Carbon Nanotube Scheme (image) Stanford University Caption This drawing shows the damaged outer wall of a carbon nanotube with nanosized graphene pieces (white patches), which facilitate the formation of catalytic sites made of iron (yellow) and nitrogen (red) atoms. The catalyst reduces oxygen to water. Credit Guosong Hong Usage Restrictions Photographs provided by the Precourt Institute for Energy at Stanford University are to be used -- with appropriate credit -- for editorial purposes only. Flopping, altering or otherwise embellishing these photos in any way that changes the photographs' editorial content is prohibited. Images provided for web use must be resized to low resolution. Permission is for one-time use only. Supplied image file must be deleted after use. For more information, email email@example.com. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.