Carbon dioxide (CO2) is one of the major greenhouse gases causing global warming. If carbon dioxide could be converted into energy, it would be killing two birds with one stone in addressing environmental issues. A joint research team led by City University of Hong Kong (CityU) has developed a new photocatalyst which can produce methane fuel (CH4) selectively and effectively from carbon dioxide using sunlight. According to their research, the quantity of methane produced was almost doubled in the first 8 hours of the reaction process.