Green Synthesis of High-Strength Lignocellulose Paper with Barrier and Catalytic Functions

Paper-based materials from renewable lignocellulosic resources are promising for clean production systems but are often limited by insufficient mechanical strength and poor moisture resistance. Herein, a sustainable strategy is proposed to fabricate high-strength and low-permeability lignocellulose paper-based composites reinforced with lignin-containing lignocellulose nanofibrils (LCNFs). Micro–nano fibrils were prepared directly from unbleached poplar pulp without extensive chemical purification. With an optimized LCNF content of 10%, the resulting composite exhibited markedly improved mechanical properties, achieving a tensile index of 82 N·m/g and a burst strength of 390 kPa, along with substantially reduced water vapor transmission. The enhanced structural integrity improves dimensional stability under humid or aqueous conditions, contributing to prolonged service lifetime of paper-based materials in sustainable applications. In addition to structural reinforcement, the retained lignin enables sustainability-oriented functionalization. Lignin acted as an intrinsic reductant for the in situ immobilization of palladium nanoparticles without external reducing agents. These composites exhibited enhanced barrier properties and outstanding catalytic performance in the reduction of Cr(VI) to Cr(III), demonstrating their potential for environmental remediation applications. This work underscores the value of lignocellulose as a renewable, sustainable material for functional composites with broad environmental and energy-related applications, marking a promising route toward eco-friendly, high-performance polymer composites.