Cobalt with porous carbon architecture: Towards of 4-nitrophenol degradation and reduction

Abstract

Sustainable synthesis of earth-abundant metal/porous carbon architecture as a bifunctional catalyst for efficient 4-nitrophenol (4-NP) destruction and reduction is highly desirable but challengeable from the perspective of environmental protection and fine chemical syntheses. Here, we develop a simple, effective and sustainable salt-template method to prepare a cobalt@porous carbon nanosheets (Co/PCNS) through pyrolysis of cobalt oleate@Na2SO4 precursor by carefully controlling the calcination temperature at 700 ℃. The achieved Co/PCNS reveals an excellent performance for peroxymonosulfate (PMS) activation toward 4-NP destruction with a removal efficiency of 99.5% and rate constant of 0.6186 min−1 at 25 ℃. The main active substances of the Co/PCNS/PMS system are demonstrated to be sulphate radical (SO4∙−) and singlet oxygen (1O2) by radical scavenging experiments and electron paramagnetic resonance tests. The possible degradation pathways for 4-NP in the Co/PCNS/PMS system is also proposed. Impressively, the developed Co/PCNS also exhibits an excellent catalytic activity for 4-NP reduction to 4-aminophenol with NaBH4 at 25 ℃. The Co/PCNS hybrid can be easily recovered by an external magnet and reused for five times with relatively high remained activity for the studied reactions. This study presents a facile and sustainable approach for fabricating low-cost but efficient catalysts toward organic pollutant destruction and fine chemical synthesis.