Continuous-Flow Plasma Synthesis of Single-Atom Au₁/CeO₂-Fe for Wide-Temperature-Window Water-Gas Shift Reaction

The water-gas shift (WGS) reaction is pivotal for H₂ production and purification, yet conventional processes rely on coupled middle and high temperature stages (180-300 °C). Development of wide-temperature-window catalysts could avoid temperature switching and reduce the energy demand. However, room-temperature WGS is particularly limited by sluggish water splitting. Here, we report a continuous-flow solution plasma (CSP) strategy to construct an oxygen vacancy-rich Au₁/CeO₂-Fe single-atom catalyst (SAC). Fe is uniformly doped into the CeO₂ lattice to increase the density of oxygen vacancies and Au is stabilized as isolated atomic sites on the CeO₂ surface. By photothermal excitation, the catalyst delivers high WGS activity across 25-300 °C. Notably, at 25 °C, the CO conversion rises from near-zero for conventional catalysts to 35%, overcoming the kinetic barrier of room-temperature WGS for a low CO conversion rate. Mechanistic studies reveal that Fe doping selectively promotes H₂O dissociation, and Au SACs enhance CO adsorption and oxidation. Meanwhile, light activates CeO₂ lattice oxygen and engages a Mars-van Krevelen cycle. The as-developed catalyst maintains significant activity from ambient temperature to 300 °C without temperature switching, providing a process toward energy-efficient H₂ production and purification.