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ZnAl 2 O 4 ‐Functionalized Zinc Oxide Microstructures for Highly Selective Hydrogen Gas Sensing Applications
Author(s) -
Hoppe Mathias,
Lupan Oleg,
Postica Vasile,
Wolff Niklas,
Duppel Viola,
Kienle Lorenz,
Tiginyanu Ion,
Adelung Rainer
Publication year - 2018
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201700772
Subject(s) - crystallite , microstructure , materials science , high resolution transmission electron microscopy , zinc , hydrogen , raman spectroscopy , oxide , chemical engineering , transmission electron microscopy , nanotechnology , analytical chemistry (journal) , composite material , metallurgy , optics , chemistry , organic chemistry , engineering , physics
In this work, a simple method of ZnAl 2 O 4 ‐functionalization of ZnO microstructures is presented. The different characterization methods (structural, chemical, and micro‐Raman) demonstrated the presence of only ZnO and ZnAl 2 O 4 crystalline phases. ZnAl 2 O 4 nano‐crystallites grow on the surfaces of ZnO 3D microstructures having diameters of 50–100 nm and with high density. Transmission electron microscopy (TEM) and high‐resolution TEM (HRTEM) results clearly show ZnAl 2 O 4 crystallites functionalizing zinc oxide tetrapod arms. The individual structures (microwires (MWs) and three‐dimensional (3D) tetrapods (Ts)) are integrated into functional devices, suitable for gas sensing applications. All devices show excellent hydrogen gas selectivity at relatively low operating temperature in the range of 25–100 °C. The highest gas sensing performances are obtained based on individual ZnAl 2 O 4 ‐functionalized ZnO tetrapods (ZnAl 2 O 4 /ZnO‐T, with an arm diameter ( D ) of ≈400 nm) and a response of ≈2 at 25 °C to 100 ppm of hydrogen gas (H 2 ), while a ZnAl 2 O 4 /ZnO‐MW ( D ≈ 400 nm) shows only a response of ≈1.1. The Al‐doped ZnO MW ( D ≈ 400 nm) without ZnAl 2 O 4 elaborated in another work, chosen only for comparison reason, shows no response up to 800 ppm H 2 gas concentration. A gas sensing mechanism is proposed for a single ZnAl 2 O 4 /ZnO‐T microstructure based sensor. The obtained results on ZnAl 2 O 4 /ZnO‐T‐based devices is superior to many reported performances of other individual metal oxide nanostructures with much lower diameter, showing promising results for room temperature H 2 gas sensing applications.