High Sulfurization Research Articles

Novel titanium silicon micro-mesoporous composites via nano-assembly strategy for efficient hydrodesulfurization of dibenzothiophene

A unique hierarchical TS-1/FDU-12 (TF) micro-mesoporous composite was synthesized by nano-assembly method, and was used as an excellent support for high-efficiency hydrodesulfurization (HDS) catalyst (NiMo/TF) of dibenzothiophene (DBT). The introduction of TS-1 nanocrystals provided more S vacancies and more acidic sites to the NiMo/TF catalysts, and showed no effect on the highly ordered three-dimensional structure of the composites, leading to excellent HDS performance of NiMo/TF catalysts. The superior acidity of NiMo/TF favored the HYD pathway of DBT, resulting in improved DBT HDS activity with up to 98.0 % desulfurization degree. In addition, NiMo/TF presented an optimal reaction rate constant (kHDS) of 5.9 × 10-4 mol g-1 h−1, a turnover frequency (TOF) value of 1.6 h−1 and a low activation energy (Ea) of 47.7 kJ mol−1, which are due to the synergistic effect of large specific surface area, appropriate pore size, abundant Brønsted & Lewis acidic sites, suitable MSI, high sulfurization degree and highly dispersed MoS2 active phases.

An in-situ combo Mo-based ionic liquid and SAPO-11 catalyst for efficient biolipids hydrodeoxygenation and isomerization

The design of novel practical catalysts is critical for the blossoming of biodiesel green-energy, in which Mo-based catalysts are of particular interest. In this work, an in-situ synthesis method was proposed to obtain a combo Mo-based ionic liquid and SAPO-11 catalyst. The catalyst presents both highly dispersed MoS2 as hydrodeoxygenation active sites and acidic sites for isomerization. MoS2 with a few fine layers can be identified based on TEM images and the Brønsted acid sites are dominant based on Pyridine-IR analysis. A great performance of MoS2/C8min-15 %SA can be obtained under optimized reaction conditions with 100 % conversion of methyl palmitate, 75.0 mol% hydrodeoxygenation to n-C15-C16, and 20.5 mol % isomerization to i-C15-C16. The structure and activity of the catalyst can be retained at least for 4 cycles. Thin layers and high sulfurization, large amount of Brønsted acid sites, and suitable reaction conditions are key points to achieve a significant performance and avoid over cracking and deactivation. On basis of detected intermediates and kinetic data simulations, a complex reaction pathway was proposed and the specific k values for each elementary reaction were provided for the hydrodeoxygenation and isomerization of methyl palmitate.

Sulfur-graded kesterite structured film drives improvement of VOC.

Realizing the graded bandgap in absorber layer is very essential for high efficient thin film solar cells. However, such bandgap modification in kesterite-structured Cu2ZnSnSe4 is normally realized via high temperature sulfurization process (above 500°C), which is not only difficult to control the sulfurization depth, but also introduces additional deep defects because of the decomposition of absorber layer at such high temperature. In this study, a low-temperature sulfurization process (150°C) is developed. Such process not only inhibits the decomposition of Cu2ZnSnSe4 films and controls the elemental distribution very well, but also increase the surface bandgap of the absorber layer and form a gradient energy bandgap. Also, the density of deep-level defects in the Cu2ZnSnSe4 layer is reduced. As a consequence, the open circuit voltage of the solar cell is improved by 60 mV. This study paves the way towards the high efficient kesterite solar cell and other solar cells.

A rGO/Cu0.7Fe0.3S2 composite electrode for asymmetric supercapacitor prepared via MIL-101 template strategy

As a branch of MOF, MIL has attracted much attention in the field of electrochemistry because of its high porosity and potential high charge storage capacity. Graphene oxide is considered as an ideal supercapacitor material because of its high electrical conductivity, high specific surface area and rich surface functional groups. The metal sulfides prepared with MIL as template not only inherit the structural characteristics of MIL, but also improve the electrical conductivity of the materials, which thus show excellent energy storage properties. In this work, the rGO/Cu0.76Fe0.24S2 composite was prepared through in-situ growth of MIL-101 on the surface of GO followed by copper nitrate etch, high temperature carbonization and hydrothermal sulfurization. To the best of our knowledge, it is the first time to report that rGO/Cu0.7Fe0.3S2 is used as the electrode of supercapacitor and tested for energy storage. The optimized rGO/Cu0.7Fe0.3S2 electrode exhibited good capacitive performances, including high specific capacitance of 661.2 F g−1 at 1 Ag−1 and remarkable cycle stability with 69 % after 5000 cycles. Employing the as-prepared rGO/Cu0.7Fe0.3S2 composites as positive electrode, the hybrid supercapacitor device displayed spectacular capacity of energy density (54.37 Wh kg−1), great power density (887.75 W kg−1) and impressive long-term stability of 70 % retention after 5000 cycles. The results show that the composite prepared with graphene oxide as substrate and MIL-101 (Fe) as template should be a promising materials for fabricating high-performance supercapacitor.

Construction of high content CoMoS active sites through the combination of Co5Mo10 molecular precursors and inert carbon matrix support for deep hydrodesulfurization

The rational design of high sulfurization and abundant CoMoS active phases catalysts is the key to drive the industrialization of hydrodesulfurization (HDS). Herein, we prepared a nano-catalyst with well-dispersed and numerous CoMoS active sites through confining Co3(II)[Co2(III)Mo10O38H4] (Co5Mo10) polyoxometalates (POMs) molecules with high Co/Mo ratio in hollow mesoporous carbon spheres (HMCS). On the one hand, POMs acted as pre-assembled molecular platform can build and regulate the structure of active phases by precisely adjusting the Co/Mo atomic ratio at molecular level. Meanwhile, the intimate interaction of Co-Mo on the POMs precursor also ensures that the Co species mainly exists as Co-promoted MoS2 active phase after the sulfidation process, thus the highly efficient synergism of the bimetals can be fully utilized in the reaction. On the other hand, the mesoporous carbon sphere with homogeneous pore size and high specific surface area can effectively confine the growth of the catalyst to disperse the active metals. The weakening metal–metal interaction property of such inert support enables the S-Co5Mo10/HMCS-10 catalyst to realize higher sulfurization, shorter slab length and higher stacking number. In addition, the abundant mesopores and high pore capacity of support greatly facilitate the mass transfer process and provide sufficient space for the HDS reaction as the nanoreactor. The unique combination of POMs and HMCS enabled the S-Co5Mo10/H10 catalyst to achieve up to 99.2% conversion of dibenzothiophene (DBT) after 4 h of HDS reaction, while obtaining a TOF value of 1.3 × 10−3 s−1 (calculated when keeping the low conversion at 42% after 0.5 h of reaction). The structural orientation of the POMs precursors to the active phases of HDS catalysts was investigated using various characterization methods, and the structure–activity relationship between the catalytic performance and the sulfide active phases was also revealed in this work.

Photoelectrochemical and Photovoltaic Performance of As-deposited Ink-based CuInS2 Heterojunction Thin Film

In this report, we demonstrate low-temperature ink-based fabrication of CuInS2-based photoelectrodes for hydrogen production capable of producing photocurrent densities as high as 8.8 mA.cm−2. In this process, molecular ink made of metal chlorides and thiourea dissolved in methanol was spin coated onto Mo-coated soda lime glass substrates. Samples were then placed on a hot plate (sample surface temperature: 250 °C) to induce CuInS2 formation and remove the solvent and by-products. No further processing, such as high temperature sulfurization, was performed. The CuInS2 films were then integrated as photocathode for hydrogen evolution by photoelectrodeposition of Pt nanoparticles. Photocurrent density of 0.4 mA.cm−2 at 0 V vs. RHE was detected from such electrodes. However, samples coated with CdS/ZnO/ITO overlayers forming heterojunction prior to Pt deposition exhibited significant improvement of the photocurrent density, reaching 8.8 mA.cm−2 at 0 V vs. RHE, highlighting the improved charge transfer by the p-n junction formed at the CuInS2/CdS interface. The charge transfer resistance of the CuInS2/CdS/ZnO/ITO-Pt photoelectrode was almost 5 times lower than that of the CuInS2-Pt photoelectrode as revealed by electrochemical impedance spectroscopy analysis. In addition, the onset potential was shifted by ca. 0.45 V toward the anodic direction, reaching 0.75 V vs. RHE. Solar cell made of identical structure (Mo/CuInS2/CdS/ZnO/ITO) showed power conversion efficiency of 2.1% with short-circuit photocurrent density and open circuit voltage of 7.4 mA.cm−2 and 820 mV, respectively.

10.3% Efficient Green Cd-Free Cu2 ZnSnS4 Solar Cells Enabled by Liquid-Phase Promoted Grain Growth.

Small grain size and near-horizontal grain boundaries are known to be detrimental to the carrier collection efficiency and device performance of pure-sulfide Cu2 ZnSnS4 (CZTS) solar cells. However, forming large grains spanning the absorber layer while maintaining high electronic quality is challenging particularly for pure sulfide CZTS. Herein, a liquid-phase-assisted grain growth (LGG) model that enables the formation of large grains spanning across the CZTS absorber without compromising the electronic quality is demonstrated. By introducing a Ge-alloyed CZTS nanoparticle layer at the bottom of the sputtered precursor, a Cu-rich and Sn-rich liquid phase forms at the high temperature sulfurization stage, which can effectively remove the detrimental near-horizontal grain boundaries and promote grain growth, thus greatly improving the carrier collection efficiency and reducing nonradiative recombination. The remaining liquid phase layer at the rear interface shows a high work function, acting as an effective hole transport layer. The modified morphology greatly increases the short-circuit current density and fill factor, enabling 10.3% efficient green Cd-free CZTS devices. This work unlocks a grain growth mechanism, advancing the morphology control of sulfide-based kesterite solar cells.

Disulfide Dichloride: A High Efficiency Vulcanizing Agent for Sulfurized Polyacrylonitrile

Sulfurized polyacrylonitrile (SPAN) cathodes have shown great prospects in commercial applications due to the high discharge capacity, good cycle stability, and low self-discharge rate. However, high sulfurization temperature results in loss of nitrogen atoms, which leads to imperfect SPAN structure and is not conducive to fast electron transfer. A high efficiency vulcanizing agent of S2Cl2 was used to reduce the reaction temperature in this work. We found that S2Cl2 promotes PAN cyclization, reduces the cyclization reaction temperature, and avoids the loss of nitrogen atoms and the agglomeration of SPAN primary particles in high-temperature reactions. The SPAN cathode material prepared using S2Cl2 has a more regular structure six-membered ring main chain structure and a smaller primary particle size, which is beneficial to the rapid conduction of electrons and lithium ions in the electrode material. The electrochemical test results confirmed that the SPAN cathode material prepared by S2Cl2 has higher active material utilization, better cycle stability, and better rate performance.

Highly Reflective Silver-Enhanced Coating with High Adhesion and Sulfurization Resistance for Telescopes.

Highly reflective metal coatings are essential for manufacturing reflecting telescope mirrors to achieve the highest reflectivity with broad spectral bandwidth. Among metallic materials, enhanced silver-based coatings can provide higher reflectivity in the 400–500 nm spectral range to better performance from visible to near IR. Moreover, over-coating a dielectric protective layer on the mirror’s front side attains additional hardness and oxidation stability. In this paper, we study a combination of thermal and electron beam evaporation as a technology to form protected enhanced high reflective Ag coatings. A newly designed multiplayer film can pass ASTM 5B adhesive performance testing and give sulfurization inhibition. The average specular reflectivity for the enhancement coating is about 98% in wavelengths across the spectral range from 400–1000 nm. This innovation has been demonstrated on a Newtonian type telescope, with storage in an ambiance humidity H = 60–85%, and temperature T = 10–35 °C, for more than six months without degradation in coating performance.

Metal-Support interaction modulate the sulfidation and dispersion of MoS2 slabs on hierarchical KNiMo|ZnCrAl-Based multifunctional catalysts for selective conversion of syngas to higher alcohols

Catalytic conversion of syngas into high value-added chemicals such as higher alcohols (C2+OH) are vitally crucial in chemical industry but still remains a challenge due to the low conversion and C2+OH selectivity. Herein, the combination of powerful CO activation on ZnCr-based sites and strong C–C coupling for chain propagation on KNiMoS is highly desirable to achieve high C2+OH yield on hierarchical KNiMoS|ZnCrAlS-based multifunctional catalysts. The hierarchical structure can facilitate the dispersion of MoS2 slabs with dominant double-layer stacking to enable the high sulfuration degree of Mo and high proportion of NiMoS active phases due to the appropriate metal-support interaction. As a result, KNiMoS|ZnCrAlS-O(E) showed the highest CO conversion (20.2 %), total alcohols selectivity (63.8 %) with high C2+OH/ROH fraction of 68.5 %, TOF (176.8 h−1), STY (116.4 mg g-1h−1) and excellent stability. A plausible reaction path was also proposed on hierarchical KNiMoS|ZnCrAlS-O(E) multifunctional catalyst that the alkoxy intermediates species formed on ZnCr active species can partially transform to MoS2-based active phase to form CHyCHxO* species for the favourable C2+OH synthesis. This work offers a promising strategy through the integration of multifunctional catalyst with hierarchical pore to strengthen CO activation and C–C coupling for selective conversion of syngas to C2+OH.

Growth and photovoltaic device using Cu3VS4 films prepared via co-sputtering from Cu–V and V targets

CVS (Cu3VS4) materials have the potential to become a new generation of thin film solar cell absorber materials, due to the availability of the constituent materials and a nearly ideal energy gap (1.3–1.5eV). In this study, we investigated the effects of co-sputtering using targets of Cu–V and V and various sulfurization temperatures to produce thin films of various Cu/V ratios. In experiments, CVS films with a high Cu/V ratio presented large surface grains of Cu2-XS with the appearance of secondary phases (CuS, Cu1.8S, Cu2S, and Cu0.7V2.3S4) during H2S sulfurization process. A low Cu/V ratio with high sulfurization temperature produced nearly single-phase CVS. The optimal CVS absorber layer was prepared using a Cu/V ratio of 2.76 with sulfurization for 20 min at a temperature of 550 °C. A prototype CVS thin film solar cell achieved a maximum power conversion efficiency of 3.11%.

Decorating sulfur and nitrogen co-doped graphene quantum dots on graphite felt as high-performance electrodes for vanadium redox flow batteries

This paper reports on decorating sulfur (S)/nitrogen (N) co-doped graphene quantum dots (S/N co-doped GQDs) on graphite felt as high-performance electrodes for vanadium redox flow batteries (VRFBs). The S/N co-doped GQDs are synthesized through an efficient infrared-assisted pyrolysis of glucose, urea, and ammonia sulfate at 280 °C. The S/N co-doped GQDs, having an average diameter of 6.2 nm, contain high oxidation, amidation, and sulfuration levels (45.8 (O/C), 22.7 (N/C), and 7.8 at.% (S/C), respectively). Electrochemical impedance spectroscopy is utilized to assess the overpotential distributions for VRFBs equipped with untreated GF and S/N co-doped GQDs/GF. With the aid of S/N co-doped GQDs, the catalytic activity, equivalent series resistance, durability, and voltage efficiency are substantially improved. The improved performance is attributed to the synergistic effect of GQDs containing O functionalities, lattice N atoms, and S dopants, facilitating surface catalytic activity and accelerating charge transfer across the anode/anolyte interface for the vanadium redox couples (V(II)/V(III)). Accordingly, hierarchical S/N co-doped GQD/GF electrode paves the pathway for engineering the electrodes’ nano-structure with improved catalytic activity and enhanced durability for redox flow batteries.

Oxide route for production of Cu2ZnSnS4 solar cells by pulsed laser deposition

In this work, we have investigated Cu2ZnSnS4 (CZTS) solar cells made from oxide, oxy-sulfide and sulfide precursors produced by pulsed laser deposition (PLD). Although sulfide precursors are widely used to fabricate CZTS solar cells, Sn loss is commonly observed due to the high volatility of SnxSy species during high temperature sulfurization. This can lead to a non-ideal absorber composition and a high density of detrimental Sn-related defects that severely affect the performance of the device. By using oxide precursors, we have shown that the Sn loss can be significantly reduced due to the higher thermal stability of SnxOy species when compared to their sulfide counterparts. However, the reaction mechanism for the oxide route results in rough CZTS films. We hypothesize that the SO2 gas that forms during the conversion from oxide to sulfide is trapped in the film during sulfurization, and can lead to grains with hollow cavities and thus increase the surface roughness. Therefore, we have developed an annealing route for the oxide precursors at lower annealing pressures, which leads to improved film morphology and device performance. As a result, we report a power conversion efficiency of 5.4% for solar cells made from oxide precursors. This is the highest value reported for a CZTS absorber produced by PLD.

Solution-processed extremely thin films of Cu2SnS3 nanoparticles for planar heterojunction solar cells

Cu2SnS3 is a potential absorber material for thin film solar cells. However, Cu2SnS3 solar cells are normally prepared by high temperature sulfurization process. In this work, the Cu2SnS3 nanoparticle films with a porously structured surface are in situ prepared by a new and facile molecular precursor solution approach featuring a low annealing temperature (250 °C–350 °C) and a short annealing time (5 min); furthermore, the novel planar heterojunction solar cells configured as FTO/TiO2/CdS/Cu2SnS3/P3HT/MoO3/Ag are fabricated, in which poly(3-hexylthiophene) (P3HT), an organic conjugated polymer, mainly acts as hole transporting material. It is found that the annealing temperature imposes a significant influence on the structure of Cu2SnS3 nanoparticle film. While increasing annealing temperature leads to a higher crystallinity of Cu2SnS3 nanoparticle film, the pores on the film surface become larger at annealing temperature >300 °C. It is also revealed that the solar cell performance depends on the annealing temperature and Cu2SnS3 film thickness, and the efficiency of 2.03% is obtained in the solar cells with 60 nm thick Cu2SnS3 thin film prepared at 300 °C. The results here demonstrate a low-temperature solution preparation strategy to prepare Cu2SnS3 thin films for solar cells and other optoelectronic devices.

Development and characterization of photodiode from p-Cu2CdSnS4/n-Bi2S3 heterojunction

Here we investigated the photo response behaviour of p-Cu2CdSnS4 (p-CCTS)/n-Bi2S3 heterojunction photodiode. The solution processed CCTS films without any high temperature sulfurization demonstrated the photo response behaviour, suggesting the material is well suited for low temperature processed photovoltaic applications. A CCTS film was deposited on an ITO coated glass substrate using simple sol-gel based spin coating method. Current–voltage (I–V) characteristic of the p-CCTS/n-Bi2S3 heterojunction photodiode showed a good rectifying behaviour indicating better junction formation between CCTS and Bi2S3 layers. The obtained photocurrent is 4 times higher than that of the dark current. The I–V curves are asymmetric with respect to voltages and the photocurrent in the positive bias region is considerably higher than the corresponding values in the negative bias region. With these results, it is concluded that the CdS material in traditional thin film PV devices can be replaced with Bi2S3 for better transportation of charge carriers in the PN-junction.

Monolithic thin-film chalcogenide–silicon tandem solar cells enabled by a diffusion barrier

Following the recent success of monolithically integrated Perovskite/Si tandem solar cells, great interest has been raised in searching for alternative wide bandgap top-cell materials with prospects of a fully earth-abundant, stable and efficient tandem solar cell. Thin film chalcogenides (TFCs) such as the Cu2ZnSnS4 (CZTS) could be suitable top-cell materials. However, TFCs have the disadvantage that generally at least one high temperature step (>500 °C) is needed during the synthesis, which could contaminate the Si bottom cell. Here, we systematically investigate the monolithic integration of CZTS on a Si bottom solar cell. A thermally resilient double-sided Tunnel Oxide Passivated Contact (TOPCon) structure is used as bottom cell. A thin (<25 nm) TiN layer between the top and bottom cells, doubles as diffusion barrier and recombination layer. We show that TiN successfully mitigates in-diffusion of CZTS elements into the c-Si bulk during the high temperature sulfurization process, and find no evidence of electrically active deep Si bulk defects in samples protected by just 10 nm TiN. Post-process minority carrier lifetime in Si exceeded 1.5 ms, i.e., a promising implied open-circuit voltage (i-Voc) of 715 mV after the high temperature sulfurization. Based on these results, we demonstrate a first proof-of-concept two-terminal CZTS/Si tandem device with an efficiency of 1.1% and a Voc of 900 mV. A general implication of this study is that the growth of complex semiconductors on Si using high temperature steps is technically feasible, and can potentially lead to efficient monolithically integrated two-terminal tandem solar cells.

Tackling the Stability Issues of Silver Nanowire Transparent Conductive Films through FeCl3 Dilute Solution Treatment

Silver nanowires (AgNWs) have been investigated as alternatives to indium tin oxide in transparent conductive films (TCFs) for electronics. However, AgNW TCFs still pose stability issues when exposed to thermal, chemical, and mechanical stimuli. Herein, we demonstrate a facile and effective route to improve stability by treating the films with dilute ferric chloride solution. Our results indicate that after treatment the films exhibit a dramatically enhanced stability against aging, high temperature oxidation, chemical etching, sulfurization, and mechanical straining. Size-dependent instability is fully explored and explained regarding surface atomic diffusion, which could be blocked by enhancing the activation energy of surface diffusion through forming a AgCl cap under ferric chloride solution treatment. Chemisorption-related Fermi level shift of silver nanowires is applied to tune their chemical reactivity to ferric chloride solution for balancing between size-dependent stability improvement and maintaining optoelectrical properties. Owing to the dilute treatment solution, the treated films exhibit a negligible change in light transmittance, whereas sheet resistance decreases by 30% and flexibility increases because of capillary-force-induced welding of contacting AgNWs and AgCl layer mediated tightening. These findings are significant for real-world applications of AgNW TCFs.

Controlled sulfurization of MnCO3 microcubes architectured MnS2 nanoparticles with 1.7 fold capacitance increment for high energy density supercapacitor

Recently, sulfurization and phosphorylation protocols are employed in porous nano-materials preparation beneficial to improve energy density and power density of pseudocapacitors. Due to well-defined redox activity and higher theoretical capacitance, manganese sulfide electrode is used in supercapacitor application. In present work, MnCO3 microcubes are converted into MnS2 nanoparticles using cost-effective high diffusion rate sulfurization method. Reducing size of material from microcubes to nanoparticles has facilitated rate capability in the material along with improved capacitance. MnS2 nanoparticles exhibit 713 Fg-1 specific capacitance at 5 mVs−1 scan rate compared with 407 Fg-1 obtained for MnCO3 microcubes. The impedance study analyzes improvement in interfacial conductivity for MnS2 nanoparticles observed form 1.83 Ωcm−2 equivalent series resistance in comparison with 2.35 cm−2 for MnCO3 microcubes.Fabricated solid state MnS2//MoS2 asymmetric supercapacitor exhibits 41.7 Whkg−1 energy density, and 450 Wkg-1 power density with the respectable 88 % capacitance retention for the continuous 2000 CV cycles charging and discharging at 100 mVs−1 scan rate.

Toward a high-performance Li-ion battery: Constructing a Co1−xS/ZnS@C composite derived from metal-organic framework @3D disordered polystyrene sphere template

Composites are usually better than a single material because they combine advantages of their component materials and, as a result, achieve better performance. Using a high temperature sulfuration process, a Co1−xS/ZnS@C composite was successfully synthesized by using a 3D disordered polystyrene spheres (PS) template coated on metal-organic framework (ZIF) precursor. The Co1−xS/ZnS in the composite was firmly encapsulated by C that came from the 3D disordered PS template. The carbon can efficiently reduce the volume expansion triggered by metal sulfide particles during the charge/discharge process. Furthermore, due to a synergistic effect between the composite's components, the Co1−xS/ZnS@C composite displays better cycling performance and rate capacity compared to Co1−xS@C and ZnS@C. The Co1−xS/ZnS@C composite electrode showed a higher stable capacity of ~586 mAh g−1 after ~100 cycles with a current density is 0.3 A/g and it also exhibited a more excellent rate capability compare with Co1−xS@C and ZnS@C.

Effect of sulfurization temperature on the phase purity of Cu2SnS3 thin films deposited via high vacuum sulfurization

In this study, the deposition of Cu2SnS3 (CTS) thin films was carried out at different sulfurization temperatures in the range of 350–550°C under high vacuum of 1 Pa using the sputtered Cu/Sn/Cu metal precursor layers in the sulfur vapor atmosphere. In order to reduce the Sn loss, a particular metal stack of Cu/Sn/Cu was used. Single phase monoclinic (M)-CTS thin film was obtained at 500 °C. The high intensity Raman modes at 292 cm−1 and 350 cm−1 further confirmed the formation of M-CTS. The M-CTS thin film sulfurized at 500 °C showed a composition of Cu/Sn = 1.89 and an optical band gap energy of 0.94 eV. Hall effect measurement of the film sulfurized at 500 °C with Cu/Sn ratio of 1.82 showed an electrical resistivity of 7.30 Ω-cm, carrier concentration of 6.29 × 1017 cm−3, and mobility of 1.36 cm2/Vs. Our results indicate that the copper-poor composition with a stacking order of Cu/Sn/Cu is favored in order to attain the single phase M-CTS.