Spontaneous Chirality Transition‐Mediated Piezo‐Pyroelectric Synergy for Photocatalytic Hydrogen Production from Saturated Vapor of VOC Aqueous Solutions

Abstract This study aims to develop a Janus‐structure piezo‐pyroelectric photocatalytic membrane for integrated temperature‐mechanical‐electric field coupling, targeting hydrogen (H ₂ ) production from the saturated vapor of volatile organic compound (VOC) aqueous solutions. The strategy utilizes the unique features of the Janus architecture by combining a piezoelectric effect induced by spontaneous chiral curling and a tertiary pyroelectric effect arising from strain gradients under thermal non‐uniformity to enhance photocatalytic performance. The Janus membrane consists of two functional layers: succinic acid‐modified polyvinyl alcohol, which swells with humidity, and ferroelectric poly(vinylidene fluoride‐co‐hexafluoropropylene), which expands in response to photothermal and organic solvent stimuli. Under coupled piezo‐pyroelectric effects, the photocatalytic H ₂ release rate from saturated vapor of VOC aqueous solution reaches 336.6 µmol h ⁻¹ under atmospheric pressure, which is 14.6 times higher than that from a liquid‐phase water splitting system, with an average apparent quantum yield of 16.6%. The 44.8% reduction in photoluminescence intensity and the 1016.7‐fold enhancement in photocurrent confirm the improvement in photo‐generated carrier separation efficiency. COMSOL simulations reveal a synergistic enhancement of the built‐in electric field through piezo‐pyroelectric coupling. This work presents a strategy for designing high‐efficiency photocatalytic materials and multi‐field coupled energy conversion systems, while simultaneously achieving pollutant‐to‐resource conversion and clean energy production.