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Developing efficient and low-energy hydrogen isotope separation technology is one of the key requirements for fuel cycle and deuterium tritium wastewater treatment in the current development of nuclear fusion. Due to the almost identical physical and chemical properties of hydrogen isotopes, the rapid production of H2 is an important challenge for selective photocatalytic hydrogen isotope separation. We report an effective strategy for hydrogen isotope separation based on N–O–C3N4 photocatalysis. By simultaneously doping nitrogen and oxygen, the microstructure and band structure of the g-C3N4 catalyst were significantly optimized, resulting in improved catalytic activity. The inherent differences in flow states between H2O and D2O, as well as the differences in binding energy between H–O and D–O, provide opportunities for the separation of hydrogen isotopes. The hydrogen production rate of the N–O–C3N4 catalyst under visible light conditions is 7.439 mmol g−1 h−1 and the H/D separation factor is about 6.44. The photocatalytic strategy has mild and environmentally friendly reaction conditions, and this research work provides a reference for the development of efficient and advanced isotope separation systems. [ABSTRACT FROM AUTHOR]

Designing waste forms using the cocktail effect of high‐entropy ceramics can improve the efficiency of ceramic waste forms. In this work, traditional garnet (Y1.2Nd1.8Fe5O12, YIG) and high‐entropy (HE) garnet (Y0.6Gd0.6Sm0.6Eu0.6Dy0.6Fe5O12, HEG) are synthesized through ignition and plasma sintering to form dense ceramic waste forms. The chemical stability of YIG and HEG was studied by using static leaching tests at pH = 3, 5, 7, 9, 11. The results indicate that acidic environments can increase the leaching rate of ceramics. Leaching behavior leads to a decrease in lattice volume, but the elements remain uniformly distributed. The leaching mechanism indicates that YIG and HEG are controlled by dissolution and surface effect in the early stage (1–7 days) of leaching. The leaching mechanism in the later stage (14–42 days) is characterized by diffusion control. The diffusion coefficient of long‐term leaching indicates that HEG is more suitable as the immobilization substrate for high‐level radioactive waste (HLW) than YIG. [ABSTRACT FROM AUTHOR]

Effective capture of the radionuclide strontium is essential for the sustainable development of nuclear energy. Zirconium phosphate, with its tunable interlayer spacing and excellent ion exchange properties, holds potential applications in this field. In this work, a calcium zirconium phosphate (Ca0.55ZrH0.9(PO4)2) with ultra-wide spacing was obtained by means of layer spacing modulation. The saturable adsorption capacity of this material for Sr2+ was close to twice that of commercial zirconium phosphate, reaching 226.9 mg g−1. Particularly noteworthy is its saturation adsorption capacity at pH = 1, which is 6.7 times higher than that of commercial ZrP. Leveraging Ca2+ involvement in ion exchange reactions, calcium zirconium phosphate exhibits exceptional selectivity for Sr2+ capture in simulated acidic competitive ion solutions. Moreover, it demonstrates outstanding acid resistance and radiation tolerance. Through a comprehensive approach involving characterization techniques, experimental analyses, and density functional theory calculations, we elucidated its potential adsorption mechanisms at the molecular level. Crucially, the material synthesis and experimental processes are free from harmful ion byproducts, rendering it amenable to large-scale production. This advancement provides a promising avenue for the efficient capture of Sr2+ in practical wastewater treatment scenarios. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4)-based materials are considered promising catalysts for organic waste photodegradation due to their excellent photocatalytic activity and stability. Herein, a ternary thin layer system based on g-C3N4 was prepared by hexagonal boron nitride (h-BN) deposition followed by liquid phase ultrasonic stripping and Ag deposition (marked as Ag-BCN), which increased the specific surface area of g-C3N4, expanded the corresponding range of the visible-near-infrared spectrum of g-C3N4 and promoted the photo-generated electron–hole pair separation in g-C3N4 to improve the photocatalytic efficiency of pure g-C3N4. The results showed that after deposition of h-BN and Ag into bulk g-C3N4 and liquid phase ultrasonic stripping, the efficiency of photocatalytic degradation of tannic acid (TA) was enhanced. The efficiency of photocatalytic degradation of TA by Ag-BCN-2 was 84.3% at 90 min, which was 1.6 times the efficiency of bulk g-C3N4. After deposition of h-BN and Ag into pure g-C3N4, Ag-BCN was prepared and had enhanced efficiency of photocatalytic degradation of TA. The electronegativity of h-BN promoted the separation of photo-generated electron-hole pair in g-C3N4 and the low Fermi level of Ag passed negative charges. When the mass fraction of Ag was 10wt%, the Ag-BCN-2 showed the highest photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Re‐extracting environmentally transportable hexavalent uranium from wastewater produced by spent fuel reprocessing using the photocatalytic technology is a crucial strategy to avoid uranium pollution and recover nuclear fuel strategic resources. Here, we have designed S‐scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts based on the built‐in electric field and the energy band bending theory, and have further revealed the immobilization process of hexavalent uranium conversion into relatively insoluble tetravalent uranium in terms of thermodynamics and kinetics. According to the results, the hexavalent uranium removal and recovery ratios in wastewater are as high as 93.38% and 83.58%, respectively. Besides, C3N5/Fe2O3 heterojunctions also exhibit satisfactory catalytic activity and selectivity even in the presence of excessive impurity cations (including Na+, K+, Ca2+, Mg2+, Sr2+, and Eu3+) or various organics (such as xylene, tributylphosphate, pyridine, tannic acid, citric acid, and oxalic acid). It is believed that this work can provide a potential opportunity for S‐scheme heterojunction photocatalysts to re‐enrich uranium from spent fuel wastewater. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4)-based materials are considered promising catalysts for organic waste photodegradation due to their excellent photocatalytic activity and stability. Herein, a ternary thin layer system based on g-C3N4 was prepared by hexagonal boron nitride (h-BN) deposition followed by liquid phase ultrasonic stripping and Ag deposition (marked as Ag-BCN), which increased the specific surface area of g-C3N4, expanded the corresponding range of the visible-near-infrared spectrum of g-C3N4 and promoted the photo-generated electron–hole pair separation in g-C3N4 to improve the photocatalytic efficiency of pure g-C3N4. The results showed that after deposition of h-BN and Ag into bulk g-C3N4 and liquid phase ultrasonic stripping, the efficiency of photocatalytic degradation of tannic acid (TA) was enhanced. The efficiency of photocatalytic degradation of TA by Ag-BCN-2 was 84.3% at 90 min, which was 1.6 times the efficiency of bulk g-C3N4. After deposition of h-BN and Ag into pure g-C3N4, Ag-BCN was prepared and had enhanced efficiency of photocatalytic degradation of TA. The electronegativity of h-BN promoted the separation of photo-generated electron-hole pair in g-C3N4 and the low Fermi level of Ag passed negative charges. When the mass fraction of Ag was 10wt%, the Ag-BCN-2 showed the highest photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Photocatalysts have been extensively used for hydrogen evolution or organic degradation. In this work, two different heterojunction types of composite photocatalysts, 1T-MoS 2 @TiO 2 with Schottky heterojunction and 2H-MoS 2 @TiO 2 with type-II heterojunction, are synthesized via hydrothermal synthesis. These two composite materials exhibit excellent photocatalytic activity toward the degradation of tannic acid, which is a typical organic in nuclear wastewater. At an optimal loading of 16% 1T-MoS 2 , the 1T-MoS 2 @TiO 2 shows the highest degradation capacity of 98%, which is 3.2 times higher than that of pure TiO 2 . The degradation rate of 16% 1T-MoS 2 @TiO 2 is much higher than that of 13% 2H-MoS 2 @TiO 2 . The enhanced photocatalytic activity might be attributed to the improved charge transfer according to the mechanism investigation, supported by the X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) analyses. This work provides new opportunities for constructing highly efficient catalysts for nuclear waste disposal., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)