Cellulose nanofiber-scaffolded rGO/WO3 membrane for photocatalytic degradation of methylene blue under visible light irradiation

Abstract

Although membrane-based water treatment has advanced significantly and many commercial products are currently available, its practical application remains limited, particularly in regions with inadequate electricity infrastructure. In this study, cellulose-based photocatalytic membranes incorporating visible light-active rGO/WO₃ nanoparticles into a cellulose nanofiber (CNF) scaffold were fabricated using a simple casting method. The structure–property relationships of the nanostructures and the membranes were examined, and the membranes were tested for the photocatalytic degradation of methylene blue (MB). The CNF/rGO/WO₃ composite membrane demonstrated significantly higher photodegradation capacity (89.3%) compared to pure WO₃ (50.13%) for MB under visible light, with consistent performance for up to ten cycles. After ten cycles of repeated use, the membrane retained a degradation efficiency of 48%, which is comparable to that of WO₃. This notable performance was attributed to improved charge separation, enhanced visible light absorption, larger surface area, and synergistic interactions among the components within the composite membrane. Besides enhancing photodegradation capacity through increased charge carrier separation, CNF played a vital role in immobilizing and stabilizing the photocatalyst. The principal active species identified in the photocatalytic material include h+, ˙O₂⁻, and ˙OH, with a slight predominance of h⁺. The simplicity of cellulose-mediated, visible-light active functional membrane design and fabrication creates opportunities for low-cost solutions to address water and energy challenges in environments with limited infrastructure. These visible light-responsive membrane materials hold great promise for applications in areas such as food packaging, surface disinfection, and the development of self-healing materials.