Listeria monocytogenes, which is abundant in environment, can lead to many kinds of serious illnesses and even death. Nowadays, indirectly detecting the metabolite biomarker of L. monocytogenes, 3-hydroxy-2-butanone, has been verified to be an effective way to evaluate the contamination of L. monocytogenes. However, this detection approach is still limited by sensitivity, selectivity, and ppb-level detection limit. Herein, low-cost and highly sensitive and selective 3-hydroxy-2-butanone sensors have been proposed based on the bimetallic AuPd decorated hierarchical flower-like WO3 nanospheres. Notably, the 1.0 wt % AuPd-WO3 based sensors displayed the highest sensitivity (Ra/Rg = 84 @ 1 ppm) at 250 °C. In addition, the sensors showed outstanding selectivity, rapid response/recovery (8/4 s @ 10 ppm), and low detection limit (100 ppb). Furthermore, the evaluation of L. monocytogenes with high sensitivity and specificity has been achieved using 1.0 wt % AuPd-WO3 based sensors. Such a marvelous sensing performance benefits from the synergistic effect of bimetallic AuPd nanoparticles, which lead to thicker electron depletion layer and increased adsorbed oxygen species. Meanwhile, the unique hierarchical nanostructure of the flower-like WO3 nanospheres benefits the gas-sensing performance. The AuPd-WO3 nanosphere-based sensors exhibit a particular and highly selective method to detect 3-hydroxy-2-butanone, foreseeing a feasible route for the rapid and nondestructive evaluation of foodborne pathogens.
Wen Guan,Yunlei Zhang,Yanan Wei,Bing Li,Yonghai Feng,Changhao Yan,Pengwei Huo,Yongsheng Yan
As an important renewable alternative to the production of petroleum-derived terephthalic acid, selective aerobic oxidation of biomass derivative 5-hydroxymethylfurfural (HMF) into high value-added 2,5-furandicarboxylic acid (FDCA) is attracting increasing attention. Herein, a novel hierarchical porous nitrogen-doped carbon (NC) supported bimetallic AuPd catalyst was synthesized by Pickering high internal phase emulsions (Pickering HIPEs) templating method, subsequent carbonization and the sol-curing technique. By varying Pickering HIPEs parameter, nitrogen-doped content and the loaded AuPd nanoparticles, Au x Pd y /NC catalysts with adjustable porous structure and basicity were obtained. Benefiting from the synergistic effects of the high basicity of NC support and efficient bimetallic AuPd catalyst, tandem oxidation of HMF to FDCA reactions can be carried out under base-free condition in water, which makes the biomass transformation process environmental friendliness and economic. And the highest yield of FDCA at 96.7% was achieved under the optimal reaction conditions. Regeneration test revealed the obtained Au x Pd y /NC catalyst was recovered and reused at least five times without significant loss of catalytic activity. The present work offers a versatile strategy for developing nitrogen-doped carbon supported highly efficient bimetallic catalysts with hierarchical porous structure and adjusting basicity for a wide range of base-free catalytic oxidation in water.
A highly efficient heterogeneous catalyst was synthesized by delicate engineering of NH2-functionalized and N-doped hollow mesoporous carbon spheres (NH2–N-HMCS), which was used for supporting AuPd alloy nanoparticles with ultrafine size and good dispersion (denoted as AuPd/NH2–N-HMCS). Without using any additives, the prepared AuPd/NH2–N-HMCS catalytic formic acid dehydrogenation possesses superior catalytic activity with an initial turnover frequency value of 7747 mol H2 per mol catalyst per h at 298 K. The excellent performance of AuPd/NH2–N-HMCS derives from the unique hollow mesoporous structure, the small particle sizes and high dispersion of AuPd nanoparticles and the modified Pd electronic structure in the AuPd/NH2–N-HMCS composite, as well as the synergistic effect of the modified support.
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