Synergistic Effects in Bimetallic (Co, Mn)-Doped SnO₂ Nanobelts for Greatly Enhanced Gas-Sensing Properties

Enhanced physical and chemical properties of materials through bimetallic synergistic effects remain a challenging problem because it is difficult to construct well-defined bimetallic synergies. Here, a series of bimetallic (Co, Mn)-codoped SnO₂ nanobelts were synthesized through the chemical vapor deposition (CVD) method by precisely controlling Co and Mn contents. The results show that the interaction between Co and Mn sites not only affects the chemical coordination environment of SnO₂ nanobelts and promotes the activity of an electronic catalytic reduction reaction but also greatly improves the gas-sensing properties. At the working temperature of 300 °C, the response value of the gas sensor to 200 ppm ethanol reaches an amazing 311.9. The amount of oxygen adsorbed on the surface of the sensitive material plays a crucial role in the gas-sensing response of the material. X-ray photoelectron spectroscopic analysis (XPS) spectra of the O 1s region of the sensor show that the adsorption oxygen content is 37.96%, which is higher than that of pure SnO₂ (27.41%). The increase of adsorbed oxygen content can be attributed to the synergistic effect of Co and Mn bimetal, which leads to electron enrichment on the surface of SnO₂ and promotes the activation of SnO₂, and helps to improve the gas-sensitive characteristics of SnO₂.