Enhancing methanol/water activation for photothermal hydrogen production: Modulation of Cu-pyridine sites in UiO-67 metal-organic frameworks

To achieve highly efficient in situ hydrogen release from methanol/water reforming at lower temperature, integrating solar-energy provides a promising strategy to activate methanol/water while significantly reducing the activation energy. Herein, we report a series of novel MOF-based photothermal catalysts, mUiO-67-bpy-CuX, featuring enhanced H 2 O affinity and spatially isolated Cu-pyridine active sites for photothermal-driven reforming process of methanol solutions (PTRM). These catalysts exhibit distinct active sites that separately adsorb and activate H 2 O and CH 3 OH, with synergistically photothermal effect leading to an exceptional H 2 evolution activity of 121.1 mmol‧g cat −1 ‧h −1 within 80 min at 210 ℃ and an overall turnover number (TON) of 25904 over 68 hours without significant deactivation, with a high apparent quantum efficiency (AQE) of 54 %. Notably, the activation energy is reduced by 44 % compared to thermal-only systems, and the H 2 production is initiated even at 100 °C. The photothermal H 2 evolution activities of mUiO-67-bpy-CuX correlate with the lability of X counteranions, suggesting open coordination environments of Cu sites generated by labile X groups facilitate Cu + -N intermediate formation upon photoexcitation. Additionally, the Zr 6 nodes and increased mesoporosity in the modulated MOF enhance H 2 O adsorption and dissociation at low temperatures, promoting OH‧ generation. While Cu + -N interfaces are responsible for effective cleavage of the C-H bonds in CH 3 OH. This work highlights the design of MOF-based photothermal catalyst with isolated metal sites for enhanced H 2 production from CH 3 OH/H 2 O reforming at low temperatures.