Bidimensional Engineered Amorphous a-SnO2 Interfaces: Synthesis and Gas Sensing Response to H2S and Humidity

• DOI: 10.1021/acssensors.2c00887
• Publication Date: 2022-06-25T15:49:07Z
• Authors: Valentina Paolucci; Jessica De Santis; Vittorio Ricci; Luca Lozzi; Giacomo Giorgi; Carlo Cantalini
• Keywords: H2S; amorphous SnO2; thermal oxidation; cross-influence; water vapor; mechanism; DFT; H2S; SnSe2; amorphous SnO2; cross-influence; mechanism; thermal oxidation; water vapor; DFT; 01 natural sciences; SnSe2; 0104 chemical sciences

Two-dimensional (2D) transition metal dichalcogenides (TMDs) and chalcogenides (MCs), despite their excellent gas sensing properties, are subjected to spontaneous oxidation in ambient air, negatively affecting the sensor's signal reproducibility long run. Taking advantage of oxidation, we synthesized fully amorphous a-SnO2 2D flakes (≈30 nm thick) by annealing air SnSe2 for two weeks at temperatures below crystallization temperature SnO2 (T < 280 °C). These engineered interfaces, preserving all precursor's surface-to-volume features, stable dry/wet up 250 °C, with baseline H2S (400 ppb 1.5 ppm) humidity (10-80% relative (RH)) 100 °C one year. Specifically, combined density functional theory ab initio molecular dynamics, demonstrated that H2O compete dissociative chemisorption over same adsorption sites, disclosing cross-response sensing. Tests confirmed decreases resistance, hampers (i.e., response (RR) = Ra/Rg), increases limit detection (LOD). At 1 ppm, from an RR 2.4 ± 0.1 0% RH 1.9 80% RH, while LOD 210 380 ppb. Utilizing a suitable thermal treatment, here, report amorphization procedure can be easily extended large variety TMDs MCs, opening extraordinary applications layered oxide sensors.