Efficient gas-solid NO-to-NH3 photoreduction over dynamic PtOx/PtO(x−δ) cluster sites with boosted proton-electron coupled transfer

Under mild continuous-flow gas-solid conditions, the direct conversion of gaseous nitric oxide (NO) in flue gas to pure ammonia (NH 3 ) is hindered by the challenges of sustaining continuous proton-electron coupling and transfer. Here, we develop a PtO x -TiO 2 photocatalyst featuring ultrafine PtO x clusters that sustain continuous electron transfer via dynamic PtO x /PtO ( x−δ ) redox cycling. Upon illumination, PtO x continuously captures photogenerated electrons to form PtO ( x−δ ) and injects them into NO antibonding orbitals, while the PtO x -TiO 2 interface simultaneously drives H 2 O dissociation to provide a steady proton flux. This persistent electron-proton coupling orchestrated by PtO x /PtO ( x−δ ) cluster interface promotes exciton dissociation, interfacial charge separation, and stepwise hydrogenation of NO to NH 3 . Under continuous-flow conditions with 200 ppm NO, PtO x -TiO 2 achieves 76.0% NO conversion, 808.25 mmol m −2 h −1 NH 3 yield, and 98.1% selectivity, representing a 9.1-fold enhancement over pristine TiO 2 and representing the current best performance in the gas-solid phase NO reduction for NH 3 synthesis. In situ spectroscopy and density functional theory (DFT) calculations reveal that the exceptional activity mainly stems from the facilitated electron-proton coupled transfer via the unique role of PtO x /PtO ( x−δ ) cluster. This work establishes a practical strategy for sustainable NO abatement with green NH 3 production without separation in gas-solid systems.