Shanpeng Wen

Visible-light photodetector with enhanced performance based on a ZnO@CdS heterostructure

In this article, the heterostructure of ZnO particles on single-crystal CdS nanowires (ZnO@CdS) has been successfully synthesized via a facile two-step solvothermal process. The appealing application of the ZnO@CdS heterostructure as visible-light photodetector (PD) is presented. Photocurrent illuminated with light (shorter than 510 nm) to dark-current ratio of structurally-optimized ZnO@CdS nanomaterials based photon detector was enhanced significantly compared to the value of the pristine CdS nanowires based one. The corresponding mechanism for the phenomenon was discussed. Additionally, measurements of time resolved responses were conducted. The ZnO@CdS heterostructure based device kept a fast rise (5 ms) and decay (10 ms) speed to irradiation. This work demonstrates a promising application of ZnO@CdS heterostructure based visible-light detectors with high photocurrent/dark-current ratio, ultrafast time response and very good stability.

Special nanostructure control of ethanol sensing characteristics based on Au@In2O3 sensor with good selectivity and rapid response

A unique Au@In2O3 core–shell nanostructure was firstly prepared through a simple sol–gel method, the structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The results showed that unique architectures were core–shell nanostructure assembled from an Au core and an In2O3 shell. The gas sensing properties of the as-prepared pure In2O3 and Au@In2O3 core–shell samples were tested toward various gases. The sensor based on a Au@In2O3 core–shell nanostructure showed excellent selectivity toward ethanol at the operating temperature of 160 °C, giving a response of about 36.14 to 100 ppm, which was about 1.5 times higher than that of the sensor based on pure In2O3. The τres and the τrec values of the Au@In2O3 sensor to 100 ppm ethanol were 4 s and 2 s respectively, while those of the pure In2O3 sensor were relatively long. The enhancement might be attributed to the unique core–shell structure and existence of a Schottky junction between Au/In2O3.

A new type of acetylene gas sensor based on a hollow heterostructure

A new type of acetylene gas sensor based on the hollow NiO/SnO2 heterostructure synthesized by a two-step hydrothermal method followed by calcination was fabricated. The properties of the sensing material were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) and transmission electron microscopy (TEM). The acetylene gas-sensing performances were investigated. Compared with the pure SnO2 gas sensor, the response of the hollow NiO/SnO2 heterostructure gas sensor to 100 ppm acetylene (C2H2) was raised to 13.8 from 5.4 at the optimum operating temperature of 206 °C. A wide detection range from 1 to 1000 ppm and a low minimum detection limit of 1 ppm were obtained. In addition, the hollow NiO/SnO2 heterostructure gas sensor had a good repeatability, selectivity, stability and rapid response–recovery characteristics.

Three dimensions sphere formaldehyde nanosensor applications: preparation and sensing properties

Zn@SnO2 microspheres with hierarchical structure were prepared through a simple solvothermal method; the structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) showing the materials with extraordinary 3D nanoarchitectures. The gas sensing properties of the as-prepared pure SnO2 and Zn-doped SnO2 were tested toward various gases. The results showed that the SnO2 sensor with 6.67 wt% Zn-doping displayed an excellent selectivity toward formaldehyde at the operating temperature 160 °C, which was considerably lower than most formaldehyde sensors in heater type among previous reports, in addition to giving a response of about 15.2 to 100 ppm, which is about 2.1 times higher than that of sensors based on pure SnO2. The τres and the τrec values of the 6.67 wt% Zn-doped SnO2 sensor to 100 ppm formaldehyde were 2 s and 2 s respectively, demonstrating extraordinary gas sensing properties, whereas those of the pure SnO2 sensor were relatively long. The enhancement might be attributed to the unique morphology and increased oxygen vacancy due to the Zn doping.