Enhanced room temperature gas sensing performance of ZnO with atomic-level Pt catalysts facilitated by the polydopamine mediator

The poor sensitivity of metal-oxide(MO)sensing material at room temperature can be enhanced by the modi-fication of noble metal catalysts.However,the large size and uncontrollable morphology of metal nanoparticles(NPs)compromise the catalytic activity and selectivity.Downsizing metal NPs to the atomic level is a promising solution because it offers high activity and selectivity.Nevertheless,a facile and universal approach for stable loading atomic-level metal on MO-based sensing materials is still challenging.Herein,we present a strategy to construct synergetic coordination interface for uniform loading of atomic-level metal catalysts on MO-based gas-sensing materials using a difunctional mediator layer.In this work,atomically dispersed Pt catalysts are coor-dinately anchored on ZnO nanorods(NRs)using polydopamine(PDA)as a mediator.As a result,compared with pristine ZnO NRs,a six-fold enhanced response of 18,489%is achieved toward 100 ppm NO_(2)on 0.20 wt%Pt-ZnO@PDA-1.5 nm,and the selectivity is also promoted.Such sensitivity is higher than that of most reported noble metal-modified MO NO_(2)-sensing materials.This work provides a simple and general strategy for building highly sensitive and selective gas-sensing materials using atomic-level noble metal catalyst.

Ferroelectric perovskite-type films with robust in-plane polarization toward efficient room-temperature chemiresistive sensing

Ferroelectric materials have become key components for versatile device applications,and their thin films are highly desirable for integrating the miniaturized devices.Despite substantial endeavors,it is still challenging to achieve effective chemiresistive sensing in the ferroelectric films.Here,for the first time,we have exploited ferroelectric thin films of 2D hybrid perovskite BA_(2)EA_(2)Pb_(3)I_(10)(1),to fabricate the high-performance chemiresistor gas sensors.The spin-coated films of 1 exhibit high orientation and good crystallinity,thus preserving robust in-plane spontaneous polarization(P_(s)~2.0μC/cm^(2))and low electric coercivity.Notably,such ferroelectric filmbased sensors after electric poling enable the dramatic room-temperature sensing responses to NO_(2) gas,including high sensitivity(0.05 ppm^(-1)),extremely low detection limit(1 ppm)and fast responding rate(~6 s).Besides,the chemiresistive responses are remarkably enhanced by threefold(up to 320%)through electric poling.It is proposed that this behavior closely involves with strong in-plane ferroelectric polarization of 1 that generates a built-in electric field inhibiting the recombination of charge carriers.As far as we know,this ferroelectric-based film chemiresisor is one of the best room-temperature sensors for NO_(2) gas among all the existing candidate materials.These findings highlight great potential of ferroelectrics toward effective chemiresistive performances,and also establish a bright direction to explore their future device applications.

Layer-by-layer assembled dual-ligand conductive MOF nano-films with modulated chemiresistive sensitivity and selectivity

In this paper,a dual-ligand design strategy is demonstrated to modulate the performance of the electronically conductive metalorganic frameworks(EC-MOFs)thin film with a spray layer-by-layer assembly method.The thin film not only can be precisely prepared in nanometer scale(20-70 nm),but also shows the pin-hole-free smooth surface.The high quality nano-film of 2,3,6,7,10,11-hexaiminotriphenylene(HITP)doped Cu-HHTP enables the precise modulation of the chemiresistive sensitivity and selectivity.Selectivity improvement over 220%were realized for benzene vs.NH3>as well as enhanced response and recovery properties.In addition,the selectivity of the EC-MOF thin film sensors toward other gases(e.g.triethylamine,methane,ethylbenzene,hydrogen,butanone,and acetone)vs.NH3 at room temperature is also discussed.

A new 3D cupric coordination polymer as chemiresistor humidity sensor:narrow hysteresis,high sensitivity,fast response and recovery

A new three-dimensional coordination polymer composed of Cu^(2+) centres and semiquinoid linkers(dhbq^(2-)) was synthesized which was composed by two independent,enantiomeric,interpenetrated[Cu_2(dhbq)_3]^(2-) networks with(10,3)-a topology.The compound has good water stability and typical behaviors of semiconductor,whose conductivity increases along with raising temperature.The chemiresistive humidity sensor made from this material shows good properties including linear sensitivity,high response,fast response and recovery,and particularly narrow hysteresis during humidity adsorption and

超疏水MOF膜的构建及其在醇水快速分离中的应用

Separation and purification play crucial roles in the oil and gas industry, which includes the most energy-intensive distillation process, accounting for 10%-15% of global energy use [1,2]. Membrane-based separation has emerged as a promising alternative method because of its innate advantage of low energy consumption [3-5]. The difference in the molecular size between the target molecule and the impurity can be as small as a few angstroms(0.1 nm), which requires precise control of the membrane pore size at the subnanometer scale and thus, is extremely difficult [6].

Single-Component MLCT-Active Photodetecting Material Based on a Two-Dimensional Coordination Polymer

Conductive coordination polymers(CCPs)have shown great potential for electronic purposes.However,their applications in photodetection have been limited by poor sensitivity,low on/off current ratio,and slow response owing to the low charge generation and/or separation efficiency.In this work,metal-to-ligand chargetransfer(MLCT)in PhSeAg was used to fabricate a single-component MLCT photodetecting material for the first time to solve the above challenges.The material obtained possesses ultrahigh sensitivity to weak-light intensity(0.03 mW cm^(−2)),the highest on/off ratio,and the fastest response speed than other wellknown CCPs materials tested.Our work might provide a simple but common strategy for designing high-performance CCPs composites for optoelectrical applications.