyst, is uniformly distributed on the surface of molybdenite, which serves vital roles in the redox reversibility. Owing to the fascinating architecture, the as‐obtained samples deliver a considerable capacity of 803.1 mA h g−1, with high coulombic efficiency of 86.32%. After 500 cycles, the capacity increases up to ≈1200 mA h g−1. Even at 5.0 A g−1, its capacity can be remained ≈550 mA h g−1after 100 cycles. Assisted by the detailed kinetic behaviors, the improved energy‐storage capability mainly comes from the enhancements of pseudocapacitive behaviors. Moreover, benefiting from the detailed resistance analysis, the existing of La2O3 can induce the evolution of redox reactions stability. Thus, the work is expected to provide effective modified strategy for natural molybdenite in energy‐storage systems.

Effective peroxymonosulfate activation by natural molybdenite for enhanced atrazine degradation: Role of sulfur vacancy, degradation pathways and mechanism

In this study, natural molybdenite (MoS2) was applied to activate peroxymonosulfate (PMS) for the removal of atrazine (ATZ) and its degradation mechanism was investigated. Molybdenite exhibits superior catalytic performance. The best condition for atrazine degradation efficiency (>99%) was obtained with molybdenite concentration of 0.4 g/L, PMS concentration of 0.1 mM, and ATZ concentration of 12 μM within 10 min under experimental conditions. Electron paramagnetic resonance (EPR) test and chemical probe test further proved that HO• and SO4•− played important roles in the molybdenite/PMS system, and SO4•− was dominant. Meanwhile, Electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) tests showed that sulfur vacancies and edge sulfur played important roles in the system. Edge sulfur was conducive to Mo4+ exposure, while sulfur vacancy facilitated electron transfer and reduced Mo6+ back to Mo4+. Combined with DFT calculation, the role of sulfur in the degradation process was verified. Besides, five ATZ degradation pathways were proposed. Finally, the degradation ability of the molybdenite/PMS system for different pollutants and in actual water bodies was also explored. This work provided ideas for exploring the degradation of organic contaminants by natural minerals.

Natural ore molybdenite as a high-capacity and cheap anode material for advanced lithium-ion capacitors

Hybrid lithium-ion capacitors (LICs) receive special interests because they work by combining the merits of high-capacity lithium-ion batteries and high-rate capacitors in a Li salt containing electrolyte, so as to bridge the gap between the two devices. One of main challenges for LICs is to develop inexpensive and superior anode materials at high rates. In this work, natural molybdenite was utilized as precursor to achieve the scalable production of cheap MoS2/carbon composites. This molybdenite-derived MoS2/carbon electrode can not only exhibit excellent Li+-storage performances including ultrahigh specific capacity (1427 mAh g–1 after 1000 cycles at 1 A g–1) and rate capability (554 mAh g–1 at 10 A g–1), but also possess four-times higher tap density than that of commercial graphite. By employing MoS2/carbon as the anode and activated carbon as the cathode, the as-assembled LIC device delivers both high energy//high power density and long cycle lifespan. Furthermore, the price is nearly 200 orders of magnitude lower than the traditional high-purity chemicals, which can be easily scaled up to achieve high-throughput production.

Fabrication of TiO2 @MoS2 heterostructures with improved visible light photocatalytic activity

The spread application of Titanium dioxide (TiO2) is severely limited by the rapid recombination of photogenerated electron-hole pairs (e--h+). For many applications, two-dimensional (2D) molybdenum disulfide (MoS2), with large specific surface area and sufficient active sites, has been widely researched as a beneficial support for TiO2 photocatalytic activity enhancement. The synthesized heterostructures, the 2D MoS2 nanosheets loaded with brown TiO2 particles (b-TiO2@MoS2) were manufactured through an ultrasound aided electrochemical exfoliation of natural bulk molybdenite coupled with sol-gel technique at low temperature (180 ºC). SEM, TEM, HRTEM, XRD, XPS, UV–vis absorption, Raman, PL spectra, and photocurrent analysis were used to investigate the morphology, microstructure, composition, and charge separation property of the samples. It was determined that b-TiO2 @MoS2 heterostructures had photocatalytic activity by observing their degradation of butyl xanthate during 120 min of visible light irradiation. Furthermore, the photocatalytic effectiveness of the 1 wt% b-TiO2 @MoS2 heterostructures is 94.80%, with a maximum rate constant (k value) of 0.01764 min−1. In contrast to brown TiO2, the findings indicated that the b-TiO2 @MoS2 heterostructures enhanced visible light absorption, the expansion of active sites, the separation and transfer of photogenerated charges. A probable degradation mechanism of photodegradation butyl xanthate and charge transfer process of b-TiO2 @MoS2 heterostructures under visible light irradiation were also postulated.

Natural Molybdenite- and Tyrosinase-Based Amperometric Catechol Biosensor Using Acridine Orange as a Glue, Anchor, and Stabilizer for the Adsorbed Tyrosinase.

To develop a natural mineral-based electrochemical enzyme biosensor, natural molybdenite (MLN), tyrosinase (TYR), and acridine orange (AO) were coadsorbed onto a glassy carbon electrode (GCE). The developed TYR/AO/MLN-GCE-based amperometric TYR biosensor exhibited excellent performance for highly sensitive determination of catechol (linear range, 0.1–80 μM; sensitivity, 0.0315 μA/μM; LOD, 0.029 μM; response time, <4 s) with good reproducibility and good operational and storage stabilities. The electrochemical impedance spectroscopy (EIS) and quartz crystal microbalance with dissipation (QCM-D) revealed interesting roles of AO: (1) an efficient glue for enhancing the amount of the adsorbed TYR on the MLN-GCE, (2) an anchor for efficient orientation of the adsorbed TYR on the MLN-GCE, and (3) a stabilizer providing a suitable microenvironment for the adsorbed TYR on the MLN-GCE surface. This physical adsorption-based AO-coupled enzyme-modification strategy onto natural MLN would be a versatile strategy to develop cost-effective and environment-friendly natural mineral-based electrochemical biosensors and bioelectronic devices.

High temperature induced S vacancies in natural molybdenite for robust electrocatalytic nitrogen reduction

Defect engineering is an important strategy to regulate electronic structure of electrocatalysts for electrochemical N2 fixation, aiming at improving the electron state density and enhancing the adsorption and activation of inert N2. In this paper, a high-temperature strategy to anneal the natural molybdenite under Ar atmosphere was developed, and the as-obtained molybdenite with S vacancies boosted a high activity for N2 reduction reaction. In 0.1 M HCl, the catalyst annealed at 800 °C exhibits a high Faradic efficiency of 17.9% and a NH3 yield of 23.38 μg h−1 mg-1cat. at −0.35 V versus reversible hydrogen electrode, two times higher than that of the pristine molybdenite. The facile one-step annealing method introduces the defects (e.g., S vacancies) in the surface of the natural molybdenite particles to prepare catalysts for generating ammonia by reducing nitrogen at room temperature under ordinary pressure, promoting the development of low-carbon economic prospect.

Incorporation of incompatible trace elements into molybdenite: Layered PbS precipitates within molybdenite

Abstract Trace elements in molybdenite can provide important information regarding the composition of ore-forming fluid and the evolution and genesis of ore deposits. However, the occurrence states and behavior of relatively incompatible trace elements (e.g., Pb and Os) in natural molybdenite remain ambiguous. Here, we report an abnormally high enrichment of Pb and layered PbS precipitate within molybdenite grains from the Huanglongpu carbonatite-hosted Mo-Pb deposit in the Qinling orogenic belt of Northern China. High-resolution transmission electron microscopy (HRTEM) and related nanobeam techniques were applied to characterize the occurrence states of Pb within molybdenite at the atomic scale. The results show that up to several weight percent of Pb can be incorporated into the molybdenite structure during initial crystallization, which can lead to the formation of screw dislocations and 3R/disordered stacking of S-Mo-S sandwich layers. Observations using a scanning transmission electron microscope also reveal that Pb diffuses from the host molybdenite into the layered PbS precipitates under prolonged electron beam irradiation. Pb-bearing molybdenite tends to transform into a Pb-poor ordered 2H1 polytype upon Pb exsolution during cooling. Pb preferentially exsolves along the (001) plane of molybdenite and is stored in structural defects (e.g., dislocation loops) and grain boundaries, resulting in nano-scale Pb heterogeneities in molybdenite. Further coarsening of the exsolved Pb results in the formation of layered PbS precipitates along the (001) plane of molybdenite. This study provides an example of the consequences of the incorporation and exsolution of incompatible trace elements in molybdenite and demonstrates that careful mineralogical examination is required to interpret geochemical data obtained by in situ analysis techniques.

Activation of peroxymonosulfate by natural molybdenite for dye degradation: Identification of reactive species and catalytic mechanism

In this study, natural molybdenite (MDN) was employed to activate peroxymonosulfate (PMS) to remove organic contaminant orange G (OG). Degradation rate reached up to 100% and 44.4% TOC decayed in the MDN/PMS system within 60 min. The degradation rate increased with the increase of temperature, catalyst and PMS dosages, but initial pH affected little to the system. Moreover, the sensitivity test of coexisting anion and other organic contaminants to the MDN/PMS system was studied to investigated its application in natural water matrix. Through the analysis of electron paramagnetic resonance and quenching experiments, reactive oxygen species including sulfate radicals ( SO 4 ⋅ − ), hydroxyl radical ( ⋅ OH), superoxide radical (O 2 ⋅ − ) and singlet oxygen ( 1 O 2 ) had been proven to account for OG degradation in the MDN/PMS process. Surface-bonded Mo(IV) activated PMS producing radicals and it could be regenerated by the reaction with vicinity sulfur element in MDN. This work not only provided a reference for PMS activation by natural sulfide mineral but also elucidated the activation mechanism. • MDN could active PMS for organic pollutants degradation. • The roles of molybdenum and sulfur species of MDN were investigated. • SO 4 ⋅ − , ⋅ OH, O 2 ⋅ − and 1 O 2 were responsible for the removal of OG in MDN/PMS system. • The activation mechanism of PMS by MDN was proposed.

Construction of 1T@2H MoS2 heterostructures in situ from natural molybdenite with enhanced electrochemical performance for lithium-ion batteries.

Natural molybdenite, an inexpensive and naturally abundant material, can be directly used as an anode material for lithium-ion batteries. However, how to release the intrinsic capacity of natural molybdenite to achieve high rate performance and high capacity is still a challenge. Herein, we introduce an innovative, effective, and one-step approach to preparing a type of heterostructure material containing 1T@2H MoS2 crafted from insertion and expansion of natural molybdenite. The metallic 1T phase formed in situ can significantly improve the electronic conductivity of MoS2. At the same time, 1T@2H MoS2 heterostructures can provide an internal electric field (E-field) to accelerate the migration rate of electrons and ions, promote the charge transfer behaviour, and ensure the reaction reversibility and lithium storage kinetics. Such worm-like 1T@2H MoS2 heterostructures also have a large specific surface area and a large number of defects, which will help shorten the lithium-ion transmission distance and provide more ion transmission channels. As a result, it exhibits a discharge capacity of 788 mA h g−1 remarkably at 100 mA g−1 after 485 cycles and stable cycling performance. It also shows excellent magnification performance of 727 mA h g−1 at 1 A g−1, compared to molybdenite concentrate. Briefly, this work's heterostructure architectures open up a new avenue for applying natural molybdenite in lithium-ion batteries, which has the potential to achieve large-scale commercial applications.

Natural molybdenite mineral enhanced polymeric carbon nitride nano-composites for efficient noble-metal-free photocatalytic hydrogen evolution

Photocatalytic hydrogen evolution reaction (HER) is an ideal strategy to convert solar energy into chemical energy, while the efficiency is suppressed by limited light absorption, charge carrier separation and transfer, and interface reaction. Polymeric carbon nitride (PCN) as a metal-free visible-light photocatalyst has attracted increasing attention. However, expensive noble metal such as Pt nanoparticles are generally needed to co-catalyze HER on PCN and other photocatalysts. Herein, natural molybdenite mineral was introduced for the first time as co-catalyst to construct PCN/molybdenite nano-composites (PCN/Mo-x) by Na2SO4-assisted ball milling, which displayed a favorable noble-metal-free photocatalytic HER rate under visible light. Molybdenite not only replaced Pt co-catalyst to promote the separation efficiency of photo-induced electrons and holes but also enhanced the light absorption, synergistically increasing photocatalytic activities of PCN. The proposed path may pave the way to utilize the cheap minerals as promising candidates for co-catalysts in noble-metal-free photocatalysis on PCN and/or other photocatalysts.

TiO2 anchored on MoS2 nanosheets based on molybdenite exfoliation as an efficient cathode for enhanced Cr (VI) reduction in microbial fuel cell

MoS2 nanosheet-decorated TiO2 nanocomposites were prepared via facile liquid-phase exfoliation of natural molybdenite combined with in situ hydrolysis route. These materials were used as a photocathode for the first time in microbial fuel cell (MFC) to reduce hexavalent chromium (Cr (VI)). Results showed the maximum power density of 1 wt% MoS2/TiO2-based MFC was 3.7 and 1.9 times higher than that of blank graphite and TiO2-based MFC, respectively. This MFC achieved 99.57% removal of Cr (VI) with a concentration of 20 mg L−1 within 8 h under visible light illumination at pH 2 and high degradation rate of 2.49 g m−3 h−1. The introduction of MoS2 nanosheets as a cocatalyst can expand the absorption of visible light, thereby leading to increased electronic participation in Cr (VI) reduction. Moreover, the appropriate amounts of MoS2 nanosheets also contribute to electrons migration and additional active site. The enhanced power output and Cr (VI) reduction efficiency of MFC can be attributed to the synergistic coupling between bioanode and MoS2/TiO2 photocathode. On the basis of its facile and scalable synthetic strategy as well as its stable and outstanding photoelectrocatalytic performance for MFC, this MoS2/TiO2 nanocomposite showed potential in the efficient treatment of wastewater.