Promoting electron and ion transport by a self-assembled WO3/MXene composite structure for improved electrochromic performance

Abstract

Electrochromic materials are pivotal for energy conservation, yet their practical performance is often constrained by inefficient ion and electron transport. To overcome these limitations, the development of novel electrochromic systems with enhanced charge-transfer kinetics is imperative. Inspired by the high conductivity of transition-metal carbides/nitrides, a novel chemical-bonding-mediated self-assembly strategy was employed to fabricate WO₃/MXene composite films. This method promotes intimate interfacial contact between WO₃ and MXene, expanding the electroactive area and facilitating rapid ion/electron transport. As a result, the composite films exhibit significantly improved electrochromic performance, achieving optical modulation of 52.8% and high coloration efficiency of 114.82 cm² C⁻¹, along with fast switching times of 3.8 s for coloring and 9.3 s for bleaching. Moreover, the Li⁺ diffusion coefficients for insertion and extraction increased by 112% and 128%, respectively. This study offers an effective approach for constructing high-performance electrochromic films through rationally integrated WO₃/MXene heterostructures.