Influence of Ce, Pr, and Gd Doping on Optical and Electrochemical Energy Storage Capabilities of Ca_0.15Zr_0.85O_1.85

The quest to find stable energy materials is ongoing. In this study, we investigate the influence of lanthanoid doping, specifically, Ce, Gd, and Pr, on the storage of optical and electrochemical energy at room temperature. The samples were prepared using the sol–gel method at room temperature, followed by annealing at 550 °C for 2 h to enhance crystallinity and phase purity. All samples crystallize in the rare Ca0.15Zr0.85O1.85 phase with a cubic crystal structure. The undoped sample exhibits a prominent photoluminescence emission at 345 nm (UV-A region). In contrast, the lanthanoid-doped samples show significant emissions at 310 and 355 nm (UV-A and UV-B regions). Lifetime studies were performed to understand the kinetics of charges in their excited state. All samples display strong persistent luminescence (PersL) in the UV region for at least 15 min due to the trapping, detrapping, and retrapping of charges at room temperature. Additionally, room temperature-induced tunneling is observed in the Pr-doped sample, which also demonstrates a strong redox peak at 0.25 V during electrochemical measurements. All samples exhibit a quasi-rectangular shape in the potential range of −1.0 to 1.0 V across different scan rates. Among the doped samples, the Pr-doped sample shows the highest conductivity, while the Ce-doped sample exhibits the highest resistance. Overall, we have successfully incorporated UV-B PersL into these samples, and with Pr doping, the conductivity of the material is improved, suggesting the potential use of this material for multifunctional energy applications.