Curland Sofia, Javitt Leah, Weissbuch Isabelle, Ehre David, Lahav Meir, Lubomirsky Igor
Department of Materials and Interfaces, The Weizmann Institute of Science, 76100-, Rehovot, Israel.
Angew Chem Int Ed Engl. 2020 Sep 1;59(36):15570-15574. doi: 10.1002/anie.202006433. Epub 2020 Aug 11.
By performing icing experiments on hydrophilic and hydrophobic surfaces of pyroelectric amino acids and on the x-cut faces of LiTaO , we discovered that the effect of electrofreezing of super cooled water is triggered by ions of carbonic acid. During the cooling of the hydrophilic pyroelectric crystals, a continuous water layer is created between the charged hemihedral faces, as confirmed by impedance measurements. As a result, a current of carbonic acid ions, produced by dissolved environmental CO , flows through the wetted layer towards the hemihedral faces and elevates the icing temperature. This proposed mechanism is based on the following: (i) on hydrophilic surfaces, water with dissolved CO (pH 4) freezes at higher temperatures than pure water of pH 7. (ii) In the absence of the ionic current, achieved by linking the two hemihedral faces of hydrophilic crystals by a conductive paint, water of the two pH levels freeze at the same temperature. (iii) On hydrophobic crystals with similar pyroelectric coefficients, where there is no continuous wetted layer, no electrofreezing effect is observed.
通过对热释电氨基酸的亲水和疏水表面以及钽酸锂的X切割面进行结冰实验，我们发现过冷水的电冷冻效应是由碳酸离子引发的。在亲热水释电晶体冷却过程中，通过阻抗测量证实，在带电的半面之间形成了连续的水层。结果，由溶解在环境中的二氧化碳产生的碳酸离子电流，流经湿润层流向半面并提高了结冰温度。该提出的机制基于以下几点：(i) 在亲水表面上，溶解有二氧化碳（pH值为4）的水比pH值为7的纯水在更高温度下结冰。(ii) 在没有离子电流的情况下，通过用导电漆连接亲热水释电晶体的两个半面来实现，两种pH值水平的水在相同温度下结冰。(iii) 在具有相似热释电系数的疏水晶体上，由于没有连续的湿润层，未观察到电冷冻效应。
