Organic Farming Could Feed the World, But..
15/11/2017 · What about Ricin, Unc
(The CO can then be converted into hydrocarbon fuels through an established industrial process called Fischer-Tropsch synthesis.) Zhang, who contributed to the work while a post-doctoral fellow at U of T and is now a professor at Fudan University, said, "Over the last couple of years, our team has developed very high-performing catalysts for both the first and the second reactions. “But while the second catalyst works under neutral conditions, the first catalyst requires high pH levels in order to be most active." That means that when the two are combined, the overall process is not as efficient as it could be, as energy is lost when moving charged particles between the two parts of the system. The team has now overcome this problem by developing a new catalyst for the first reaction — the one that splits water into protons and oxygen gas. Unlike the previous catalyst, this one works at neutral pH, and under those conditions it performs better than any other catalyst previously reported. Zheng, who is now a postdoctoral scholar at Stanford University, said, "It has a low overpotential, which means less electrical energy is needed to drive the reaction forward. “On top of that, having a catalyst that can work at the same neutral pH as the CO₂ conversion reaction reduces the overall potential of the cell." In the paper, the team reports the overall electrical-to-chemical power conversion efficiency of the system at 64 percent. According to De Luna, this is the highest value ever achieved for such a system, including their previous one, which only reached 54 percent. The new catalyst is made of nickel, iron, cobalt and phosphorus, all elements that are low-cost and pose few safety hazards. It can be synthesized at room temperature using relatively inexpensive equipment, and the team showed that it remained stable as long as they tested it, a total of 100 hours. Armed with their improved catalyst, the Sargent lab is now working to build their artificial photosynthesis system at pilot scale. The goal is to capture CO₂ from flue gas — for example, from a natural gas-burning power plant — and use the catalytic system to efficiently convert it into liquid fuels. De Luna said, "We have to determine the right operating conditions: Flow rate, concentration of electrolyte, electrical potential. "From this point on, it's all engineering." The team and their invention are semi-finalists in the NRG COSIA Carbon XPRIZE, a $20 million challenge to develop breakthrough technologies that will convert CO?
Conference Gallery | Falling Walls
For hydrogen generation, a molecule is needed to absorb photons and transfer electrons to a , which in turn transfers the electrons to the water molecules’ protons, producing hydrogen. Unfortunately, in many of the artificial photosynthesis schemes that have been tried, this light-absorbing molecule decomposes quickly. Two days has been the upper limit for systems that use organic dyes or compounds containing metals like iridium as photosynthesizers. To overcome the decomposition problem, researchers looked to semiconductor nanocrystals. These are more stable, but those tested so far have produced little hydrogen.