▎ 摘　　要

In this article, we demonstrated an extremely high-sensitivity formaldehyde (HCHO) gas sensor, where the graphene oxide (GO) in situ modified two-dimensional (2D) SnO2 nanosheets with in-plane mesopores were utilized as the sensing materials. The sensor response (Ra/Rg) was larger than 2000 toward 100 ppm HCHO at 60 degrees C. In addition, the selectivity for detecting HCHO was excellent against other interferences including ethanol, acetone, methanol, toluene, ammonia, water, etc. The outstanding sensing performance of 2D mesoporous GO/SnO2 nanosheets was attributed to the synergism of the sensitizer effect of GO, large surface areas of 2D nanostructure, suitable particle size, and abundant in-plane mesopores. The high sensitivity, high selectivity, and low working temperature of the sensor reported here endowed it a great potential in selective detection of HCHO. Meanwhile, the design and synthesis of GO/SnO2 nanocomposites will provide new paradigms in the future development of HCHO-sensitive materials.