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Light enhanced room temperature resistive NO2 sensor based on a gold-loaded organic–inorganic hybrid perovskite incorporating tin dioxide
摘要： A material is described for sensing NO2 in the gas phase. It has an architecture of type Au/MASnI3/SnO2 (where MA stands for methylammonium cation) and was fabricated by first synthesizing Au/MASnI3 and then crystallizing SnO2 on the surface by calcination. The physical and NO2 sensing properties of the composite were examined at room temperature without and with UV (365 nm) illumination, and the NO2-sensing mechanism was studied. The characterization demonstrated the formation of a p-n heterojunction structure between p-MASnI3 and n-SnO2. The sensor, best operated at a voltage of 1.1 V at room temperature, displays superior NO2 sensing performance. Figures of merit include (a) high response (Rg/Ra = 240 for 5 ppm NO2; where Rg stands for the resistance of a sensor in test gas, and Ra stands for the resistance of a sensor in air), (b) fast recovery (about 12 s), (c) excellent selectivity compared to sensors based on the use of SnO2 or Au/SnO2 only, both at room temperature under UV illumination; (d) a low detection limit (55 ppb), and (e) a linear response between 0.5 and 10 ppm of NO2. The enhanced sensing performance is mainly attributed to the high light absorption capacity of MASnI3, the easy generation and transfer of photo-induced electrons from MASnI3 to the conduction band of SnO2, and the catalytic effect of gold nanoparticles.
关键词： Light absorbing material,SPR effect,Photo generated electrons,Gas sensing,P-n junction,Catalytic effect,Heterojunction,SnO2,UV light,MASnI3
更新于2025-09-23 15:23:52
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In situ growth of Ni-encapsulated and N-doped carbon nanotubes on N-doped ordered mesoporous carbon for high-efficiency triiodide reduction in dye-sensitized solar cells
摘要： A new micro-nanostructured composite (NOMC-Ni@NCNTs) of Ni-encapsulated and N-doped carbon nanotubes (Ni@NCNTs) pinned on N-doped ordered mesoporous carbon (NOMC) is constructed by a two-step synthesis strategy. The strategy involves the self-assembly preparation of water-soluble phenolic resin/F127 colloid by a hydrothermal route and the subsequent catalytic pyrolysis of as-prepared phenolic resin/F127 copolymer and melamine with nickel acetate as Ni source and self-generated catalyst, leading to the in situ growth of dispersive Ni@NCNTs pinned on NOMC through the Ni junction. In the resultant NOMC-Ni@NCNTs, the NOMC shows reduced particle size and shortened mesopore channel length of 15-30 μm compared to 850 μm-2 mm of pristine NOMC. The pinned Ni@NCNTs constructs a 3D conductive scaffold in the composite and the conductivity is correspondingly raised from 20.4 S cm-1 of pristine NOMC to 254.1 S cm-1 of NOMC-Ni@NCNTs. The particle size, mesoporosity and surface area of NOMC-Ni@NCNTs composite are also flexibly regulated by tailoring the relative content of Ni@NCNTs and NOMC. The new-structured NOMC-Ni@NCNTs composites are developed as counter electrode (CE) materials for DSSCs, which demonstrates an excellent catalytic activity towards I3? reduction. The optimum NOMC-Ni@NCNTs CE delivers a low charge-transfer resistance of 2.21 Ω and the assembled DSSC achieves a high power conversion efficiency of 8.39%. Moreover, the NOMC-Ni@NCNTs CE based DSSC also manifests a preeminent electrochemical stability in corrosive I?/I3? electrolyte with a remnant efficiency of 7.82% after 72 h of illumination. The outstanding electrocatalytic performance is mainly correlated with their unique architecture, in which the pinned Ni@NCNTs conductive substrate accelerates the electron transportation among NOMC micron-particles, and the amorphous NOMC with short-range mesopores accelerates the electrolyte diffusion and supplies abundant ions-accessible defects for I3? reduction.
关键词： Counter electrode,Synergistic catalytic effect,Dye-sensitized solar cell,Ni@NCNTs pinned NOMC composite,Two-step synthesis strategy
更新于2025-09-16 10:30:52