Pore-confined and pore size-dependent peroxymonosulfate activation mechanism for MOF-derived Mn2O3

Conventional Mn 2 O 3 catalysts, typically synthesized via co-precipitation using inorganic precursors, exhibit satisfactory peroxymonosulfate (PMS) activation efficiency depending on their structure and Mn valence. However, the interplay between pore architecture and intrinsic activity remains poorly understood, limiting rational design of Mn 2 O 3 . Herein, a series of Mn 2 O 3 catalysts with tunable pore sizes (1.6–16.2 nm) and Mn valence states were synthesized via pyrolysis of three distinct Mn-MOF precursors (Mn-BDC, Mn-MOF-74, Mn-BTC) at different temperatures. Among eight MOF-derived Mn 2 O 3 , BDC-400 with the largest pore-size derived from Mn-BDC calcined at 400℃ demonstrated superior performance, achieving 93.5% sulfamethoxazole (SMX) removal via PMS activation. Its degradation rate constant (0.0237 min⁻¹) was 1.45–3.34 times higher than those of catalysts with smaller pores (ranging from1.6–12.6 nm). Counterintuitively, multiple linear regression identified pore size, not Mn(III) content, as the dominant performance descriptor (β = 0.784). This is demonstrated as a pore-size-sieving effect by HA interference experiments and contact angle measurements: larger pores (e.g., 16.2 nm in BDC-400) drastically reduce mass transfer barriers for PMS/SMX, facilitating their access to the Mn(III)-enriched confined interior and thereby maximizing radical (SO₄•⁻/•OH) generation. This work shifts the design paradigm, demonstrating that engineering pore architecture to mitigate diffusion limitations is as critical as optimizing active sites for developing high-performance catalysts.