/Tag: PtS2

Wafer-scale fabrication of 2D van der Waals heterojunctions for efficient and broadband photodetection. (arXiv:1803.04695v1 [cond-mat.mes-hall])

2018-03-14T19:59:00+00:00March 14th, 2018|Categories: Publications|Tags: , , , |

A variety of fabrication methods for van der Waals heterostructures have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we report few-layer van der Waals PtS2/PtSe2 heterojunction photodiodes fabricated on a 2″ SiO2/Si substrate that is only limited by the size of work chamber of the growth equipment, offering throughputs necessary for practical applications. Theoretical simulation results show that the bandgap of PtS2 is shrunk to half of its original size in the PtS2/PtSe2 heterostructures, while PtSe2 exhibits a limited response to the coupling. Both PtSe2 and PtS2 layers in the coupled system are still semiconductors. Dynamic photovoltaic switching in the heterojunctions is observed at zero-volt state under laser illuminations of 532 to 2200 nm wavelengths. The PtS2/PtSe2 photodiodes show excellent characteristics in terms of a high photoresponsivity of 361 mAW-1, an external quantum efficiency (EQE) of 84%, and a fast response speed (66 ms). The wafer-scale production of 2D photodiodes in this work accelerates the possibility of 2D materials for practical applications in the next-generation energy-efficient electronics.

Published : "arXiv Mesoscale and Nanoscale Physics".

Fast, Self-Driven, Air-Stable, and Broadband Photodetector Based on Vertically Aligned PtSe2/GaAs Heterojunction

2018-02-16T08:28:42+00:00February 16th, 2018|Categories: Publications|Tags: , |

Abstract Group-10 layered transitional metal dichalcogenides including PtS2, PtSe2, and PtTe2 are excellent potential candidates for optoelectronic devices due to their unique properties such as high carrier mobility, tunable bandgap, stability, and flexibility. Large-area platinum diselenide (PtSe2) with semiconducting characteristics is far scarcely investigated. Here, the development of a high-performance photodetector based on vertically aligned PtSe2-GaAs heterojunction which exhibits a broadband sensitivity from deep ultraviolet to near-infrared light, with peak sensitivity from 650 to 810 nm, is reported. The Ilight/Idark ratio and responsivity of photodetector are 3 × 104 and 262 mA W−1 measured at 808 nm under zero bias voltage. The response speed of τr/τf is 5.5/6.5 µs, which represents the best result achieved for Group-10 TMDs based optoelectronic device thus far. According to first-principle density functional theory, the broad photoresponse ranging from visible to near-infrared region is associated with the semiconducting characteristics of PtSe2 which has interstitial Se atoms within the PtSe2 layers. It is also revealed that the PtSe2/GaAs photodetector does not exhibit performance degradation after six weeks in air. The generality of the above good results suggests that the vertically aligned PtSe2 is an ideal material for high-performance optoelectronic systems in the future. This work shows the large-area growth of high-quality vertically aligned PtSe2, and its application to photodetectors based on PtSe2-GaAs heterojunctions which exhibit a broadband sensitivity to illumination ranging from deep ultraviolet to near-infrared light, with a peak sensitivity in the region from 650 to 810 nm. The high-performance broadband photodetector will develop the

Published in: "Advanced Functional Materials".

Nitrogen-Doped Single Graphene Fiber with Platinum Water Dissociation Catalyst for Wearable Humidity Sensor

2018-02-14T16:32:51+00:00February 14th, 2018|Categories: Publications|Tags: , , |

Abstract Humidity sensors are essential components in wearable electronics for monitoring of environmental condition and physical state. In this work, a unique humidity sensing layer composed of nitrogen-doped reduced graphene oxide (nRGO) fiber on colorless polyimide film is proposed. Ultralong graphene oxide (GO) fibers are synthesized by solution assembly of large GO sheets assisted by lyotropic liquid crystal behavior. Chemical modification by nitrogen-doping is carried out under thermal annealing in H2(4%)/N2(96%) ambient to obtain highly conductive nRGO fiber. Very small (≈2 nm) Pt nanoparticles are tightly anchored on the surface of the nRGO fiber as water dissociation catalysts by an optical sintering process. As a result, nRGO fiber can effectively detect wide humidity levels in the range of 6.1–66.4% relative humidity (RH). Furthermore, a 1.36-fold higher sensitivity (4.51%) at 66.4% RH is achieved using a Pt functionalized nRGO fiber (i.e., Pt-nRGO fiber) compared with the sensitivity (3.53% at 66.4% RH) of pure nRGO fiber. Real-time and portable humidity sensing characteristics are successfully demonstrated toward exhaled breath using Pt-nRGO fiber integrated on a portable sensing module. The Pt-nRGO fiber with high sensitivity and wide range of humidity detection levels offers a new sensing platform for wearable humidity sensors. Nitrogen-doped graphene fiber functionalized by Pt nanoparticles (Pt-nRGO fiber) is integrated on a flexible and transparent polyimide substrate for application in real-time and on-site monitoring of humidity. This work demonstrates the humidity sensing characteristic of Pt-nRGO fiber, which further expands versatility of graphene-based fiber in wearable sensing electronics.

Published in: "Small".

Pt decorated MoS 2 nanoflakes for ultrasensitive resistive humidity sensor

2018-02-06T16:30:40+00:00February 6th, 2018|Categories: Publications|Tags: , |

In this work, we report the fabrication of a low power, humidity sensor where platinum nanoparticles (NPs) decorated few-layered molybdenum disulphide (MoS 2 ) nanoflakes have been used as the sensing layer. A mixed solvent was used to exfoliate the nanoflakes from the bulk powder. Then the Pt/MoS 2 composites were prepared by reducing Pt NPs from chloroplatinic acid hexahydrate using a novel reduction technique using sulphide salt. The successful reduction and composite preparation were confirmed using various material characterization tools like scanning electron microscopy, atomic force microscopy, transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy and UV–visible spectroscopy. The humidity sensors were prepared by drop-coating the Pt-decorated MoS 2 on gold interdigitated electrodes and then exposed to various levels of relative humidity (RH). Composites with different weight ratios of Pt were…

Published in: "Nanotechnology".

Architecting Graphene Oxide Rolled-Up Micromotors: A Simple Paper-Based Manufacturing Technology

2017-11-24T12:31:24+00:00November 24th, 2017|Categories: Publications|Tags: , , |

Abstract A graphene oxide rolled-up tube production process is reported using wax-printed membranes for the fabrication of on-demand engineered micromotors at different levels of oxidation, thickness, and lateral dimensions. The resultant graphene oxide rolled-up tubes can show magnetic and catalytic movement within the addition of magnetic nanoparticles or sputtered platinum in the surface of graphene-oxide-modified wax-printed membranes prior to the scrolling process. As a proof of concept, the as-prepared catalytic graphene oxide rolled-up micromotors are successfully exploited for oil removal from water. This micromotor production technology relies on an easy, operator-friendly, fast, and cost-efficient wax-printed paper-based method and may offer a myriad of hybrid devices and applications. A graphene oxide rolled-up tube production process is presented using wax-printed membranes for the fabrication of micromotors. The resultant graphene oxide rolled-up tubes show magnetic and catalytic movement within the addition of magnetic nanoparticles or sputtered platinum in the surface of graphene oxide before the scrolling process. These micromotors are successfully exploited for oil removal from water.

Published in: "Small".

Robust quasi-ohmic contact against angle rotation in noble transition-metal-dichalcogenide/graphene heterobilayers

2017-09-26T14:28:54+00:00September 26th, 2017|Categories: Publications|Tags: , |

RSC Adv., 2017, 7,45896-45901DOI: 10.1039/C7RA09945B, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Siyao Hou, Lihong Han, Liyuan Wu, Ruge Quhe, Pengfei LuSmall Schottky barriers appear in PtS2/graphene and PdS2/graphene against interlayer rotation angles.The content of

Published in: "RSC Advances".

Electrochemistry: Development and Simulation of Sulfur-doped Graphene Supported Platinum with Exemplary Stability and Activity Towards Oxygen Reduction (Adv. Funct. Mater. 27/2014)

2016-10-15T13:08:39+00:00July 14th, 2014|Categories: Publications|Tags: , |

By Drew Higgins, Md Ariful Hoque, Min Ho Seo, Rongyue Wang, Fathy Hassan, Ja-Yeon Choi, Mark Pritzker, Aiping Yu, Jiujun Zhang, Zhongwei Chen

Thumbnail image of graphical abstract

Unique sulfur-doped graphene-supported platinum nanoparticles prepared by Z. Chen and co-workers provide excellent oxygen reduction activity and stability, rendering them highly attractive electrode materials for fuel cell applications. On page 4325, the enhancements arise due to specific interactions between the sulfur dopant atoms and the platinum nanoparticles, leading to a “tethering” effect that increases the stability and modulates the electronic properties that improve the activity.

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Via: Advanced Functional Materials

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