Au atomic clusters engineered on sea urchin-like In6WO12 nanospheres for high-performance ppb-level NO2 sensing at room temperature

Abstract

Conventional metal oxide semiconductor sensors frequently face challenges in detecting trace harmful gases at room temperature (RT) due to their limited sensing capabilities. Addressing this challenge, we construct a novel binary metal oxide sensors based on In₆WO₁₂ for the detection of NO₂ at RT according to the synergistic effect of effective volume depletion and electron scattering. The sea urchin-like In₆WO₁₂ nanospheres with large surface area (124.5 cm²g⁻¹) and multiple diffusion paths are assembled from 7.5 nm nanoparticles via an ethylenediamine-assisted coprecipitation method. Additionally, the decorating of Au atomic cluster with ∼4.5 nm further optimizes the surface reaction path of NO₂. The 1 wt%Au-In₆WO₁₂ sensor demonstrates a remarkably high response value (203) to 2 ppm NO₂ at RT, which was 54.8 times greater than that of the pristine In₆WO₁₂. Significantly, the sensor also shows exceptional selectivity, with a selectivity coefficient exceeding 98 %, and it can detect NO₂ at concentrations as low as 1.73 ppb, outperforming state-of-the-art conventional MOS-based NO₂ sensors. In-situ DRIFTS and energy band structures analyses confirm surface reaction processes of NO₂ and elucidate the reasons for the optimization of surface reactions. Reaction kinetics calculations indicate that the reaction process is accelerated due to the anchoring of Au atomic clusters. The unprecedented NO₂ sensing performances of the 1 wt%Au-In₆WO₁₂ sensor renders it an exceptional choice for precise real-time detection of ppb-level NO₂ at RT, and offers a novel strategy to enhance NO₂ sensing properties.