The electrochemical conversion of CO 2 and H 2 O into liquid fuel is ideal for high-density renewable energy storage and could provide an incentive for CO 2 capture. However, efficient electrocatalysts for reducing CO 2 and its derivatives into a desirable fuel1,2,3 are not available at present. Although many catalysts4,5,6,7,8,9,10,11 can reduce CO 2 to carbon monoxide (CO), liquid fuel synthesis requires that CO is reduced further, using H 2 O as a H+ source. Copper (Cu) is the only known material with an appreciable CO electroreduction activity, but in bulk form its efficiency and selectivity for liquid fuel are far too low for practical use. In particular, H 2 O reduction to H 2 outcompetes CO reduction on Cu electrodes unless extreme overpotentials are applied, at which point gaseous hydrocarbons are the major CO reduction products12,13. Here we show that nanocrystalline Cu prepared from Cu 2 O (‘oxide-derived Cu’) produces multi-carbon oxygenates (ethanol, acetate and n-propanol) with up to 57% Faraday efficiency at modest potentials (–0.25 volts to –0.5 volts versus the reversible hydrogen electrode) in CO-saturated alkaline H 2 O. By comparison, when prepared by traditional vapour condensation, Cu nanoparticles with an average crystallite size similar to that of oxide-derived copper produce nearly exclusive H 2 (96% Faraday efficiency) under identical conditions. Our results demonstrate the ability to change the intrinsic catalytic properties of Cu for this notoriously difficult reaction by growing interconnected nanocrystallites from the constrained environment of an oxide lattice. The selectivity for oxygenates, with ethanol as the major product, demonstrates the feasibility of a two-step conversion of CO 2 to liquid fuel that could be powered by renewable electricity. ||||| Scientists said on Wednesday they have developed a new way to make liquid ethanol efficiently without using corn or other crops needed in the conventional method for producing the biofuel. 
 
 The scientists said their process turns carbon monoxide gas into liquid ethanol with the help of an electrode made of a form of copper. They said the new technique may be more environmentally friendly and efficient than the current method. 
 
 Critics say that growing crops for biofuels is energy-intensive and takes up vast tracts of nonagricultural land, using too much water and fertilizer. They also say diverting corn and sugar to make biofuels pushes up food prices. 
 
 The United States leads the world in ethanol production, with 13.3 billion gallons in 2013, followed by Brazil's 6.3 billion gallons, according to the Washington-based Renewable Fuels Association, which represents the U.S. ethanol industry. 
 
 E85 ethanol fuel is pumped into a vehicle at a gas station in the town of Nevada, Iowa, on Dec. 6, 2007. Scientists say they have developed a new way to make liquid ethanol fuel in an efficient process that does not use corn or other crops. JASON REED / Reuters 
 
 A group of scientists led by Stanford University chemist Matthew Kanan described the new method in research published in the journal Nature. Kanan said a prototype device could be ready in two to three years, enabling an assessment on whether the process can become commercially viable. 
 
 "I emphasize that these are just laboratory experiments today. We haven't built a device," Kanan said. "But it demonstrates the feasibility of using electricity that you could get from a renewable energy source to power fuel synthesis — in this case ethanol. There are some real advantages to doing that relative to using biomass to produce ethanol." 
 
 Ethanol fuel generally is produced at high-temperature fermentation facilities that chemically transform corn, sugarcane and other plants into liquid fuel. 
 
 Kanan and his colleagues built an electrochemical cell — a device consisting of two electrodes that were put in water saturated with carbon monoxide gas. One of the electrodes was made of a material they call "oxide-derived copper." 
 
 When voltage was applied across the electrodes, the carbon monoxide gas was converted into ethanol, they said. 
 
 The researchers hope to take carbon dioxide from the atmosphere and convert it to carbon monoxide, which then would be fed into the copper-oxide catalyst. The researchers hope the catalytic cell would be powered by a renewable energy source such as solar or wind. 
 
 — Reuters ||||| Stanford scientists Matthew Kanan and Christina Li have created an oxide-derived copper catalyst that converts carbon monoxide to ethanol. The catalyst consists of a continuous network of copper nanocrystals with well-defined grain boundaries. The nanocrystalline network may be critical for producing ethanol, the scientists say. Credit: Matthew Kanan, Stanford University Stanford University scientists have found a new, highly efficient way to produce liquid ethanol from carbon monoxide gas. This promising discovery could provide an eco-friendly alternative to conventional ethanol production from corn and other crops, say the scientists. Their results are published in the April 9 advanced online edition of the journal Nature. 
 
 "We have discovered the first metal catalyst that can produce appreciable amounts of ethanol from carbon monoxide at room temperature and pressure – a notoriously difficult electrochemical reaction," said Matthew Kanan, an assistant professor of chemistry at Stanford and coauthor of the Nature study. 
 
 Most ethanol today is produced at high-temperature fermentation facilities that chemically convert corn, sugarcane and other plants into liquid fuel. But growing crops for biofuel requires thousands of acres of land and vast quantities of fertilizer and water. In some parts of the United States, it takes more than 800 gallons of water to grow a bushel of corn, which, in turn, yields about 3 gallons of ethanol. 
 
 The new technique developed by Kanan and Stanford graduate student Christina Li requires no fermentation and, if scaled up, could help address many of the land- and water-use issues surrounding ethanol production today. "Our study demonstrates the feasibility of making ethanol by electrocatalysis," Kanan said. "But we have a lot more work to do to make a device that is practical." 
 
 Novel electrodes 
 
 Two years ago, Kanan and Li created a novel electrode made of a material they called oxide-derived copper. They used the term "oxide-derived" because the metallic electrode was produced from copper oxide. 
 
 "Conventional copper electrodes consist of individual nanoparticles that just sit on top of each other," Kanan said. "Oxide-derived copper, on the other hand, is made of copper nanocrystals that are all linked together in a continuous network with well-defined grain boundaries. The process of transforming copper oxide into metallic copper creates the network of nanocrystals." 
 
 For the Nature study, Kanan and Li built an electrochemical cell – a device consisting of two electrodes placed in water saturated with carbon monoxide gas. When a voltage is applied across the electrodes of a conventional cell, a current flows and water is converted to oxygen gas at one electrode (the anode) and hydrogen gas at the other electrode (the cathode). The challenge was to find a cathode that would reduce carbon monoxide to ethanol instead of reducing water to hydrogen. 
 
 "Most materials are incapable of reducing carbon monoxide and exclusively react with water," Kanan said. "Copper is the only exception, but conventional copper is very inefficient." 
 
 In the Nature experiment, Kanan and Li used a cathode made of oxide-derived copper. When a small voltage was applied, the results were dramatic. 
 
 "The oxide-derived copper produced ethanol and acetate with 57 percent faradaic efficiency," Kanan said. "That means 57 percent of the electric current went into producing these two compounds from carbon monoxide. We're excited because this represents a more than 10-fold increase in efficiency over conventional copper catalysts. Our models suggest that the nanocrystalline network in the oxide-derived copper was critical for achieving these results." 
 
 Carbon neutral 
 
 The Stanford team has begun looking for ways to create other fuels and improve the overall efficiency of the process. "In this experiment, ethanol was the major product," Kanan said. "Propanol would actually be a higher energy-density fuel than ethanol, but right now there is no efficient way to produce it." 
 
 In the experiment, Kanan and Li found that a slightly altered oxide-derived copper catalyst produced propanol with 10 percent efficiency. The team is working to improve the yield for propanol by further tuning the catalyst's structure. 
 
 Ultimately, Kanan would like to see a scaled-up version of the catalytic cell powered by electricity from the sun, wind or other renewable resource. 
 
 For the process to be carbon neutral, scientists will have to find a new way to make carbon monoxide from renewable energy instead of fossil fuel, the primary source today. Kanan envisions taking carbon dioxide (CO2) from the atmosphere to produce carbon monoxide, which, in turn, would be fed to a copper catalyst to make liquid fuel. The CO2 that is released into the atmosphere during fuel combustion would be re-used to make more carbon monoxide and more fuel – a closed-loop, emissions-free process. 
 
 "Technology already exists for converting CO2 to carbon monoxide, but the missing piece was the efficient conversion of carbon monoxide to a useful fuel that's liquid, easy to store and nontoxic," Kanan said. "Prior to our study, there was a sense that no catalyst could efficiently reduce carbon monoxide to a liquid. We have a solution to this problem that's made of copper, which is cheap and abundant. We hope our results inspire other people to work on our system or develop a new catalyst that converts carbon monoxide to fuel." 
 
 Explore further: Newly discovered catalyst could lead to the low-cost production of clean methanol 
 
 More information: Electroreduction of carbon monoxide to liquid fuel on oxide-derived nanocrystalline copper, Nature, dx.doi.org/10.1038/nature13249 
 
 ||||| Today, nearly all ethanol fuel is made from corn or sugarcane, which requires vast tracts of land and huge quantities of water and fertilizer. Researchers at Stanford University have now developed an electrochemical process that could be far cheaper and better for the environment. 
 
 The work is still experimental, but it’s significant because the group was able to synthesize ethanol and other desired products with so little energy input. “The levels of activity for CO reported here are unprecedented and a large step toward the realization of a practical system for converting CO to ethanol,” says Clifford Kubiak, professor of chemistry and biochemistry at the University of California, San Diego. 
 
 The scientists created a copper-based catalyst that is very effective at producing ethanol and other carbon compounds from carbon monoxide and water in a simple chemical reaction. They say the process, described in a paper published in Nature on Wednesday, could be powered by renewable sources of electricity, such as solar and wind, and would be an alternative to traditional biofuel production. 
 
 Making ethanol is normally remarkably energy-intensive, involving gathering and treating biomass and then fermenting the sugar found in the plant matter. The Stanford paper shows it’s feasible to produce ethanol directly from water and waste gases using an electric current. 
 
 “You get the same fuel, although in principle it could be much more efficient because you are not relying on biomass,” says Matthew Kanan, an associate professor of chemistry at Stanford who co-authored the paper. 
 
 The researchers envision a two-step process in which carbon dioxide is first converted into carbon monoxide using either existing processes or more energy-efficient ones currently under development. Then the carbon monoxide would be converted to ethanol or other carbon-based compounds electrochemically. 
 
 Existing methods for turning carbon monoxide into fuel are complicated, requiring very large reactors and high pressures. An electrolyzer, which uses an electrical current to drive a chemical reaction, could make the required system much smaller, says Joel Rosenthal, an assistant professor at the University of Delaware. This could allow ethanol production to be miniaturized and distributed. 
 
 One could image, for example, having a rooftop solar panel produce liquid fuel stored in a tank the size of a water heater. “The big value of chemical fuels in general, and liquid fuels in particular, is that they have much, much higher energy density than typical battery technologies, so you can store a lot more energy in a smaller amount of space,” Rosenthal says. 
 
 Ib Chorkendorff, the director of the Catalysis for Sustainable Energy research center at the Technical University of Denmark, describes the work as “an important step towards the goal of finding an efficient route for storing electricity as chemical energy.” 
 
 The key to the new catalyst is preparing the copper in a novel way that changes its molecular structure. Until now, copper catalysts produced a wide range of carbon-based compounds, rather than one desired product, and required a lot of energy. 
 
 The Stanford group starts with copper metal and, by heating it in air, grows a layer of copper oxide on top. Then that surface layer is chemically converted back to metallic copper. In the process, the copper takes on a very different surface with more active area for it to act as a catalyst. 
 
 It will take years to know whether a device based on this chemistry would be commercially viable. But if perfected, it could provide an economic incentive for removing carbon dioxide from the atmosphere.
– Could ethanol someday essentially be produced out of thin air? A group of scientists has published research in Nature detailing a new method of making ethanol out of carbon monoxide gas, instead of corn or sugarcane, Reuters reports. Researchers saturated water with the gas, then zapped it with a novel device featuring two electrodes, one made of what they're calling "oxide-derived copper," to convert it into fuel. "I emphasize that these are just laboratory experiments today," lead researcher Matthew Kanan says. He expects to have a prototype device ready in two to three years. The environmental implications are profound. Critics of ethanol say it drives up food prices and consumes loads of land and water. It can take more than 800 gallons of water to grow enough corn to make 3 gallons of ethanol, Phys.org points out. What's more, researchers envision a two-step process in which the carbon monoxide is derived from carbon dioxide in the air, providing an "economic incentive" for scrubbing carbon from the atmosphere, the MIT Technology Review reports. The new process could also work on a far smaller scale than biomass methods; the Review envisions rooftop solar panels generating fuel that's kept in water heater-sized tanks. (More on the toll ethanol takes on the environment here.)