In2O3/ZnO S-scheme heterojunction nanocomposite hollow microtubes with highly sensitive response to formaldehyde

As we all know, formaldehyde (HCHO) is extremely harmful to human health and has been identified as a primary carcinogen by the World Health Organization. Therefore, there is an urgent need to design efficient formaldehyde-sensing materials. In this work, a highly responsive formaldehyde sensor of In 2 O 3 @ZnO derived from MIL-68(In)@ZIF-8 precursor was successfully prepared. By adjusting the ratio of In 2 O 3 and ZnO, it can be found that the performance of the resulting sensor has greatly improved under 100 ppm HCHO at an operating temperature of 220 °C and the detection limit can be as low as 4 ppb. Additionally, it also has excellent selectivity (Q≥10), anti-interference (the deviation value≤3.5%), and long-lasting stability (the variation value≤4%). Such distinguished sensing performance can be attributed to the metal-organic framework (MOF) derived step-scheme (S-scheme) heterojunction , which ultimately increases the adsorption of oxygen and HCHO. This work verifies that ingenious heterojunction construction can significantly improve gas sensing performance.