Regulating the d-Band Center of an FeCu/NC Dual-Metal Catalyst for Self-Powered and Smart Sensing of Oxidizing and Reducing Gas
Xiao Wang, Ningning Zhang, Feifei Li, Zhaokun Sun, Xinyu Li, Ce Guo, Xijin Xu
Abstract
Gas sensors based on zinc–air batteries that integrate battery functionality expand the self-powered and energy-harvesting capabilities of sensing systems. However, the sluggish and inadequate reaction kinetics at the interface and exclusive detection of oxidizing gases restrict their sensing response and the sensing scenario. Herein, a dual-metal FeCu/NC catalyst is fabricated to facilitate the reduction reaction at the interface. The incorporation of Fe shifts the d-band center of the Cu catalyst to the Fermi level, facilitating NO 2 gas adsorption and decreasing Gibbs free energy of NO 2 reduction. The O atoms of NO 2 will generate a covalent bond with Fe atoms, leading to an elevated charge redistribution with more electrons adsorbed by NO 2 gas molecules (0.61 |e| as calculated by Bader charge analysis). As a result, the constructed sensors exhibit a remarkable NO 2 sensing performance with a high response (0.16 V@10 ppm), an ultralow detection limit (10 ppb), and a fast response transience (40 s). Moreover, for H 2 S gas sensing, the partial Cu catalyst is oxidized to the Cu–S bond at the surface and subsequently reduced to a Cu substance at the three-phase interface, generating a lower redox potential and open-circuit voltage. As a consequence, the sensors exhibit a response of 0.1 V to 25 ppm H 2 S at room temperature. Finally, the sensing device is assembled into an intelligent sensing system capable of wireless information transmission for remote gas monitoring.