Photocatalytic and electrochemical exploration of a novel Pd modified FeVO₄/ZrO₂ nanocomposite materials for organic pollutant decontaminants in water

The present investigation is focused on the synthesis of FeVO₄/ZrO₂ photocatalysts with varying percentages of FeVO₄ on ZrO₂ (10 % 20 % and 30 % wt%) and subsequent deposition of Pd on these binary composites at different Pd weight percentages (2 %, 3 %, and 5 % wt%). ZrO₂ and FeVO₄ were synthesized using the hydrothermal method. FeVO₄ is integrated in situ onto ZrO₂ in the binary composite followed by Pd deposition by chemical reduction. The fabricated materials comprehensively analyzed their crystalline structures, morphological characteristics, charge carrier recombination dynamics, band gap energies, chemical compositions, and surface charge. This analysis employed sophisticated methods, including XRD, XPS, UV–Vis DRS, HRTEM, EDX, PL, FESEM, and Zeta potential analysis. The efficacy of photocatalysts was determined on two organic pollutants: the antibiotic ciprofloxacin (CP) and the cationic dye Rhodamine B (RhB). The incorporation of FeVO₄ significantly enhanced degradation efficiency compared to using the pure ZrO₂ photocatalyst alone. The heterojunctions in binary composites facilitated efficient charge separation and enhanced light harvesting, thereby augmenting the photocatalytic efficiency of the synthesized composites. Furthermore, subsequent Pd deposition further augmented the photocatalytic efficiency to a greater extent due to the surface plasmon effect. Among the ternary composites, ZFPd-2 (3 % wt% Pd on 20 % FeVO₄/ZrO₂) exhibited the highest degradation efficiencies, achieving 95.43 % degradation for RhB and 91.44 % for CP within 180 min. Trapping agents were utilized to examine the role of active species during the degradation process. Photogenerated holes and electrons were identified as active species in RhB degradation, whereas in CP degradation, oxygen radicals and holes predominated. The effect of pH on the photocatalytic performance of the photocatalyst was also investigated, along with the reusability and stability of the photocatalyst over five cycles. Electrochemical analysis via Mott-Schottky curves and EIS supported higher donor density and lower charge resistance after composite formation.