Synergistic charge transfer in 3D-V2O5/1D-Co3O4 composite for ultra-sensitive NO2 gas detection

Abstract

The development of high-performance gas sensors for industrial safety and environmental protection demands innovative material design. Thus, advancing gas sensor technology necessitates innovative approaches to material synthesis, particularly in developing high-performance composites. This study presents a surfactant- and reducing agent-free method to synthesize 3D V2O5 with a high surface area (72 m2 g−1) and 1D Co3O4 with superior charge transfer capabilities. The distinct surface energy (-40 mV for V2O5 vs. -5 mV for Co3O4) and Fermi level differences (-5.62 eV for Co3O4 vs. -4.36 eV for V2O5) enable the formation of a robust 3D-V2O5/1D-Co3O4 composite. This composite, investigated as a gas sensor for the first time, demonstrated significant synergistic effects. Among various ratios, the 0.5:0.5 V2O5:Co3O4 composite demonstrated exceptional NO2 sensing performance, with high responses (0.1 % to 250 ppb, 3.7 % to 50 ppm), sensitivity (0.53 Ω ppm−1 over 5–200 ppm), and rapid response/recovery times (25 s/22 s) at 270 °C. The sensor's selectivity towards NO2 is attributed to the NO2's high electron affinity and it unpaired electron, which bond with surface oxygen atoms, enhancing chemisorption and electron transfer. Notably, each composite outperforms bare and layered (Co3O4/ V2O5) structures due to efficient charge transfer, increased surface area, and synergistic effects. Gas sensing mechanism and synergistic effects were confirmed via Mott-Schottky, XPS, Raman, zeta potential and Tauc-law analyses. The sensor achieved a low detection limit (250 ppb) and stable performance (>30 days), highlighting its practical potential for environmental and industrial safety applications. © 2025 Elsevier B.V.