Polydopamine-driven microstructural optimization and performance enhancement of Co-based multichannel ceramic catalytic membranes

Efficient catalytic membranes are crucial for reactor performance, yet traditional membranes suffer from metal nanoparticle agglomeration during high-temperature sintering, which increases particle size and reduces activity. Here, we introduce a novel “molecular scissors” strategy based on polydopamine (PDA) to address this challenge. By coating the membrane with PDA and thermally decomposing it into nitrogen-doped carbon (CN), the CN traps cobalt nanoparticles (Co NPs) via nitrogen defects, preventing migration and inducing redispersion. Simultaneously, precise control of dopamine concentration and pyrolysis temperature regulates membrane porosity and permeability, while tuning the carbon layer thickness optimizes mass and electron transfer. The optimized membrane, Co@CM-3.0-700, reduces the mean Co NP size from 53.1 nm to 40.2 nm, converts p-nitrophenol completely in 20 min (versus 30 min for the unmodified membrane), and increases the specific reaction rate by 1.71 times. Moreover, Co@CM-3.0-700 maintains excellent stability during a continuous 9-h reaction with negligible agglomeration or carbon layer degradation. This study not only demonstrates that the strategy effectively redisperses Co NPs and enhances catalytic activity but also shows its potential applicability to MOF-derived nanoparticles and other metal systems (e.g., Pt, Pd), providing new insights into nanoparticle size control and stability in metal loaded catalytic membranes.