Redox-Active Mayenite Ca ₁₂ Al ₁₄ O ₃₃ Nanostructures: Unveiling Enhanced Photocatalytic Performance and Unique Electrochemical Reversibility Nature

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Ca 12 Al 14 O 33 is a multifunctional oxide known for its unique electronic and structural characteristics. The main objective of this study is to develop a green synthesis route for Ca 12 Al 14 O 33 nanostructures and investigate their dual functionality in photocatalysis and electrochemical energy storage. This study presents the first-time green synthesis of spindle- and needle-like Ca 12 Al 14 O 33 nanostructures using Lepidagathis ananthapuramensis leaf extract as a natural stabilizing and structure-directing agent, offering an eco-friendly alternative to conventional synthesis methods. Structural analysis confirms a cubic crystal phase with high crystallinity, while morphological studies reveal well-defined spindle- and needle-like nanostructures. The unique morphology obtained without any dopants or composite fabrication highlights the novelty of the work. Optical studies demonstrate a bandgap of 4.55 eV, enabling good photocatalytic activity. The material exhibited excellent performance in dye degradation, achieving 96.25% efficiency under UV light irradiation in 50 min. Electrochemical investigations on Ca 12 Al 14 O 33 nanostructures in three different electrolytes, KCl, KOH, and HCl, revealed unique capacitive behavior in each medium, attributed to its inherent redox nature. These findings highlight its potential as an electrode material for supercapacitors. The Ca 12 Al 14 O 33 electrode exhibited a specific capacitance of 91.2 F/g at 5 mV/s in KCl (neutral), 31.54 F/g at 0.5 A/g in KOH (alkaline), and lower capacitance in HCl (acidic), attributed to the absence of redox activity. Additionally, the electrode retained 96.54% of its capacitance after 1000 cycles, demonstrating excellent cyclic stability. This synergy between its photocatalytic and electrochemical capabilities highlights the importance of this study and makes Ca 12 Al 14 O 33 a promising, eco-friendly material for sustainable energy and environmental applications without using any additional dopants or composite fabrication.