Unlocking Enhanced Piezocatalytic CO ₂ Reduction on BaTiO ₃ via Cu Single Atoms within a Hydrophobic Metal−Organic Framework Shell

Piezocatalytic CO2 reduction provides a promising route for converting CO2 to value-added chemicals driven by ubiquitous mechanical energy. However, the efficiency of current piezocatalysts is limited by sluggish CO2 adsorption in water, scarce active sites, and inefficient charge-transfer pathways. Herein, we demonstrate that coating barium titanate (BaTiO3, BT) with a hydrophobic shell of a Cu single atom doped zeolitic imidazolate framework-8 (Cu-ZIF-8) facilitates piezocatalytic CO2 reduction. Optimized Cu-ZIF-8/BT exhibited a CO yield of 114 μmol·g−1·h−1, approximately five-fold higher than that observed for pristine BT (24 μmol·g−1·h−1). Comprehensive analyses revealed that the Cu-ZIF-8 coating on BT enhanced piezocatalytic CO2 reduction, which was due to the improved utilization of piezo-generated electrons, increased the interfacial availability of CO2, and activated CO2 by the hydrophobic CO2-enriching shell containing atomically dispersed redox-active Cu centers. This work highlights a rational interfacial engineering strategy for designing piezocatalysts, offering insights into improved CO2 conversion and the development of advanced piezocatalytic systems.