In-situ synthesis of N-doped biochar encapsulated Cu(0) nanoparticles with excellent Fenton-like catalytic performance and good environmental stability

Abstract

Low-valent transition metal catalysts show promising application in the catalytic degradation of organic pollutants in wastewater. However, the catalysts themselves are susceptible to be oxidized and easy to agglomerate, thus reducing the catalytic ability. Herein, a facile in-situ carbonization method is utilized to synthesize N-doped biochar encapsulated zero valent copper (Cu(0)) nanoparticles (Cu@N: C). The formed Cu(0) nanoparticles are uniformly dispersed in biochar. The carbon layers wrapped outside of Cu(0) nanoparticles can present the oxidation of Cu(0) to a certain extent. Therefore, the 12% Cu@N: C catalyst exhibits good environmental stability. The catalytic ability remains basically unchanged after directly exposing it to air for four months. In addition, the 12% Cu@N: C catalyst exhibits excellent catalytic performances for the degradation of various organic pollutants at near neutral pH range (pH = 4.0 ∼ 8.0). Low valent copper (Cu(0)/Cu(Ⅰ)) and pyridinic N both contribute to the excellent catalytic ability. Furthermore, the catalytic performances are less interfered in natural water matrices, and even obviously enhanced in sea water. Based on the experimental and characterization results, a possible catalytic mechanism is also proposed.