Simultaneous engineering of the surface (oxygen/amorphous carbon) and interface (amorphous carbon/ZnO) of ZnO using a one-spoon amorphous carbon deposition technique

Conceptual diagram illustrating the principle of increased resistance at the surface and interface in aC/ZnO PNSs. • This study introduces a novel one-spoon amorphous carbon deposition (OSaCD) method. • Amorphous carbon/ZnO porous nanosheets were synthesized using the water-quenching technique. • This method utilizes the synergistic effect of the surface and interface of amorphous carbon. Amorphous carbon/ZnO porous nanosheets (aC/ZnO PNSs) were synthesized using an innovative one-spoon amorphous carbon deposition (OSaCD) coating technique combined with water quenching during flame chemical vapor deposition (FCVD). The coating characteristics can be precisely tuned by adjusting simple processing parameters. The incorporation of amorphous carbon (aC) enhances NO 2 gas-sensing performance at both the surface and interfacial levels. At the surface, this improvement arises from interactions among oxygen species, the target gas, and aC. At the interface, it is associated with the aC/ZnO junction. An enhanced sensor response of 18.8 ± 1.2 was achieved at a NO 2 concentration of 4 ppm at 200 °C. Notably, the sensor was capable of detecting NO 2 at concentrations as low as 200 ppb. This enhanced performance is attributed to the expansion of the surface electron depletion layer and the reduction of oxygen vacancies at the interface. Owing to the intrinsic fluidity of the OSaCD process, this strategy is broadly applicable. Its applicability extends beyond specific material systems, morphologies, compositions, or degrees of crystallinity.