Construction of hexagonal hollow rod-shaped NiCo2O4–In2O3 p-n heterojunction for low concentration formaldehyde detection

Publication Name



The construction of p-n heterostructures using n-type and p-type semiconductor is a very important way to enhance gas sensing performance. In this work, hexagonal rod-shaped NiCo2O4/In2O3 with larger surface area was prepared via a simple water bath approach and subsequent calcination process. The microscopic morphology characterization results show that the NiCo2O4/In2O3 composite has a hexagonal hollow rod-shaped structure, where NiCo2O4 grows in situ on the surface of In2O3, forming p-n heterojunctions. Notably, the NiCo2O4/In2O3 composites formed with 6% NiCo2O4 addition (In-NC6) at 200 °C showed the best gas sensing performance for 1 ppm formaldehyde with a response value of 9.11 and a theoretical detection limit as low as 10.83 ppb. The rich oxygen vacancies, active site and p-n heterojunction are conducive to the adsorption of formaldehyde and electron transfer. This in situ growth approach provides novel ideas and promising prospects to synthesize other p-n heterojunction materials for applying to toxic gas detection.

Open Access Status

This publication is not available as open access



Article Number


Funding Number


Funding Sponsor

National Natural Science Foundation of China



Link to publisher version (DOI)