In this work, a low-temperature formaldehyde sensor based on a hydrothermally synthesized tin dioxide/tin selenide (SnO2/SnSe2) nanostructure was demonstrated. The SnO2 nanosheets were decorated on the SnSe2 nanoblocks. The microstructural characterization proves this unique morphology. At 150 °C, the SnO2/SnSe2 composite gas sensor exhibits more than three times the response to formaldehyde gas compared to pure SnO2, with a response of 13.47 to 10 ppm formaldehyde and a response recovery time of 63 s/12 s. In addition, the SnO2/SnSe2 gas sensor is capable of detecting formaldehyde gas at the ppb level. The sensor also exhibits excellent repeatability, excellent long-term performance stability, and resistance to humidity interference. The n–n heterojunction formed between SnO2 and SnSe2, along with its unique microstructure, significantly enhances the performance of the SnO2/SnSe2 sensor. The adsorption behavior of formaldehyde molecules on sensitive material surfaces was studied by using density functional theory.
Ao Shen,Zhichen Shi,Wenyuan Zhang,Yi Zhai,Yongbao Feng,Wenbin Gong,Peng Xu,Qiulong Li
Tin-based compounds have an ultrahigh theoretical capacity and low oxidation-reduction potential, making them as a very important type of anode matrix for lithium-ion batteries (LIBs). Nevertheless, the enormous volume dilatation causes structural collapse, limiting its cyclic stability. Herein, a nanoscale SnO 2 /SnSe 2 @rGO has been designed, in which the interface of SnO 2 /SnSe 2 heterostructure generates a built-in electric field, improving charge transfer efficiency. And rGO, as a 3D interconnection network coating SnO 2 /SnSe 2 nanoparticles, improves conductivity and serves as a buffer medium for volume expansion. DFT calculations confirm that the formation of built-in electric field enhances the adsorption energy of Li + and reduces the migration energy barrier. As expected, the initial capacity of the SnO 2 /SnSe 2 @rGO electrode can reach 1405.9 mAh g −1 at 2.0 A g −1 . The reversible capacity is 1459.1 mAh g −1 at 0.1 A g −1 after 50 cycles, with 78.1 % capacity retention. Finally, a SnO 2 /SnSe 2 @rGO//LiFePO 4 (LFP) full battery was assembled, which exhibits a high capacity of 213.1 mAh g −1 at 0.1 A g −1 and energy density of 492.8 Wh kg −1 at 270 W kg −1 . The design of this nanoscale heterostructure provides a feasible strategy for developing LIBs anodes with enhanced capacity and extended lifespan.
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