MXene-mediated interface synergistic regulation of Prussian blue films for high-performance electrochromic devices

Abstract In order to address the key bottlenecks in Prussian blue (PB)-based electrochromic devices—including low crystallinity, sluggish ion diffusion kinetics, and weak interfacial bonding. This study proposes a multidimensional synergistic modification strategy using 2D MXene. Through a combination of molecular structural and electrochemical testing, the study systematically elucidates the modification mechanism of MXene and its performance optimization effects. The results of the study indicate that MXene enhances PB performance through the synergistic effects of interfacial bonding, structural support, and electronic regulation. The results of this study demonstrate that the formation of Fe–O–Ti coordination bonds and the establishment of physical anchoring enhance the adhesion strength between PB films and substrates by approximately 5.4 times. MXene has been demonstrated to promote PB crystallization as a heterogeneous nucleation site. The hybridization of Ti 3d and PB orbitals results in a reduction of the bandgap from 2.18 eV to 1.92 eV, thereby increasing the carrier density by a factor of 4.03. PB-M demonstrates a diffusion coefficient that is 5.1 times greater than that of pure PB, accompanied by markedly diminished charge transfer resistance and diffusion resistance in comparison to pure PB films. During the de-pressurization, fading, and coloring processes, the charge transfer resistance of PB-M decreased by 36.7%, 21.4%, and 70.1%, respectively, compared to pure PB. The response times of PB-M were 2.9 s and 2.0 s, representing improvements of 2.7 times and 6.4 times over pure PB. Concurrently, the flexible network formed by MXene buffers stresses from lattice expansion and contraction, enabling the device to maintain 71.6% current retention after 1000 cycles. This study provides a universal strategy for designing high-performance electrochromic materials, advancing their practical applications in smart buildings and flexible displays.