Rigid-flexible dual network hydrogel photoelectrodes for ultrafast and stable catalytic degradation of bisphenol A with minimal metal leaching

Photoelectrocatalytic (PEC) technologies provide a promising and sustainable approach for the elimination of persistent organic pollutants, but their practical deployment is limited by catalyst deactivation and metal leaching. Here, we proposed a rational design strategy to address this challenge by constructing a rigid-flexible dual network hydrogel photoelectrode (CCMPCu) for ultrafast and stable catalytic degradation of bisphenol A (BPA) with minimal metal leaching. CCMPCu was fabricated by incorporating Cu₂O@ZIF-67 into a chemically cross-linked chitosan/cellulose nanofibril (CNF)-MXene matrix (rigid network), which was further embedded within an in situ polymerized polyaniline network (flexible network). CCMPCu exhibited a high BPA adsorption capacity of 211.1 ± 6.2 mg g^-1, ~4× that of Cu₂O@ZIF-67. Under visible light, CCMPCu achieved nearly complete BPA removal (~100%) within 40 min, with a pseudo-first-order rate constant (k = 0.0836 ± 0.0041 min^-1), representing a ninefold enhancement over Cu₂O@ZIF-67. CCMPCu also showed excellent durability, maintaining over 90% removal efficiency after ten consecutive cycles with negligible Cu (< 5 ppb) and Co (< 8 ppb) leaching. Mechanistic studies revealed that synergistic integration of the rigid-flexible dual network, MXene, and Cu₂O@ZIF-67 facilitated pollutant preconcentration and photogenerated charge separation, thereby collectively contributing to the enhanced PEC performance. Additionally, CCMPCu showed broad applicability by effectively degrading structurally diverse bisphenol analogues. This work presents a generalizable strategy for fabricating robust, multifunctional CS/CNF-based hydrogel photoelectrodes and offers valuable insights for the sustainable remediation of endocrine-disrupting contaminants.