The development of highly efficient bifunctional catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for improving the efficiency of the Zn-air battery. Herein, we report porous NiO/CoN interface nanowire arrays (PINWs) with both oxygen vacancies and a strongly interconnected nanointerface between NiO and CoN domains for promoting the electrocatalytic performance and stability for OER and ORR. Extended X-ray absorption fine structure spectroscopy, electron spin resonance, and high-resolution transmission electron microscopy investigations demonstrate that the decrease of the coordination number for cobalt, the enhanced oxygen vacancies on the NiO/CoN nanointerface, and strongly coupled nanointerface between NiO and CoN domains are responsible for the good bifunctional electrocatalytic performance of NiO/CoN PINWs. The primary Zn-air batteries, using NiO/CoN PINWs as an air-cathode, display an open-circuit potential of 1.46 V, a high power density of 79.6 mW cm, and an energy density of 945 Wh kg. The three-series solid batteries fabricated by NiO/CoN PINWs can support a timer to work for more than 12 h. This work demonstrates the importance of interface coupling and oxygen vacancies in the development of high-performance Zn-air batteries.

Understanding the mechanism of ice adhesion on surfaces is crucial for anti-icing surfaces, and it is not clear if superhydrophobic surfaces could reduce ice adhesion. Here, we investigate ice adhesion on model surfaces with different wettabilities. The results show that the superhydrophobic surface cannot reduce the ice adhesion, and the ice adhesion strength on the superhydrophilic surface and the superhydrophobic one is almost the same. This can be rationalized by the mechanical interlocking between the ice and the surface texture. Moreover, we find that the ice adhesion strength increases linearly with the area fraction of air in contact with liquid.

A robust prototypical anti-icing coating with a self-lubricating liquid water layer (SLWL) is fabricated via grafting cross-linked hygroscopic polymers inside the micropores of silicon wafer surfaces. The ice adhesion on the surface with SLWL is 1 order of magnitude lower than that on the superhydrophobic surfaces and the ice formed atop of it can be blown off by an action of strong breeze. The surface with self-lubricating liquid water layer exhibits excellent capability of self-healing and abrasion resistance. The SLWL surface should also find applications in antifogging and self-cleaning by rainfall, in addition to anti-icing and antifrosting.

A spontaneous and controllable removal of condensed microdroplets at high supersaturation via self-propelled jumping is achieved by introducing a designed micropore array on a nanostructured superhydrophobic surface. The fabricated surface was demonstrated to delay the ice formation for 1 hour at -15 °C with a supersaturation of 6.97.

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Removing condensed water from a cold surface can improve the surface heat-exchange coeffi cient by at least one order of magnitude, compared with the case of condensed water staying on the surface, [1][2][3] which is very important for all cooling systems due to increasing energy concerns nowadays. Because of their excellent water-repellent properties, superhydrophobic surfaces with low adhesion to water are promising candidates for effi cient removal of condensed water microdroplets. [4][5][6][7] It has been reported that coalescing microdroplets can self-remove from superhydrophobic surfaces when powered by the released surface energy, [ 8 , 9 ] which has aroused interest. [10][11][12][13] Though the self-removal of condensed microdroplets is energy saving, its effi ciency depends on the growth rate and the coalescing frequency of condensed droplets. Generally, faster growth and more frequent coalescence will lead to higher self-removal efficiency of condensed droplets. However, though hydrophilic surfaces are favorable for the quick nucleation and growth of condensed water, they are unfavorable for the self-removal of condensed microdroplets. [ 1 , 14 , 15 ] While the high nucleation energy barrier on hydrophobic or superhydrophobic surfaces slows down the growth of condensed droplets, [ 16 ] the uncontrollable distance between condensed microdroplets decreases the coalescing frequency, resulting in a low self-removal efficiency. Thus, how to control the condensation and coalescence processes and accelerate the self-removal of condensed microdroplets remains a great challenge for developments of new antifogging, anti-icing materials and heat exchangers.Herein, inspired by the peculiar hydrophilic/hydrophobic structures on a beetle's elytra, [ 14 , 17 , 18 ] a micro-/nanoporous superhydrophobic surface modifi ed with hydrophilic polymer was designed for effi ciently controlling microdroplet self-removal. The hierarchical micro-/nanoporous structure was fabricated on aluminum by integrating microcontact printing [ 19 , 20 ] and chemical bath deposition. [ 11 , 21 ] After modifying the bottom of arrayed micropores with hydrophilic polymers, water vapor nucleated mainly in the arrayed micropores. Controllable and quick self-removal was also achieved on the porous superhydrophobic surface when poly(vinyl alcohol) (PVA) was adsorbed in the micropores. The synergistic combination of superhydrophobic hierarchical porous surface and PVA adsorbed in micropores contributes directly to the quick nucleation, controllable coalescence, and highly effi cient self-removal of water. Exploitation of such coupling between hierarchical structure and chemical composition is important in developing optimal surfaces for wide applications such as heat transfer, micromachines, and cooling systems of high-performance electronics.In our previous work, we have found that the most probable diameter of coalescing microdroplets followed by self-removal was in the range of 20 -25 μ m on the superhydrophobic Al surface. [ 11 ] If the dist...

Surfaces obtained by modifying poly(N,N'-dimethylaminoethyl methacrylate) (PDMAEMA) on rough silicon substrates are highly hydrophilic at low pH and highly hydrophobic at high pH; such surfaces effectively supplement the research on the wettability of solid surfaces based on the pH-responsive polymers.

An intelligent photo-responsive spiropyran (SP)-contained surface that combines reversible wettability conversion with photochromic behavior was prepared on etched silicon substrates by atom transfer radical polymerization. The heterocyclic ring cleavage of SP moieties under UV irradiation leads to the change of the surface wettability and color. Water contact angle (CA) of the prepared surfaces change from 138.8 6 1.3 to 42.7 6 1.7 after 5 min under 365 nm UV irradiation and recover to its original state after 20 min of visible light irradiation, accompanied by the color change between yellowish and purple. To our knowledge, this result is the highest and fastest CA variation reported for surfaces containing SPs.