Emerging novel applications at the forefront of innovation horizon raise new requirements including good flexibility and unprecedented properties for the photoelectronic industry. On account of ...diversity in transport and photoelectric properties, 2D layered materials have proven as competent building blocks toward next‐generation photodetectors. Herein, an all‐2D Bi2Te3‐SnS‐Bi2Te3 photodetector is fabricated with pulsed‐laser deposition. It is sensitive to broadband wavelength from ultraviolet (370 nm) to near‐infrared (808 nm). In addition, it exhibits great durability to bend, with intact photoresponse after 100 bend cycles. Upon 370 nm illumination, it achieves a high responsivity of 115 A W−1, a large external quantum efficiency of 3.9 × 104%, and a superior detectivity of 4.1 × 1011 Jones. They are among the best figures‐of‐merit of state‐of‐the‐art 2D photodetectors. The synergistic effect of SnS's strong light–matter interaction, efficient carrier separation of Bi2Te3–SnS interface, expedite carrier injection across Bi2Te3–SnS interface, and excellent carrier collection of Bi2Te3 topological insulator electrodes accounts for the superior photodetection properties. In summary, this work depicts a facile all‐in‐one fabrication strategy toward a Bi2Te3‐SnS‐Bi2Te3 photodetector. More importantly, it reveals a novel all‐2D concept for construction of flexible, broadband, and high‐performance photoelectronic devices by integrating 2D layered metallic electrodes and 2D layered semiconducting channels.
An all‐2D flexible Bi2Te3‐SnS‐Bi2Te3 photodetector is successfully fabricated using a facile pulsed‐laser deposition method. It demonstrates multicolor photoresponse from 370 to 808 nm. Its highest responsivity, external quantum efficiency, and detectivity are 115 A W−1, 3.9 × 104%, and 4.1 × 1011 Jones, rivaling state‐of‐the‐art 2D photodetectors. The finding reveals an all‐2D concept for next generation photoelectronic devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We have synthesized the hybrid supercapacitor electrode of Co3O4 nanoparticles on vertically aligned graphene nanosheets (VAGNs) supported by carbon fabric. The VAGN served as an excellent backbone ...together with the carbon fabric, enhancing composites to a high specific capacitance of 3480 F/g, approaching the theoretical value (3560 F/g). A highly flexible all-solid-state symmetric supercapacitor device was fabricated by two pieces of our Co3O4/VAGN/carbon fabric hybrid electrode. The device is suitable for different bending angles and delivers a high capacitance (580 F/g), good cycling ability (86.2% capacitance retention after 20 000 cycles), high energy density (80 Wh/kg), and high power density (20 kW/kg at 27 Wh/kg). These excellent electrochemical performances, as a result of the particular structure of VAGN and the flexibility of the carbon fabric, suggest that these composites have an enormous potential in energy application.
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IJS, KILJ, NUK, PNG, UL, UM
To maximize the performance of photocatalytic hydrogen production, photocatalysts need to be modified by various means such as energy band engineering and cocatalyst. Here, we propose a strategy of ...self-integrated effects for promoting photocatalysts performance. We firstly design and fabricate a 2D ZnIn2S4 and amorphous Mo2C nanoparticles composite photocatalyst by integrating heterojunction effect, cocatalyst effect and photothermal effect in one, and then demonstrate that self-integrated effects of Mo2C/ZnIn2S4 composite can greatly enhance photocatalytic hydrogen evolution. Based on in situ characterization techniques and theoretical calculations, we also establish that the photocatalytic mechanism of self-integrated effects consisting heterojunction effect, cocatalyst effect and photothermal effect is attributed to the increased absorption capacity, the enhanced carrier separation, the reduced ΔGH*, the more active sites, the increased electron density and the enhanced carrier's mobility. Especially, the contribution of photothermal effect can elevate temperature to accelerate the photocatalytic reaction and the photothermal contribution exceeds 100% under irradiation. Consequently, 2D ZnIn2S4/amorphous Mo2C nanoparticles has a remarkable photocatalytic hydrogen evolution rate respectively up to 22.11 and 40.93 mmol/g/h upon visible and AM1.5 illumination, promoting 164% and 156% for the available values reported of modified ZnIn2S4 photocatalysts so far. These findings suggest that the proposed self-integrated effects can greatly promote photocatalytic hydrogen production.
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•2D ZnIn2S4/amorphous Mo2C nanoparticles photocatalyst with self-integration effects was designed.•Mo2C/ZnIn2S4 exhibited a remarkable photocatalytic hydrogen evolution rate.•In situ characterization techniques were developed to clarify the photocatalytic mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Semiconductor photocatalysis for hydrogen production is a promising route to address current energy demands. It is still a great challenge to spatially separate photogenerated electrons and holes in ...bulk photocatalysts because of the long carrier transport pathway from the bulk to the surface. 2D heterostructured photocatalysts with the type II band alignment can not only shorten the carrier transport pathway, but also create an electric field at the interface to suppress the carrier recombination. However, ultrathin and intimate-contact 2D heterostructured photocatalysts have rarely been achieved so far. Herein, we reported that ZnIn2S4 nanosheets were self-assembled on few-layer MoS2 nanosheets to fabricate ultrathin and intimate-contact 2D heterostructured photocatalysts. This 2D heterostructure was formed thanks to the strong electrostatic adsorption between MoS2 and ZnIn2S4. Under visible light irradiation, the H2 evolution rate of 2D MoS2/ZnIn2S4 heterostructured photocatalysts can reach 8898 μmol g−1 h−1, which is almost 16 times higher than that of the pure ZnIn2S4 photocatalysts. The dramatically enhanced photocatalytic performance was ascribed to the better charge separation and the accelerated surface reaction due to the heterostructure and more active sites provided by MoS2. These results provided a new insight for the design and development of 2D heterostructured photocatalysts.
Amorphous materials are usually evaluated as photocatalytically inactive due to the amorphous nature-induced self-trapping of tail states, in spite of their achievements in electrochemistry. NiO ...crystals fail to act as an individual reactor for photocatalytic H2 evolution because of the intrinsic hole doping, regardless of their impressive cocatalytic ability for proton/electron transfer. Here we demonstrate that two-dimensional amorphous NiO nanostructure can act as an efficient and robust photocatalyst for solar H2 evolution without any cocatalysts. Further, the antenna effect of surface plasmon resonance can be introduced to construct an incorporate antenna-reactor structure by increasing the electron doping. The solar H2 evolution rate is improved by a factor of 19.4 through the surface plasmon resonance-mediated charge releasing. These findings thus open a door to applications of two-dimensional amorphous NiO as an advanced photocatalyst.
The successful peeling of graphene heralded the era of van der Waals material (vdWM) electronics. However, photodetectors based on semiconducting transition metal dichalcogenides (TMDs), formulated ...as MX2 (M = Mo, W; X = S, Se), often suffer either poor responsivity or long response time because of their high density of deep-level defect states (DLDSs). Alloy engineering, which can shift the DLDSs to shallow-level defect states, is proposed to be an efficient strategy to solve this problem. However, proof-of-concept is still lacking, which is probably because of the absence of a facile technology to grow high-quality alloyed TMDs. Here, we report the growth of large-scale and high-quality Mo0.5W0.5S2 alloy films via pulsed laser deposition (PLD). We demonstrate that the resulting Mo0.5W0.5S2 photodetector possesses a stable photoresponse from 370 to 1064 nm. The photocurrent exhibits positive dependence on both the source–drain voltage and incident power density, providing good tunability for multifunctional photoelectrical applications. We also establish that, because of the suppression of DLDSs with alloy engineering, the Mo0.5W0.5S2 photodetector achieves a good responsivity of 5.8 A/W and a response time shorter than 150 ms. The working mechanism for the suppression of DLDSs in Mo0.5W0.5S2 is unveiled by qualitatively analyzing the alloying-dressed band structure. In conclusion, the excellent performance of the PLD-grown Mo0.5W0.5S2 photodetector may pave the way for next-generation photodetection. The approach shown here represents a fundamental and universal scenario for the development of alloyed TMDs.
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IJS, KILJ, NUK, PNG, UL, UM
Broadband photodetection is central to various technological applications including imaging, sensing and optical communications. On account of their Dirac-like surface state, Topological insulators ...(TIs) are theoretically predicted to be promising candidate materials for broadband photodetection from the infrared to the terahertz. Here, we report a vertically-constructed ultra-broadband photodetector based on a TI Bi2Te3-Si heterostructure. The device demonstrated room-temperature photodetection from the ultraviolet (370.6 nm) to terahertz (118 μm) with good reproducibility. Under bias conditions, the visible responsivity reaches ca. 1 A W(-1) and the response time is better than 100 ms. As a self-powered photodetector, it exhibits extremely high photosensitivity approaching 7.5 × 10(5) cm(2) W(-1), and decent detectivity as high as 2.5 × 10(11) cm Hz(1/2) W(-1). In addition, such a prototype device without any encapsulation suffers no obvious degradation after long-time exposure to air, high-energy UV illumination and acidic treatment. In summary, we demonstrate that TI-based heterostructures hold great promise for addressing the long lasting predicament of stable room-temperature high-performance broadband photodetectors.
2D layered materials (2DLMs) have come under the limelight of scientific and engineering research and broke new ground across a broad range of disciplines in the past decade. Nevertheless, the ...members of stoichiometric 2DLMs are relatively limited. This renders them incompetent to fulfill the multitudinous scenarios across the breadth of electronic and optoelectronic applications since the characteristics exhibited by a specific material are relatively monotonous and limited. Inspiringly, alloying of 2DLMs can markedly broaden the 2D family through composition modulation and it has ushered a whole new research domain: 2DLM alloy nano‐electronics and nano‐optoelectronics. This review begins with a comprehensive survey on synthetic technologies for the production of 2DLM alloys, which include chemical vapor transport, chemical vapor deposition, pulsed‐laser deposition, and molecular beam epitaxy, spanning their development, as well as, advantages and disadvantages. Then, the up‐to‐date advances of 2DLM alloys in electronic devices are summarized. Subsequently, the up‐to‐date advances of 2DLM alloys in optoelectronic devices are summarized. In the end, the ongoing challenges of this emerging field are highlighted and the future opportunities are envisioned, which aim to navigate the coming exploration and fully exert the pivotal role of 2DLMs toward the next generation of electronic and optoelectronic devices.
A comprehensive overview on the synthesis of 2D layered material alloys, as well as, the corresponding electronic and optoelectronic devices is provided. In addition, the ongoing challenges are highlighted and the future opportunities are envisioned, which aim to navigate the coming exploration and fully exert the pivotal role of 2D materials toward the next generation of electronic and optoelectronic devices.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Because of their great potential for academic investigation and practical application in next-generation optoelectronic devices, ternary layered semiconductors have attracted considerable attention ...in recent years. Similar to the applications of traditional layered materials, practical applications of ternary layered semiconductor alloys require the synthesis of large-area samples. Here, we report the preparation of centimeter-scale and high-quality Mo0.5W0.5Se2 alloy films on both a rigid SiO2/Si substrate and a flexible polyimide (PI) substrate. Then, photodetectors based on these alloy films are fabricated, which are capable of conducting broad-band photodetection from ultraviolet to near-infrared region (370–808 nm) with high performance. The photodetector on SiO2/Si substrates demonstrates a high responsivity (R) of 77.1 A/W, an outstanding detectivity (D*) of 1.1 × 1012 Jones, and a fast response time of 8.3 ms. These figures-of-merit are much superior to those of the counterparts of binary material-based devices. Moreover, the photodetector on PI substrates also achieves high performance (R = 63.5 A/W, D* = 3.56 × 1012 Jones). And no apparent degradation in the device properties is observed even after 100 bending cycles. These results make Mo0.5W0.5Se2 alloy a highly qualified candidate for next-generation optoelectronic applications.
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IJS, KILJ, NUK, PNG, UL, UM
Molybdenum-containing and selenium-containing enzymes are generally prevalent in the biosphere, and the active sites of these involve molybdenum and selenium respectively. Herein, we for the first ...time demonstrated that few-layered molybdenum selenide (MoSe2) nanosheets possess intrinsic peroxidase-like activity. The few-layered MoSe2 nanosheets were prepared by a simple liquid exfoliation method. The catalytic process of the MoSe2 nanosheets accords with the Michaelis–Menten behavior and they have a higher affinity to both TMB and H2O2 compared to HRP. In addition, we established that the MoSe2 nanosheets catalyze the oxidation of TMB by promoting the electron transfer process from TMB to H2O2. More importantly, we applied the MoSe2 nanosheets to the field of biological detection by developing a highly sensitive and selective colorimetric detection of H2O2 and xanthine concentration. With these advantages, the few-layered MoSe2 nanosheets have critical potential in the diagnostics and biomedical fields.
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