Ant nest-like WO₃ films for improving electrochromic and energy-storage dual-functional performance by the surface modification of N-doped carbon

Electrochromic energy-storage materials based on WO₃ that fuse electrochromic with electrochemical energy-storage technologies are receiving great attention. In this present, WO₃ and N-doped carbon (WO₃/xNC) nano-hybrid films were built through the carbonization process of WO₃/polydopamine films. The ion transport ability of WO₃ film and its interface was effectively improved using NC as a surface modification layer. Furthermore, NC also played the role of a protective film to avoid structural damage, as well an ionic storage film during the electrochemical process of the WO₃/xNC films. Hence, in comparison with the ant nest-like WO₃ nanoporous film, WO₃/xNC films exhibited better electrochromic energy-storage performance. The colored/bleached response times of WO₃/1.0NC were 5.3 s/5.5 s and 60.2%/36.0% shorter than that of WO₃ film, respectively. WO₃/1.0NC could retain 91.6% of initial optical contrast after 2500 cycles. Moreover, the area capacitance of WO₃ was also improved by 61.7% using the surface modification of 1.0NC. Thus, the WO₃/xNC nano-hybrid films display great prospects in the field of electrochromic energy storage.