Rapid droplet removal by regulating surface topology and wettability has been exploited in nature and it is of great importance for a broad range of technological applications including water desalination and harvesting, power generation, environmental control, and thermal management. Recently there have been tremendous efforts in developing nanostructured surfaces for wettability control and enhancing phase-change heat transfer. However, the tendency of condensed droplets to form as pinned state rather than mobile mode on the nanostructured surfaces is likely to limit the applicability of such functionalized surfaces for condensation heat transfer enhancement. Here, we demonstrate enhanced condensation heat transfer on a nanowired hydrophobic copper surface where molecular permeation of water vapor into the separations between nanowires is greatly decreased, rendering spatial control on droplet nucleation and wetting dynamics. We show experimentally and theoretically that this novel strategy allows to achieve a 100% higher overall heat flux over a broadened surface subcooling range, up to 24 K, due to highly efficient droplet jumping compared to the state-of-the-art hydrophobic surfaces. These findings reveal that the droplet behaviors and condensation modes can be regulated by spatially controlling the nucleation events on the nanostructured surfaces, which paves the way for the design of nanostructured surfaces for enhanced phase-change heat transfer.
An FeGa@P(VDF-TrFE) wire-shaped magnetoelectric nanorobot is designed and fabricated to demonstrate a proof-of-concept integrated device, which features wireless locomotion and on-site triggered therapeutics with a single external power source (i.e., a magnetic field). The device can be precisely steered toward a targeted location wirelessly by rotating magnetic fields and perform on-demand magnetoelectrically assisted drug release to kill cancer cells.
Amorphous bimetallic borides are an emerging class of catalytic nanomaterial that has demonstrated excellent catalytic performance due to its glass-like structure, abundant unsaturated active sites, and synergistic electronic effects. However, the creation of mesoporous Earth-abundant bimetallic metal borides with tunable metal proportion remains a challenge. Herein, we develop a sophisticated and controllable dual-reducing agent strategy to synthesize the mesoporous nickel−cobalt boron (NiCoB) amorphous alloy spheres (AASs) with adjustable compositions by using a soft template-directed assembly approach. The selective use of tetrabutylphosphonium bromide (Bu 4 PBr) is beneficial to generate well-defined mesopores because it both moderates the reduction rate by decreasing the reducibility of M 2+ species and prevents the generation of soap bubbles. Our meso-Ni 10.0 Co 74.5 B 15.5 AASs generate the highest catalytic performance for the hydrolytic dehydrogenation of ammonia borane (AB). Its high performance is attributed to the combination of optimal synergistic effects between Ni, Co, and B as well as the high surface area and the good mass transport efficiency due to the open mesopores. This work describes a systematic approach for the design and synthesis of mesoporous bimetallic borides as efficient catalysts.
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