Micro-heater embedded Ni-SnO2 ordered nanoporous films: On-chip fabrication for fast, sensitive, and selective gas sensing towards multiple VOCs for air quality monitoring

Abstract

The ability to simultaneously detect multiple volatile organic compounds (VOCs) is crucial for assessing indoor air quality and addressing significant health hazards. In this study, we present a sacrificial template approach for on-chip fabrication of two-dimensional (2D) Ni-doped SnO2 nanoporous sensing films on micro-heater substrates. The technical analysis shows that the resulting honeycomb-like ultrathin Ni-SnO2 sensing layer on a suspended substrate maintains perfect structural integrity and consistency. The Ni-SnO2 sensors exhibit exceptional characteristics, including a ppb-level detection limit, high sensitivity, fast response/recovery time, and signal repeatability for typical VOCs, while operating at a low power consumption of 25 mW. Additionally, the Ni-doping enhances the sensors' cross-sensitivity to various forms of VOCs, while causing a discernible response inhibition towards flammable or exhaust gases. Furthermore, X-ray photoelectron spectroscopy (XPS) and in-situ Raman spectra reveal a Ni2+-substitution induced surface adsorbed oxygen species enrichment mechanism for sensing enhancement. Thus, the developed Ni-SnO2 sensors hold promise as future candidates for reliable air quality assessment by real-time monitoring of overall concentrations of multiple VOCs.