▎ 摘　　要

NOVELTY - Self-supporting preparation of nitrogen-doped porous carbon membrane involves mixing polyionic liquid and polyacrylic acid; adding 10-500 ml dimethylformamide or dimethyl sulfoxide; heating and dissolving solution at 25-70 degrees C to obtain polymer solution into which carbon nanotubes, graphene oxide or carbon black is dispersed; pouring mixture on glass plate; drying solvent to obtain polymer composite membrane; soaking polymer composite membrane in 0.1-28 wt.% aqueous ammonia solution for 1-10 hours to obtain porous polymer film; and carbonizing porous polymer film in inert atmosphere. USE - Self-supporting preparation of nitrogen-doped porous carbon membrane used as electrode in electrocatalysis or as electrode for nitrogen reduction (claimed). ADVANTAGE - The method produces nitrogen-doped porous carbon membrane with high catalytic activity, has thickness of 20 nm to 10 cm, has multi-stage pore structure with gradient distribution. The nitrogen-doped porous carbon membrane has controllable thickness, pore size, designable shape, and is easy to prepare on large-scale. It is suitable for use as self-supporting electrode material to efficiently and stably convert large-scale nitrogen gas in air into ammonia through electrocatalysis to prepare 0.09 g of ammonia per hour per square meter of carbon film. It has broad application prospects in field of energy conversion. DETAILED DESCRIPTION - Self-supporting preparation of nitrogen-doped porous carbon membrane comprises mixing polyionic liquid and polyacrylic acid at molar ratio of (1:1)-(1:3); adding 10-500 ml dimethylformamide or dimethyl sulfoxide; heating and dissolving solution at 25-70 degrees C to obtain polymer solution; dispersing carbon nanotubes, graphene oxide or carbon black in polymer solution; pouring mixture on glass plate; heating at 25-120 degrees C for 2-48 hours to dry solvent to obtain polymer composite membrane; soaking polymer composite membrane in 0.1-28 wt.% aqueous ammonia solution for 1-10 hours to obtain porous polymer film; carbonizing porous polymer film in inert atmosphere at 300-1200 degrees C under 1.5 Torr to atmospheric pressure for 1-10 hours; and cooling at room temperature to obtain nitrogen-doped porous carbon membrane. An INDEPENDENT CLAIM is included for application of nitrogen-doped porous carbon membrane as electrode for nitrogen reduction by directly using nitrogen-doped porous carbon membrane as working electrode, silver/silver chloride (Ag/AgCl) as reference electrode, platinum wire as counter electrode, and aqueous hydrochloric acid solution as electrolyte, in which Faraday efficiency of electrocatalytic reduction of ammonia gas is 6% and has very high stability when tested continuously for 192 hours and nitrogen gas can be continuously converted to ammonia gas at is 86.4 g yield of ammonia gas per square meter of carbon membrane per month.