Because it can simulate vibration in natural conditions, piezocatalysis has been a research hotspot in solving environmental and energy issues in recent years. Significant progress has been made, which needs to be re-summarized and reorganized to present a concise and logical work to readers. Therefore, in this review, recent progress of reported piezocatalysts (such as oxide, perovskite, sulfide, PVDF, MOFs and COFs), the way to enhance the performance of piezocatalysis (such as defects, heterojunctions, and piezo-coupled photocatalysis), and the application of piezocatalysis in environmental and energy fields (such as dyes, pesticides and antibiotics, heavy metal, piezocatalytic hydrogen production, and piezocatalytic CO2 reduction), have been summarized. Finally, the future development trends of piezocatalysis are prospected and discussed.

Excessive nitrites present in water pose a severe threat to human health. Given its high solubility, nitrite is hard to eliminate. Thus, it is crucial to assess the nitrite concentration in water bodies to avoid risk in advance. In this study, an enhanced Raman detection method through augmenting the polarization for nitrite in water is reported, which is triggered by the synergistic effect of internal and external electric fields. The nitrite is transformed into azo compounds for Raman detection on the substrate of Ag/NH2-Ni-MOFs. By the polarization induced by the internal and external electric fields, the Raman peak intensity of azo compounds increases by 2.20 times. The method is capable of reproducibly and selectively detecting nitrite within the concentration range of 10-8-10-3 mol L-1, and achieving a limit of detection (LOD) of 3.76 x 10-9 mol L-1, which is substantially below the national standard (0.71 x 10-3 mol L-1). In addition, this strategy has found application in evaluating the solutions containing methylene (MB) and U(VI), etc. This work puts forward an effective approach to devising high-performance and highly selective techniques for assessing solution pollutants, which demonstrates outstanding detection capabilities in practical applications.

ABSTRACT Piezocatalysis has garnered unprecedented research enthusiasm for applications in energy and environmental fields, as it can harvest the tiny vibration energy from the natural environment and convert it into electrical energy to drive catalytic reactions. However, the fundamental principles underlying this strategy remain a subject of controversy. Herein, a leakage current‐based mechanism is first proposed and employed to elucidate piezocatalysis. It is demonstrated that the cyclic ultrasonic vibration induces an asymmetric cyclic internal electric field, which drives the directional migration of free electrons (i.e., leakage current) and thus facilitates the occurrence of piezocatalysis. As an example, Na(AlSi 2 O 6 )H 2 O (NASO) nanobelts are fabricated from perlite powder and utilized for highly efficient and low‐cost piezocatalytic extraction of uranium (U[VI]) from seawater and the direct conversion of air to nitrate. The extraction of U(VI) is ascribed to the formation of UO 4 ·2H 2 O by combining UO 2 2+ and H 2 O 2 , and the extraction efficiency is up to 96.97%. Moreover, nitrate is successfully produced from air, and the yield reaches 3.85 mg g −1 h −1 . This work offers new insights into the catalytic process, holds substantial application potential for addressing energy and environmental challenges, and sheds important light on the rational design and optimization of piezocatalysts.

As a product of neutron-induced fission reactions of nuclear fuels, neodymium (Nd) has significant application potential in industry. However, the high-efficiency separation of Nd is still an urgent issue. In this paper, the separation of Nd from a simulated spent fuel system is enhanced by adding a small quantity of AlF3 (2 %) in molten LiF-KF (51:49) molten salt at 600 degrees C. Nd(III) and Al(III) ions were found to be co-reduced to Nd(0) and Al (0) on the tungsten electrode by a one-step exchange of three electrons process. It is found that as the Al/Nd = 1:1, the electrolysis shows the reversible reaction characters, and the amount of charge by electrolysis increases from 7.21C (withoutAlF3) to 8.85C (with AlF3) within 800 s of electrolysis, and the electrolytic products are rodlike and dendritic structures with a length of 0.5-3.9 mu m and a diameter of 0.1-0.7 mu m. NdAl and AlNd3 alloys are formed, and Nd is extracted from molten salt in the form of alloys. This work provides a new idea for the green preparation of Nd metal, and promotes the efficient and low-carbon recycling of rare earth resources in strategic industries such as permanent magnet materials.

Piezocatalysis has garnered unprecedented research enthusiasm for applications in energy and environmental fields, as it can harvest the tiny vibration energy from the natural environment and convert it into electrical energy to drive catalytic reactions. However, the fundamental principles underlying this strategy remain a subject of controversy. Herein, a leakage current-based mechanism is first proposed and employed to elucidate piezocatalysis. It is demonstrated that the cyclic ultrasonic vibration induces an asymmetric cyclic internal electric field, which drives the directional migration of free electrons (i.e., leakage current) and thus facilitates the occurrence of piezocatalysis. As an example, Na(AlSi2O6)H2O (NASO) nanobelts are fabricated from perlite powder and utilized for highly efficient and low-cost piezocatalytic extraction of uranium (U[VI]) from seawater and the direct conversion of air to nitrate. The extraction of U(VI) is ascribed to the formation of UO4 & centerdot;2H2O by combining UO2 2+ and H2O2, and the extraction efficiency is up to 96.97%. Moreover, nitrate is successfully produced from air, and the yield reaches 3.85 mg g-1 h-1. This work offers new insights into the catalytic process, holds substantial application potential for addressing energy and environmental challenges, and sheds important light on the rational design and optimization of piezocatalysts. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic) ( (sic)(sic)(sic)(sic) ) (sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)Na(AlSi2O6)H2O ( NASO ) (sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) ( U(VI) ) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic) ( U(VI) ) (sic)(sic)(sic)(sic)(sic)(sic)UO4 & centerdot;2H2O(sic)(sic)(sic) , (sic)UO2 2+(sic)H2O2(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)96.97%.(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)3.85 mg g-1 h-1.(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) , (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

The NaF-BeF2 (FNaBe) molten salt has been widely recognized as a promising alternative to LiF-BeF2 (FLiBe) molten salt in molten salt reactor applications due to its lower melting point and superior economic feasibility. In this study, machine learning force field (MLFF) models for FLiBe and FNaBe systems were first trained based on high-accuracy first-principles datasets and deep neural networks. Subsequently, systematic investigations into the microscopic structure, thermophysical properties, and transport properties of the FNaBe molten salt system were conducted using the Deep Potential Molecular Dynamics (DPMD) method. The positions of the first peaks in the radial distribution functions (RDFs) of FLiBe and FNaBe systems obtained from DPMD simulations showed excellent agreement with experimental results, validating the accuracy of our trained force fields. Furthermore, the variations of microscopic structures, thermophysical properties, and transport properties of the FNaBe molten salt with temperature and NaF concentration were comprehensively analyzed and compared with experimental data. A comparative analysis of key physical properties between FNaBe and FLiBe molten salts was also performed. This work provides profound insights into the structure-property relationships of the FNaBe molten salt system and serves as a critical reference for future studies on the physicochemical properties of high-temperature fluoride molten salts and the development of MLFF.

Calcium silicate hydrate (C-S-H), the principal binding phase in Portland cement, plays a critical role in the immobilization of heavy metals, yet a quantitative and mechanistic understanding of Cu2+ uptake by C-S-H remains incomplete. This study investigates the immobilization behavior of Cu2+ by C-S-H with systematically controlled Ca/Si ratios (0.6-1.6) and develops a thermodynamically consistent sublattice solid-solution model. The C-S-Hs were synthesized under sorption equilibrium conditions and characterized to determine their structural evolution with Ca/Si ratio. Cu2+ sorption was subsequently examined on pre-synthesized C-S-Hs, combined with spectroscopic analyses to elucidate Cu coordination environments. The results show that Cu2+ is immobilized predominantly through structural incorporation at low Cu2+ loadings rather than hydroxide precipitation. With increasing Cu2+ concentration, Cu2+ progressively intercalates into the interlayers of C-S-H, partially replacing interlayer Ca2+ and forming Si-O-Cu linkages associated with Q2 silicate sites. The Ca/Si ratio strongly controls both uptake capacity and binding mechanism. High Ca/Si ratios promote silicate-chain polymerization through conversion of Q1 to Q2 units, whereas extremely low Ca/Si ratios induce redistribution between Q2 and Qb2 species. At intermediate Ca/Si ratios, Cu2+ is mainly stabilized as hydroxyl-associated species. Once the sorption capacity is exceeded, excess Cu2+ transforms into CuO under alkaline conditions. Based on these observations, a CASH+Cu thermodynamic model incorporating five Cu-bearing endmembers was developed and calibrated using both aqueous and solid-phase data. The model quantitatively reproduces Cu uptake, solution chemistry, and phase assemblages, providing a predictive framework for Cu2+ retention in cementitious systems.

Precise regulation of the surface coordination environment of zirconia (ZrO2) is crucial for understanding its catalytic behavior in the selective hydrogenation of carbon–oxygen (C=O) bonds. However, establishing a single-variable correlation between the morphology of the support and its surface active sites—while eliminating multivariable interference—remains a major challenge in structure–performance relationship studies. Herein, we propose a morphology-driven single-variable regulation strategy, achieving controlled adjustment of the concentration of low-coordinated Zr–O sites (LCSs) on ZrO2 simply by varying the type of precipitant used during hydrothermal synthesis. Using the selective hydrogenation of diethyl oxalate (DEO) as a model reaction, and combining in situ spectroscopic characterization with density functional theory (DFT) calculations, we reveal an LCS-capture/Ov-activation–driven “adsorption–migration” mechanism. The LCSs serve as high-density, weak adsorption sites that rapidly capture DEO molecules and thus ensure high selectivity; subsequently, at reaction temperature, the adsorbed DEO species migrate to adjacent oxygen vacancies (Ov) to complete hydrogenation. This study establishes a clear morphology–coordination–reaction-pathway correlation, providing new theoretical insights and design strategies for the rational development of efficient and tunable heterogeneous catalysts.

The environmental pollution and resource shortage issues caused by uranium mining and utilization have garnered growing attention, leading to two concerns of nuclear wastewater treatment and the extraction of U(VI) from seawater. The monotony of traditional U(VI) extraction/removal methods often restricts their application potential due to low efficiency. Additionally, the separation of U-containing products from the catalyst remains an urgent challenge. Therefore, this study demonstrates a friction-assisted piezocatalytic synergistic effect of bentonite to enhance U(VI) extraction/removal from water. It is found that the piezo catalytic efficiency of U(VI) reaches over 26.6 % in 2 h, while friction assistance boosts this efficiency to 63.5 % in the same time. Characterizations confirm that center dot O2- and H2O2 serve as the primary active species in the reaction. Most notably, it is found that the solid U(VI)-containing product of UO3 center dot(H2O2)center dot(H2O) is loosely bound with bentonite, enabling easy separation via suction filtration process. This significantly reduces the processing steps. This work presents a highly efficient friction-enhanced piezocatalytic strategy for U(VI) solidification in water, offering a facile approach to separate U-containing products from the catalyst. Moreover, the method is cost-effective and holds substantial potential for practical applications.

Due to most of the U(VI) extraction methods suffering the issues of high cost and low efficiency, finding a new method is still urgent. In this work, we report a way to remove U(VI) from water by tribocatalysis, where a natural mineral of attapulgite is used as the tribocatalyst. By a careful investigation, it is confirmed that the ultrasonic-generated microbubbles rub with the attapulgite to form free radicals of h+, center dot O-2(-) , and center dot OH, which could then be transformed to H2O2 to react with U(VI) to form UO2O2. The extraction rate of U(VI) from water is up to 87.88% (50 ppm) in 200 min. This work using the natural mineral attapulgite being tribocatalyst has the advantages of low cost and high efficiency, which also provide new insight into the conversion of U(VI) in natural conditions and will have great potential in the treatment of nuclide wastewater and seawater.

The development of high efficiency and low-temperature molten salt electrolysis methods can solve the difficulties of poor operation, high equipment requirements, and high cost of high-temperature molten salt electrolysis. In this study, a way to promote efficiency at a relatively low temperature of 563 K in the electrolysis separation of Th4+ in LiCl-KCl-CsCl molten salt by applying an external magnetic field was reported. The influence of the magnetic field on the electrochemical, kinetic, and thermodynamic properties is explored. The results show that by applying a magnetic field, the ionic current of Th4+ is subjected to Lorentzian force and thus leads to differences from that without a magnetic field. The Th4+ exchange current density i0 increased by 73.9 %, the diffusion coefficient increased by an order of magnitude, and Ea decreased by 23.7 %. At the same time, Th production significantly increased by 16.03 % after the application of a magnetic field under the condition of constant potential electrolysis at-2.5 V. The results of this study provide theoretical support and new insights for spent fuel reprocessing.

Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investigated in LiCl-KCl-SrCl2 molten salts at 773 K using various electrochemical methods. The chemical reaction potentials of Li and Sr on reactive Zn/Al electrodes were determined. We observed that Sr could be extracted by decreasing the activity of the deposited metal Sr on the reactive electrode, although the standard reduction potential of Sr(II)/Sr was more negative than that of Li(I)/Li. The electrochemical extraction products of Sr on reactive Zn and Al electrodes were Zn13Sr and Al4Sr, respectively, with no codeposition of Li observed. Based on the density functional theory calculations, both Zn13Sr and Al4Sr were identified as stable intermetallic compounds with Zn-/Al-rich phases. In LiCl-KCl molten salt containing 3wt

Europium is an important element in the nuclear industry, which is usually applied in the high-temperature melt system. Therefore, due to relatively limited progress in understanding europium among all lanthanide elements, this study aims to disclose the important behavior of Eu3+ (Eu2O3) in the LiCl-KCl molten salt system employing optical and electrochemical strategies and to provide a theoretical basis for the subsequent electrolytic separation of Eu from other metals in nuclear waste. The optical behavior and electrochemical behavior of Eu2O3 in LiCl-KCl molten salt were tested by Raman, UV-vis diffuse reflectance spectra and CV, SWV, CP and other electrochemical methods. Through spectroscopic studies, it was found that Eu2O3 formed a new phase EuOCl in LiCl-KCl melt at 973 K. With the increase of Eu2O3 ratio, the band gap of products first increased and then decreased. Through electrochemical studies, it was found that Eu3+ underwent a single electron exchange process in LiCl-KCl melt, corresponding to the conversion between Eu(III) and Eu(II). The process was a quasi-reversible diffusion-controlled process. A series of electrochemical tests were carried out to determine the diffusion coefficient D of Eu (III) and Eu (II) as (1.94 ± 0.05) × 10−5 cm2 s−1 and (1.95 ± 0.05) × 10−5 cm2 s−1, respectively. This work reveals the electrolytic process of Eu3+ in molten system, which may influence on the spent fuel treatment.

Europium is an important element in the nuclear industry, which is usually applied in the high-temperature melt system. Therefore, due to relatively limited progress in understanding europium among all lanthanide elements, this study aims to disclose the important behavior of Eu3+ (Eu2O3) in the LiCl-KCl molten salt system employing optical and electrochemical strategies and to provide a theoretical basis for the subsequent electrolytic separation of Eu from other metals in nuclear waste. The optical behavior and electrochemical behavior of Eu2O3 in LiCl-KCl molten salt were tested by Raman, UV-vis diffuse reflectance spectra and CV, SWV, CP and other electrochemical methods. Through spectroscopic studies, it was found that Eu2O3 formed a new phase EuOCl in LiCl-KCl melt at 973 K. With the increase of Eu2O3 ratio, the band gap of products first increased and then decreased. Through electrochemical studies, it was found that Eu3+ underwent a single electron exchange process in LiCl-KCl melt, corresponding to the conversion between Eu(III) and Eu(II). The process was a quasi-reversible diffusion-controlled process. A series of electrochemical tests were carried out to determine the diffusion coefficient D of Eu (III) and Eu (II) as (1.94 +/- 0.05) x 10-5 cm2 s-1 and (1.95 +/- 0.05) x 10-5 cm2 s-1, respectively. This work reveals the electrolytic process of Eu3+ in molten system, which may influence on the spent fuel treatment.

Extraction of U(VI) from waters has recently been considered a promising way towards solving the energy and environmental issues. To enhance the extraction efficiency, various ways have been adopted, while most of them rely on extra energy, which enhances the extraction cost. In this work, a friction-assisted piezocatalytic strategy is proposed to enhance the extraction of U(VI) from aqueous solutions under simulated vibration and dynamic conditions that mimic natural environments. As an example, a diatomite/C3N4 nanocomposite is fabricated and utilized as a catalyst, and the extraction rate of U(VI) reaches 95.7 % within 3 h under 120 W ultrasonication and stirring. The research on the catalytic mechanism shows that center dot O2- and H2O2 play a dominant role in the catalytic process. The modification of C3N4 on diatomite was found to enhance the generation of micro-nano bubbles, and then the bubbles were subjected to the relative movement to produce free radicals to facilitate the catalysis of U (VI). The U(VI)-containing product was proved to be UO4. This work has provided a low-cost and highly efficient catalyst, offering a new insight into designing low-cost synergistic catalysts for the extraction of U(VI) in aqueous solutions.

In nuclear reactors, nuclear fuel undergoes a complex fission process, Ce and Gd are fission products generated directly from the fissile materials. Generally, Ce and Gd are difficult to separate individually due to their similar chemical properties. In this study, a method to achieve the separation and co-reduction of Ce and Gd in LiCl–KCl molten salt system at 873 K is presented. It is found that Gd could be separated by electrolysis at −2.0 V, and Ce and Gd could be co-reduced at −2.4 V. A relatively pure product could be obtained by the potentiostatic electrolysis (PE) mode.

Nitrite ions originate from various natural and anthropogenic sources and can cause health issues including methemoglobinemia and potential carcinogenic effects. As the nitrite in water has become an increasing threat to human health, the accurate evaluation of nitrite is urgently needed for environmental quality and safety management. In this paper, we designed a CTAB/SF5/GCE sensor, which exhibited an obvious enhancement compared to the pristine glassy carbon electrode (GCE). The morphology characterization confirmed the hexagonal nanosheets of SnS2 and the even distribution of Fe element. The energy band, Tafel plots, and EIS spectroscopy were employed to investigate the enhancement mechanism, demonstrating that improving charge transfer on the sensing interface is crucial in enhanced signals. Cyclic voltammetry (CV) was adopted as the electrochemical method to measure the nitrite in water and a sensitivity of 0.129 mu A & sdot;mu M- 1 was exhibited in the range of 30-500 mu M, and the limit of detection (LOD) was calculated to be 6.51 mu M. The reliability including the repeatability, reproducibility, and stability of this sensor were estimated and showed satisfactory results. The test in real samples and the assessment of interfering substances showed the CTAB/SF5/GCE possesses a large potential in the practical application of electrochemical sensing of nitrite.

This study developed a high-precision deep potential (DP) model based on density functional theory (DFT) and the DP-GEN workflow to efficiently simulate the microscopic structures and thermophysical properties of LiF-NaF-KF molten salt systems with varying compositions. Through iterative optimization of the training data set using the DP-GEN active learning strategy, our DP model demonstrated excellent agreement with DFT calculations in predicting energies, forces, and stresses. Leveraging this model, we systematically investigated the local structures and properties of 22 FLiNaK molten salt compositions, including radial distribution functions (RDFs), coordination numbers (CNs), density (ρ), heat capacity (Cp), self-diffusion coefficients (SDCs), electrical conductivity, and shear viscosity. The analysis revealed that Li-F ion pairs exhibit the strongest localized coordination, with the coordination numbers of all cations increasing with higher LiF content. Density was found to be primarily governed by NaF concentration, showing a positive correlation with NaF content. Viscosity was significantly influenced by both temperature and composition, decreasing notably with increasing temperature - the viscosity of the eutectic composition decreased from 3.933 mPa·s at 873 K to 1.622 mPa·s at 1073 K. Higher KF content led to lower viscosity due to the weaker interactions of K-F ion pairs. Additionally, noneutectic compositions with high LiF content (e.g., 80% LiF) exhibited significantly superior Cp compared to the eutectic system. This work elucidates the regulatory effects of composition and temperature on the structure-property relationships of molten salts, expands the property database for noneutectic FLiNaK systems, and provides a theoretical foundation for the design and performance optimization of molten salt reactor materials.

The elimination of U(VI) from acidic nuclear wastewater is important for solving the problems in environmental and energy fields. However, the adsorbents used for U(VI) extraction/removal usually undergo the issues of high cost, low efficiency, and long adsorption time. In this work, surface-acidified hydroxyapatite (SAHAP) powders were obtained by soaking chicken leg bone in acetic acid combined with hydrothermal treatment, which shows super fast removal/extraction capacity of U(VI) from the solution. The surface of the SAHAP is highly acidified by large quantities of hydrogen phosphate radicals. The characterization and mechanistic investigations indicate that the U(VI) substitute with Ca2+/H+ via an ion-exchange related monolayer chemisorption process. At room temperature, over 99 % of U(VI) could be sequestrated by SAHAP within 20 s at pH 4.0, and the extraction amount could reach 1270 mg/g. Moreover, the SAHAP shows great application potential in the removal/ extraction of U(VI) from seawater, and 25 mM CO3 2- ions could only reduce the adsorption ability by 4.18 % at pH 4.0. This study provides a new approach to fabricating adsorbents for highly effective, selective and low-cost extraction of U(VI) from wastewater.