ZIF-67-Confined Pd Single-Atom Catalysts Implanted Into Polydopamine-Modified Bamboo Microchannels for Robust Continuous-Flow Hydrogenation

Developing efficient catalytic hydrogenation microreactors with minimal catalyst loading yet high active-site density for treating concentrated organic pollutants remains challenging. Herein, a facile room-temperature method is presented to stabilize Pd single-atom catalysts (SACs) within ZIF-67 crystals during their formation, aiming to fabricate an efficient, low-loading hydrogenation catalytic microreactor (Pd@Z-P/b CMR). ZIF-67 is constructed into polydopamine (PDA)-modified bamboo microchannels under flow conditions, utilizing preimmobilized Co 2+ seeds in PDA. Despite an ultralow Pd loading (0.0014 wt.%), the Pd@Z-P/b CMR featuring atomically dispersed Pd─N 4 sites in ZIF-67 considerably outperforms its Pd nanoparticle–loaded counterpart (Pd 0.0035 wt.%) in continuous-flow hydrogenation, demonstrating superior robustness and maximized Pd utilization with 94.3% conversion efficiency for saturated 4-nitroaniline over 10 d and 97.5% conversion efficiency for gram-level methylene blue (1.0 g L −1 ) over 5 d. Crucially, it exhibits consistent, high performance in real environmental water samples. The high surface area and porosity of ZIF-67 stabilize the Pd SACs, enhance dispersion, and ensure accessibility. Simultaneously, the Pd─N 4 configuration facilitates electron transfer and optimizes hydrogen binding energy, dramatically boosting the catalytic activity. This work provides a novel strategy for room-temperature SAC synthesis and the effective treatment of high-concentration organic pollutants for sustainable wastewater remediation.