Effects of organotin halide perovskite and Pt nanoparticles in SnO_2-based sensing materials on the detection of formaldehyde

摘要

HC(NH_2)_2SnI_3 (FASnI_3) organotin halide perovskite was firstly synthesized by a solution method and then decorated with Pt nanoparticles by immersion method. HC(NH_2)_2SnI_3/SnO_2/Pt was obtained by calcining the sample to oxidize part of the HC(NH_2)_2SnI_3 into SnO_2 at different temperature in air. The structural, morphological characteristics and formaldehyde sensing performance were studied at length. The results indicated that HC(NH_2)_2SnI_3/SnO_2/Pt obtained at 240 ℃ showed superior sensing properties, of which the response to 10 ppm formaldehyde at 80 ℃ was 47.5 and the response and recovery time was 40 s and 37 s, respectively. The corresponding detection limit was estimated as low as 65 ppb. The high performance of the sample could be ascribed to the reason that the introduction of moderate HC(NH_2)_2SnI_3 into SnO_2 could lead to the formation of n-n heterojunction, and the organic-inorganic hybrid perovskites with narrow bandgap could generate abundant electrons from low-temperature excitation and the electrons could be transferred through the n-n heterojunction to SnO_2. Consequently, the optimum operating temperature for formaldehyde detection could be reduced by 120 ℃ compared with pure SnO_2. Moreover, the Pt nanoparticles improved response value more than twofold generally, which might be attributed to spillover effect and high catalytic activity.