Regulating the d-Band Center of an FeCu/NC Dual-Metal Catalyst for Self-Powered and Smart Sensing of Oxidizing and Reducing Gas.

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 NO2 gas adsorption and decreasing Gibbs free energy of NO2 reduction. The O atoms of NO2 will generate a covalent bond with Fe atoms, leading to an elevated charge redistribution with more electrons adsorbed by NO2 gas molecules (0.61 |e| as calculated by Bader charge analysis). As a result, the constructed sensors exhibit a remarkable NO2 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 H2S 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 H2S at room temperature. Finally, the sensing device is assembled into an intelligent sensing system capable of wireless information transmission for remote gas monitoring.