Room temperature gas sensor based on tube-like hydroxyapatite modified with gold nanoparticles

Abstract

The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite (HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange membrane and gold (Au) nanoparticles were added by a hydrothermal method. The morphology, structure and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The gas sensing properties were also investigated. Results show that Au nanoparticles are dispersed into the HA powder, which is tube-like, with rough inner and outer surfaces. Compared with pure HA, Au-modified HA exhibits improved sensing properties for NH3. 5% (mass fraction) Au-modified HA shows the highest response with relatively short response/recovery time. The response is up to 79.2% when the corresponding sensor is exposed to 200×10-6 NH3 at room temperature, and the response time and recovery time are 20 s and 25 s, respectively. For lower concentration, like 50×10-6, the response is still up to 70.8%. Good selectivity and repeatability are also observed. The sensing mechanism of high response and selectivity for NH3 gas was also discussed. These results suggest that Au-HA composite is a promising material for NH3 sensors operating at room temperature.