Integration of Photo‐Fenton Reaction and Membrane Filtration using Lignin@t‐FeC ₂ O ₄ /g‐C ₃ N ₄ Nanofibers Toward Accelerated Fe(III)/Fe(II) Cycling and Sustainability

Abstract Photocatalysis water treatment without artificial energy is cost‐effective, waste‐free and sustainable. Coventional powder photocatalysts have tiny contact surfaces, low catalytic efficiency, and are difficult to recycle and reuse, restricting their usage. Herein, a Lignin@t‐FeC 2 O 4 /g‐C 3 N 4 material is developed by engineering hollow quadrangle t‐FeC 2 O 4 and g‐C 3 N 4 nanosheets on lignin membranes through facile impregnation coating and precipitation reaction. Fast mass transport, catalytic activity and accessibility characterize hollow tetragonal FeC 2 O 4 · 2H 2 O. TEM, SEM and FTIR show that lignin binds t‐FeC 2 O 4 and g‐C 3 N 4 . The g‐C 3 N 4 nanosheets are uniformly wrapped on the surface of lignin fibers, and t‐FeC 2 O 4 is loaded between them. This structure increases visible light absorption and active site‐contaminant contact. The chain reaction produces extremely active hydroxyl radicals from hydrogen peroxide because the Lignin@t‐FeC 2 O 4 /g‐C 3 N 4 modules are rich inFe II , according to XPS. Transient photocurrent response curves and electrochemical impedance spectroscopy suggest a promoted charge migration and isolation at the redox reaction interface in the Lignin@t‐FeC 2 O 4 /g‐C 3 N 4 system. As a result, Lignin@t‐FeC 2 O 4 /g‐C 3 N 4 degrades 99% Rhodamine B within 40 minutes, and this performance is stable even under difficult conditions, such as low hydrogen peroxide concentration and high pH. This study combines lignin membranes with the photo‐Fenton reaction, and thus provides new concept for the development and application of membranes and photocatalysis.