Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

C-doped and N-doped reduced graphene oxide/TiO2 composites with exposed (0 0 1) and (1 0 1) facets controllably synthesized by a hydrothermal route and their gas sensing characteristics

Abstract: Element doping and controllably facet exposing are efficient solutions for enhancing gas sensing performances of TiO2 nanomaterials. In this study, C-doped and N-doped reduced graphene oxide/TiO2 composites with special exposed facets C-RGO/TiO2 (with HF) and N-RGO/TiO2 (with HF) were controllably synthesized via a hydrothermal method using HF as the morphology-controlling agent at 180 °C for 12 h. The as-prepared composites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other measurements. Their gas sensing results demonstrate that the gas sensing performance of N-RGO/TiO2 (with HF) is much better than that of C-RGO/TiO2 (with HF), such as higher sensitivity, and shorter response and recovery time. The sensor based on N-RGO/TiO2 (with HF) exhibits the highest gas response toward isopropanol, ethanol, and acetone at a working temperature of 210, 240, and 270 °C, respectively. The lowest detection of these gases was 1 ppm. The gas sensing mechanism was also carefully analyzed. The TiO2 particles of composite with exposed facets generate electron–hole pairs efficiently. The N element dopant plays the roles of narrowing the band gap of TiO2 based composite, and strengthening the chemical binding between N-RGO and TiO2, which is of benefit to charge separation and electron mobility.

IGZO nanoparticle-modified silicon nanowires as extended-gate field-effect transistor pH sensors

Abstract: A high aspect ratio silicon nanowire (SiNW) sensing membrane modified with amorphous indium–gallium–zinc–oxide nanoparticles (IGZO NPs) was developed for use in extended-gate field-effect transistor (EGFET) pH sensors. The IGZO/SiNWs sensing membranes were first fabricated using the Ag-assisted electroless etching technique and were then decorated with IGZO NPs by sputtering in five separate batches for 3, 6, 9, 12 and 15 min to improve the pH sensing properties. SEM, TEM and FTIR spectroscopy were used to respectively analyze surface morphology, crystallinity and chemical binding. The IGZO NPs provided more oxygen-related binding sites than the pristine SiNWs to adsorb additional H + ions, thus effectively improving pH sensitivity. The 9 min IGZO/SiNW sensor exhibited the best sensitivity of 50 mV/pH, an improvement of about 39% over that of the pristine SiNW sensor (36 mV/pH). The IGZO/SiNW sensor exhibited good pH sensing properties and stability that had potential for mass production in disposable biosensors.