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Preorganization is an effective strategy for f-element separation, but the complexity of extractant synthesis hinders large-scale application. Here the authors discuss an alternative strategy induced by in situ self-assembly that borrows principles of multivalent cooperativity from Nature to separate f-elements. [ABSTRACT FROM AUTHOR]

The fundamental problem of point defects under different phase equilibrium conditions in zircon (ZrSiO 4 ) is carried out by first-principles calculation. The formation energies with the structural deformation of various native defects, i.e., single vacancy, interstitial, Frenkel and Schottky pairs at different charge states are calculated, which agree well with the available results. We identify V O 2 + shows an important role in non-stoichiometric regime of ZrSiO 4− x ( x  < 1). When Fermi level ( ε F ) locates close to the CBM, the V Zr 4 − becomes more easily observed than V O 2 + in O-rich environment. In turn, the most abundant interstitial defects are I Zr 4 + and I Si 4 + . The non-interacting Si Frenkel-pair, made of the association of quadruply charged defect in energy of 5.947 eV, is more likely to form than other type of Frenkel-pairs. By formation the complex defects associating partial and full Schottky defects requires higher formation energy. These results provide a good reference to understand storage state as well as disposal of excess weapons-grade Pu and high-actinide wastes. [ABSTRACT FROM AUTHOR]

The low-lying electronic transitions of the neptunyl(NpO22+) ion are characterized as either chargetransfer (CT)or intra- 5f. Comparison of these classes of electronic transitionsreveals significantly different photophysical properties, especiallyin vibronic coupling. An empirical model developed for analyses ofuranyl CT vibronic transitions is used here to simulate the absorption(excitation) spectra of neptunyl in two compounds of different chemicalcompositions and structural symmetries. Analyses reveal that CT vibroniccoupling in neptunyl has the same characteristics as that in typicaluranyl analogues. The primary profile of the CT spectra is similarfor neptunyl respectively with respect to chloride- and oxide-neptuniumbonding interactions. On the other hand, vibronic coupling to theCT transitions is significantly different from that of f-f transitions,even within a given neptunyl compound. Electronic energy levels, vibroniccoupling strength, and frequencies of various vibration modes wereevaluated for transitions to the excited states of different originsin the region from 8000 cm–1to 21000 cm–1for two neptunyl compounds. [ABSTRACT FROM AUTHOR]

A radiochemistry laboratory presents potential radiological hazards due to the handling of multiple radionuclides with various half-lives and modes of radiation emission. To minimize these hazards, appropriate safety management and radiation protection strategies should be in place. The radiochemistry laboratory at Soochow University is one such workplace that handles therapeutic radionuclides, fission products, and actinides in liquid, solid, and gas forms. This work highlights the significance of using safety precautions and radiation protection strategies before conducting experiments in such laboratories. The practical knowledge gained from a case of radioactive contamination is discussed to provide valuable experience for safely conducting radiochemistry experiments. [ABSTRACT FROM AUTHOR]

The Haber–Bosch process produces ammonia (NH3) from dinitrogen (N2) and dihydrogen (H2), but requires high temperature and pressure. Before iron-based catalysts were exploited in the current industrial Haber–Bosch process, uranium-based materials served as effective catalysts for production of NH3 from N2. Although some molecular uranium complexes are known to be capable of combining with N2, further hydrogenation with H2 forming NH3 has not been reported to date. Here, we describe the first example of N2 cleavage and hydrogenation with H2 to NH3 with a molecular uranium complex. The N2 cleavage product contains three uranium centers that are bridged by three imido μ 2-NH ligands and one nitrido μ 3-N ligand. Labeling experiments with 15N demonstrate that the nitrido ligand in the product originates from N2. Reaction of the N2-cleaved complex with H2 or H+ forms NH3 under mild conditions. A synthetic cycle has been established by the reaction of the N2-cleaved complex with trimethylsilyl chloride. The isolation of this trinuclear imido-nitrido product implies that a multi-metallic uranium assembly plays an important role in the activation of N2. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Zr(IV)-based MOF with high-density free carboxylic groups was constructed. • The MOF demonstrates high stability and excellent uranium removal performance. • Dynamic sorption tests highlight its potential for treating radioactive wastewater. • The mechanism for its excellent ability to adsorb U(VI) was investigated. The extraction of uranium from aqueous environments, including the ocean and radioactive wastewater, represents a significant challenge with profound implications for energy resources and environmental remediation. This work presents the design and synthesis of a novel highly stable carboxylated metal–organic framework, BUT-12-3COOH, which achieves excellent U(VI) extraction ability from water. BUT-12-3COOH features high-density free carboxylic groups, exceptional chemical stability, fast kinetics, and high adsorption capacity for U(VI). Dynamic sorption experiments further demonstrated the potential of BUT-12-3COOH in treating real radioactive wastewater. The mechanisms for the U(VI) capture of BUT-12-3COOH are investigated through the combination of EDS, FT-IR, and XPS analysis. The results of this study underscore the promising utility of BUT-12-3COOH as an effective sorbent for extracting radionuclides from environmental specimens and liquid nuclear waste streams. [ABSTRACT FROM AUTHOR]

• New uranyl uptake strategy with combined complexation and photoreduction is shown. • An ultrahigh uranyl uptake capacity not limited by the sorption site is achieved. • Uranyl can be removed completely regardless of its initial concentration. • Uranyl extraction is not affected by the coexisting metal cations. Uranium enrichment is perhaps the most critical chemical process throughout the nuclear fuel cycle including uranium mining, uranium extraction from seawater, used fuel reprocessing and disposal, and environmental contamination remediation. New uranium extraction technology is still highly desirable at current stage, although a variety of extraction methods have been established and developed in the past several decades but all with clear demerits. Herein we present a new uranium extraction strategy with combined ligand complexation and photocatalytic reduction based on postsynthetically functionalized metal-organic frameworks (MOFs). The highly robust and photoactive MOF PCN-222 is modified with phosphono- and amino groups that can capture U(VI) from solution. Upon visible light irradiation, the photo-induced electrons from the MOF host can efficiently reduce U(VI) pre-enriched in MOF, affording neutral uranium species that evacuate the MOF structure and regenerating the active site readily for capturing additional U(VI). This auto-recycled process offers an ultrahigh uranium extraction capacity not limited by the number of adsorption sites and more importantly an extra uranium uptake selectivity over these non-redox-active competing metal cations, and can be utilized for uranium separation over extremely wide uranium concentrations and pH ranges, showing a powerful application potential. [ABSTRACT FROM AUTHOR]

Hematite is an excellent catalyst for solar water splitting but its practical performance is still low. In this work, a hetero phase of β-Fe 2 O 3 was firstly introduced in α-Fe 2 O 3 to optimize the internal structure, which can synergistically work with oxygen vacancy to enhance the charge extraction, facilitate the charge transport, and suppress the electron-hole recombination. As a result, the obtained hematite exhibits a high initial photocurrent of 2.72 mA/cm2 at 1.23 V vs. RHE, and can be well coupled with various further modifications such as P, Hf, and FeNiOOH to achieve an excellent photocurrent of 5.24 mA/cm2 at 1.23 V vs. RHE with a good stability over 100 h. Moreover, it can realize a benchmark solar-to-hydrogen conversion efficiency of 5.3% when connected to a commercial Si solar cell. The low cost, efficient, and stable hematite-based photoanodes may pave the way for practical solar water splitting. [Display omitted] • β-Fe 2 O 3 in hematite has been firstly reported to improve the PEC performance. • Hetero phase and oxygen vacancy can effectively enhance the bulk charge utilization. • It can achieve a high and stable photocurrent of 5.24 mA/cm2 at 1.23 V RHE. • A benchmark solar-to-hydrogen conversion efficiency of 5.3% can be obtained. [ABSTRACT FROM AUTHOR]

Abstract In the present study, the macroscopic sorption behaviors and microscopic immobilization mechanisms of Ni(II) at cryptomelane/water interfaces were explored using the combination of batch sorption technique, desorption procedure, theoretical simulation, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) analyses. The good simulation of the pseudo-second-order model on the sorption kinetics data suggests a driving force of chemical sorption rather than mass transport or physical interaction. The sorption trends and uptake mechanisms are obviously related to the solution pH, with cation exchange or outer-sphere surface complexation at an acidic pH of 4.0, inner-sphere surface complexation in both the edge-shared (ES) and double corner-shared (DCS) modes at a neutral pH of 7.0, and precipitation of α-Ni(OH) 2 (s) phase at a highly alkaline pH of 10.0. The gradual increase of Ni(II) sorption amount with solution temperature rising from 293 K to 333 K is consistent with the increased ratio of the weak DCS configuration. The research findings herein can help us better understand the migration and transformation trends of Ni(II) in the manganese mineral-riched aquatic environment. Graphical abstract Image 1 Highlights • Interaction mechanisms of Ni(II) with cryptomelane were explored by combining multiple techniques. • Relative contributions of different uptake processes were verified from ligand extraction data. • Ni(II) binding modes were clearly identified with theoretical simulation and spectroscopic analyses. • Temperature rising enhanced the sorption amount of Ni(II) in double corner-shared binding mode. • Research findings facilitated the assessment of Ni(II) migration and fate in Mn-riched environment. [ABSTRACT FROM AUTHOR]

In the present work, the titanate nanotubes (TNTs) were synthesized via the hydrothermal approach and the phytic acid decorated TNTs (PA/TNTs) were prepared by using the one-pot method. Batch technique was adopted to explore the removal performance of TNTs and PA/TNTs towards Eu(III) under various environmental conditions. At pH 4.0 and 5.5, the sorption of Eu(III) on TNTs decreased with increasing NaNO 3 concentration, while the removal of Eu(III) by PA/TNTs was independent of ionic strength. The saturated Eu(III) sorption capacities of TNTs and PA/TNTs were calculated to be 9.52 × 10 −4 and 9.57 × 10 −4 mol/g at pH 5.5 and 298 K, being higher than a variety of previously reported adsorbents. PA/TNTs also exhibited high selectivity for capturing Eu(III) from a simulated wastewater containing multiple competing metal ions. According to the Fourier transform infrared spectroscopy (FTIR), solid fluorescence and X-ray photoelectron spectroscopy (XPS) analysis, the predominant removal mechanisms of TNTs and PA/TNTs towards Eu(III) at pH 5.5 were ion exchange/outer-sphere surface complexation and inner-sphere surface complexation, respectively. These experimental findings demonstrated the wide application prospects of TNTs and PA/TNTs for the highly efficient purification of Eu(III)-bearing wastewater. [ABSTRACT FROM AUTHOR]

The present study sheds some light on the long‐standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X‐ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl–amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO22+ and the amidoxime ligand is η2 coordination with tris‐amidoximate species. In such a uranyl–amidoximate complex with η2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single‐crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools. [ABSTRACT FROM AUTHOR]

In this study, the inorganic-organic hybrid of PA/TNTs was synthesized and characterized by using multiple analysis techniques. Batch experiments were conducted to investigate the removal performance of PA/TNTs towards U(VI). The sorption kinetics procedure achieved equilibrium within 6 h. The maximum sorption capacity at 293 K and pH 5.0 was calculated to be 1.16 × 10 −3 mol/g. In addition, the PA/TNTs composite showed a higher sorption selectivity towards U(VI) over many other metal ions. The ionic strength experiments, desorption results, X-ray diffraction (XRD), solid fluorescence, extended X-ray adsorption fine structure (EXAFS) and Fourier transform infrared spectroscopy (FTIR) analysis suggested the predominant sorption mechanism was inner-sphere complexation rather than ion exchange or precipitation. Overall, the synthesized PA/TNTs composite could be utilized as a cost-effective material for the removal of U(VI) from wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-step uranium oxide reduction recovery process has been developed. • The uranium recovered by this process achieved a purity of over 99.9% • The overall recovery rate of uranium reached 98.6%. • Heavy metal concentrations in wastewater meet WHO guidelines by this process. Resource utilization of uranium from the nuclear wastewater is of significance, and the facile strategy to recover high purity uranium oxide directly from wastewater is urgent to develop. Herein, a three-step uranium oxide reduction recovery process (URRP), that is integrated solid–liquid separation (SLS) and electrochemical purification (EP) together with solid-phase uranium re-recovery (SUR), is designed and applied for uranium reduction and purification. The SEM and ICP results were used to determine the carbonate system as the optimal separation system and the Ti electrode as the optimal electrochemical purification electrode. The single electron transfer process of uranyl ions in carbonate was established using cyclic voltammetry. Such three-step recovery process achieves a high-efficient recovery of uranium with a purity of over 99.9% in complex wastewater systems, and an improved return rate of uranium as high as 98.6%. Furthermore, the concentration of metal ions in wastewater is reduced to the standard set by the World Health Organization. Such a URRP offers a very promising solution for the treatment of wastewater and the recovery of high purity uranium. [ABSTRACT FROM AUTHOR]

Uranium (U(VI)) pollution comes from the development and utilization of natural minerals. Based on a new concept of ecological restoration of uranium pollution into natural minerals, a new artificial mineralized process was proposed to immobilize uranium (U(VI)) for wastewater decontamination. In this work, three systems of Mg 3 (PO 4) 2 + UO 2 2+, Mg2+ + PO 4 3− + UO 2 2+ and Mg2+ + PO 4 3− + Mg 3 (PO 4) 2 + UO 2 2+ were designed. Batch experiments and theoretical calculation were conducted to study the U(VI) immobilization effectiveness and artificial mineralization mechanisms. U(VI) removal efficiencies reached up to 96% in the pH value of 5.0 in the three systems. Both precipitation and surface adsorption contributed to favorable U(VI) removal in Mg 3 (PO 4) 2 + UO 2 2+, but resulting in U desorption. Precipitation of Mg2+, PO 4 3− and UO 2 2+ into saleeite (Mg(UO 2) 2 (PO 4) 2 ·10H 2 O) crystal contributed to UO 2 2+ immobilization in the Mg2+ + PO 4 3− + UO 2 2+ and Mg2+ + PO 4 3− + Mg 3 (PO 4) 2 + UO 2 2+ systems, resulting in the negligible U desorption. It is due to the crystallization of the Mg(UO 2) 2 (PO 4) 2 ·10H 2 O through precipitation of Mg2+ and PO 4 3− with UO 2 2+ in acidic medium. PHREEQC and Visual MINTEQ fitting confirmed the favorable precipitation of Mg2+ and PO 4 3− with UO 2 2+ into saleeite in acidic medium. Thus, the U(VI) immobilization effectiveness and artificial mineralization mechanism were understood, providing a promising strategy of artificial induced mineralization of Mg(UO 2) 2 (PO 4) 2 ·10H 2 O for U(VI) decontamination in wastewater. [Display omitted] • Artificially mineralization is proposed for immobilizing uranium. • Formation of Saleéite and chernikovite is the fate of uranium immobilization. • Theorical fitting confirmed the mineralization of dissolved Mg2+ and PO 4 3− with UO 2 2+. • The leaching rate of saleéite and chernikovites is negligible. • P/U and Mg/U molar ratios determined the artificially mineralization process. [ABSTRACT FROM AUTHOR]

Barium cerate doped with tetravalent Th is successfully synthesized by a traditional Pechni method. The BaCe 0.7 Th 0.1 Y 0.2 O 3−δ (BCT71) composites were applied to an anode supported coin single cell consisting of Ni-BCT71 anode/BCT71 electrolyte/ BCT71-La 0.7 Sr 0.3 FeO 3−δ cathode. The assembled cell is tested from 600 °C to 700 °C with humidified hydrogen (∼3% H 2 O) as the fuel and the static air as the oxidant. An open-circuit potential of 0.93 V and a maximum power density of 104 mW cm −2 are obtained for the single cell with an interface resistance of 0.98 Ω cm 2 at 700 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Co LDO could be obtained by calcination of Ni-Co LDH. • The morphology of the Ni-Co LDO can be adjusted by the calcination temperature. • The Ni-Co LDO-500 prefer removing uranium to Ni-Co LDH. • Electrostatic attraction, surface complexation and memory effect contributed to U(VI) recovery. • Ni-Co LDO-500 showed good stability and excellent regeneration ability. The utilization and development of nuclear energy has resulted in the discharge of uranium-containing wastewater. Layer double hydroxides (LDHs) and oxides (LDOs) were reported for efficient extracting U(VI) from wastewater. In this work, nickel–cobalt layered double oxide (Ni-Co LDO-X, X represents the calcination temperature) with excellent electrostatic attraction and complexation was synthesized via calcination of nickel–cobalt layered double hydroxide (Ni-Co LDH) under air atmosphere for extracting U(VI) comparing to Ni-Co LDH. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential analysis were conducted to characterize the Ni-Co LDO-X. Batch adsorption experiments were carried out to investigate the U(VI) extraction properties. The U(VI) adsorption capacity on Ni-Co LDO-500 increased over 3 times compared to that of Ni-Co LDH. The process of uranium removed by Ni-Co LDO-500 conforms to the Langmuir model, the calculated maximum adsorption capacity is 707.91 mg/g. The results suggested that the excellent U(VI) adsorption ability on Ni-Co LDO-500 mainly dominated by the memory effect, electrostatic interaction, and complexation on the outer-sphere surface. Ni-Co LDO-500 has excellent regeneration ability in five adsorption/desorption experiments. The Ni-Co LDO-500 had favorable ability in removing uranium in actual wastewater with the residual concentration being lower than 0.05 mg/L. The above results highlight that the Ni-Co LDO-500 is promising to be used for the decontamination of uranium in actual uranium-containing wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZJU-X6 is a 3-fold interlocking cationic MOF and could capture 99TcO 4. • ZJU-X6 exhibited superior sorption ability and reusability toward 99TcO 4. • PDF and crystal structure clearly elucidated the sorption mechanism. Technetium-99 is one of most problematic radionuclides with a long half-life, high environmental mobility and solubility, which exists mainly in the form of anionic pertechnetate (99TcO 4 -). Searching for sorbents that hold efficient and selective elimination of radioactive 99TcO 4 - from aqueous solution is still a big challenge and further visualizing it in the sorbents is extremely difficult. Herein, we utilized an elongated organic neutral pyridyl ligand linked with Ni2+ to yield a novel 3-fold interlocking cationic metal–organic framework (ZJU-X6). Unexpectedly, the structure of ZJU-X6 held unique displaceable water pairs on the Ni2+ node in comparison to cationic metal–organic framework constructed by Ni2+. Attainable Ni2+ nodes distinctly improved the positive charge density of the framework, affording high sorption capacity, excellent selectivity, and removal depth toward 99TcO 4 -. Pair distribution functions (PDF) were applied to analyze the changes of atom distances in materials before and after capturing ReO 4 -, clearly showing that ReO 4 - entered into the body of ZJU-X6. More detailed sorption mechanism was atomically elucidated by obtaining the single crystal structure of 99TcO 4 --incorporated ZJU-X6. It is found that the water pairs were replaced by 99TcO 4 - and each Ni2+ coordinated with two 99TcO 4 - through oxygen atoms. In addition, each 99TcO 4 - engaged in multiple C–H...O hydrogen bonding with H atoms of aromatic rings that enhanced the trapping of 99TcO 4 -. [ABSTRACT FROM AUTHOR]

Recently, an increasing number of publications concerned on the catalytic oxidation of refractory organic pollutants in wastewater dependent on the iron-based catalysts. Until now, the iron-based catalysts are diversity including Fe2+/Fe3+, ZVI, iron oxides (FeOOH, Fe 2 O 3 , Fe 3 O 4 , FeO), iron sulfides (Fe x S y) and Fe-bimetallic due to various valences and phases. A comprehensive understanding on the synthesis and applications of them as catalysts were little concerned. In this work, the methods for synthesis and control of the size, morphology, crystal phase and chemical valent properties of the iron-based catalysts were reviewed by classifying as Fe2+/Fe3+, ZVI, iron oxides, pyrite, Fe-MOF and Fe-bimetallic. Their applications in Fenton/Fenton-like oxidation, ozonation, wet air oxidation, PMS/PS activation, photocatalytic oxidation etc., for refractory organic pollutants oxidation were summarized. Generation of free radicals for oxidation of refractory organic pollutants in different systems was regarded as the main catalytic mechanisms. Refining controlled growth of size, morphology, crystal phase and chemical valence of iron-based catalysts will be prospective and challenge in synthesis of iron-based catalysts. Co-catalytic reaction will be promising for accelerating the electron transfer for generation of radicals. Quantitative analysis of the free radical is remained the challenge to understand the catalytic oxidation mechanism. We look forward to the fact that this review could inspire the readers to refine the synthesis of iron-based catalysts with special catalytic property for constructing the catalytic oxidation process and to understand the mechanism of degradation of refractory organic pollutants in wastewater. [Display omitted] • Synthesis of iron-based catalysts in various valent were reviewed. • Diversity of iron species resulted in various catalytic oxidation processes. • Electron transfer contributed to the iron induced catalytic oxidation. • Coupling catalytic oxidation with biological is promising for refractory organic pollutants degradation. [ABSTRACT FROM AUTHOR]

With the wide application of nuclear energy and the rapid development of mining, a great quantity of uranium (U(VI)) containing wastewater is inevitably generated. In this work, a facile environmental-friendly coprecipitation method was proposed for the green synthesis of binary layered double hydroxides (Ni–Co LDH W -7), which could be used to efficiently adsorb U(VI) from wastewater. Pseudo-second-order kinetic model and Dubinin-Radushkevich model fitted well with the adsorption of U(VI) on Ni–Co LDH W -7, the maximum adsorption capacity of U(VI) on Ni–Co LDH W -7 was 201.09 mg/g calculated by the Langmuir model. Adsorption equilibrium reached after 30 min, which is a spontaneous and endothermic process. Fourier Transform Infrared Spectrometer (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurements manifested that the favorable U(VI) extraction on Ni–Co LDH W -7 is mainly ascribed to inner-layer surface electrostatic interaction and complexation, which is dominated by abundant oxygen-containing M-OH and interlayer OH− ions. Briefly, this work provides a facial and environmental-friendly Ni–Co LDH W -7 for removing U(VI) in actual uranium-containing wastewater. [Display omitted] • A facile environmental-friendly coprecipitation method was proposed for green synthesis of Ni–Co LDH W -7. • Adsorption capacity of uranium reached 201.09 mg/g calculated by Langmuir model at pH = 6 and 298 K. • Metal hydroxyl group configuration and the hydroxyl groups contributed to U(VI) binding on Ni–Co LDH W -7. • Ni–Co LDH W -7 showed good stability. [ABSTRACT FROM AUTHOR]

A Fe 2 ZrO 5 layer was firstly decorated on hematite with both enhanced photocurrent and lowered onset potential up to 180 mV. • A Fe 2 ZrO 5 layer was firstly decorated on hematite by using Zr-MOFs as precursor. • The layer can finally improve the photocurrent to 2.88 mA cm−2 at 1.23 V vs. RHE. • The layer also leads to a large cathodic shift of the onset potential up to 180 mV. • The layer is a bi-functional material as a passivation layer and the Zr-source for doping. Surface modification on hematite is widely used to improve its photoelectrochemical (PEC) performance for water splitting. Here by using Zr-based metal-organic frameworks as precursor, a thin Fe 2 ZrO 5 layer has been created on hematite surface, which can both significantly improve the photocurrent and reduce the onset potential with a prominent value of 180 mV. Moreover, by coupling with Ti-based modification and Co-Pi cocatalyst, the hematite photoanode decorated with Fe 2 ZrO 5 layer can achieve an excellent photocurrent of 2.88 mA cm−2 at 1.23 V vs. RHE, which is more than 3 times higher than that of the original hematite. To the best of our knowledge, it is the first report for the decoration of Fe 2 ZrO 5 on hematite to improve the water splitting efficiency. The Fe 2 ZrO 5 layer acts as a bi-functional material to enhance the PEC performance, which can form a perfect passivation layer to suppress the charge recombination and provide Zr for Zr-doping in hematite to highly increase the carrier density. [ABSTRACT FROM AUTHOR]

• Composite thin films comprising 2D/2D MOF/rGO heterostructures for photocatalytic CO 2 reduction. • Modulated electronic structure of metal centers unveiled by XPS and XANES. • The activity and selectivity are among the best reported in literature. • The thin-film catalysts are highly stable and extremely easy to recycle. • High activity is well rationalized by the heterostructure configuration and electrostatic charge transfer. In this work, composite thin films comprising the 2D/2D MOF/rGO heterostructures assembled via Coulomb interaction are employed as the cocatalyst for photocatalytic CO 2 reduction for the first time. The electrostatic charge transfer and the strong π-π interaction induced in the heterostructure effectively modulate the electronic structure of the metal centers in the conductive 2D MOF (Ni 3 HITP 2), evidenced by Zeta Potentials, HR-TEM, XPS and XANES. The best thin-film catalyst with an optimal MOF/rGO ratio demonstrates a high CO evolution rate of 3.8 × 104 μmol h−1 g film −1 (0.46 min−1 in TOF) and a good selectivity of 91.74%, synergically contributed by the improved photoelectron harvesting on the rGO scaffold, the efficient charge transportation/transfer within the conductive and intimate 2D heterostructure, the coherent energy flow owing to aligned energy levels, and the enriched electron density at the isolated Ni-N 4 sites boosted by electrostatic charge transfer. [ABSTRACT FROM AUTHOR]

Various types of polyoxometalates (POMs) have been synthesized since the 19th century, but their assortment has been mostly limited to Groups 5 and 6 metals. Herein, a new family of POMs composed of a carbon group element as the addenda atoms with two distinct phases, LnPbOClO4‐1 (Ln = Sm to Ho, Y) and LnPbOClO4‐2 (Ln = Er and Tm) is reported. Both structures are built from [Ln6O8] rare‐earth metal hexamers being incorporated in [Pb18O32]/[Pb12O24] polyplumbites, and unbound perchlorates as charge‐balancing anions. Impressively, YPbOClO4‐1 and ErPbOClO4‐2 exhibit exceptional uptake capacities (434.7 and 427.7 mg g−1) toward ReO4−, a chemical surrogate for the key radioactive fission product in the nuclear fuel cycle 99TcO4−, which are the highest values among all inorganic anion‐exchange materials reported until now. The sorption mechanism is clearly elucidated and visualized by single‐crystal‐to‐single‐crystal structural transformation from ErPbOClO4‐2 to a perrhenate‐containing complex ErPbOReO4, revealing a unique ReO4− uptake selectivity driven by specific interaction within Pb···O‐ReO3− bonds. [ABSTRACT FROM AUTHOR]