Yan Wenqian, Liu Yiming, Shao Gaofeng, Zhu Kunmeng, Cui Sheng, Wang Wei, Shen Xiaodong
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China.
Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 210009, China.
ACS Appl Mater Interfaces. 2021 May 5;13(17):20467-20478. doi: 10.1021/acsami.1c00302. Epub 2021 Apr 21.
An acidified SnO/rGO aerogel (ASGA) is an attractive contributor in ethanol gas sensing under ultralow concentration because of the sufficient active sites and adsorption pores in SnO and the rGA, respectively. Furthermore, a p-n heterojunction is successfully constructed by the high electron mobility between ASP and rGA to establish a brand-new bandgap of 2.72 eV, where more electrons are released and the surface energy is decreased, to improve the gas sensitivity. The ASGA owns a specific surface area of 256.1 m/g, far higher than SnO powder (68.7 m/g), indicating an excellent adsorption performance, so it can acquire more ethanol gas for a redox reaction. For gas-sensing ability, the ASGA exhibits an excellent response of / = 137.4 to 20 ppm of ethanol at the optimum temperature of 210 °C and can reach a response of 1.2 even at the limit detection concentration of 0.25 ppm. After the concentration gradient change test, a nonlinear increase between concentration and sensitivity (- curve) is observed, and it indirectly proves the chemical adsorption between ethanol and ASGA, which exhibits charge transfer and improves electron mobility. In addition, a detailed energy band diagram and sensor response diagram jointly depict the gas-sensitive mechanism. Finally, a conversed calculation explains the feasibility of the nonlinear - curve from the atomic level, which further verifies the chemical adsorption during the sensing process.
酸化的SnO/rGO气凝胶（ASGA）由于SnO和rGA中分别存在足够的活性位点和吸附孔，在超低浓度乙醇气体传感方面是一种有吸引力的材料。此外，通过ASP和rGA之间的高电子迁移率成功构建了p-n异质结，以建立2.72 eV的全新带隙，在此过程中释放出更多电子且表面能降低，从而提高了气敏性。ASGA的比表面积为256.1 m²/g，远高于SnO粉末（68.7 m²/g），表明其具有优异的吸附性能，因此它可以获取更多乙醇气体用于氧化还原反应。对于气敏能力，ASGA在210℃的最佳温度下对20 ppm乙醇表现出/ = 137.4的优异响应，甚至在0.25 ppm的极限检测浓度下也能达到1.2的响应。经过浓度梯度变化测试，观察到浓度与灵敏度之间呈非线性增加（-曲线），这间接证明了乙醇与ASGA之间的化学吸附，表现出电荷转移并提高了电子迁移率。此外，详细的能带图和传感器响应图共同描绘了气敏机理。最后，逆向计算从原子层面解释了非线性-曲线的可行性，进一步验证了传感过程中的化学吸附。
