Synergy of nitrogen doping and structural defects on hierarchically porous carbons toward catalytic oxidation via a non-radical pathway

Abstract

Engineered carbonaceous materials are promising metal-free catalysts for heterogeneously catalytic oxidation. In this study, hierarchically nitrogen-doped porous carbons are prepared via a one-pot pyrolysis process. The hierarchically porous carbons have a large surface area up to 1641 m2 g−1 with a high nitrogen content of 8.63 at.%. The carbons manifested much high catalytic activity in phenol degradation by activation of peroxymonosulfate (PMS) via a non-radical pathway, evidenced by radical screening test, electrochemical measurement and Raman spectra. NZC-S0.5 exhibits outstanding catalytic performance with a turnover frequency (TOF) of 26.0 min−1. A very high rate constant of 1.3 min−1 and a small activation energy of 25.1 kJ/mol are achieved. Density functional theory (DFT) calculations illustrate that the most reactive catalytic sites are the N-doped vacancies, confirming the synergetic enhancement by the simultaneously induced heteroatom and structural defects (edges and vacancies). This work enables new insights into heteroatom, structural defects and non-radical pathway in metal-free catalytic PMS activation.