Au/CuO/Cu2O heterostructures for conductometric triethylamine gas sensing

Au decorated CuO/Cu2O composite was synthesized using a water bath method. Surface characterization results show that the materials are composed of needle-like nanoarchitectures. Cu and Au elements are uniformly distributed to form heterojunctions in the interfaces of CuO, Cu2O and Au. Gas sensing characterization results indicate that CuO/Cu2O composite exhibits enhanced response of 45.5–100 ppm triethylamine (TEA) gas at 160 ℃ and Au decoration dramatically improves its TEA gas sensing performance to 261.8 at 180 ℃. It also shows enhanced sensing selectivity as well as long-term stability. It is illustrated that the good gas sensing performance is attributed to the multi-heterojunctions in those materials. The heterojunction of CuO and Cu2O forms an accumulation layer of holes in copper oxide composite, which will be depleted by introduced reducing gas, further improving the response. Moreover, after decorating Au nanoparticles (NPs), the synergy effect between Au/CuO, Au/Cu2O, and CuO/Cu2O multi-heterojunctions induce an electronic sensitization effect, which facilitate the surface oxygen adsorptions and provide a larger content of adsorbed oxygen species, dramatically enhancing the response to analyte gas. The synthesis strategy presented in this work could benefit the development of highly sensitive gas sensors in the future.