Selective reduction of nitrate to ammonium over charcoal electrode derived from natural wood

Electrocatalytic nitrate reduction has been regarded as an efficient alternative route for ammonia production. Developing efficient, economical and environment-friendly cathodes is a significant concern for the practical applications of this method. Herein, we report a charcoal electrode fabricated by carbonizing natural wood for efficient nitrate reduction. It displays high overpotential for hydrogen evolution, moderate sp3 C structure and oxygen-containing surface groups. Benefiting from these features, the charcoal cathode exhibits high nitrate removal rate (91.2%), outstanding selectivity (98.5%) and fast production rate (0.570 mmol L-1 h-1 cm-2) for ammonium. Both removal rate and selectivity are superior to other carbon materials and comparable to metal-containing cathodes. These results exhibit the possibility of using charcoal as cathodes for denitrification and ammonia recovery from wastewater.