Carbonized nitrogen-containing conjugated microporous polymers: Versatile platforms for high-performance carbon catalytic membranes and their angstrom-confined activation mechanism on peroxymonosulfate

Engineering high-performance N-doped carbon catalysts for peroxymonosulfate (PMS) activation and elucidating their activation mechanism are crucial for the degradation of emerging pollutants. In this study, we propose a novel self-template carbonization strategy (NSCS) based on a N-containing conjugated microporous polymer (NCMP, poly(triphenylamine)) to fabricate high-performance N-doped porous carbon catalysts. Owing to the unique N-mediated catalytic sites within the confined micropores of the NCMP precursor, the NSCS approach enables the investigation of reactive oxygen species evolution and their formation mechanisms as carbonization temperature increases from 200 to 1400 °C. The catalyst carbonized at 1000 °C exhibited high degradation activity (k = 0.170 min⁻¹), driven primarily by O₂^•− and ¹O₂, with minor contributions from •OH and SO₄^•−. Additionally, a PMS self-decomposition and ¹O₂ generation mechanism within angstrom-confined spaces was identified. A self-supported carbon catalytic membrane was fabricated from CPTPA-1000 (CPTPA-CNT) due to its high conjugation and thermal stability. This membrane demonstrated efficient removal of organic pollutant (k = 123.54 min⁻¹, 220.3 L m⁻² h⁻¹ bar⁻¹, 120 h, 99.4 %), outperforming the carbonized CNT membrane (k = 19.54 min⁻¹, 67.5 L m⁻² h⁻¹ bar⁻¹, 120 h, 14.8 %). This work paves an avenue for the design of high-performance carbon-based membranes and gives new insights into the ¹O₂ generation mechanism in N-doped carbon catalysts.