In the paper, "Methyl Termination of p-Type Silicon Enables Selective Photoelectrochemical CO2 Reduction by a Molecular Ruthenium Catalyst," published in ACS Energy Letters, the researchers explain how they use a process called methyl termination that uses a simple organic compound of one carbon atom bonded to three hydrogen atoms to modify the surface of silicon, an essential component in solar cells, to improve its performance in converting carbon dioxide into carbon monoxide using sunlight. "One challenge with solar energy is that it's not always available when we have the highest need for it," said Gabriella Bein, the paper's first author and a Ph.D. student in chemistry. "Another challenge is that renewable electricity, like that from solar panels, doesn't directly provide the raw materials needed for making chemicals. Our goal is to store solar power in the form of liquid fuels that can be used later." Jillian Dempsey, a co-author of the paper and Bowman and Gordon Gray Distinguished Term Professor, said that when they ran experiments in a solution filled with carbon dioxide, they found that they could produce carbon monoxide at 87% efficiency, meaning the system using the modified silicon photoelectrodes is comparable or better than systems using traditional metal electrodes, such as gold or platinum. In addition, the silicon photoelectrode used 460 millivolts less electrical energy to produce a reaction than one would have using only electricity. Dempsey called this significant, because the process uses direct light harvesting to supplement or offset the energy required to drive the chemical reaction that converts carbon dioxide into carbon monoxide. "What's interesting is normally silicon surfaces make hydrogen gas instead of carbon monoxide, which makes it harder to produce it from carbon dioxide," said Dempsey, who is also deputy director of CHASE. "By using this special methyl-terminated silicon surface, we were able to... |