Printed Flexible and Recyclable Heterojunction for Water Cleanup

Abstract To address the issues of easy agglomeration, difficult recovery, and poor engineering applicability faced by traditional powdered photocatalysts in water treatment, this study proposes a laser-induced transient thermal modulation electrohydrodynamic jet (LTMJ) printing strategy, enabling the direct immobilization of pre-synthesized g-C3N4/BiOI heterojunction particles on flexible quartz fiber cloth in a single printing step, thereby fabricating a high-performance and recyclable photocatalytic platform. By virtue of the real-time coupling between the laser field and the electrohydrodynamic jet printing process, a controllable transient non-equilibrium thermal environment is established in the flying droplet region. The explosive evaporation triggered by laser-droplet energy coupling effectively suppresses the secondary agglomeration of particles and regulates the deposition and interparticle assembly of the pre-synthesized heterojunction particles. Without damaging the crystalline phase and heterojunction structure of the materials, this method simultaneously achieves particle size refinement and enhancement of the uniformity and compactness of the deposited layer. Under visible light irradiation, this flexible platform exhibits excellent degradation activity and cyclic stability toward various organic dyes, while it is easy to recover and regenerate. This study not only provides a new method for the precise fabrication of flexible and recyclable photocatalytic devices, but also offers novel insights into the multi-physics field coupling-regulated assembly and functionalization of micro-nanostructures.