Caffeine Makes Fuel Cells More Efficient, Cuts Cost of Energy Storage

Dan Robinson reports via The Register: Adding caffeine can enhance the efficiency of fuel cells, reducing the need for platinum in electrodes and significantly reducing the cost of making them, according to researchers in Japan. [...] The study, published in the journal Communications Chemistry, concerns the catalysis process at the cathode of a fuel cell and making this reaction more efficient. Fuel cells work somewhat like batteries. They generate power by converting the chemical energy of a fuel (or electrolyte) and an oxidizing agent into electricity. This is typically hydrogen as a fuel and oxygen as an oxidizer. Unlike batteries with limited lifespans, fuel cells can generate power as long as fuel is supplied. The hydrogen undergoes oxidation at the anode, producing hydrogen ions and electrons. The ions move through the hydrogen electrolyte to the cathode, while the electrons flow through an external circuit, generating electricity. At the cathode, oxygen combines with the hydrogen ions and electrons, resulting in water as a by-product. However, this water impacts the performance of the fuel cell, reacting with the platinum (Pt) to form a layer of platinum hydroxide (PtOH) on the electrode and interfering with the catalysis of the oxygen reduction reaction (ORR), according to the researchers. To maintain efficient operation, fuel cells require a high Pt loading (greater platinum content), which significantly ups the costs of fuel cells. A quick look online found market prices for platinum of $29.98 per gram, or $932.61 per ounce, at the time of writing. The researchers found that adding caffeine can improve the ORR activity of platinum electrodes 11 fold, making the reaction more efficient. If you are wondering (as we were) how they came to be experimenting with this, the paper explains that modifying electrodes with hydrophobic material is known to be an effective method for enhancing ORR. Caffeine is less toxic than other hydrophobic substances, and it activates the hydrogen evolution and oxidation reactions of Pt nanoparticles and caffeine doped carbons. Got that? Chiba University's work was led by Professor Nagahiro Hoshi at the Department of Applied Chemistry and Biotechnology. He explained that the researchers found a notable improvement in the electrode's ORR activity with an increase in caffeine concentration in the electrolyte. This forms a thin layer on the electrode's surface, effectively preventing the formation of PtOH, but the effect depends on the orientation of the platinum atoms on the electrode's surface. The paper refers to these as Pt(100), Pt(110) and Pt(111), with the latter two showing increased ORR activity, while there was no noticeable effect with Pt(100). The researchers do not explain if this latter effect might be a problem, but instead claim that their discovery has the potential to improve the designs of fuel cells and lead to more widespread adoption.

Read more of this story at Slashdot.