In 2012, the Obama administration announced fuel-efficiency standards that would require U.S. vehicles to average 54.5 miles per gallon by 2025. Improving gas mileage could help reduce greenhouse gas emissions and global dependence on fossil fuels. One approach scientists are exploring to help address these issues involves capturing waste heat from engines and other power systems and turning it into electricity. Many compounds can do this but are heavy, costly, toxic or only operate at high temperatures. Ian A. Kinloch, Robert Freer and colleagues sought new alternatives.
The researchers started with a material called strontium titanium dioxide and added a small amount of graphene, a stable material with excellent conductive properties. The resulting composite was able to capture and convert heat into electric current efficiently over a broad temperature range.