Sustainable Conversion of Corncob Biomass Waste into High Performance Carbon Materials for Detection of VOCs at Room Temperature

The demand for reliable, cost-effective, room temperature gas sensors with high sensitivity, selectivity, and short response times is rising, particularly for environmental monitoring, biomedicine, and agriculture. In this study, corncob waste-derived activated carbon (ACC) was combined with CuO nanoparticles and polyvinyl alcohol (PVA) to fabricate ACC/PVA/CuO composites with CuO loadings of 5, 10, and 15 wt.%. The CuO nanoparticles (average size: 21.79 ± 9.88 nm) were successfully incorporated into the ACC matrix, as confirmed by TEM, XRD, and N₂ adsorption-desorption analyses. Increasing CuO content reduced the specific surface area due to pore blockage but enhanced the composites' ethanol sensing performance. The ACC/PVA/CuO (15 wt.%) sensor exhibited the highest response and fastest recovery times (125 s and 130 s, respectively, at 100 ppm ethanol), outperforming other composites and pristine ACC. This improvement was attributed to surface defects and increased active sites promoting vapor adsorption and diffusion. These results demonstrate the potential of ACC/PVA/CuO as an effective ethanol sensor at room temperature.