Scientists at the I-CORE Research Center of Solar Fuel Integration of Israel Institute of Technology have developed a new method of hydrogen production by photolysis. The invention based on nano-materials technology makes it possible to produce hydrogen by photolysis of water at low cost. If photovoltaic cell technology is grafted, it may lead to the generation of hydrogen photovoltaic industry and realize the junction of photovoltaic power generation and photolysis of water to produce hydrogen by two green energy production modes. All right.

This achievement has attracted wide attention. Some people compare it with the famous "artificial blade" at that time, and think that its future is brighter. This achievement also makes I-CORE, a research platform of "brain reflux" that the Israeli government has been working hard to build in recent years, particularly noticeable. Recently, a reporter from Sci-Tech Daily interviewed Professor Avner Rothschild, the chief researcher of the project of Solar Fuel Centralization Research Center of Israel Institute of Technology.

Revolution brought about by nanomaterials technology

"It is completely feasible to use integrated series photovoltaic cells to produce hydrogen by photolysis of water. Photovoltaic power generation can produce and store hydrogen simultaneously. Hydrogen fuel can be used to supplement the power generation needs in dark and cloudy days." Rothschild told reporters, "We have found a way to capture light, using ultrathin iron oxide film, that is, using rust 5,000 times thinner than office paper, that is, iron oxide to store light, which is the key to achieving high efficiency and low cost." Their research results are published in Natural Materials. The title of the paper is "Using Ultra Thin Materials to Capture Resonance Light to Realize Water Cracking".

Ferric oxide is a common semiconductor material, which has low production cost, is not easy to oxidize, corrosion resistance and decomposition resistance in water, and is more stable than other semiconductor materials. But its low conductivity is the biggest challenge facing researchers. For many years, researchers have struggled to find a compromise between absorption and separation of light and collection of photogenerated loads.

"Our optical capture scheme has broken this bottleneck, and the ultrathin iron oxide film can effectively absorb photogenerated charges." "Mirror-like films are placed on a reflective substrate, and a quarter of the wavelength or deeper sub-wavelength of light is captured by the film," Rothschild said. At the same time, the absorption surface is enhanced between the forward and backward light waves, and the absorption efficiency of photogenerated charge carriers is better.

Speaking of the significance of the discovery, Rothschild believed that the research results made it possible for photovoltaic power generation and hydrogen production to proceed simultaneously. People can design and manufacture relatively inexpensive solar cells with ultrathin iron oxide photoelectrodes. This kind of solar cells can use traditional products based on silicon or other materials, but can realize photovoltaic power generation and hydrogen production at the same time. He said that these batteries achieve solar energy storage, so that photovoltaic power generation is no longer affected by night and cloudy days, which is incomparable with traditional photovoltaic power generation.

The invention also reduces the use of extremely rare metals in second-generation photovoltaic cells, which theoretically saves 90% of tellurium and indium, without sacrificing power generation performance.

Water consumption is also an unavoidable problem for such photovoltaic power plants, Rothschild said. Currently, they use fresh water to test and calculate the results, and their water consumption and economy are almost the same as traditional power generation. They will also be confident in the use of seawater for hydrogen production by photolysis. He said that since the release of their scientific research results at the end of last year, they have made great progress in improving the efficiency of hydrogen production. In theory, photovoltaic power plants based on this technology have been able to compete with traditional power generation, and their costs are comparable. If considering the factors of green, environmental protection and low carbon, such photovoltaic power plants have advantages.

Occupying a large amount of land is another problem faced by photovoltaic power plants. Rothschild is not very worried about this. He said that every country has a large amount of land that can not be cultivated but is fully illuminated. They are natural choices for building photovoltaic power plants, and the need for land to comprehensively solve energy problems is not excessive compared with other uses. He takes Israel as an example. The land occupied by roads in Israel is 3% of the total land area, and the new photovoltaic power plant can completely solve Israel's electricity demand by only 1% of the land area, and completely achieve national energy independence, and completely abandon fossil energy.

Three Steps to Realize Clean Energy

Rothschild analyzed the possibilities of realizing the human clean energy dream. He believed that solar photovoltaic power generation was the most successful clean energy solution so far compared with wind, geothermal, nuclear and tidal energy. This expensive energy technology, which was only used in military and space 20 years ago, has become very mature and popular, and has a high degree of industrialization. Although some people are still questioning its power generation cost, the unit price of photovoltaic power generation in Israel has converged with that of traditional power plants in terms of current technology level. If the operation cycle is compared over a period of 30 years, the generation cost of photovoltaic power plants will be lower than the current price. This does not include the production safety costs and environmental pollution costs of traditional power plants. Rothschild said that a former deputy director of the Israeli Ministry of Finance had calculated the real price of traditional power plants at twice the current price of photovoltaic power generation.

Rothschild does not think much of biofuels. He believes that biofuels are inefficient in generating electricity and that photosynthesis in nature requires a lot of land. With the large-scale development of biofuels, human beings will face the problem of using limited land to produce food or livelihood.