High sensitivity and selectivity of formaldehyde sensor based on Nd2O3 @In2O3 heterojunction rod-like composites

The rare-earth material Nd2O3, which has abundant oxygen vacancy defects and unique structural property of 4f4f electron leap, shows its great potential for chemical sensing applications. However, the difficulty in selecting suitable Nd-precursor complexes has limited the synthesis and further applications of Nd2O3 materials. Herein, we synthesized Nd(OH)3 using a simple solvent method, followed by calcination by mixing it with the precursor MIL-68(In) to generate Nd2O3 surface-modified In2O3 composites. After that, its gas-sensitive performance was investigated. It was observed that the response of 5 wt% Nd2O3 @In2O3 to formaldehyde (100 ppm) is the highest (850.3), which is 25 times higher than that of In2O3. Compared with In2O3, Nd2O3-decorated In2O3 not only exhibited higher sensitivity and better selectivity but also reduced response time. The improved gas-sensing performance could be attributed to the formation of heterojunctions between Nd2O3 and In2O3 as well as the increase of adsorbed oxygen and defective oxygen. This kind of gas sensor based on Nd2O3-decorated In2O3 has more obvious advantages for fast and high-response detection of formaldehyde.