Ti–Fe Nodes in the Presynthesized MUV-101 Metal–Organic Framework Enable a Competitive Oxygen Evolution Precatalyst

Ti-based metal-organic frameworks (MOFs) are widely regarded as electrochemically inert scaffolds and have therefore been only rarely explored as direct oxygen evolution reaction (OER) precatalysts. Here, the behavior of the presynthesized heterometallic MUV-101 platform under OER conditions is revisited through a systematic study of MUV-101(Ti-M) materials (M = Fe, Co, Ni, Fe/Co, Fe/Ni). Among this series, MUV-101(Fe) exhibits the most favorable OER performance, requiring an overpotential of 256 ± 5 mV at 10 mA cm-2 and showing a Tafel slope of 43.5 ± 2 mV dec-1 in 1.0 M KOH, together with good stability under the tested alkaline conditions. Correlated ex situ spectroscopy and node-resolved density functional theory (DFT) support a cooperative division of roles within the Ti-Fe node. Within the detection limits of ex situ X-ray photoelectron spectroscopy (XPS), Ti centers remain consistent with Ti(IV) after OER and appear to contribute primarily to structural robustness and electronic modulation, whereas the Fe centers are more directly associated with the formation of an Fe-rich, oxyhydroxide-like surface/interface under anodic polarization. Because the present conclusions rely on ex situ characterization and finite-cluster DFT models, the exact nature and extent of the reconstructed surface cannot be assigned unambiguously, and future operando studies will be required for definitive mechanistic resolution. Despite these limitations, MUV-101(Fe) emerges as a competitive Ti-Fe node-based MOF precatalyst for alkaline OER. More broadly, this work highlights the potential of heterometallic node engineering as a strategy for balancing reconstruction, catalytic activity, and durability in Ti-containing MOF electrocatalysts.