MoS2‐Based All‐Purpose Fibrous Electrode and Self‐Powering Energy Fiber for Efficient Energy Harvesting and Storage

Here an all‐purpose fibrous electrode based on MoS₂ is demonstrated, which can be employed for versatile energy harvesting and storage applications. In this coaxial electrode, ultrathin MoS₂ nanofilms are grown on TiO₂ nanoparticles coated carbon fiber. The high electrochemical activity of MoS₂ and good conductivity of carbon fiber synergistically lead to the remarkable performances of this novel composite electrode in fibrous dye‐sensitized solar cells (showing a record‐breaking conversion efficiency of 9.5%) and high‐capacity fibrous supercapacitors. Furthermore, a self‐powering energy fiber is fabricated by combining a fibrous dye‐sensitized solar cell and a fibrous supercapacitor into a single device, showing very fast charging capability (charging in 7 s under AM1.5G solar illumination) and an overall photochemical‐electricity energy conversion efficiency as high as 1.8%. In addition, this wire‐shaped electrode can also be used for fibrous Li‐ion batteries and electrocatalytic hydrogen evolution reactions. These applications indicate that the MoS₂‐based all‐purpose fibrous electrode has great potential for the construction of high‐performance flexible and wearable energy devices.     

Few‐Layer MoS2 Flakes as Active Buffer Layer for Stable Perovskite Solar Cells

Solution‐processed few‐layer MoS₂ flakes are exploited as an active buffer layer in hybrid lead–halide perovskite solar cells (PSCs). Glass/FTO/compact‐TiO₂/mesoporous‐TiO₂/CH₃NH₃PbI₃/MoS₂/Spiro‐OMeTAD/Au solar cells are realized with the MoS₂ flakes having a twofold function, acting both as a protective layer, by preventing the formation of shunt contacts between the perovskite and the Au electrode, and as a hole transport layer from the perovskite to the Spiro‐OMeTAD. As prepared PSC demonstrates a power conversion efficiency (η) of 13.3%, along with a higher lifetime stability over 550 h with respect to reference PSC without MoS₂ (Δη/η = ?7% vs. Δη/η = ?34%). Large‐area PSCs (1.05 cm² active area) are also fabricated to demonstrate the scalability of this approach, achieving η of 11.5%. Our results pave the way toward the implementation of MoS₂ as a material able to boost the shelf life of large‐area perovskite solar cells in view of their commercialization.     

Designing Active and Stable Silicon Photocathodes for Solar Hydrogen Production Using Molybdenum Sulfide Nanomaterials

Silicon is a promising photocathode for tandem photoelectrochemical water splitting devices, but efficient catalysis and long term stability remain key challenges. Here, it is demonstrated that with appropriately engineered interfaces, molybdenum sulfide nanomaterials can provide both corrosion protection and catalytic activity in silicon photocathodes. Using a thin MoS₂ surface protecting layer, MoS₂‐n⁺p Si electrodes that show no loss in performance after 100 h of operation are created. Transmission electron microscopy measurements show the atomic structure of the device surface and reveal the characteristics of the MoS₂ layer that provide both catalytic activity and excellent stability. In spite of a low concentration of exposed catalytically active sites, these electrodes possess the best performance of any precious metal‐free silicon photocathodes with demonstrated long term stability to date. To further improve efficiency, a second molybdenum sulfide nanomaterial, highly catalytically active [Mo₃S₁₃]^2? clusters, is incorporated. These photocathodes offer a promising pathway towards sustainable hydrogen production.     

Ultrastable In‐Plane 1T–2H MoS2 Heterostructures for Enhanced Hydrogen Evolution Reaction

Metallic 1T MoS₂ is highly desirable for catalyzing electrochemical hydrogen production from water owing to its high electrical conductivity. However, stable 1T MoS₂ is difficult to be produced in large‐scale by either common chemical or physical approaches. Here, ultrastable in‐plane 1T–2H MoS₂ heterostructures are achieved via a simple one‐pot annealing treatment of 2H MoS₂ bulk under a mixture gas of Ar and phosphorous vapor, where phosphorus cannot only occupy the interspace of MoS₂ bulk, resulting in the expansion of MoS_2, but also embed into the lattice of MoS_2, inducing the partial phase transition from 2H to 1T phases of MoS₂. Benefiting from its significantly improved electrical conductivity, highly exposed active sites, and hydrophily property, in‐plane 1T–2H MoS₂ heterostructures exhibit largely improved electrocatalytic properties for hydrogen evolution reaction (HER) in alkaline electrolytes.     

Dual‐Functional N Dopants in Edges and Basal Plane of MoS2 Nanosheets Toward Efficient and Durable Hydrogen Evolution

Herein, the authors explicitly reveal the dual‐functions of N dopants in molybdenum disulfide (MoS₂) catalyst through a combined experimental and first‐principles approach. The authors achieve an economical, ecofriendly, and most efficient MoS₂‐based hydrogen evolution reaction (HER) catalyst of N‐doped MoS₂ nanosheets, exhibiting an onset overpotential of 35 mV, an overpotential of 121 mV at 100 mA cm^?2 and a Tafel slope of 41 mV dec^?1. The dual‐functions of N dopants are (1) activating the HER catalytic activity of MoS₂ S‐edge and (2) enhancing the conductivity of MoS₂ basal plane to promote rapid charge transfer. Comprehensive electrochemical measurements prove that both the amount of active HER sites and the conductivity of N‐doped MoS₂ increase as a result of doping N. Systematic first‐principles calculations identify the active HER sites in N‐doped MoS₂ edges and also illustrate the conducting charges spreading over N‐doped basal plane induced by strong Mo 3d –S 2p –N 2p hybridizations at Fermi level. The experimental and theoretical research on the efficient HER catalysis of N‐doped MoS₂ nanosheets possesses great potential for future sustainable hydrogen production via water electrolysis and will stimulate further development on nonmetal‐doped MoS₂ systems to bring about novel high‐performance HER catalysts.     

Biomimetic MXene Textures with Enhanced Light‐to‐Heat Conversion for Solar Steam Generation and Wearable Thermal Management

2D materials are of particular interest in light‐to‐heat conversion, yet challenges remain in developing a facile method to suppress their light reflection. Herein, inspired by the black scales of Bitis rhinoceros, a generalized approach via sequential thermal actuations to construct biomimetic 2D‐material nanocoatings, including Ti₃C₂T_x MXene, reduced graphene oxide (rGO), and molybdenum disulfide (MoS₂) is designed. The hierarchical MXene nanocoatings result in broadband light absorption (up to 93.2%), theoretically validated by optical modeling and simulations, and realize improved light‐to‐heat performance (equilibrium temperature of 65.4 °C under one‐sun illumination). With efficient light‐to‐heat conversion, the bioinspired MXene nanocoatings are next incorporated into solar steam‐generation devices and stretchable solar/electric dual‐heaters. The MXene steam‐generation devices require much lower solar‐thermal material loading (0.32 mg cm^?2) and still guarantee high steam‐generation performance (1.33 kg m^?2 h^?1) compared with other state‐of‐the‐art devices. Additionally, the mechanically deformed MXene structures enable the fabrication of stretchable and wearable heaters dual‐powered by sunlight and electricity, which are reversibly stretched and heated above 100 °C. This simple fabrication process with effective utilization of active materials promises its practical application value for multiple solar–thermal technologies.     

Pseudocapacitive Charge Storage in Thick Composite MoS2 Nanocrystal‐Based Electrodes

A synthesis methodology is demonstrated to produce MoS₂ nanoparticles with an expanded atomic lamellar structure that are ideal for Faradaic‐based capacitive charge storage. While much of the work on MoS₂ focuses on the high capacity conversion reaction, that process is prone to poor reversibility. The pseudocapacitive intercalation‐based charge storage reaction of MoS₂ is investigated, which is extremely fast and highly reversible. A major challenge in the field of pseudocapacitive‐based energy storage is the development of thick electrodes from nanostructured materials that can sustain the fast inherent kinetics of the active nanocrystalline material. Here a composite electrode comprised of a poly(acrylic acid) binder, carbon fibers, and carbon black additives is utilized. These electrodes deliver a specific capacity of 90 mAh g^?1 in less than 20 s and can be cycled 3000 times while retaining over 80% of the original capacity. Quantitative kinetic analysis indicates that over 80% of the charge storage in these MoS₂ nanocrystals is pseudocapacitive. Asymmetric full cell devices utilizing a MoS₂ nanocrystal‐based electrode and an activated carbon electrode achieve a maximum power density of 5.3 kW kg^?1 (with 6 Wh kg^?1 energy density) and a maximum energy density of 37 Wh kg^?1 (with 74 W kg^?1power density).     

Extending the Continuous Operating Lifetime of Perovskite Solar Cells with a Molybdenum Disulfide Hole Extraction Interlayer

Solution‐processed organic–inorganic lead halide perovskite solar cells (PSCs) are considered as one of the most promising photovoltaic technologies thanks to both high performance and low manufacturing cost. However, a key challenge of this technology is the lack of ambient stability over prolonged solar irradiation under continuous operating conditions. In fact, only a few studies (carried out in inert atmosphere) already approach the industrial standards. Here, it is shown how the introduction of MoS₂ flakes as a hole transport interlayer in inverted planar PSCs results in a power conversion efficiency (PCE) of ≈17%, overcoming the one of the standard reference devices. Furthermore, this approach allows the realization of ultrastable PSCs, stressed in ambient conditions and working at continuous maximum power point. In particular, the photovoltaic performances of the proposed PSCs represent the current state‐of‐the‐art in terms of lifetime, retaining 80% of their initial performance after 568 h of continuous stress test, thus approaching the industrial stability standards. Moreover, it is further demonstrated the feasibility of this approach by fabricating large‐area PSCs (0.5 cm² active area) with MoS₂ as the interlayer. These large‐area PSCs show improved performance (i.e., PCE = 13.17%) when compared with the standard devices (PCE = 10.64%).     

Copper and molybdenum absorption by rats given ammonium tetrathiomolybdate

Previous studies have shown that the tetrathiomolybdate ion [MoS_4^2?] is a potent antagonist of Cu metabolism. Effects of orally administered MoS_4^2? on the absorption and tissue distribution of ⁶⁴Cu in rats have now been investigated. Four or 12 mg Mo/kg diet, when given as MoS_4^2?, strongly inhibited ⁶⁴Cu absorption and modified the fate of absorbed Cu, decreasing hepatic and renal uptake but increasing plasma retention of ⁶⁴Cu. These effects were not induced by equivalent dietary concentrations of Mo as MoS_4^2? or when S^2? was given as CaS. Clinical and biochemical effects induced by orally administered MoS_4^2? were abolished by increasing dietary concentrations of Cu. Such treatment also inhibited the absorption and tissue retention of ⁹⁹Mo derived from ⁹⁹MoS_4^2?. Intraperitoneal administration of Cu ameliorated clinical effects attributable to MoS_4^2? but neither inhibited ⁹⁹Mo absorption nor the appearance of systemic defects in Cu metabolism. Since the absorption of MoS_4^2? (or its derivatives) from the gastrointestinal tract is inhibited by Cu, it is evident that the site of its action as an antagonist influencing either the absorption or the subsequent metabolic fate of Cu depends upon the ratio Cu/MoS_4^2? in the diet.     

Rear Surface Passivation for Ink-Based,Submicron CuIn(S,Se)2 Solar Cells

A N, N-dimethylformamide and thiourea-based route is developed to fabricate submicron (0.55 and 0.75 µm) thick CuIn(S,Se)₂ (CISSe) thin films for photovoltaic applications, addressing challenges of material usage, throughput, and manufacturing costs. However, reducing the absorber film thickness below 1 µm in a regular CISSe solar cell decreases the device efficiency due to losses at the highly-recombinative, and mediocre-reflective Mo/CISSe rear interface. For the first time, to mitigate the rear recombination losses, a novel rear contacting structure involving a surface passivation layer and point contact openings is developed for solution processed CISSe films and demonstrated in tangible devices. An atomic layer deposited Al₂O₃ film is employed to passivate the Mo/CISSe rear surface while precipitates formed via chemical bath deposition of CdS are used to generate nanosized point openings. Consequently, Al₂O₃ passivated CISSe solar cells show an increase in the open-circuit voltage (V_OC) and short-circuit current density when compared to reference cells with equivalent absorber thicknesses. Notably, a V_OC increase of 59 mV contributes to active area efficiencies of 14.2% for rear passivated devices with 0.75 µm thick absorber layers, the highest reported value for submicron-based solution processed, low bandgap CISSe solar cells.     

Chemical Consequences of Alkali Inhomogeneity in Cu2ZnSnS4 Thin‐Film Solar Cells

This study offers new insight into the role of Na in Cu₂ZnSnS₄ (CZTS) thin film solar cells by studying samples with a spatially varying alkali distribution. This is achieved by omitting a diffusion barrier between the soda‐lime glass substrate and the Mo back contact, where compositional variations of the glass inherently result in non‐uniform alkali distributions in the CZTS. By correlating light beam induced current (LBIC) maps with secondary ion mass spectrometry composition maps, it is shown that samples containing regions of higher Na concentration (“hot spots”) have corresponding LBIC hot spots on comparable length scales. Samples containing an alkali diffusion barrier have lower LBIC dispersion; thus, LBIC can be used to evaluate non‐uniformity in CZTS devices, where a common cause is Na inhomogeneity. Moreover, it is shown that the Na hot spots are strongly correlated with other compositional variations in the device, including increased Cu in‐diffusion with the underlying MoS₂ layer and decreased diffusion of Cd to the back contact. Neither of these effects are well understood in CZTS devices, and neither have previously been correlated with the presence or absence of Na.     

H2‐Directing Strategy on In Situ Synthesis of Co‐MoS2 with Highly Expanded Interlayer for Elegant HER Activity and its Mechanism

MoS₂ has drawn great attention as a promising Pt‐substituting catalyst for the hydrogen evolution reaction (HER). This work utilizes H₂ as the structure directing agent (SDA) to in situ synthesize a range of Co‐MoS₂‐n (n = 0, 0.5, 1.0, 1.4, 2.0) with expanded interlayer spacings (d = 9.2 – 11.1 Å), which significantly boost their HER activities. The Co‐MoS₂‐1.4 with an interlayer spacing of 10.3 Å presents an extremely low overpotential of 56 mV (at 10 mA cm^?2) and a Tafel slope of 32 mV dec^?1, which is superior than most reported MoS₂‐based catalysts. Density function theory calculations are used to gain insights that i) the H₂ can be dissociatively adsorbed on MoS₂ and greatly affect the related surface free energy by regulating the interlayer spacing; ii) the expanded interlayer spacing can significantly decrease the absolute value of ΔG_H, thereby leading to greatly promoted HER activity. Additionally, the large amounts of 1T phase (73.9–79.2%) and Co‐Mo‐S active sites (40.9–91.3%) also contribute to the enhanced HER activity of the synthesized samples. Overall, a simple new strategy for in situ synthesis of Co‐MoS₂ with an expanded interlayer spacing is proposed, which sheds light on other 2D energy material designs.     

Supercapacitor Electrodes Obtained by Directly Bonding 2D MoS2 on Reduced Graphene Oxide

Layered molybdenum disulfide (MoS₂) is deposited by microwave heating on a reduced graphene oxide (RGO). Three concentrations of MoS₂ are loaded on RGO, and the structure and morphology are characterized. The first layers of MoS₂ are detected as being directly bonded with the oxygen of the RGO by covalent chemical bonds (Mo‐O‐C). Electrochemical characterizations indicate that this electroactive material can be cycled reversibly between 0.25 and 0.8 V in 1 m HClO₄ solution for hybrids with low concentrations of MoS₂ layers (LCMoS₂/RGO) and between 0.25 and 0.65 V for medium (MCMoS₂/RGO) and high concentrations (HCMoS₂/RGO) of MoS₂ layers on graphene. The specific capacitance measured values at 10 mV s^?1 are 128, 265, and 148 Fg^?1 for the MoS₂/RGO with low, medium, and high concentrations of MoS₂, respectively, and the calculated energy density is 63 W h kg^?1 for the LCMoS₂/RGO hybrid. This supercapacitor electrode also exhibits superior cyclic stability with 92% of the specific capacitance retained after 1000 cycles.     

Drastic Layer‐Number‐Dependent Activity Enhancement in Photocatalytic H2 Evolution over nMoS2/CdS (n ≥ 1) Under Visible Light

Exploiting noble‐metal‐free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. As an efficient cocatalyst in photocatalysis, MoS₂ is shown promise as a low‐cost alternative to Pt for hydrogen evolution. Here we report a systematical study on controlled synthesis of MoS₂ with layer number ranging from ≈1 to 112 and their activities for photocatalytic H₂ evolution over commercial CdS. A drastic increase in photocatalytic H₂ evolution is observed with decreasing MoS₂ layer number. Particularly for the single‐layer (SL) MoS₂, the SL‐MoS₂/CdS sample reaches a high H₂ generation rate of ≈2.01 × 10^?3m h^?1 in Na₂S–Na₂SO₃ solutions and ≈2.59 × 10^?3m h^?1 in lactic acid solutions, corresponding to an apparent quantum efficiency of 30.2% and 38.4% at 420 nm, respectively. In addition to the more exposed edges and unsaturated active S atoms, valence band–XPS and Mott–Schottky plots analysis indicate that the SL MoS₂ has the more negative conduction band energy level than the H⁺/H₂ potential, facilitating the hydrogen reduction.     

Rational Design of Core@shell Structured CoSx@Cu2MoS4 Hybridized MoS2/N,S‐Codoped Graphene as Advanced Electrocatalyst for Water Splitting and Zn‐Air Battery

A novel hybrid of small core@shell structured CoS_x@Cu₂MoS₄ uniformly hybridizing with a molybdenum dichalcogenide/N,S‐codoped graphene hetero‐network (CoS_x@Cu₂MoS₄‐MoS₂/NSG) is prepared by a facile route. It shows excellent performance toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The hybrid exhibits rapid kinetics for ORR with high electron transfer number of ≈3.97 and exciting durability superior to commercial Pt/C. It also demonstrates great potential with remarkable stability for HER and OER, requiring low overpotential of 118.1 and 351.4 mV, respectively, to reach a current density of 10 mA cm^?2. An electrolyzer based on CoS_x@Cu₂MoS₄‐MoS₂/NSG produces low cell voltage of 1.60 V and long‐term stability, surpassing a device of Pt/C + RuO₂/C. In addition, a Zn‐air battery using cathodic CoS_x@Cu₂MoS₄‐MoS₂/NSG catalyst delivers a high cell voltage of ≈1.44 V and a power density of 40 mW cm^?2 at 58 mA cm^?2, better than the state‐of‐the‐art Pt/C catalyst. These achievements are due to the rational combination of highly active core@shell CoS_x@Cu₂MoS₄ with large‐area and high‐porosity MoS₂/NSG to produce unique physicochemical properties with multi‐integrated active centers and synergistic effects. The outperformances of such catalyst suggest an advanced candidate for multielectrocatalysis applications in metal‐air batteries and hydrogen production.     

Large‐Area,Ultrathin Inorganic Network Coverages–Graphene Hierarchical Electrodes for Flexible,Heat‐Resistant Energy Storage Application

Graphene and quasi‐2D graphene‐like materials with an ultrathin thickness have been investigated as a new class of nanoscale materials due to their distinctive properties. A novel “molecular tools‐assistances” strategy is developed to fabricate two kinds of graphene‐based electrodes, ultrathin Fe‐doped MnO₂ network coverage–graphene composites (G‐MFO) and ultrathin MoS₂ network coverage–graphene composites (G‐MoS₂) with special hierarchical structures. Such structures enable a large contact interface between the active materials and graphene and thus fully exploit the synergistic effect from both the high specific capacitance of MFO or MoS₂ and the superb conductivity of graphene. Benefiting from their unique structural features, G‐MFO and G‐MoS₂ films directly use as free‐standing electrodes for flexible asymmetric supercapacitors with a nonaqueous gel electrolyte. The device achieves a high energy/power density, superior flexibility, good rate capability as well as outstanding performance stability even at a high temperature. This work represents a promising prototype to design new generation of hybrid supercapacitors for future energy storage devices.     

Highly Efficient Solar‐Driven Carbon Dioxide Reduction on Molybdenum Disulfide Catalyst Using Choline Chloride‐Based Electrolyte

Conversion of CO₂ to energy‐rich chemicals using renewable energy is of much interest to close the anthropogenic carbon cycle. However, the current photoelectrochemical systems are still far from being practically feasible. Here the successful demonstration of a continuous, energy efficient, and scalable solar‐driven CO₂ reduction process based on earth‐abundant molybdenum disulfide (MoS₂) catalyst, which works in synergy with an inexpensive hybrid electrolyte of choline chloride (a common food additive for livestock) and potassium hydroxide (KOH) is reported. The CO₂ saturated hybrid electrolyte utilized in this study also acts as a buffer solution (pH ≈ 7.6) to adjust pH during the reactions. This study reveals that this system can efficiently convert CO₂ to CO with solar‐to‐fuel and catalytic conversion efficiencies of 23% and 83%, respectively. Using density functional theory calculations, a new reaction mechanism in which the water molecules near the MoS₂ cathode act as proton donors to facilitate the CO₂ reduction process by MoS₂ catalyst is proposed. This demonstration of a continuous, cost‐effective, and energy efficient solar driven CO₂ conversion process is a key step toward the industrialization of this technology.     

Molybdenum Disulfide/Nitrogen‐Doped Reduced Graphene Oxide Nanocomposite with Enlarged Interlayer Spacing for Electrocatalytic Hydrogen Evolution

Facile design of low‐cost and highly active catalysts from earth‐abundant elements is favorable for the industrial application of water splitting. Here, a simple strategy to synthesize an ultrathin molybdenum disulfide/nitrogen‐doped reduced graphene oxide (MoS₂/N‐RGO‐180) nanocomposite with the enlarged interlayer spacing of 9.5 Å by a one‐step hydrothermal method is reported. The synergistic effects between the layered MoS₂ nanosheets and N‐doped RGO films contribute to the high activity for hydrogen evolution reaction (HER). MoS₂/N‐RGO‐180 exhibits the excellent catalytic activity with a low onset potential of ?5 mV versus reversible hydrogen elelctrode (RHE), a small Tafel slope of 41.3 mV dec^?1, a high exchange current density of 7.4 × 10^?4 A cm^?2, and good stability over 5 000 cycles under acidic conditions. The HER performance of MoS₂/N‐RGO‐180 nanocomposite is superior to the most reported MoS₂‐based catalysts, especially its onset potential and exchange current density. In this work, a novel and simple method to the preparation of low‐cost MoS₂‐based electrocatalysts with the extraordinary HER performance is presented.     

Analysis of molybdenite bioleaching by Thiobacillus ferrooxidans in the absence of iron (II)

Summary Thiobacillus ferrooxidans attachment on MoS² and Mo dissolution are increased by the addition of the tensioactive agent Tween 80 in absence of iron(II), which suggests that the poor bioleaching of MoS² is caused by its hydrophobic character. Additionally, inhibition ofThiobacillus ferrooxidans growth by the presence of MoO₄ ^2– and the effect of variable amounts of Tween 80 on bacteria growth and on MoS² bioleaching are considered in this paper. Data confirm the need of bacterial attachment to insoluble substrate for bioleaching by the direct mechanism.     

A Review of Molybdenum Adsorption in Soils/Bed Sediments: Speciation,Mechanism, and Model Applications

Mo is an essential trace element for both plants and animals in low concentrations (<5 ppm). However, provoked by uncontrolled industrial waste releases in freshwater or seawater, it is plausible that excessive availability of soluble Mo(VI) would be potentially toxic. In the environment, soluble Mo(VI) is mainly present in anionic forms of molybdate (MoO₄ ^2?) and/or tetrathiomolybdate (MoS₄ ^2?). The fate and transport of soluble Mo(VI) anions in surface and subsurface aquatic environments is typically controlled by adsorption in acidic soils and sediment. As such, the ability of soils/bed sediments to retain Mo(VI) is a key to determine its general mobility in the aquatic environment. This article reviews the sources and distribution of Mo speciation in solution and Mo(VI) anions adsorption mechanisms in soils and bed sediments, and evaluates the surface adsorption complexation models at the solid-water interface to estimate Mo(VI) anions adsorption in these chemical systems. Mo(VI) anions adsorption mechanisms included MoO₄ ^2? and MoS₄ ^2? adsorption by several prevailing adsorbent contents (including clay, Fe, Al oxides, iron sulfide, manganese oxides, and organic matter) of soils and bed sediments, and the influence of the competitive adsorption of other anions (e.g., sulfate, selenate, phosphate, arsenate, silicate, or tungstate). Models to estimate Mo(VI) anions adsorption include the triple layer model (TLM), the diffuse layer model (DLM), the constant capacitance surface complexation model (CCM), and charge distribution multisite complexation model (CD-MUSIC).