Two-Dimensional Polymers as Modular Metal-Free Solid-State Catalysts for Efficient Sono-Piezo-Photocatalytic Hydrogen...

Piezo-photocatalysis synergistically integrates the features of piezocatalysis and photocatalysis, offering promising applications in environmental remediation, energy conversion, and biomedical therapy. Herein, we introduce modularly designed solid molecular catalysts (SMCs) comprised of metal-free, polyaromatic, two-dimensional polymers which offer an unprecedented level of control over piezopolarization-and consequently, piezo-photocatalysis-through the rational design of structural motifs (diphenylpyridine or terpyridine) and backbone functionalities (methyl group, aliphatic amine antenna, or aromatic pyrrole ring). We demonstrate that piezopolarization, induced by ultrasound across a wide frequency range (35 kHz to 2.6 MHz), enables highly efficient sono-piezo-photocatalytic hydrogen peroxide production. The SMC AP5 featuring the terpyridine motif and pyrrole functionalization is the most active metal-free piezo-photocatalyst for hydrogen peroxide production under ambient conditions. Furthermore, the instantaneous on/off-switchability of the sono-piezo-photocatalysts is shown, underscoring their potential for applications requiring spatiotemporal control over catalytic activity.