Self‐Tuned Ligand‐to‐Metal–Metal Charge Transfer in Node‐Engineered Al‐Doped NH 2 ‐UiO‐66 Boosts CO 2 Photoreduction Activity

ABSTRACT Photocatalytic reduction of CO 2 to a single product with high activity and selectivity remains a significant challenge, largely because many potential products possess similar redox potentials. Herein, we report an Al‐doped NH 2 ‐UiO‐66 (Al x NHU) synthesized via a metal organic framework (MOF) self‐tuning strategy. Al 30 NHU (30 denotes molar percentage of Al to the total metals (Al + Zr)) delivers a CO selectivity of 92.84% and a CO yield of 147.61 µmol g −1 within 5 h, six times higher than that of pristine NH 2 ‐UiO‐66, while maintaining excellent stability over five cycles. We unveil a previously unreported ligand‐to‐metal‐metal charge transfer (LMMCT) mechanism, in which the photoexcited electrons migrate from the 2‐aminoterephthalic acid linkers to Al sites and subsequently to the Zr nodes. This mechanism is supported by photoluminescence, time‐resolved photoluminescence, electrochemical measurements, and in‐situ X‐ray photoelectron spectroscopy, which facilitates efficient charge separation and prolongs charge‐carrier lifetimes. In situ Fourier Transform Infrared Spectroscopy identifies * COOH as the key CO intermediates, consistent with the high CO selectivity. Density functional theory calculations further indicate that Al doping elevates the d‐band center, strengthens CO 2 adsorption, and enhances electron transfer to catalytic centers. The work establishes a rational strategy for tuning MOF photocatalysts to achieve enhanced solar‐driven CO 2 ‐to‐C 1 product conversion.