Ping Li

Photocatalytic separation of uranium presents a promising approach for resource recovery, yet its efficiency remains limited by severe carrier recombination. Integrating piezocatalysis with photocatalysis provides an attractive pathway to overcome this barrier. Herein, a type-II scheme CdS@BaTiO₃ heterojunction was fabricated by growing CdS nanoparticles onto a BaTiO₃ matrix, which enables efficient piezo-photocatalytic uranium extraction. The built-in electric field of the heterojunction, reinforced by the stirring-induced piezoelectric polarization of CdS@BaTiO₃, drives directional charge migration and greatly enhances carrier separation. As a result, CdS@BaTiO₃ achieved 98% uranium removal within 10 mins under stirring and light irradiation, being 2.5 times and 8.3 times higher than that of photocatalysis and piezocatalysis alone, respectively. The composite also delivers a high uranium separation capacity of 1893.2 mg g^-1, exceeding most previously reported piezo-photocatalytic uranium extraction systems. Mechanistic investigations identify superoxide radicals (•O₂^⁻) as the dominant reactive species responsible for U(VI) reduction and immobilization. This work demonstrates a promising water-flow-driven energy coupling strategy for uranium extraction.

Photocatalytic reduction of U(VI) is a promising approach for the treatment of uranium‐containing solutions and resource recovery. However, due to the low charge transfer efficiency and the weak ability to activate dissolved oxygen, most photocatalysts are unable to reduce U(VI) under ambient air conditions, limiting the practical application of this approach. In this study, nano‐hollow cubic NiCo‐layered double oxide (NiCo‐LDO) was prepared using Ni ²⁺ ‐etched ZIF‐67 as a precursor and was employed for the photocatalytic reduction of U(VI). Within 180 min of illumination, the NiCo‐LDO achieved a U(VI) removal efficiency of 98.0% under ambient air conditions, which is 2.5 and 4.2 times higher than those of NiO and Co ₃ O ₄ , respectively. The efficiency of U(VI) removal remained above 98% after five cycles of reuse. Benefiting from uniformly dispersed heterojunctions and the oxygen vacancies, NiCo‐LDO exhibits efficient separation of photogenerated charge carriers. Furthermore, the increased d‐band center and hollow cubic structure effectively enhance its adsorption for U(VI) as well as the activation of dissolved oxygen. Together, these features promote electron transfer and oxygen activation, enabling the efficient U(VI) reduction under ambient air conditions. These findings offer implications for designing catalysts applicable to the photocatalytic reduction of U(VI) in practical scenarios.

Photocatalysis offers a promising method for uranium extraction from seawater. However, the conventional photocatalytic reduction pathway faces challenges due to the adverse effects of oxygen and carbonate under ambient conditions. In this study, an S‐scheme heterojunction is constructed by loading TiO ₂ onto tubular graphitic carbon nitride (PCN) for the photocatalytic U(VI) extraction. The photogenerated electrons from the conduction band of TiO ₂ transfer to the valence band of PCN, enhancing both the oxidation and reduction capabilities of the catalytic system. This process induces significant H ₂ O ₂ generation via both reduction and oxidation reactions. The produced H ₂ O ₂ further complexes with uranyl ions to form studtite precipitates, thereby achieving efficient uranium separation. The system achieves a U(VI) separation efficiency of 95.8% within 210 min of illumination. Unlike traditional photocatalytic reduction of U(VI), this reaction is unaffected by air atmosphere or carbonate, enabling 100% uranium extraction from 4 L of natural seawater under sunlight.

Birnessite is regarded as an efficient oxidizing agent that would significantly influence the environmental fate of elements such as arsenic. This study compared the chemical and photocatalytic oxidation of As(III) over birnessite. During the chemical oxidation, As(III) was oxidized to As(V), while Mn(IV) was reduced to Mn(II), subsequently forming MnOOH. The coverage of the reactive sites by MnOOH inhibited the chemical oxidation of residual As(III). At pH 5.0, after 360 min of reaction, 61% of As(III) was oxidized to As(V), and the oxidation of As(III) decreased with an increase in pH. The photocatalytic oxidation of As(III), where almost all As(III) could be oxidized to As(V) over a pH range of 5.0–8.0 and 360 min, was much more efficient compared to chemical oxidation. In contrast to chemical oxidation, the formation of MnOOH slightly affected the photocatalytic performance of birnessite. It was demonstrated that •O₂⁻ radicals and holes (h_vb⁺) played an important role in the photocatalytic oxidation of As(III) over birnessite. Our findings confirmed that light dramatically promoted the oxidation of As(III) by birnessite, broadening the understanding of the environmental behaviors of arsenic.

Nuclear power has experienced rapid development as a green energy source due to the increasing global demand for energy. Uranium, as the primary fuel for nuclear reactions, plays a crucial role in nuclear energy production, and seawater-uranium extraction has gained significant attention. However, the extraction of uranium is usually susceptible to contamination by microorganisms, such as bacteria, which can negatively affect the adsorption performance of uranium adsorption materials. Therefore, an important challenge lies in the development of new antibacterial and antiadhesion materials to inhibit the attachment of marine microorganisms. These advancements aim to reduce the impact on the adsorption capability of the adsorbent materials. This paper reviews the antibiofouling materials used for extracting seawater uranium, and corresponding mechanisms are discussed.

The uptake of radiocesium (RCs) by plants is key to the assessment of its environmental risk. However, the transfer process of RCs in the water-vegetable system still remains unclear. In this work, the uptake and accumulation processes of Cs⁺ (0-10 mM) in lettuce were explored under different conditions by using hydroponics. The results showed that the higher exposure concentration of Cs⁺ could lead to a faster uptake rate and would be beneficial to the uptake and accumulation of Cs⁺. The uptake of K⁺ by roots and leaves was inhibited significantly when Cs⁺ concentration increased, but unapparent for Ca²⁺ and Mg²⁺. It was found that the higher K⁺ and Ca²⁺ concentration was, the higher inhibition was found for the uptake of Cs⁺ in root. The uptake of Cs⁺ leads the decrease of chlorophyll content and brought a negative effect on plant photosynthesis, consequently, a negative effect on lettuce morphology and obvious decrease of biomass and root length. The contents of glutathione (GSH), malondialdehyde (MDA), and root vitality were increasing during the growth following stress of high concentrations of Cs⁺, which caused stresses on the antioxidant system of lettuce. The enrichment coefficient for Cs⁺ in leaves was in the range of 8-217. Moreover, the transfer factor was in the range of 0.114-0.828, which suggested that the high Cs⁺ concentration could enhance the transfer of Cs⁺ from lettuce root to leaf. This study provides more information on the transfer of RCs from water to food chain, promoting the understanding of the potential risk of RCs.

In this study, the cytotoxicity and toxic mechanism of carbon quantum dots (CQDs) to E. coli were evaluated in vitro. The synthetic CQDs were extremely small in size (~2.08 nm) and displayed strong fluorescence. The results demonstrated that CQDs showed good biocompatibility with E. coli within a short culture time. However, when the exposure time exceeded 24 h, the toxicity of CQDs became apparent, and the contents of reactive oxygen species, lactate dehydrogenase, and the crystal violet absorption rate increased significantly. To further explore the cytotoxic mechanism, approaches including confocal laser scanning microscopy, scanning electron microscopy, and biological transmission electron microscopy combined with zeta potential tests, osmotic pressure measurement, and comet assays were performed. On the one hand, the CQDs altered the surface charges of cells and induced lipid peroxidation by adhesion on the surface of E. coli, leading to an increase in the permeability of the cell wall. On the other hand, when the concentration of CQDs reached 200 µg/mL, the osmotic pressure of the extracellular environment was significantly reduced. These are the main factors that lead to cell edema and death. Finally, the comet assays confirmed that CQDs could induce DNA damage, which could inhibit the proliferation of E. coli.

The photocatalytic conversion of soluble U(VI) into insoluble U(IV) is a robust strategy to harvest aqueous uranium, but remains challenging owing to the intermittent availability of solar influx and reoxidation of U(IV) without illumination. Herein, a dual platform based on K⁺ and cyano group co‐decorated poly(heptazine imide) (K‐CN‐PHI) is reported that can drive persistent U(VI) extraction upon/beyond light. K‐CN‐PHI achieves the photocatalytic reduction of U(VI) with a reaction rate of 0.89 min⁻¹, being 47 times greater than that over pristine carbon nitride (PCN). This system can further be triggered by light to form long‐living radicals, driving the reduction of U(VI) in the dark for over 3 d. The flexible structural K⁺ as counterions stabilize the electrons trapped by cyanamide groups, enabling the long lifetime of the generated radicals. The results collectively prove K‐CN‐PHI to be a novel and efficient photocatalyst enabling persistent U(VI) extraction around the clock, and broadening the practical applications of the photocatalytic extraction of U(VI).