Researchers at Tokyo Metropolitan University in Japan have developed a material which can be attached to chimneys of power plants and factories to remove carbon dioxide (CO 2 ) from emissions and help protect against global warming. This material, a sieve-like membrane which can selectively remove CO 2 from mixed gases containing nitrogen and methane, is a two-tiered structure having a sponge-like layer covered by another thin layer that selectively absorbs CO 2 and retains it within its layers, thereby separating CO 2 from other gases.