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Both 3-hydroxy-2-butanone and triethylamine are highly toxic and harmful to human health, and their chronic inhalation can cause respiratory diseases, eye lesions, dermatitis, headache, dizziness, drowsiness, and even fatality. Developing sensors for detecting such toxic gases with low power consumption, high response with superselectivity, and stability is crucial for healthcare and environmental monitoring. This study presents a typical gas sensor fabricated based on AuPdO modified Cu-doped K 2 W 4 O 13 nanowires, which can selectively detect 3-hydroxy-2-butanone and triethylamine at 120 and 200 °C, respectively. The sensor displays excellent sensing performance at reduced operating temperature, high selectivity, fast response/recovery, and stability, which can be attributed to a synergistic effect of Cu dopants and AuPdO nanoparticles on the K 2 W 4 O 13 host. The enhanced sensing response and selectivity could be attributed to the oxygen vacancies/defects, bandgap excitation, the electronic sensitization, the reversible redox reaction of PdO and Cu, the cocatalytic activity of AuPdO, and Schottky barrier contacts at the interface of tungsten oxide and Au. The significant variations in the activation capacities of Cu-doped K 2 W 4 O 13 , Pd/PdO, and Au nanoparticles toward 3H-2B and TEA, and the diffusion depth of the two gases in the coated sensing layer may cause dual selectivity. The designed gas sensor materials can serve as a sensitive target for detecting toxic biomarkers and hold broad application prospects in food and environmental safety inspection.

It has been suggested that irreversible adsorption at the gas/liquid interface of bulk nanobubbles will reduce the Laplace pressure, leading to their stability. However, most previous studies have focused on the stability of individual nanobubbles. Bulk nanobubbles are polydispersed suspensions, and gas molecules can diffuse between bubbles, leading to their collective dynamics, which may be crucial to understanding their formation process and stability. In this study, we proposed a mean-field theory for computing the evolution of the size-distribution function of bulk nanobubbles with size-dependent surface tension. We applied this theory to investigate the evolution of bulk nanobubbles with insoluble surfactants pinned at their gas/water interface. The results show that Ostwald ripening can be suppressed when enough surfactants are adsorbed. Bulk nanobubbles can be produced by the shrinkage of microbubbles in an air-saturated solution. The mean stable size is controlled by the amount of surfactants and the initial microbubble concentration; these predictions are qualitatively consistent with the experimental results of micro/nanobubbles produced using the microfluidic method.

Spatiotemporal coordination of a nanorobot ensemble is critical for their operation in complex environments, such as tissue removal or drug delivery. Current strategies of achieving this task, however, rely heavily on sophisticated, external manipulation. We here present an alternative, biomimetic strategy by which oscillating Ag Janus micromotors spontaneously synchronize their dynamics as chemically coupled oscillators. By quantitatively tracking the kinetics at both an individual and cluster level, we find that synchronization emerges as the oscillating entities are increasingly coupled as they approach each other. In addition, the synchronized beating of a cluster of these oscillating colloids was found to be dominated by substrate electroosmosis, revealed with the help of an acoustic trapping technique. This quantitative, systematic study of synchronizing micromotors could facilitate the design of biomimetic nanorobots that spontaneously communicate and organize at micro- and nanoscales. It also serves as a model system for nonlinear active matter.

The absorption of gas molecules at hydrophobic surfaces may have a special state and play an important role in many processes in interfacial physics, which has been rarely considered in previous theory. In this paper, force spectroscopic experiments were performed by a nanosized AFM probe penetrated into individual surface nanobubbles and contacted with a highly ordered pyrolytic graphite (HOPG) substrate. The results showed that the adhesion force at the gas/solid interface was much smaller than that in air measured with the same AFM probe. The adhesion data were further analyzed by the van der Waals force theory, and the result implied that the gas density near the substrate inside the surface nanobubbles was about 3 orders of magnitude higher than that under the standard pressure and temperature (STP). Our MD simulation indicated that the gas layers near the substrate exhibited a high-density state inside the surface nanobubbles. This high-density state may provide new insight into the understanding of the abnormal stability and contact angle of nanobubbles on hydrophobic surfaces, and have significant impact on their applications.