Hydrogen‐Bonds‐Confined Ag 9 Cluster in Poly(ionic liquid): A Floating Quasi‐Homogeneous Microreactor for Highly Efficient CO 2 Photoreduction

ABSTRACT Atomically precise silver nanoclusters (Ag 9 ) exhibit abundant surface‐active sites and exceptional solar light utilization efficiency. However, their practical application on a large scale is hindered by poor stability and low recovery rates. To address these challenges, this study proposes the in situ confinement of Ag 9 nanoclusters within a poly(ionic liquid) (PILs) matrix to fabricate a floating, quasi‐homogeneous microreactor for efficient, stable, and recyclable CO 2 photoreduction. Synergistic spatial confinement is achieved through hydrogen bonds (O···H─C), electrostatic attraction, and the 3D PILs network.This confinement suppresses the aggregation and photocorrosion of Ag 9 clusters, maintaining an ultrafine dispersion of approximately 1.25 nm. Multiple H‐bonds can also promote the directional electron transfer, stabilize * CO intermediates, and optimize the Gibbs free energy of CO 2 reduction, yielding a CO evolution rate of 58.23 µmol/g/h, surpassing most Ag and carbon‐based photocatalysts. The hydrophobic, floating architecture ensures selective CO 2 adsorption while repelling water, achieving nearly 100% CO selectivity and effective suppression of the hydrogen evolution. Without external stirring or energy input, the catalyst retains 94% of its initial activity after eight consecutive cycles. This work offers a rational design method for floating photocatalysts in the field of energy convertion.