Syntheses and Crystal Structures of Two New Bismuth Hydroxyl Borates Containing [Bi2O2]2+ Layers: Bi2O2[B3O5(OH)] and Bi2O2[BO2(OH)]

Efficient Proton Conductor Based on Bismuth Oxide Clusters and Polyoxometalates

Developing new solid-state electrolyte materials for improving the proton conductivity remains an important challenge. Herein, a novel two-dimensional layered solid-state proton conductor Bi2O2-SiW12 nanocomposite, based on silicotungstic acid (H4SiW12O40) and Bi(NO3)3·5H2O, was synthesized and characterized. The composite consists of a layered cation framework [Bi2O2]2+ and interlayer-embedded counteranionic [SiW12O40]4-, which forms continuous hydrogen bond (O-H···O) networks through the interaction of adjacent oxygen atoms on the surface of the [Bi2O2]2+ and oxygen atoms of the H4SiW12O40. Facile proton transfer along these pathways endows the Bi2O2-SiW12 (30:1) nanocomposite with an excellent proton conductivity of 3.61 mS cm-1 at 90 °C and 95% relative humidity, indicating that the nanocomposite has good prospects as a highly efficient proton conductor.

A Comprehensive Review on Graphitic Carbon Nitride for Carbon Dioxide Photoreduction

Inspired by natural photosynthesis, harnessing the wide range of natural solar energy and utilizing appropriate semiconductor-based catalysts to convert carbon dioxide into beneficial energy species, for example, CO, CH₄ , HCOOH, and CH₃ COH have been shown to be a sustainable and more environmentally friendly approach. Graphitic carbon nitride (g-C₃ N₄ ) has been regarded as a highly effective photocatalyst for the CO₂ reduction reaction, owing to its cost-effectiveness, high thermal and chemical stability, visible light absorption capability, and low toxicity. However, weaker electrical conductivity, fast recombination rate, smaller visible light absorption window, and reduced surface area make this catalytic material unsuitable for commercial photocatalytic applications. Therefore, certain procedures, including elemental doping, structural modulation, functional group adjustment of g-C₃ N₄ , the addition of metal complex motif, and others, may be used to improve its photocatalytic activity towards effective CO₂ reduction. This review has investigated the scientific community's perspectives on synthetic pathways and material optimization approaches used to increase the selectivity and efficiency of the g-C₃ N₄ -based hybrid structures, as well as their benefits and drawbacks on photocatalytic CO₂ reduction. Finally, the review concludes a comparative discussion and presents a promising picture of the future scope of the improvements.

Efficient NO removal and photocatalysis mechanism over Bi-metal@Bi2O2[BO2(OH)] with oxygen vacancies

Photocatalysis technology prevails as a feasible option for air pollution control, in which high-efficiency charge separation and effective pollutant activation are the crucial issues. Here, this work designed Bi-metal@ Bi₂O₂[BO₂(OH)] with oxygen vacancies (OVs) catalyst for photocatalytic oxidation of NO under visible light, to shed light on the above two processes. Experimental characterizations and density functional theory (DFT) calculations reveal that a unique electron transfer covalent loop（[Bi₂O₂]²⁺ → Bi-metal → O^2-）can be formed during the reaction to guide the directional transfer of carriers, significantly improving the charge separation efficiency and the yield of active oxygen species. Simultaneously, the defect levels served by OVs also play a part. During the NO purification process, in-situ DRIFTS assisted with DFT calculations reveal that Bi metals could be functioned as electron donors to activate NO molecules and form NO^-, a key intermediate. This induces a new reaction path of NO → NO^- → NO₃^- to achieve the harmless conversion of NO, effectively restraining the generation of noxious intermediates (NO₂, N₂O₄). It is expected that this study would inspire the design of more artful photocatalysts for effective charge transfer and safe pollutants purification.

Recent advances in g-C3N4 composites within four types of heterojunctions for photocatalytic CO2 reduction

Studies of photocatalytic conversion of CO₂ into hydrocarbon fuels, as a promising solution to alleviate global warming and energy issues, are booming in recent years. Researchers have focused their interest in developing g-C₃N₄ composite photocatalysts with intriguing features of robust light harvesting ability, excellent catalysis, and stable performance. Four types of heterojunctions (type-II, Z-scheme, S-scheme and Schottky) of the g-C₃N₄ composites are widely adopted. This review aims at presenting and comparing the photocatalytic mechanisms, characteristics, and performances of g-C₃N₄ composites concerning these four types of heterojunctions. Besides, perspectives and undergoing efforts for further development of g-C₃N₄ composite photocatalysts are discussed. This review would be helpful for researchers to gain a comprehensive understanding of the progress and future development trends of g-C₃N₄ composite heterojunctions for photocatalytic CO₂ reduction.

The first bismuth borate oxyiodide, Bi4BO7I: commensurate or incommensurate?

The first bismuth borate oxyiodide, Bi₄BO₇I, has been prepared by solid-state reaction in evacuated silica ampoules. Its crystal structure [space group Immm(00γ)000] comprises litharge-related layers of edge-sharing OBi₄ tetrahedra; the interlayer space is filled by I^- and [BO₃]^3- anions. The wavevector, q = 0.242 (3)c*, is very close to the rational value of c*/4, yet refinement based on commensurate modulation faces serious problems indicating the incommensurate nature of the modulation. The I-/[BO₃]^3- anions are ordered in a complex sequence along [001], i.e. -<-BO₃-BO₃-I-I->_n = 28-I-I-I-<-BO₃-BO₃-I-I->_{n = 28}-BO₃-BO₃-BO₃-, leading to a structural modulation. The principal feature of the latter is the presence of -I-I-I- and -BO₃-BO₃-BO₃- sequences that cannot be accounted for in the a × b × 4c supercell. The thermal expansion of Bi₄BO₇I is weakly anisotropic (α_a = 8, α_b = 15 and α_c = 17 × 10^-6 K^-1 at 500 K) which is caused by preferential orientation of the borate groups.

NH4B11O16(OH)2: a new ammonium borate with wavy-shaped polycyclic 2∞[B11O16(OH)2] layers

The ammonium borate NH₄B₁₁O₁₆(OH)₂ has been successfully synthesized by a mild hydrothermal method.

New fluoroborate Cd8B5O15F with two different isolated borate anions prepared by an open high-temperature solution method

The first cadmium fluoroborate Cd₈B₅O₁₅F containing two different isolated anions BO₃and B(O/F)₄was prepared by the open high-temperature solution method.

An efficient visible-light photocatalyst made from a nonpolar layered semiconductor by grafting electron-withdrawing organic molecules to its surface

The UV-light responsive Bi₂O₂(HCOO)₂ (BFM) becomes an efficient visible-light photocatalyst when it is chemically modified with 4-substituted electron-withdrawing thiophenolates ⁻S-C₆H₄Z.

A new two-dimensional extended adenine and thiophenecarboxylate mixed-ligand zinc(II) complex: synthesis, structure, thermostability and luminescent properties

The design and preparation of crystalline polymeric materials has attracted increasing attention due to their diverse applications as functional materials in gas storage, separation, catalysis, sensing and photoluminescence. The judicious selection of organic linkers is critical for varying the coordination behaviour of the metal ions and determining the overall characteristics of the networks. A new adenine-based Zn(II) coordination polymer, [Zn(C6H2O4S)(C5H5N5)]n or [Zn(tdc)(9H-ade)] (H2tdc is thiophene-2,5-dicarboxylic acid and ade is adenine), has been prepared hydrothermally and the crystal structure exhibits in its packing two-dimensional (4,4) grid sheets parallel to the ab plane, featuring two distinct square cavities delimited by the two types of ligands and the Zn(II) ions with the dimensions 6.6 × 6.6 and 10.2 × 10.2 Å (based on the Zn...Zn distance). The title complex shows enhanced photoluminescence at 378 nm compared to the free ligands, suggesting that the coordination of H2tdc or adenine to the metal centre effectively increases the rigidity of the ligands and reduces the energy loss by radiative decay of intraligand excited states.

Pb6Ba2(BO3)5X (X = Cl, Br): new borate halides with strong predicted optical anisotropies derived from Pb2+and (BO3)3−

Two new compounds, Pb₆Ba₂(BO₃)₅X (X = Cl, Br), were successfully synthesized by solid-state reactions. First-principles calculations show that they have large birefringence of 0.1582 and 0.1810 at 532 nm.

Ca3Be6B5O16F: the first alkaline-earth beryllium borate with fluorine anions

The first all-alkaline-earth beryllium borate with fluorine anions, Ca₃Be₆B₅O₁₆F, was synthesized by a spontaneous crystallization flux method using LiF–B₂O₃as the flux.

Layered photocatalyst Bi2O2[BO2(OH)] nanosheets with internal polar field enhanced photocatalytic activity

Layered photocatalyst Bi₂O₂[BO₂(OH)] nanosheets efficiently separated photogenerated carriers due to the internal polar electric field, which enhances the photocatalytic activity.