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The capabilities to manipulate light-matter interaction at the nanoscale lie at the core of many promising photonic applications. Optical nanoantennas, made of metallic or dielectric materials, have seen a rapid development for their remarkable optical properties facilitating the coupling of electromagnetic waves with subwavelength entities. However, high-throughput and cost-effective fabrication of these nanoantennas is still a daunting challenge. In this work, we provide a versatile nanofabrication method capable of producing large scale optical nanoantennas with different shapes. It is developed from colloidal lithography with no dry etching required. Furthermore, both metallic and all-dielectric nanoantennas can be readily fabrication in a high-throughput fashion. Au and Si nanodisks were fabricated and employed to assemble heterostructures with monolayer tungsten disulfide. Strong coupling is observed in both systems between plasmon modes (Au nanodisks) or anapole modes (Si nanodisks) with excitons. We believe that this nanofabrication method could find a wide range of applications with the diverse optical nanoantennas it can engineer.

Constructing mixed dimensional materials have been regarded as an outstanding approach to maximum the advantages from materials of different dimensions. In this work, we prepared a mixed dimensional photocatalyst based on Formamidinium lead bromide (FAPbBr3 ) perovskite and 2D materials (2DMs). The aim of this work is to utilize distributions of the active sites in 2DMs, through growing FAPbBr 3 on the different position of 2DMs, the concentration of photogenerated charges is manipulated, thus conducting different reactions. A pre-treatment using HBr to increase the unsaturated bonds in MoS2 presents significant influence on the FAPbBr3 growth and its photocatalytic product. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) confirm that the perovskite nanoparticles were well loaded on the 2D materials. The photocatalytic process and the heterojunction arrangement are demonstrated by X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence (TRPL), electron paramagnetic resonance (EPR) and surface photovoltage microscopy (SPVM). By adjusting the weight ratios and growth of FAPbBr3 on the top of 2DMs, the optimized composite photocatalyst (with 30 wt% of FAPbBr3) exhibits remarkable photoactivity for oxidation of benzyl alcohol into benzaldehyde (30 wt% FAPbBr3@WS2 performed 75.9% conversion in 4 h, approximately 9-fold than the pure 2DMs). Meanwhile, by growing FAPbBr3 on the edge of 2DMs, benzoic acid is obtained as the product. Although longer reaction time is needed, the photocatalyst performs outstanding activity (30 wt% FAPbBr 3@MoS2 reached 84.5% conversion in 5 h).

In the past few decades, a variety of red phosphors have been designed and developed. However, most of them are not satisfying for the sake of low brightness and poor thermal stability. Here, we report the preparation and luminescence properties of a promising red phosphor Mg3Y2Ge3O12: Bi3+, Eu3+. Eu3+ singly doped samples can emit bright reddish light. In Bi3+ and Eu3+ co-doped samples, there exists effective energy transfer from Bi3+ to Eu3+. The co-doping of Bi3+ can remarkably enhance the luminescence of Eu3+. The integrated emission intensity of Mg3Y1.19Ge3O12: 0.01Bi3+, 0.8Eu3+ is greater than that of commercial red phosphor Y2O3: 0.05Eu3+. More importantly, the luminescence of this phosphor also shows excellent thermal stability and relatively high quantum efficiency (63.89%). When the ambient temperature rises to 423 K, the integrated emission intensity remains 94.42% of the one at room temperature and quantum efficiency still remains 51.24%. All these investigation results prove that Mg3Y2Ge3O12: Bi3+, Eu3+ is a promising red phosphor for white light-emitting diodes.

In recent years, photodetectors have very important applications in image sensing, optical communication, fire detection, environmental monitoring, space detection, safety detection, many other scientific research and industrial technology fields, which are regarded as the key components of wearable devices. Due to its great carrier mobility, high absorption coefficient and relatively narrower bandgap engineering, various of photodetector based on 2D group IVA metal chalcogenides, the corresponding ternary alloys and the heterostructures have been reported. Importantly, most of them basically have excellent performance of photodetecting properties, such as large photocurrent, high detectivity, perfect responsivity, high external quantum efficiency, short response and recovery time, broadband photo adsorption and response from ultraviolet to mid infrared range. Moreover, this group of semiconductors is made up of earth-abundant and environmental-friendly elements with prominent chemical stability, which makes them particularly attractive for practical optic electronic applications. Therefore, this concept introduces the recent advances on the materials, synthesis, device fabrication and photodetection mechanism for various of 2D group IVA metal chalcogenides photodetector from an overall perspective. Moreover, challenges and future development trends are discussed.

Two-dimensional layers of metal dichalcogenides have attracted much attention because of their ultrathin thickness and potential applications in electronics and optoelectronics. In this regard, we further explore the optoelectronic properties of monolayer MoS2 synthesized by chemical vapor deposition on sapphire substrate and contacted the Au electrode by lithographie method for applications in photodetectors. The device exhibits broadband photoresponse (UV–Vis-NIR), a lower subthreshold swing (0.5 V), higher detectivity (1010 Jones) and superior responsivity (0.0084 A/W). We believe that this work provides important scientific insights for photoelectric response properties of emerging atomically layered 2D materials for optoelectronic applications.

ispartof: MATERIALS & DESIGN vol:215 status: published

Structural and electronic properties of graphdiyne/MoS2 van der Waals (vdW) heterostructure under external electric field are investigated by first-principle calculations for the first time. The direct bandgap of graphdiyne/MoS2 heterostructure can be significantly modulated by the electric field, and a transition from semiconductor to metal is observed. It is demonstrated that the graphdiyne/MoS2 bilayer transfers from type-I to type-II heterostructure under a certain electric field, leading to the spatial separation of the lowest energy electron-hole pairs, which is beneficial to photodetection and solar energy conversion. The calculation results pave the way for applications of graphdiyne/MoS2 heterostructure in future micro-/nano- electronics and photoelectronics.

With the rapid development of photocatalysis field, photocatalysts have received increasing attention due to their important role in environmental pollution and energy crisis. As a nonmetallic polymeric material, graphite carbon nitride (g-C3N4) is rich in sources and its preparation is simple, and thus has been widely used as a visible-light-responsive photocatalyst. In this review, we have summarized the recent progress related to the design, modification, and construction of g-C3N4 based photocatalysts with excellent photocatalytic performances. First, we have described the basic structure and properties of g-C3N4. Thereafter, we have pointed out that the defects of pristine g-C3N4 and illustrated the general design principles for all of modified strategies. Subsequently, we have discussed various strategies to optimize the photocatalytic properties of g-C3N4 in detail, including constructing Z-scheme heterojunctions based on g-C3N4, morphological controlling, metal deposition, ion doping, dye sensitization, quantum dots modification, and acid treatment. Particularly, we have comprehensively explicated the critical factors governing the performance of the photocatalyst and the enhanced photocatalytic mechanisms of each modification strategy with examples. Finally, we have indicated the challenges of photocatalysis technology using g-C3N4 and proposed the opportunities for further development.

Gas sensors play a vital role on many aspects in our society, and have gained much progress, propelled by the development of nanoscience and nanotechnology. In this regard, metal oxides with heterojunctions have attracted tremendous attention owing to their enhanced gas sensing properties. Herein, belt-tooth shape ZnO/In2O3 nano-heterostructures has been achieved through a chemical vapor deposition process. The gas sensor fabricated from the as-prepared nano-heterostructures exhibits superior sensing performances for C2H2 gas at low operating temperature (90 °C). Moreover, the Au decorated ZnO/In2O3 nano-heterostructures (Au-ZnO/In2O3) exhibit enhanced C2H2 sensing properties such as higher response, less response time, better selectivity and smaller deviation from the ideal value of power exponent. More significantly, the response to C2H2 gas is maintained well in 30 days, indicating good long-term stability. In addition, both the potential-barrier-controlled carrier transport model combining with the surface depletion model and the unique properties of Au are presented to describe the C2H2 gas sensing mechanism of Au-ZnO/In2O3. This study offers an innovative methodology to design novel gas sensing materials and enhance gas sensing performances.

The mixed dimensional materials, especially 0D/2D mixed materials have been regarded as outstanding candidates for photodetector and photovoltaic devices, while have rarely been utilized for photocatalytic reactions including photosynthesis, water splitting and CO2 reduction. In this work, a mixed dimensional material composited by cubic 0D CsPbBr3 perovskite quantum dots (PQDs) and cubic 2D-PbS is prepared for reduction of CO2 to fuels. The PQDs, as light-harvesting components, are homogeneously grown on the 2D-PbS nano-substrate which is employed for electron transport. The same cubic crystal structures and rather small lattice mismatch ( Δ d / d CsPbBr 3 = 0.84 % ) between CsPbBr3 and PbS guarantee easy in-situ growth of PQDs on PbS nano-substrate and rapid electron migration. As a result, an improved photocurrent is obtained based on the combination of the advantages of 0D and 2D materials. In addition, the size of PQDs synthesized on the 2D-PbS is dramatically reduced in comparison to that synthesized in solvent, thus endowing them wider bandgap and greater potential enough for the photocatalytic reactions. This PQDs/2D-PbS mixed dimensional materials exhibit outstanding selectivity (over 99%) and activity (yield 81.6 and 52.7 μmol g−1) for reducing CO2 to CO and CH4, from which the CH4 yielded is ca. 9-fold than that of pure PQDs.

Most gas sensors are fabricated from semiconducting metal oxides or two-dimensional nanomaterials. This study demonstrates a visible-light-driven room-temperature gas sensor made of novel carbyne nanocrystals. Carbyne nanocrystals were synthesized by laser ablation in liquids. X-ray diffraction showed that the nanocrystals were monocrystalline. Scanning electron microscopy and transmission electron microscopy revealed that they were stacked flakes consisting of rod-like crystals approximately 10 nm wide and 50–100 nm long. Under illumination by 447 nm light, a sensor containing the nanocrystals detected NO2 molecules at concentrations as low as 2 ppm at room temperature, with response and recovery times of less than 100 s. The light-driven sensing was attributed to the fluorescence emission of the carbyne nanocrystals. The device also exhibited good selectivity and stability. First-principles calculations showed that the carbyne nanocrystals had a high adsorption energy for NO2 molecules and low adsorption energies for other gases, resulting in sensitive NO2 detection. These findings demonstrate the potential of carbyne nanocrystals for use as a gas sensing material.

Eupatorium adenophorum was converted into a high-quality activated carbon (EAAC) and hydrogen rich fuel gas via steam activation. The process variables including activation temperature, activation duration and steam flow rate on the adsorption capability and activated carbon yield were identified. Additionally the surface characteristics of EAAC were characterized by nitrogen adsorption isotherms, FTIR and SEM. The operating variables were optimized utilizing the response surface methodology and were identified to be an activation temperature of 950 °C, an activation duration of 60 min and a steam flow rate of 1.2 ml/min with a iodine adsorption capacity of 1031 mg/g and yield of 25%. The key parameters that characterize quality of the porous carbon such as the BET surface area, total pore volume and average pore diameter were estimated to be 1357 m 2 /g, 1.1 ml/g and 3.31 nm, respectively. The heating value of fuel gases evolved during the process of activation at optimized process conditions were estimated to be 10.27 MJ/m 3 , with the major components being H 2 and CO. A high heating value well augurs its utility as a heat source for the whole process which would significantly alter the commercial manufacturing economy.

Our review provides a comprehensive overview on the latest progress in pulsed-laser deposition (PLD) of 2D layered materials (2DLMs), and its application in photoelectric detection. We begin with a retrospective overview on various 2DLMs and their development in photoelectric detection. Then we present the fundamentals of PLD and its unique advantages compared with the traditional growth methods. Subsequently, the PLD growth of 2DLMs and the influence of various parameters are discussed. After this, we describe the current metal-semiconductor-metal and vertical heterojunction photodetectors that incorporate the PLD-grown 2DLMs. This leads into a summary of the strategies used to improve the photosensitivity and in-depth insights into the working mechanism. We then present the PLD-fabricated transparent and flexible 2DLM photodetectors. Finally, we highlight the unresolved issues and propose the future directions in this emerging research field.