Sensitive, Selective, and Fast Detection of ppb-Level H2S Gas Boosted by ZnO-CuO Mesocrystal.

Yanan Guo,Xincun Dou,Yushu Li,Miaomiao Gong,Yunling Liu

doi:10.1186/s11671-016-1688-y

Abstract

ZnO-CuO mesocrystal was prepared via topotactic transformation using one-step direct annealing of aqueous precursor solution and assembled into a H2S sensor. The ZnO-CuO mesocrystal-based sensor possesses good linearity and high sensitivity in the low-concentration range (10–200 ppb). Compared to pure CuO, the as-prepared ZnO-CuO mesocrystal sensor exhibited superior H2S sensing performance with a response ranging from 8.6 to 152 % towards H2S concentrations from 10 ppb to 10 ppm when applied at the optimized working temperature of 125 °C. The sensor showed excellent repeatability and good selectivity towards H2S gas even at a concentration four orders of magnitude lower than the interfering gases, such as H2, CO2, CO, NO2, acetone, and NH3. The improved sensitivity could be attributed partially to the effective diffusion of analyte gas through the mesocrystal surface and the abundant accessible active sites. Moreover, the nanoscale p-n junctions within the mesocrystal, which could effectively manipulate the local charge carrier concentration, are also beneficial to boost the sensing performance.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1688-y) contains supplementary material, which is available to authorized users.

Highlights

H2S is generally produced as a by-product from petroleum refining, farming, and biogas production [1, 2]
From the phase of the ZnO-CuO mesocrystal investigated by X-ray diffraction (XRD) (Fig. 1a), one can see clearly that the mesocrystal possesses a good crystallinity and there are two phases
It is found that an annealing temperature of 250 °C is essential to achieve a topotactic transformation since intermediate phases of Zn(NO3)(OH)H2O and Cu2(OH)3NO3 exist when the annealing temperature is 200 °C (Additional file 1: Figure S1) and the reaction processes are summarized by Eqs. (1)–(4) in the supporting information

Summary

Introduction

H2S is generally produced as a by-product from petroleum refining, farming, and biogas production [1, 2]. As one of the most toxic and flammable gases, H2S affects the nervous system of human beings and can cause people to lose consciousness at very low concentrations [3]. The acceptable ambient limit for H2S (recommended by the Scientific Advisory Board on Toxic Air Pollutants, USA) is within the range of 20–100 ppb [4]. Small amount of H2S in exhaled breath is usually used as a signaling molecule for metabolic disorder called as halitosis [5, 6]. H2S with a concentration as low as 10 ppb is known to deteriorate the performance of hydrogen fuel cells [7]. There is a pressing need to explore efficient sensing devices with high sensitivity capable of detecting H2S at ppb level

Methods

Results

Conclusion