Structure-Function Relationship of Highly Reactive CuOx Clusters on Co₃O₄ for Selective Formaldehyde Sensing at Low Temperatures
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2024-03-13
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Journal Article
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yes
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Abstract
Designing reactive surface clusters at the nanoscale on metal-oxide supports enables selective molecular interactions in low-temperature catalysis and chemical sensing. Yet, finding effective material combinations and identifying the reactive site remains challenging and an obstacle for rational catalyst/sensor design. Here, the low-temperature oxidation of formaldehyde with CuOₓ clusters on Co₃O₄ nanoparticles is demonstrated yielding an excellent sensor for this critical air pollutant. When fabricated by flame-aerosol technology, such CuOₓ clusters are finely dispersed, while some Cu ions are incorporated into the Co₃O₄ lattice enhancing thermal stability. Importantly, infrared spectroscopy of adsorbed CO, near edge X-ray absorption fine structure spectroscopy and temperature-programmed reduction in H₂ identified Cu⁺ and Cu²⁺ species in these clusters as active sites. Remarkably, the Cu⁺ surface concentration correlated with the apparent activation energy of formaldehyde oxidation (Spearman's coefficient rho = 0.89) and sensor response (0.96), rendering it a performance descriptor. At optimal composition, such sensors detected even the lowest formaldehyde levels of 3 parts-per-billion (ppb) at 75 degrees C, superior to state-of-the-art sensors. Also, selectivity to other aldehydes, ketones, alcohols, and inorganic compounds, robustness to humidity and stable performance over 4 weeks are achieved, rendering such sensors promising as gas detectors in health monitoring, air and food quality control.
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published
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Volume
11 (10)
Pages / Article No.
23082243
Publisher
Wiley-VCH
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Subject
clusters; inorganic catalysis; molecular sensing; nanotechnology; semiconductors; surface engineering
Organisational unit
09794 - Güntner, Andreas / Güntner, Andreas
09794 - Güntner, Andreas / Güntner, Andreas
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Funding
ETH-05 19-2 - Personalized indoor air quality monitoring with room-temperature filter-sensor arrays (ETHZ)