SnO 2 ‐SiO 2 1D Core‐Shell Nanowires Heterostructures for Selective Hydrogen Sensing

SnO 2 is one of the most employed n ‐type semiconducting metal oxide in chemo‐resistive gas‐sensing although it presents serious limitations due to a low selectivity. Herein, the authors introduce 1D SnO 2 ‐SiO 2 core‐shell nanowires (CSNWs). The amorphous SiO 2 ‐shell layer with varying thicknesses (1.8–10.5 nm) is grown onto the SnO 2 nanowires (NWs) by atomic layer deposition (ALD). SiO 2 ‐coated SnO 2 CSNWs show a dramatic improvement of the selectivity towards hydrogen. Moreover, the sensing‐response is strongly correlated to the thickness of the SiO 2 ‐shell and the working temperature. The SnO 2 ‐SiO 2 CSNWs sensor with a 4.8‐nm SiO 2 shell thickness exhibits the best selectivity and sensitivity, having ca. 7‐fold higher response toward hydrogen compared to bare‐SnO 2 NWs. The selectivity and enhanced sensing‐response are related to the masking effect of the SiO 2 shell and an increase in the width of the electron‐depletion‐layer due to a strong electronic coupling between the SnO 2 core and SiO 2 coating, respectively.