<p>We report the utilization of SiO₂/VO_x/MnO_x/SiC (SVMG) microparticles, palladium nanoparticles (Pd-NPs), and polymeric nanoparticles (P-NPs) made of poly(vinyl acetate) (PVAc) to enhance the energy density/capacitance of flexible supercapacitors (SCs). For this, the SVMG + P@Pd composite was incorporated onto graphene (Gph) electrodes printed on recycled plastic substrates. SCs fabricated with SVMG + P@Pd composite reached a capacitance of 828.3 F g⁻¹ and energy density of 115.03 Wh kg⁻¹. This performance was 93% superior compared to a reference SC fabricated without the SVMG + P@Pd composite (made only with Gph electrodes). SCs made with SVMG + P@Pd composite demonstrated a superior electrochemical performance compared with SCs fabricated with SVMG (492.90 F g⁻¹, 68.45 Wh kg⁻¹), SVMG + Pd-NPs (507.74 F g⁻¹, 70.52 Wh kg⁻¹) and P-NPs + Pd-NPs composite (432.21 F g⁻¹, 65.78 Wh kg⁻¹). XPS analysis revealed the rich presence of oxygen vacancies and redox activity of species such as Si²⁺/Si³⁺/Si⁴⁺, Mn²⁺/Mn³⁺/Mn⁴⁺, V³⁺/V⁴⁺/V⁵⁺, and Pd²⁺/Pd⁴⁺, which acted as the primary redox centers for energy storage. Additionally, SVMG + P@Pd composite was evaluated for the photocatalytic degradation of methylene blue (MB) dissolved in drinking water. Such composite degraded 89% of MB after 30&#xa0;min under sunlight. Furthermore, photocatalytic floaters made without P-NPs or without P@Pd removed a maximum of 85% for MB. From scavenger experiments, we found that holes (h⁺) were the main oxidizing species, while •O₂⁻ and •OH radicals were the secondary oxidizing species. Adding Polymeric + Pd nanoparticles to SVMG microparticles increased the content of oxygen vacancies, which not only serves to store charge in SCs but also delays the recombination of photogenerated charges, increasing the photodegradation of MB.</p>