Reduction Of MoO3 Research Articles

Preparation of highly uniform molybdenum powder by the short-process reduction of molybdenum trioxide with hydrogen

A novel short-process for preparing molybdenum powder is proposed in this paper in which the hydrogen flow direction is changed from traditional top diffusion to bottom blowing. The results showed that the short-process prevented sintering of the MoO2 reduction product in the first stage and permitted the continuous reduction of MoO3 by hydrogen without crushing or screening. Compared with top diffusion, when the hydrogen flow rates were 300 mL min−1 and 600 mL min−1 in the short-process, the time required for complete reduction in the second stage was shortened by 33.3% and 37.5%, respectively. In addition, the molybdenum powder obtained by the short-process was finer and more uniform, and the oxygen content was lower. The average particle size of molybdenum powder was only 1.89 μm, and the lowest oxygen content was only 1050 ppm at a hydrogen flow rate of 600 mL min−1. This novel process significantly improved the reduction efficiency and shows great potential for energy conservation and emission reduction.

Heterostructured MoO2@MoS2@Co9S8 nanorods as high efficiency bifunctional electrocatalyst for overall water splitting

Developing low-cost and high-efficiency bifunctional catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to catalyze electrochemical overall water splitting is critical for the production of hydrogen. Herein, we develop an in-situ reduction and vulcanization strategy to prepare MoO2@MoS2@Co9S8 heterostructure nanorods by utilizing MoO3@ZIF-67 as a precursor. The reduction of MoO3 can produce more conductive MoO2, and the vulcanization reaction can produce highly active MoS2 for the HER as well as highly active Co9S8 for the OER. In addition, the MoS2 anchor on the MoO2 not only facilitates electron transfer, but also interacts with Co9S8 to induce a synergic catalytic effect by the electron transfer between them. Moreover, the 2D nanosheet assembled heterostructure nanorods can provide a large electrochemical surface area. Therefore, the merits of the materials are fully utilized and outstanding catalytic performances are achieved. MoO2@MoS2@Co9S8 can catalyze HER and OER effectively with overpotentials of 160 and 310 mV at 10 mA cm−2, indicating its bifunctional activity. In addition, the two electrode electrolyzer catalyzed by MoO2@MoS2@Co9S8 can reach 10 mA cm−2 current density at a cell voltage of 1.62 V with very high stability, demonstrating its practical application for water splitting.

Metal copper induced the phase transition of MoO3 to MoO2 thin films for the CdTe solar cells

Multilayered MoO3/Cu thin films were prepared by thermal evaporation in combination with the thermal treatments. As-deposited multilayers are amorphous structure. With the increase of temperature, Mo4O11 phase forms in the thin films without copper while MoO2 phase with the weak reduced molybdenum oxide appears in the copper-containing thin films. After annealing at the temperature higher than 450 °C predominant MoO2 appears in the multilayered MoO3/Cu thin films. Meanwhile, CuO and Cu2O are also present in the thin films. The formation mechanism of reduced molybdenum suboxide can be explained by the oxygen-vacancy generation reaction or the reduction of MoO3 to MoO3-x via the inter-diffusion at the MoO3/Cu interfaces. The band gaps and conductivity activation energies of multilayered MoO3/Cu thin films decrease as the annealing temperature increases, in which the smallest band gap of ~2.05 eV and activation energy of ~0.02 eV for the MoO2 thin films are found. Our results open a new road to broaden the application of reduced molybdenum suboxides as a back contact material for CdTe solar cells.

Studies on influence of hydrogen and carbon monoxide concentration on reduction progression behavior of molybdenum oxide catalyst

Temperature programmed reduction (TPR) analysis was applied to investigate the chemical reduction progression behavior of molybdenum oxide (MoO3) catalyst. The composition and morphology of the reduced phases were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM). The reduction progression of MoO3 catalyst was attained with different reductant types and concentration (10% H2/N2, 10% and 20% CO/N2 (%, v/v)). Two different modes of reduction process were applied. The first approach of reduction involved non-isothermal mode reduction up to 700 °C, while the second approach of reduction involved the isothermal mode reduction for 60 min at 700 °C. Hydrogen temperature programmed reduction (H2-TPR) results showed the reduction progression of three-stage reduction of MoO3 (Mo6+ → Mo5+ → Mo4+ → Mo0) with Mo5+ and Mo4+. XRD analysis confirmed the formation of Mo4O11 phase as an intermediate phase followed by MoO2 phase. After 60 min of isothermal reduction, peaks of metallic molybdenum (Mo) appeared. Whereas, FESEM analysis showed porous crater-like structure on the surface cracks of MoO2 layer which led to the growth of Mo phase. Meanwhile, the reduction of MoO3 catalyst in 10% carbon monoxide (CO) showed the formation of unstable intermediate phase of Mo9O26 at the early stage of reduction. Furthermore, by increasing 20% CO led to the carburization of MoO2 phase, resulted in the formation of Mo2C rather than the formation of metallic Mo, as confirmed by XPS analysis. Therefore, the presented study shows that hydrogen gave better reducibility due to smaller molecular size, which contributed to high diffusion rate and achieved deeper penetration into the MoO3 catalyst compared to carbon monoxide reductant. Hence, the reduction of MoO3 in carbon monoxide atmosphere promoted the formation of Mo2C which was in agreement with the thermodynamic assessment.

Effect of microwave radiation and mechanical activation on the Carbothermic reduction of molybdenum trioxide: Improving the practical efficiency

In this research two different paths were used to cabothermic reduction of MoO3. In the first and second path, as received MoO3 and graphite with stoichiometric ratios were mixed and mechanically activated at 5, 10, 15 and 24 h and heating by microwave oven (first path) and furnace at 700 and 1000 °C in second path. The XRD results of activated samples before heating showed that, MoO2 was produced in the planetary ball mill after 5 h milling and don't change to another phase during milling up to 24 h. the SEM and XRD results in first and second path showed that the final product was molybdenum carbide but in the non-activated samples the final products were molybdenum carbide and unreacted MoO2. The practical efficiency calculations in first and second method showed that heating of samples by microwave radiation and mechanical activation increase the practical efficiency and decrease the sublimation of molybdenum trioxide. The TGA analysis of non-activated MoO3+ C mixture indicated that the reduction goes with three steps but in the 24 h activated sample, it was seen that the reduction goes with one peak. In other words, the first and second peaks in non-activated sample were not detected in the activated sample that increases the practical efficiency due to prevent the sublimation of MoO3

Study on the reduction of commercial MoO3 with carbon black to prepare MoO2 and Mo2C nanoparticles

AbstractA simple method was developed to synthesize MoO2 and Mo2C nanoparticles via controlling nucleation and growth in carbothermic reduction of commercial MoO3 with carbon black. It was found that the appropriate C/MoO3 molar ratio for preparation of Mo2C was 2.8, and the carbothermic reduction process followed the sequence: MoO3 → transport phase (TP) → MoO2 → Mo2C. It was revealed that the most crucial issues for controlling number of produced particles of product were migration of Mo source and aid of nucleating agent, which can be achieved by using MoO3 and carbon black as starting materials. MoO2 nanosheets with the thickness of 12 nm and lateral size of 60 nm, as well as Mo2C nanoparticles with particle size of 30 nm were prepared via reduction of MoO3 with carbon black. However, MoO2 and Mo2C produced via reducing MoO3 by other kinds of carbon sources (activated carbon, graphite) or gas reductants (10% CH4/H2, CO) had much larger particle sizes of a few micrometers, which were tens of times than those using MoO3 and carbon black, due to the too small amount of formed nuclei. The effects of C/MoO3 molar ratio (0.5‐2.8), molybdenum sources and carbon sources on the reaction mechanisms were investigated in detail.

An investigation on aluminothermic reduction of MoO3 in domestic microwave oven

In the present study, feasibility of aluminothermic reduction of molybdenum oxide by microwave oven was studied. Furthermore, the effect of compaction pressure and the amount of used Al and CaO as flux on aluminothermic reduction of molybdenum oxide were investigated. Thermodynamic analysis of the corresponding reaction indicated that, aluminothermic reduction of MoO3 was possible at all temperatures. XRD patterns and thermodynamic investigation of reaction products indicated that aluminothermic reduction of molybdenum oxide progressed through the formation of intermediate phases such as Al2 (MoO4)3 and MoO2, where the final products were elemental Mo and Al2O3. Results revealed that by increasing the compaction pressure of the pellet, undesired phases of molybdenum dioxide (MoO2) and aluminum molybdate Al2(MoO4)3 can be detected among the final products. By increasing the amount of Al more than stoichiometric ratio, the intermediate phases, such as MoO2, were produced. The results indicated that by adding CaO to the MoO3-Al system, the unwanted molybdenum dioxide (MoO2) and aluminum molybdate (Al2 (MoO4)3) compounds were successfully reduced to Mo.. In the present work, metallic molybdenum could easily and successfully be separated from Al2O3 slag, as the side product of the reaction, in molten phase, based on the difference in their densities.

Formation of Mo5Si3/Mo3Si-MgAl2O4 Composites via Self-Propagating High-Temperature Synthesis.

In situ formation of intermetallic/ceramic composites composed of molybdenum silicides (Mo5Si3 and Mo3Si) and magnesium aluminate spinel (MgAl2O4) was conducted by combustion synthesis with reducing stages in the mode of self-propagating high-temperature synthesis (SHS). The SHS process combined intermetallic combustion between Mo and Si with metallothermic reduction of MoO3 by Al in the presence of MgO. Experimental evidence showed that combustion velocity and temperature decreased with increasing molar content of Mo5Si3 and Mo3Si, and therefore, the flammability limit determined for the reaction at Mo5Si3 or Mo3Si/MgAl2O4 = 2.0. Based upon combustion wave kinetics, the activation energies, Ea = 68.8 and 63.8 kJ/mol, were deduced for the solid-state SHS reactions producing Mo5Si3– and Mo3Si–MgAl2O4 composites, respectively. Phase conversion was almost complete after combustion, with the exception of trivial unreacted Mo existing in both composites and a minor amount of Mo3Si in the Mo5Si3–MgAl2O4 composite. Both composites display a dense morphology formed by connecting MgAl2O4 crystals, within which micro-sized molybdenum silicide grains were embedded. For equimolar Mo5Si3– and Mo3Si–MgAl2O4 composites, the hardness and fracture toughness are 14.6 GPa and 6.28 MPa m1/2, and 13.9 GPa and 5.98 MPa m1/2, respectively.

Temperature-dependent formation of redox sites in molybdenum trioxide studied by electron paramagnetic resonance spectroscopy

The formation and qualification of redox sites in transition metal oxides are always the active fields related to electronics, catalysis, sensors, and energy-storage units. In the present study, the temperature dependence of thermal reduction of MoO3 was surveyed at the range of 350 °C to 750 °C. Upon reduction, the formed redox species characterized by EPR spectroscopy are the MoV ion and superoxide anion radical (O2−) when the reduction was induced at the optimal temperature of 300−350 °C. When heating-up from 350 °C, the EPR signals started to decline in amplitude. The signals in the range of 400−450 °C decreased to half of that at 350 °C, and then to zero at ∼600 °C. Further treatment at even higher temperature or prolonged heating time at 500 °C caused more reduction and more free electrons were released to the MoO3 bulk, which results in a delocalized means similar to the anti-ferromagnetic coupling. These data herein are helpful to prepare and study the metal-oxide catalysts.

Mechanism and Kinetic Study of Reducing MoO3 to MoO2 with CO-15 vol % CO2 Mixed Gases.

In the present paper, the reduction reaction of high-purity MoO3 with CO–15 vol % CO2 mixed gases in the temperature range of 901–948 K is investigated via the thermogravimetric analysis technology. The results show that reduction of MoO3 to MoO2 follows a three-step reaction process, viz., MoO3 is first reduced into Mo9O26, followed by Mo4O11, and finally to MoO2. The reaction sequences of MoO3 → Mo9O26 → Mo4O11 → MoO2 are proposed, which are quite different from those observed on reduction of MoO3 by pure H2 or CO gases. Pure Mo9O26 and Mo4O11 could be synthesized once suitable time was controlled. Rate-controlling steps for the reduction from MoO3 to Mo9O26 and Mo9O26 to MoO2 (include both Mo9O26 to Mo4O11 and Mo4O11 to MoO2) are interfacial chemical reactions, with the activation energies of 318.326 and 112.047 kJ/mol, respectively. This study also discovers that the as-synthesized MoO2 keeps the same platelet-shaped and smooth morphology as the MoO3 raw material; however, its particles size gradually increased as the reaction proceeds due to the formation of low-melting-point eutectic and the sticking of different particles.

Reaction and Energy Levels at Oxide–Oxide Heterojunction Interfaces

AbstractOxide–oxide heterojunction interfaces (OHIs) are foundations for many applications such as transistors, optoelectronic devices, and chemical catalysis. The formation of OHIs involves complex events such as charge transfer, interfacial diffusion, and chemical reactions. These events collectively contribute to an OHI's energy structure and to its ability to perform an intended application. Here, multiple MoO3/oxide interfaces are studied at which changes in multiple oxidation states Mox+ can be easily tracked. For the formation of reactive interfaces, it is found that the primary driving force behind the reduction of MoO3 is redox reactions at the interfaces. For the nonreactive interface, the reduction of MoO3 occurs as a result of various factors such as oxygen deficiency. At these OHIs, band bending and formation of interface dipole are observed. It is discovered that the degrees of interface dipole and work function at the OHIs scale linearly as a function of the contacting oxide's work function. These findings provide the guide in designing OHIs for a specific application.

Reductive-annealing-induced changes in Mo valence states on the surfaces of MoO3 single crystals and their high temperature transport

Reduction of MoO3 in extreme reducing condition is a way to achieve Mo metal. However, effect of less extreme reductive-annealing, where it allows to keep the crystal structure, on physical and chemical properties of MoO3 has not been well-studied. In this work, we studied the evolution of Mo valence state during reductive annealing and its effect on high temperature transport. We found the formation of oxygen vacancies on surface of MoO3 single crystals at the low temperature, which is evidenced by increase of Mo5+ and color change. In addition, formation of Mo4+ was at the elevated temperature. For understanding the relation between bulk conductivity and Mo valence state, real-time impedance spectroscopy is employed. Use of two different gases makes it possible to distinguish impedance responses of MoO3 from those of reduced MoO3-x. Also, from time-dependent impedance measurements, we observed the evolution of transport behaviour by evolution of Mo valence state.

Tunability of MoO3 Thin-Film Properties Due to Annealing in Situ Monitored by Hard X-ray Photoemission.

The chemical and electronic structure of MoO3 thin films is monitored by synchrotron-based hard X-ray photoelectron spectroscopy while annealing from room temperature to 310 °C. Color-coded 2D intensity maps of the Mo 3d and O 1s and valence band maximum (VBM) spectra show the evolution of the annealing-induced changes. Broadening of the Mo 3d and O 1s spectra indicate the reduction of MoO3. At moderate temperatures (120–200 °C), we find spectral evidence for the formation of Mo5+ and at higher temperatures (>165 °C) also of Mo4+ states. These states can be related to the spectral intensity above the VBM attributed to O vacancy induced gap states caused by partial filling of initially unoccupied Mo 4d-derived states. A clear relation between annealing temperature and the induced changes in the chemical and electronic structure suggests this approach as a route for deliberate tuning of MoO3 thin-film properties.

Effect of mechanical activation on aluminothermic reduction of molybdenum trioxide

In the present work, two different methods were used to study the effect of mechanical activation on aluminothermic reduction of MoO3. In the first method, a stoichiometric amount of Al + MoO3 and 20% weight percent of aluminum oxide (as the heat absorber) was mixed and mechanically activated by milling process in a planetary ball mill under argon atmosphere. XRD patterns and SEM micrographs of the activated samples indicated that aluminothermic reduction of MoO3 was done in the milling media after 5 h and increasing the milling time, decreased the remaining non reacted Al and MoO3. In the second method, as received MoO3, was mechanically activated in different times in the range of 3 to 24 h. The effect of mechanical activation on molybdenum trioxide grain size was analyzed by Williamson-Hall method, and it was shown that, by increasing the activation time, the grain size and internal strain was reduced and increased, respectively. In the next step, the activated MoO3 powders were mixed with stoichiometric amount of Al and 20 wt% Al2O3 (as the heat absorber) and shaped in the form of cylindrical samples of 10 mm in diameter and height of 15–20 mm by applying 70 MPa uniaxial pressure. Aluminothermic reaction was initiated in the prepared pellets by using conventional microwave oven. The XRD patterns of the combustion products showed that, by mechanical activation of MoO3, the undesired phases of molybdenum dioxide (MoO2) and aluminum molybdate Al2(MoO4)3 was decreased. The aluminothermic reduction of activated MoO3 also was studied by non-isothermal Differential Scanning Calorimetry (DSC) with heating rate of 10 °C min−1 under argon atmosphere. The results showed that by mechanically activating MoO3 for 24 h, the ignition temperature of reduction reaction decreased from 910 to 780 °C and the practical efficiency of the reaction increased from 82.9% (for the nonactivated MoO3) to 92.5%. The comparing results between the milling mixture and the milling molybdenum trioxide indicated that the reaction in mixture cannot be completed during milling and a small amount of Al and MoO3 remained in the activated powder. But for the activated MoO3, and after igniting in a conventional microwave oven the desired reaction went to completion.

Room-temperature H2 gasochromic behavior of Pd-modified MoO3 nanowire labels

Abstract It is great significance to develop an effective eye-readable gas detection technology that would be safe, low-cost, and highly sensitive, serving as a vital complement to traditional H2 sensors. In this work, a class of flexible MoO3 nanowire labels (NWLs) modified with Pd nanoparticles have been successfully developed and studied as eye-readable hydrogen indicators at room-temperature. The nanowire labels turn from white to blue-gray even at a very low concentration (0.1%), where the eye-readable color change takes place in 65 s, and the color changes gradually from white to blue-gray. The reaction of MoO3 nanowire label with hydrogen is of high sensitivity, fast response and time-resolved. The process can be divided into two stages, i.e., fast and slow responses, which are dominated by H2 concentration and intrinsic properties of Pd MoO3, respectively. The color response is also reversible by annealing under air ambient at 200 °C for 2 h, and selective to hydrogen compared with other flammable gases (i.e., CO, CH3CH2OH, CH3OH). The gasochromic NWLs involve Pd-catalyzed reduction of MoO3 in the presence of hydrogen. They also exhibit the superior advantage of being flexible, which have promises applications in efficient eye-readable hydrogen detection.

Fabrication and reduction process of dispersive Er2O3 doped Mo super-fine powders comparing with La2O3 doped Mo powders

It is known that uniformly dispersed rare earth oxide (RE2O3) nanoparticles in molybdenum matrix could improve the ductility of Mo. However, it is reported that the agglomeration of La2O3 was quite serious when the addition amount of La2O3 was over 2 wt%, which leaded to a dramatic decrease of the ductility of Mo. In this paper, a new type of uniformly dispersed Er2O3 doped Mo powder was prepared, with the amount of Er2O3 accounting for 4 wt%. It is found that the reduction temperature of MoO3 was higher and the grain size was smaller for the Mo powders doped with Er2O3 than those doped with La2O3. First-principles calculations illustrate that La2O3/Er2O3 had a strong trend to be absorbed on the surface of MoO3, and the inhibition capability for the reduction of MoO3 to MoO2 by Er3+ was larger than La3+ due to the stronger Er-O interactions. It gives a potential explanation of the higher reduction temperature of MoO3 doped with Er2O3 than that doped with La2O3. Furthermore, the formation energies of Er-O and La-O pairs within the bulk Mo were in the sequence: La-O > Er-O > 0 eV, indicating that these systems are unstable and La2O3 is easier to escape from the interior of Mo grains and agglomerate on the Mo surface than Er2O3.

Size-controlled synthesis of nano Mo powders via reduction of commercial MoO3 with carbon black and hydrogen

In the present work, a novel method was proposed to synthesize pure nano Mo powder via temperature programmed pre-reduction of commercial MoO3 by carbon black, followed by deep deoxidation with hydrogen. It was found that the carbothermal reduction of MoO3 included three stages: MoO3 → MoO2 → MoO2 + Mo2C → Mo. It can be concluded that the morphology and size of the obtained Mo particles are mainly determined at the carbothermic reduction stage. The dispersed nucleation and controlled growth are critical issues for controlling the particle sizes of Mo, which could be achieved at the carbothermic reduction stage by using the raw materials of the MoO3 and carbon black. Whereas, when the MoO3 was directly reduced by hydrogen or active carbon with a larger particle size, or commercial MoO2 were reduced with the carbon black, the dispersed nucleation and controlled growth of products can't be achieved. Meanwhile, to reduce the residual carbon content in the final Mo product, in the carbothermic pre-reduction process, the small amount of MoO2 was kept in the pre-reduced Mo powders, which was removed by hydrogen at the deep deoxidation stage. The content of residual carbon content in the final produced Mo nanopowders can be reduced to about 0.02%. This method has the advantages of simplicity, low cost, and high efficiency. Therefore, it has great potential for the industrial preparation of nano Mo powders in a large-scale.

Temperature-Controlled Vapor Deposition of Highly Conductive p-Type Reduced Molybdenum Oxides by Hydrogen Reduction.

Reduced molybdenum oxide, generally MoO3- x, becomes increasingly metallic as the oxygen level decreases during the reduction of MoO3 to MoO2. Its interesting properties have recently intrigued research on MoO3- x in electrical and electrochemical areas. Lacking effective tools to control the oxygen level is one of the research difficulties for MoO3- x. Herein, we report facile temperature-controlled synthesis of triangular MoO2 and square Mo4O11. The triangular and square flakes showed metallic behavior with conductivity as high as ∼940 and ∼28 S/cm in DC measurement, respectively. The decrease in oxygen level from Mo4O11 to MoO2 affected the density of states mapped in Mo 4d orbitals, leading to higher conductivity for triangular MoO2. Further Mott-Schottky analysis on MoO3- x regrown on carbon fiber paper (CFP) revealed hole mobility of 105-108 cm2 V-1 s-1. The hole carriers at high frequencies are attributed to potential oxygen acceptors, and molybdenum vacancies resulted from limited reduction power of hydrogen.

Fabrication of Mo5SiB2-based composites by combustion synthesis involving aluminothermic reduction of MoO3

Fabrication of Mo5SiB2–Al2O3 composites with a broad range of the Mo5SiB2/Al2O3 ratio was conducted by thermite-based combustion synthesis in the SHS mode. Thermite reagents of MoO3 + 2Al were introduced into two Mo‒Si–B ternary systems adopting amorphous boron and MoB as their respective boron source. The boron-containing samples were more energetic and were applied to produce composites with Mo5SiB2/Al2O3 from 1.25 to 2.5, beyond which combustion was extinct. The composites with Mo5SiB2/Al2O3 from 0.8 to 1.3 were prepared from less exothermic MoB-based samples. Besides causing a decrease in combustion velocity and reaction temperature, the increase of the Mo5SiB2/Al2O3 proportion led to a transformation in combustion wave propagation from a steady to pulsating mode. For the samples featuring a pulsating combustion wave, the reaction time at peak combustion temperatures was extended and then the evolution of Mo5SiB2 from intermediate phases (Mo3Si and MoB) was significantly improved. The deduced activation energy suggests a lower kinetic barrier for thermite-based combustion synthesis to fabricate Mo5SiB2-based composites. The microstructure of synthesized composites indicates that quadrangular Mo5SiB2 grains with an average size of 10–15 µm are tightly packed and irregular Al2O3 grains are randomly dispersed.

Synthesis of few-layer 2H-MoSe2 thin films with wafer-level homogeneity for high-performance photodetector

Abstract The unique structural and physical properties of two-dimensional (2D) atomic layer semiconductors render them promising candidates for electronic or optoelectronic devices. However, the lack of efficient and stable approaches to synthesize large-area thin films with excellent uniformity hinders their realistic applications. In this work, we reported a method involving atomic layer deposition and a chemical vapor deposition chamber to produce few-layer 2H-MoSe2 thin films with wafer-level uniformity. The reduction of MoO3 was found indispensable for the successful synthesis of MoSe2 films due to the low vaporization temperature. Moreover, a metal-semiconductor-metal photodetector (PD) was fabricated and investigated systematically. We extracted an ultrahigh photoresponsivity approaching 101 A/W with concomitantly high external quantum efficiency up to 19,668% due to the produced gain arising from the holes trapped at the metal/MoSe2 interface, the band tail state contribution, and the photogating effect. A fast response time of 22 ms was observed and attributed to effective nonequilibrium carrier recombination. Additionally, the ultrahigh photoresponsivity and low dark current that originated from Schottky barrier resulted in a record-high specific detectivity of up to 2×1013 Jones for 2D MoSe2/MoS2 PDs. Our findings revealed a pathway for the development of high-performance PDs based on 2D MoSe2 that are inexpensive, large area, and suitable for mass production and contribute to a deep understanding of the photoconductivity mechanisms in atomically thin MoSe2. We anticipate that these results are generalizable to other layer semiconductors as well.