Bioinspired solar anti-icing/de-icing surfaces based on phase-change materials

Solar anti-icing/de-icing is an environmentally friendly way to convert light energy into heat with the purpose of melting/removing ice. However, the inherent intermittency of solar irradiation limits the application of solar-thermal energy-conversion technologies, when continuous de-icing is required. Herein, we investigate a solar phase-change material(SPCM) that consists of expanded graphite(EG)/paraffin/polydimethylsiloxane(PDMS), which can not only perform the solar-thermal conversion but also release/store thermal energy. Under sunlight, the SPCM effectively collects and converts the light energy into thermal energy for later antiicing/de-icing. To prepare for a no-light period, e.g., in the evening, the converted thermal energy can be stored in the SPCM using a phase transition. In this way, the energy can be released when needed to keep the temperature of a surface from freezing. The SPCM surface shows excellent anti-icing/de-icing properties such as a long droplet freeze-delay time(td> 2 h), even at an ultra-low temperature(-40℃), using only the light of one sun. This freeze-delay time is much longer than that for a surface without PCM. The tested SPCM surfaces show a high de-icing rate(2.21 kg m^(-2)h^(-1)) under real-life conditions. In addition, the SPCM shows a high de-icing rate and excellent durability. This study provides a promising route for the utilization of solar energy in anti-icing/de-icing applications.

MoSx microgrid electrodes with geometric jumping effect for enhancing hydrogen evolution efficiency

Bubble evolution behaviors play important roles in bubble emission reactions.Here we fabricated one-dimensional(1D)-aligned MoSx microgrids to investigate the influence of the periodic structure on bubble releasing.It is demonstrated that the utilization of the surface energy released during coalescence of bubbles causes them to jump from the electrode,which can be an effective route to eliminate the bubble shielding effect.Under the optimized architecture with 40-μm-wide grooves,the generated bubbles tend to coalesce and release from the electrode with much smaller size(65%less in volume).By balancing the coalescence efficiency and the adhesive work via the architecture engineering,the electrocatalytic performance can be promoted with the rapid bubble removal and lowered ohmic resistance.The results provide new insights into the rational design of novel catalytic electrode architectures and promote their applications in related fields.

Bioinspired Anti-Icing Hydrogel Enabled by Ice-Nucleating Protein

Ice-nucleating proteins(INPs)are the most effective ice-nucleating agents that play a significant role in preventing freeze injuries in freeze-tolerant organisms.INPs promote ice nucleation in the extracellular space,harvesting water from cells due to the low vapor pressure of ice compared with water,thereby protecting freeze-tolerant organisms from intracellular freezing.The antifreeze mechanism of INPs offers a unique opportunity to inhibit large-scale freezing by localized control of ice formation,with valuable enlightenment in anti-icing material sciences.By learning from nature,we transferred the excellent ice nucleation-facilitating capability of INPs along with an antifreeze concept of spatially controlled ice nucleation to anti-icing material design,fabricating icephobic coatings that consisted of patterned hydrogel-encapsulated INP(PHINP).The ice patterns were templated by patterned PHINPs via the tuning of ice nucleation so that the ice coverage fraction could be controlled by<30%on almost all PHINP-coated surfaces.Combining PHINP with solar-thermal conversion surfaces endowed the composite coatings with high anti-icing performances at any time of the day.