Binder-free CeO2 coated/Pd-decorated CuxO nanowires based on Cu foam for humidity-independent enhanced H2S gas sensing

Binder-free CeO2 coated/Pd-decorated CuxO nanowires (CuxO/Pd/CeO2_NWs) based on Cu foam were synthe-sized using a four-step process: electrochemical nanoengineering for preparing Cu nanowires, galvanic replacement between Cu nanowires and H2PdCl4, soaking in cerous nitrate solution and followed thermal annealing. Due to the optimized Pd thin layer, followed coating of the moisture-blocking CeO2 overlayer, the binder-free Pd-decorated CuxO nanowires exhibit a prominently enhanced sensing properties to H2S. The CuxO/ Pd/CeO2_NWs sensor exhibits a high response of 36.69 to 50 ppm H2S with rapid response/recovery speed (48.9 s/59.1 s), good selectivity and humidity-independent sensing properties at room temperature. Therefore, this work shows promising potential in detecting H2S and a new insight is opened up in designing binder-free devices based on metal substrate for indoor/outdoor environmental monitoring regardless of humidity fluctuations.

Automated summary

Binder-free CeO2 coated/Pd-decorated CuxO nanowires were synthesized through a four-step process involving electrochemical nanoengineering, galvanic replacement, soaking, and thermal annealing. The resulting nanowires exhibited enhanced sensing properties to H2S due to the optimized Pd thin layer and moisture-blocking CeO2 overlayer. The sensor showed a high response to H2S, rapid response/recovery speed, good selectivity, and humidity-independent sensing properties, making it suitable for environmental monitoring.