Carbon-supported Co Catalysts Research Articles

Co-enhancement of permeability and selectivity on mixed matrix catalytic membrane with high loading of porous Co-N-C filler for efficient water purification

The water treatment performance of membrane filtration is usually restricted via the paradox between permeability and selectivity. Herein, the nitrogen doped porous carbon supported Co catalysts (CoNPC), serving as both porous filler and peroxymonosulfate (PMS) activator, were firstly filled into polyvinylidene fluoride (PVDF) matrix to construct a novel mixed matrix catalytic membrane (CoNPC@PVDF) for enhanced water purification. Owing to the robust binding between CoNPC and PVDF, a high loading (50 wt%) and even dispersion of CoNPC were realized in CoNPC@PVDF, and its permeability and selectivity were both improved with the increase of CoNPC content. The optimum CoNPC@PVDF with PMS activation assistance (FCP) exhibited effective phenol removal at short retention time (1.5 s) and high permeability (256.6 L m−2h−1 bar−1). The performance of CoNPC@PVDF FCP was 2.9 and 2.5 times higher than that of filtration alone and PMS activation alone, respectively, and even dramatically outweighed the reported catalytic membranes and heterogeneous catalysts. The outstanding performance of CoNPC@PVDF catalytic membrane was mainly attributed to its thin membrane structure and high filling degree of CoNPC, resulting in ultrahigh mass transfer rate (1.8 × 10−4 m s−1) and more exposed active sites for enhanced PMS activation into radicals (mainly •OH and SO4•−) towards pollutant removal.

Effect of Cobalt Loading in Nitrogen-Doped Carbon on Oxygen Reduction Reaction for PEM Fuel Cells

Nitrogen-doped carbon supported Co catalysts (CoNC) were synthesized via condensation reaction of pre-polymer of melamine formaldehyde resin with addition of cobalt nitrate salt, followed by carbonization in nitrogen. Rotating disk electrode technique (RDE) and scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS) were used to identify the structure and oxygen reduction reaction (ORR) kinetics of the catalysts. The results show that the catalysts with 3.77 wt% Co loading yield the best ORR catalytic activity. Koutecky-Levich plots indicate ORR mechanism is governed by mixed mechanisms and the measured electron number varies between 2 and 4. SEM image shows an irregular lamellar structure of CoNC catalyst formed at high temperature, and different Co loadings in CoNC catalyst do not change its surface morphology.