The directional transport and precise control of droplets and bubbles are crucial for future applications, but remain challenging due to complex fluid dynamics and application limits. In light of existing research on droplet manipulation, a MnO 2 /carbon microsphere (MnO 2 /Cs) covalently grafted lubricant-infused slippery surface (SPM) is designed for the manipulation of droplets and bubbles. The structure and morphology of the MnO 2 /Cs are examined using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), and the elemental composition and chemical bonds of the compounds are characterized by X-ray photoelectron spectroscopy (XPS), Raman spectra and Fourier transform infrared spectrometer (FTIR). The SPM with a sliding angle as low as 3° is prepared. On the SPM, the rapid transportation and precise control of small droplets can be achieved, with the transportation speed of 5 µL droplets reaching 1 mm s −1 and the round-trip control of droplets also being feasible. The surface is capable of controlling the speed of a 100 µL droplet with a precision of 0.49 mm s −1 , while a 50 µL droplet can be directed with a load of 1 mg. Moreover, bubbles with a volume of 5 to 20 µL can also be transported.
The selection and preparation of materials is very important for the green treatment of wastewater. In our study, MnO 2 nanosheets were in-situ grown on biomass carbon microspheres (BCM) to format flower-like MnO 2 @carbon microspheres (CMn) adsorption composites. Amoxicillin (AMX) was adopted as model pollutant, and its adsorption was investigated as function of the contact time, AMX concentration, adsorbent dosage, and pH. The highest adsorption capacity of CMn was 16.094 mg/g in neutral medium. The adsorption isotherms were fitted using the Langmuir model. The kinetics of AMX adsorption was determined to follow the pseudo-first-order model. Recycle experiments indicated that CMn exhibited high adsorption efficiency (>80%) after four cycles. Therefore, the as-prepared CMn can be a promising material for removing pollutants form wastewater in the future.
Yacong Yang,Ya Zhao,Fengyan Shi,Zitao Chen,Weiguang Zhao,Yue Gao,Yingchun Miao,Yuning Huo
Micromotors with autonomous motion by multiple driving forces have attracted wide attentions. In this work, we successfully constructed MnO 2 -carbon microspheres (Mn-Cs) composite micromotors with synergistic photothermal-bubbly driving effect. The uniform MnO 2 loading and the stable combination of MnO 2 with Cs in Mn-Cs composite facilitated to improve the photothermal conversion performance. The regular morphology and large specific surface area of Mn-Cs were beneficial for the in-situ photocatalytic decomposition of H 2 O 2 under light irradiation. Notably, the photothermal conversion effect of Mn-Cs could further promote the decomposition of H 2 O 2 . The low thermal conductivity of air was beneficial for expanding the temperature gradient between the micromotor surface and the environment. As a result, the speed of optimal 1.0-Mn-Cs sample under the light irradiation and addition of H 2 O 2 (75.2 μm/s) was 14.3 and 5.88 times higher than that individual light irradiation (5.27 μm/s) and addition of H 2 O 2 (12.8 μm/s), respectively. It was indicative of the great significance of synergistic photothermal-bubbly driving effect. This study provided a new strategy for developing synergistically driven micromotors to reduce chemical fuel dependence, and showed a significant prospect in green, economic and sustainable applications.
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