Enhanced electromagnetic shielding and absorption in Ti3C2Tx MXene films via hydroxyl functionalization and interlayer spacing control

Developing flexible materials with combined electromagnetic interference (EMI) shielding and microwave absorption capabilities holds significant application potential. Ti 3 C 2 T x MXene has emerged as a flexible EMI shielding material due to its thinness, adhesion, flexibility, and dual shielding and absorption properties. High conductivity-induced reflection and layered self-stacking challenges hinder Ti 3 C 2 T x MXene performance enhancement, posing challenges demanding solutions. This study first uses simulations to analyze how functional group modifications and interlayer spacing affect Ti 3 C 2 T x MXene's electromagnetic properties. Hydroxyl groups are proposed as key regulators of Ti 3 C 2 T x MXene's properties. Subsequently, Ti 3 C 2 T x MXenes were treated with a low-concentration NaOH gradient to modulate hydroxyl groups. Ultrasonic-microwave extraction resolved delamination, enabling ultra-thin film preparation. The treatment caused hydroxyl groups to initially increase and then decrease, with interlayer spacing first contracting and then expanding, achieving synchronous modulation of Ti 3 C 2 T x MXene's surface functional groups and interlayer spacing. The EMI shielding and microwave absorption of ultrathin films were analyzed, with shielding efficiency correlating positively with hydroxyl group concentration. Ti 3 C 2 T x MXene treated with 0.2 mol/L NaOH exhibited maximum hydroxyl concentration, achieving 48.965 dB shielding at 0.016 mm thickness (SE/t = 3060.320 dB/mm), demonstrating hydroxyl groups' role in improving shielding performance. Wave absorption increased with higher NaOH concentrations, correlating with surface hydroxyl groups. The 0.3 mol/L NaOH-treated MXene showed a 12.883 dB absorption increase versus untreated samples. Additionally, the green shielding index (g s ) of Ti 3 C 2 T x MXene films increased by 32.9 % with higher NaOH concentration. Results demonstrate that surface hydroxyl modification and layer spacing adjustment significantly enhance the EMI shielding and wave absorption of Ti 3 C 2 T x MXene. Meanwhile, the prepared thin, flexible products have potential applications in aerospace, defense, and flexible electronics.