B-doped graphitic porous biochar with enhanced surface affinity and electron transfer for efficient peroxydisulfate activation

In this study, B-doped graphitic porous biochar (B-KBC) was prepared and used to activate peroxydisulfate (PDS) for the removal of sulfamethoxazole (SMX). Experimental and theoretical results revealed that the introduction of boron species not only act as Lewis acid sites enhanced the surface affinity towards PDS but also modulate the electronic structure of carbon matrix evidently increase the electron transfer rate, and thus result in an excellent catalytic capacity. More importantly, owing to the high stability boron sites, B-KBC endows a superior long-term durability in comparison with popular N-doped carbon catalysts. Given the uncertainty of quenching experiments, the electron paramagnetic resonance, materials balance calculation combined with electrochemical measures confirmed the biochar mediated electron transfer mechanism, rather than ¹O₂, was primarily responsible for the nonradical route. This study is expected to pave a new avenue to develop cost-effective and eco-friendliness metal-free carbon catalyst with adequate activity and reuse stability.