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

中文翻译：

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二维工程非晶 a-SnO2 界面：合成和对 H2S 和湿度的气体传感响应

二维 (2D) 过渡金属二硫属化物 (TMD) 和金属硫属化物 (MCs) 尽管具有出色的气体传感特性，但在环境空气中会发生自发氧化，从长远来看会对传感器的信号再现性产生负面影响。利用自发氧化的优势，我们通过在低于 SnO ₂结晶温度（T < 280 °C）的温度下在空气中退火 2D SnSe ₂两周，合成了完全无定形的 a -SnO _{2 2D 薄片（约 30 nm 厚）。}这些设计了-SnO ₂接口保留了前驱体的所有 2D 表面-体积特性，在高达 250 °C 的干/湿空气中保持稳定，对于 H ₂ S（400 ppb 至 1.5 ppm）和湿度（10– 80% 相对湿度 (RH)) 在 100 °C 下保存一年。具体而言，通过结合密度泛函理论和从头算分子动力学，我们证明了 H ₂ S 和 H ₂ O 通过解离化学吸附在相同的 a -SnO _{2吸附位点上竞争，揭示了湿度对 H 2} S 传感的交叉响应。测试证实，湿度会降低基线电阻，阻碍 H ₂ S 传感器的信号（即，相对响应 (RR) =R _a / R _g )，并增加检测限 (LOD)。在 1 ppm 时，H ₂ S 传感器的信号从 0% RH 时的 2.4 ± 0.1 RR 降低到 80% RH 时的 1.9 ± 0.1，而 LOD 从 210 增加到 380 ppb。利用合适的热处理，我们报告了一种非晶化过程，可以很容易地扩展到各种 TMD 和 MC，为二维层状非晶金属氧化物气体传感器开辟了非凡的应用。