Piezocatalytic performance enhancement using the sandwich structure of a PVDF-HFP/graphene film

Abstract

Piezocatalysis can be used to harvest widely existing and renewable mechanical vibrations in the environment to convert mechanical energy into chemical energy, which is employed in various important applications, and typically, the polyvinylidene fluoride (PVDF)/graphene composite piezocatalyst is used because of its recyclability, flexibility, and easy preparation. However, its poor piezocatalytic performance, primarily attributed to the wrapped graphene in the PVDF matrix that prevents the generated charges from fully accessing pollutants, remains a challenge. Herein, we use phase conversion and the “self-assembly strategy” to prepare a sandwich film called PVDF-hexafluoropropylene@reduced graphene oxide (PVDF-HFP@rGO) with PVDF-HFP as the interlayer and rGO as the outer layer to fully expose rGO. Under magnetic stirring at 600 rpm, the degradation efficiency of PVDF-HFP@rGO toward methylene blue reaches ∼98% within 60 min, higher than those of the traditional composite film (∼75%) and pure PVDF-HFP film (∼8.0%). The charge supply by rGO, piezoelectric field provision by PVDF-HFP, and advantage of the sandwich structure are verified through contrast experiments under different conditions such as changing rGO band structures, varying PVDF-HFP interlayer thicknesses, and using different layer structures, respectively. Therefore, the enhanced piezocatalytic performance of the sandwich structure provides new insights into the structural design of high-performance PVDF/graphene composite piezocatalysts.