The energy from the sun is much more than all the energy used by all human beings. Imagine that the sun's energy can be used to drive energy needs on earth and do it in a way that is economically, extensible, and environmentally responsible. Researchers have long seen this as one of the major challenges of the twenty-first Century.
丹尼尔·埃斯波西托，在哥伦比亚大学工程化学工程助理教授，一直在研究电解水？水分解成氧气（O 2）和氢（H 2）燃料？作为一种电力来自太阳能光伏（PV）的成可储存转换氢燃料。氢是一种清洁的燃料，目前用于在美国宇航局太空计划中推进火箭，并普遍预计在可持续能源未来发挥重要作用。今天的大多数氢气是由天然气通过称为蒸汽甲烷重整的过程产生的，该过程同时释放CO 2，但是使用来自太阳能光伏发电的水电解提供了有前途的生产H 2的途径，而没有任何相关的CO 2 排放。
Daniel Esposito, assistant professor of Engineering Chemistry Engineering at Columbia University, has been studying electrolysis water. Water is decomposed into oxygen (O 2) and hydrogen (H 2) fuel? As a kind of electric power from the solar photovoltaic (PV), the converted hydrogen fuel can be stored. Hydrogen is a clean fuel. It is currently used to launch rockets in the space program of NASA, and is widely expected to play an important role in the future of sustainable energy. Today, the vast majority of hydrogen is generated from natural gas through a process called steam methane reforming process at the same time, the release of CO 2, but from the way of solar photovoltaic power generation water electrolysis provides a promising prospect in the production of H 2, and no emission of CO 2.
Esposito's team has now developed a new type of photovoltaic electrolysis equipment that can operate as an independent platform floating on the open water surface. His floating photovoltaic cell can be regarded as a "solar fuel drilling platform", which has some similarities with deep-sea oil drilling platforms. The difference is that it can generate hydrogen fuel from sunlight and water instead of collecting oil from the bottom.
研究人员的主要创新是分离水电解产生的H 2和O 2气体的方法。比较先进的电解槽使用昂贵的膜来保持这两种气体的分离。哥伦比亚工程设备取而代之的是一种新颖的电极结构，可以利用水中气泡的浮力分离和收集气体。该设计能够以高产品纯度进行高效操作，并且不需要主动泵送电解液。基于浮力分离的概念，简单的电解槽结构产生纯度高达99％的H 2。
The main innovation of the researchers is the method of separating H 2 and O 2 gas produced by water electrolysis. The most advanced electrolyzer uses expensive membranes to maintain the separation of these two gases. The Columbia engineering equipment is replaced by a novel electrode structure that can be used to separate and collect gas from the buoyancy of the bubbles in the water. The design can operate efficiently with high product purity, and does not need to pump the electrolyte on the initiative. Based on the concept of buoyancy separation, a simple electrolytic cell structure produces a purity of up to 99% of H 2.
Esposito said: "there is no diaphragm or pump, simple structure of the photovoltaic cell we make our design used in the seawater electrolysis is particularly attractive, thanks to its low cost and high durability potential compared with existing equipment including diaphragm. Its solar fuel engineering laboratory develops solar and electrochemical technologies to convert renewable and rich solar energy into stored chemical fuels. "We believe that our prototype is a practical membrane free floating PV electrolyzer system first demonstration, and can stimulate the large-scale" solar fuel rig ", may have a large number of H 2 from the sun and the sea fuel rich, does not occupy any space in the land and freshwater for agricultural purposes or competition. "
商用电解装置依靠膜或分隔器来分离产生H 2和O 2气体的装置内的电极。电解装置的大部分研究集中在装有膜的装置上。这些膜和分隔器易于降解和破坏，需要高纯度的水源。海水中含有杂质和微生物，可以很容易地破坏这些膜。
The commercial electrolysis device relies on a membrane or separator to separate the electrodes in a device that produces H 2 and O 2 gas. Most of the research in the electrolysis device is focused on a device equipped with a membrane. These membranes and separators are easy to degrade and destroy, and require high purity water. The sea water contains impurities and microbes that can easily destroy these membranes.
The first author of the paper, and Esposito (Esposito) cooperative doctoral student Jack Davis (Jack Davis) said: "to secure the presentation of a diaphragm can be carried out without electrolysis device, we make a step forward, the seawater electrolysis may. These solar energy fuel generators are essentially artificial photosynthesis systems, which are similar to plants in photosynthesis. Therefore, our devices may generate various opportunities to generate clean renewable energy.
Esposito的PV电解器的操作的关键是一种新颖的电极配置，包括仅在一侧涂覆有催化剂的网状流通电极。这些不对称的电极仅促进催化剂已经沉积的电极的外表面上的气态H 2和O 2产物的演变。当生长的H 2和O 2气泡变得足够大时，它们的浮力使它们从电极表面分离并向上浮动到单的顶部收集室中。
The key to the operation of the Esposito's PV electrolyzer is a novel electrode configuration, including a reticulate circulating electrode with only a catalyst coated on one side. These asymmetric electrodes only promote the evolution of the gaseous H 2 and O 2 products on the outer surface of the deposited electrode. When the growth of H 2 and O 2 bubbles become large enough, their buoyancy separates them from the surface of the electrode and floats up to a separate top collection chamber.
The team used the Columbia clean room to deposit platinum electrocatalysts on the net electrodes and 3D printers of Columbia Makerspace to produce many reactor components. They also used high-speed video cameras to monitor the bubbles between H's 2 and O 2 electrodes, known as a "cross" process. The intersection between electrodes is not desirable, because it reduces the purity of products, leads to safety problems, and requires downstream separation units to make the method more expensive.
为了监测H 2和O 2交叉事件，研究人员在其所有的电解装置中安装了窗口，以便在装置运行时能够从电极上获取高速的气泡演变视频。这些视频通常以每秒500帧的速度拍摄（典型的iPhone以每秒30帧的速度拍摄视频）。
In order to monitor the H 2 and O 2 crossover events, the researchers installed windows in all of their electrolysis devices so as to get high-speed video of bubbles evolution from the electrodes when the device was running. These videos are usually photographed at a speed of 500 frames per second (typical iPhone takes 30 frames per second at the speed of video).
The team is improving their design in order to operate more efficiently in real seawater, which brings additional challenges compared with other ideal aqueous electrolytes used in other laboratory studies. They also plan to develop modular designs that can be used to build more large-scale systems.
Esposito added: "sustainable energy has a lot of feasible technical solutions in the future, but no one knows the combination of specific technology or technology is the best choice for our solar fuel technology potential excited, because we are facing huge challenges for scalable and economical technology, solar light converted into useful forms of energy, when the sun does not shine, you can also store solar energy.