Pyrolyzing soft template-containing poly(ionic liquid) into hierarchical N-doped porous carbon for electroreduction of carbon dioxide

•Soft template-containing poly(ionic liquid) was pyrolyzed to N-doped carbon.•Porosity and N species were modulated by controlling pyrolysis temperatures.•The resultant carbon featured hierarchically small-/ultra-microporous structure.•High-proportioned surface Grap-N species served as the major active sites.•Hierarchical small-/ultra-micropores accounted for the electrocatalysis activity.