An ideal porous adsorbent toward uranium with not only large adsorption capacity and high selectivity but also broad applicability even under rigorous conditions is highly desirable but still extremely scarce. In this work, a porous adsorbent, namely [NH 4 ] + [COF‐SO 3 − ], prepared by ammoniating a SO 3 H‐decorated covalent organic framework (COF) enables remarkable performance for uranium extraction. Relative to the pristine SO 3 H‐decorated COF (COF‐SO 3 H) with uranium adsorption capacity of 360 mg g −1 , the ammoniated counterpart of [NH 4 ] + [COF‐SO 3 − ] affords ultrahigh uranium uptake up to 851 mg g −1 , creating a 2.4‐fold enhancement. Such a value is the highest among all reported porous adsorbents for uranium. Most importantly, a large distribution coefficient, K d U , up to 9.8 × 10 6 mL g −1 is observed, implying extremely strong affinity toward uranium. Consequently, [NH 4 ] + [COF‐SO 3 − ] affords highly selective adsorption of uranium over a broad range of metal ions such as S U/Cs = 821, S U/Na = 277, and S U/Sr = 124, making it as effective uranium adsorbent from seawater, resulting in amazing uranium adsorption capacity of 17.8 mg g −1 . Moreover, its excellent chemostability also make it an effective uranium adsorbent even under rigorous conditions (pH = 1, 8, and 3 m acidity).

Manganese could be the element of choice for cathode materials used in large-scale energy storage systems owning to its abundance and low toxicity levels. However, both lithium and sodium ion batteries adopting this electrode chemistry suffer from rapid performance fading, suggesting a major technical barrier that must be overcome. Here we report a P3-type layered manganese oxide cathode Na 0.6 Li 0.2 Mn 0.8 O 2 (NLMO) that delivers a high capacity of 240 mAh g −1 with outstanding cycling stability in a lithium half-cell. Combined experimental and theoretical characterizations reveal a characteristic topological feature that enables the good electrochemical performance. Specifically, the -α-γ-layer stacking provides topological protection for lattice oxygen redox, whereas the reversibility is absent in P2-structured NLMO which takes a -α-β-configuration. The identified new order parameter opens an avenue towards the rational design of reversible Mn-rich cathode materials for sustainable batteries. / 32Sustainable energy applications in today's society, especially transportation and grid, require safe high-energy density lithium (Li) and sodium (Na) ion batteries with low-cost and/or abundant natural resources 1, 2 . Compared to cobalt (Co) and nickel (Ni) as the major component of commercial cathode materials, redox active manganese is the element of choice for cathode materials used in large-scale energy storage systems owning to its abundance and low toxicity levels 3 . In particular, Li/Na-rich Mn-based cathodes exhibit the excellent capacity and high potential (> 4 V vs. Li + /Li or Na + /Na), resulting from the extra lattice oxygen redox (LOR) [4][5][6][7] . However, the poor cycling stability of LOR-related processes, including voltage hysteresis and voltage fade, hampers its practical use because of the irreversible local structural transformation or the lattice oxygen loss [8][9][10] . The stability and/or reversibility of LOR is correlated significantly with the atomic structure or the local oxygen coordination environment, as elaborated by various theories, including the oxygen lone-pair states [11][12][13] , reductive coupling mechanism [14][15][16][17] , O−O dimer 18,19 , ligand-to-metal charge transfer (LMCT) 13 , and critical oxygen hole 20 theories, as well as a number of other theories [21][22][23][24][25][26] . Thus, exploring crystal structures compatible with reversible LOR in Mn-rich oxides is desirable to meet the demand for sustainable energy storage.At present, the correlation between the specific atomic structures with reversible LOR in the electrode materials has not been well established. Kang et al. 27 found that transition metal (TM) layer stacking can control the voltage decay of LOR process by comparing O2-and O3-type Li x (Li 0.2 Ni 0.2 Mn 0.6 )O 2 . Li-excess disordered (rock salt) TM oxides, such as

No abstract

No abstract

Doping elements in hematite nanostructures is a promising approach to improve the photoelectrochemical (PEC) water-splitting performance of hematite photoanodes. However, uniform doping with precise control on doping amount and morphology is the major challenge for quantitatively investigating the PEC water-splitting enhancement. Here, we report on the design and synthesis of uniform titanium (Ti)-doped hematite nanorods with precise control of the Ti amount and morphology for highly effective PEC water splitting using an atomic layer deposition assisted solid-state diffusion method. We found that Ti doping promoted band bending and increased the carrier density as well as the surface state. Remarkably, these uniformly doped hematite nanorods exhibited high PEC performance with a pronounced photocurrent density of 2.28 mA/cm(2) at 1.23 V vs reversible hydrogen electrode (RHE) and 4.18 mA/cm(2) at 1.70 V vs RHE, respectively. Furthermore, as-prepared Ti-doping hematite nanorods performed excellent repeatability and durability; over 80% of the as-fabricated photoanodes reproduced the steady photocurrent density of 1.9-2.2 mA/cm(2) at 1.23 V vs RHE at least 3 h in a strong alkaline electrolyte solution.

No abstract

No abstract

No abstract