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.

Self-supported porous heterostructure WC/WO_(3−x)ceramic electrode for hydrogen evolution reaction in acidic and alkaline media

Tungsten carbide(WC)-based materials are widely considered as the hydrogen evolution reaction(HER)process catalysts due to their“Pt-like”electronic structure.Nonetheless,traditional powder electrodes have a high cost,and display problems related to the process itself and the poor stability over operation time.This paper presented a self-supported asymmetric porous ceramic electrode with WO_(3-x)whiskers formed in situ on the walls of the finger-like holes and membrane surface,which was prepared by combining phase inversion tape-casting,pressureless sintering,and thermal treatment in a CO_(2) atmosphere.The optimized ceramic electrode displayed good catalytic HER activity and outstanding stability at high current densities.More specifically,it demonstrated the lowest overpotentials of 107 and 123 mV and the lowest Tafel slopes of 59.3 and 72.4 mV·dec^(-1)at 10 mA·cm^(-2)in acidic and alkaline media,respectively.This superior performance was ascribed to the structure of the ceramic membrane and the charge transfer efficiency,which was favored by the in situ developed WC/WO_(3-x)heterostructure and the oxygen vacancies.