Catalytic synergy in palladium-enriched tungsten oxide nanogranules: redefining electrochromic dynamics and energy storage capabilities

Abstract

The fusion of electrochromic (EC) materials with energy storage technologies has unlocked a new frontier in compact, intelligent electronic systems. This innovative synergy enables EC materials to serve as real-time visual indicators of energy levels while simultaneously enhancing energy storage performance. In this study, amorphous palladium enriched tungsten oxide (Pd-WO₃) (WPd) thin films were synthesized via a streamlined single-step electrodeposition process, with Pd doping significantly enhancing material properties. Structural analysis revealed subtle crystal modifications through X-ray diffraction and a highly uniform, interconnected nanogranular matrix through scanning electron microscopy. The WPd-3 film, containing 3 wt% Pd, emerged as a remarkable material, combining exceptional EC and energy storage capabilities. It demonstrated outstanding optical modulation of 79.73%, superior coloration efficiency of 90.18 cm² C⁻¹, and impressive cycling stability with 98.11% reversibility. On the energy storage front, it delivered a remarkable areal capacitance of 64.66 mF cm⁻², an energy density of 0.020 mW h cm⁻², and a power density of 0.075 mW cm⁻², retaining 84.79% of its capacitance after 10 000 cycles. The multifunctional WPd-3 device, employing fluorine-doped tin oxide (FTO) electrodes, efficiently powered red LEDs, underscoring its practical viability. These findings position WPd-3 as a cutting-edge material, paving the way for next-generation multifunctional, adaptive electrochromic energy storage (EES) systems.