Fabrication of heterostructured p-CuO/n-SnO2 core-shell nanowires for enhanced sensitive and selective formaldehyde detection

Zhu, L.-Y. and Yuan, K. and Yang, J.-G. and Ma, H.-P. and Wang, T. and Ji, X.-M. and Feng, J.-J. and Devi, A. and Lu, H.-L.

Volume: 290 Pages: 233-241
DOI: 10.1016/j.snb.2019.03.092
Published: 2019

Highly sensitive and selective gas sensors based on heterostructured p-CuO/n-SnO2 core-shell nanowires (NWs) with precisely controlled shell thickness were synthesized through a sequential process combining a solution processing and atomic layer deposition. The gas sensing devices were fabricated on micro-electromechanical systems, which has triggered great research interest for low power consumption and highly integrated design. The designed p-CuO/n-SnO2 core-shell NW structured gas sensors exhibited superior gas sensing performance, which is closely related to the thickness of the SnO2 shell. Specifically, p-CuO/n-SnO2 core-shell NWs with a 24 nm thick SnO2 shell displayed a high sensitivity (Ra/Rg) of 2.42, whose rate of resistance change (i.e. 1.42) is 3 times higher than the pristine CuO NW sensor when detecting 50 ppm formaldehyde (HCHO) at 250 °C. The enhanced gas sensing performance could be attributed to the formation of p-n heterojunction which was revealed by specific band alignment and the heterojunction-depletion model. Besides, the well-structured p-CuO/n-SnO2 core-shell NWs achieved excellent selectivity for HCHO from commonly occurred reducing gases. In a word, such heterostructured p-CuO/n-SnO2 core-shell NW gas sensors demonstrate a feasible approach for enhanced sensitive and selective HCHO detection. © 2019 Elsevier B.V.

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