Oxygen vacancy engineering on cerium oxide nanowires for room-temperature linalool detection in rice aging

It is a huge challenge for metal oxide semiconductor gas sensors to inspect volatile organic compounds(VOCs)at room temperature(RT).Herein,the effective utilization of cerium oxide(CeO_(2))nanowires for RT detection of VOCs was realized via regulating its surface chemical state.Oxygen vacancy engineering on CeO_(2) nanowires,synthesized via hydrothermal method,can be manipulated by annealing under various controlled atmospheres.The sample annealed under 5%H_(2)+95%Ar condition exhibited outstanding RT sensing properties,displaying a high response of 16.7 towards 20 ppm linalool,a fast response and recovery time(16 and 121 s,respectively),and a low detection of limit of 0.54 ppm.The enhanced sensing performance could be ascribed for the synergistic effects of its nanowire morphology,the large specific surface area(83.95 m^(2)/g),and the formation of extensive oxygen vacancy accompanied by an increase in Ce^(3+).Additionally,the practicability of the sensor was verified via two varieties of rice(Indica and Japonica rice)stored in various periods(1,3,5,7,15,and 30 d).The experimental results revealed that the sensor was able to distinguish Indica rice from Japonica rice.Accordingly,the as-developed sensor delivers a strategic material to develop high-performance RT electronic nose equipment for monitoring rice quality.

MXene-derived TiO_(2)nanosheets decorated with Ag nanoparticles for highly sensitive detection of ammonia at room temperature

Due to their large surface-to-volume ratio and low electronic noise,two-dimensional transition metal carbides(Ti_(3)C_(2)T_(x) MXene)and their derived transition metal oxides have demonstrated significant potential for use in high-precision gas sensing.However,the construction of high-sensitivity Ti_(3)C_(2)T_(x) MXene-based gas sensors operated at room temperature(RT)is still a major challenge.Herein,we demonstrate a sensitive nanocomposite prepared by uniformly anchoring silver nanoparticles(AgNPs)on Ti_(3)C_(2)T_(x) MXene-derived transition metal oxide(TiO_(2))nanosheets for high-sensitivity NH_(3) detection.AgNPs can not only serve as spacers to effectively prevent the restacking of MXene-derived TiO_(2)nanosheets and ensure an effective transmission highway for target gas molecules,but also enhance the sensitivity of the sensor through chemical and electronic sensitization.By integrating the unique merits of the individual components and the synergistic effects of the composites,the optimized Ag@TiO_(2)nanocomposite-based sensors revealed an extraordinary response value of 71.8 to 50 ppm NH_(3) at RT with a detection limit as low as 5 ppm.In addition,the Ag@TiO_(2)NH_(3) sensor also exhibits excellent selectivity and outstanding repeatability.This strategy provides an avenue for the development of MXene derivatives for advanced gas sensors.