Confining Sn Nanocatalysts via Ship-in-a-Bottle Strategy: Local Alkaline Microenvironment Engineering for High-Selective and Durable Acidic CO₂RR to Formic Acid

Herein, a nanoreactor-structured Sn@MCHS catalyst is fabricated via a ship-in-a-bottle method, synergizing the catalytic activity of metallic Sn with the microenvironment-modulating capability of hollow mesoporous carbon spheres (MCHS). This mesoporous shell acts as a physical barrier, restricting proton replenishment and retaining the in situ generated OH^–, thereby forming a local alkaline microenvironment.

The nanoreactor enriches K⁺ and stabilizes *OCHO. In the acidic CO₂ reduction system, the FE of the catalyst in an H-type cell reached 90.3%, and in a flow cell it reached 95.1%. It also demonstrated excellent stability for continuous operation for up to 96 h.