Abstract
We report a deposition of the tin oxide/hydroxide nanostructured layer by the potentiodynamic method from acidic nitrate solutions directly over the substrate, equipped with multiple strip electrodes which is employed as a gas-analytical multisensor array chip. The electrochemical synthesis is set to favor the growth of the tin oxide/hydroxide phase, while the appearance of metallic Sn is suppressed by cycling. The as-synthesized tin oxide/hydroxide layer is characterized by mesoporous morphology with grains, 250–300 nm diameter, which are further crystallized into fine SnO2 poly-nanocrystals following heating to 300 °C for 24 h just on the chip. The fabricated layer exhibits chemiresistive properties under exposure to organic vapors, which allows the generation of a multisensor vector signal capable of selectively distinguishing various vapors.
Highlights
There is a growing interest in bottom-up growth technologies capable of synthesizing metal oxides with characteristic dimensions in the nanometer domain for gas-sensing applications [1,2].The electrochemical deposition method fully addresses this request, yielding the oxidestructures that grow directly over the metal serving as an electrode under electric bias
The further conversion of the deposited layer into the dioxide phase is obtained by annealing at advanced temperatures. This method is found to be suitable for growing the non-stoichiometric nanostructured tin dioxide layer over the Pt multielectroded Si/SiO2 substrate, which is employed as a gas-analytical multisensor array unit to selectively detect organic vapors
We have studied the local conductance of the deposited tin oxide layer located between each multiple Pt electrodes, ca. 80 μm gap, as a part of the multisensor array chip
Summary
There is a growing interest in bottom-up growth technologies capable of synthesizing metal oxides with characteristic dimensions in the nanometer domain for gas-sensing applications [1,2]. The grown layer might have a significant Sn contribution, which should primarily depend on the [Sn2+ ]/[NO3 − ] ratio in the solution: the lower ratio results in the greater probability to grow tin oxide/hydroxide without a co-deposition of metallic Sn [5]. The practical impact of metallic Sn co-deposition is not clearly discussed in the noted reports, the appearance of the metal might complicate an implication of the method shunting the electrodes which might be relevant, e.g., to develop gas sensors Another approach to the tin oxide electrochemical deposition is based on the application of high power pulses to sputter the tin electrode in solution [26]. This method is found to be suitable for growing the non-stoichiometric nanostructured tin dioxide layer over the Pt multielectroded Si/SiO2 substrate, which is employed as a gas-analytical multisensor array unit to selectively detect organic vapors
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