We report Ni-doped MnBi2O4 (MnNiBi) as a defect-engineered material that works as efficient photocatalyst and as redox material for flexible supercapacitors (SCs). Ni incorporation induces lattice distortions that create oxygen vacancies, which act as active sites for charge storage or for the degradation of contaminants. Firstly, SCs were fabricated with graphene (G) electrodes printed on flexible polyethylene and those electrodes were coated with MnBi or MnNiBi powders. The G/MnNiBi-SC device (made with electrodes of G+MnNiBi) showed a capacitance of 810 F g− 1, high energy density of 165 Wh kg− 1, and high capacitance retention (94%) after 1000 charging-discharging cycles. Also, a device was made with MnBi powder (without Ni dopant), but the capacitance and energy density decreased to 155 F g− 1 and 48 Wh kg− 1, respectively. Thus, the presence of Ni in the redox powder increased the capacitance by 422%. Moreover, MnNiBi powder produced high photocatalytic degradation of methylene blue (MB, 93%) and glyphosate (75%) under direct sunlight, which was superior to the degradation percentages obtained with undoped MnBi (57–70%). Interestingly, the degradation % increased to 98% and to 92% for MB and glyphosate, respectively, under UV-light. Moreover, total organic carbon measurements indicated mineralization efficiencies of 75% for MB and 58% for glyphosate. XPS studies showed that oxygen vacancies defects increased ⁓225% after the use of the MnNiBi powder for photocatalysis, which accelerated the degradation of contaminants. These defects were also crucial for supercapacitors, because they worked as redox centers to store charge. Thus, multifunction MnNiBi powders were used for charge-storage/water-cleaning.

This study aimed to evaluate the long-term stability of glass wool used as insulation material in domestic nuclear power plants and to quantify its degradation mechanisms and dissolution kinetics under highly alkaline conditions (pH ≥ 12) expected in cementitious environments associated with vault-type disposal systems for low-level radioactive waste. Experiments were conducted at 20 °C and 80 °C using cement-saturated groundwater (CGW) as the primary solution, while comparative tests were performed in NaOH and Ca(OH)₂ solutions at equivalent pH levels. ICP-OES, SEM-EDS, and XRD analyses revealed that dissolved Ca²⁺ significantly suppressed glass dissolution. The presence of abundant Ca²⁺ ions promoted densification of the surface alteration layer, retarding degradation, whereas depletion of Ca²⁺ resulted in a rapid increase in the dissolution rate. Although calcium silicate hydrate (CSH) precipitates are generally known to inhibit glass corrosion, the CSH phases formed in this study exhibited limited protective capability due to their low Ca/Si ratios and high porosity. Based on the dissolution rate constant at 20 °C, the complete dissolution of glass wool was estimated to require approximately 213 years; however, under conditions of limited Ca²⁺ availability, the dissolution rate could increase by up to 70-fold, approaching that observed in NaOH solution.