Low-gas-flow strategy boosts hierarchical porosity of ZIF-8 single-atom catalysts for efficient adsorption-driven degradation

Hierarchical porosity amplifies single-atom catalyst (SAC) performance by enhancing mass transport and site accessibility, yet conventional fabrication typically relies on sacrificial-templating or post-etching protocols. Here, we construct well-connected pore networks via minimalistic gas-flow control. Lowering the N2 flow rate during pyrolysis of zeolitic imidazolate frameworks preserves furnace humidity, triggering sequential framework Zn species transformation and volatilization to refine hierarchical porosity. This additive-free strategy yields Co-SACs with a 2.7-fold mesopore and 2.6-fold micropore expansion. The optimized catalyst shows exceptional bisphenol A adsorption and complete degradation within 5 min, achieving a 20-fold turnover frequency increase. Experimental and theoretical studies reveal Co-sites become electron-enriched by extracting electrons from adsorbed pollutants. This transfer promotes peroxymonosulfate activation, elucidating the core electronic driver of adsorption-driven catalysis. Furthermore, this versatile low-flow protocol successfully produces enhanced Fe- and Cu-based analogues. Our findings demonstrate that sophisticated pore engineering can be realized via simple gas-flow regulation, fundamentally deepening adsorption-catalysis synergy. Hierarchical porosity enhances single-atom catalyst performance by facilitating mass transport and improving active-site accessibility, yet its fabrication often requires complex templating or post-synthetic etching. Here, the authors report a simple low-gas-flow strategy to engineer hierarchically porous ZIF-8 single-atom catalysts for efficient adsorption-driven degradation.