In Situ Generation of Copper Species Nanocrystals in TiO₂ Electrospun Nanofibers: A Multi-hetero-junction Photocatalyst for Highly Efficient Water Reduction

Engineering the multi-hetero-junctions in semiconductor photocatalysts has been recognized as a promising way to achieve highly efficient photocatalytic solar-fuel generation, because the photoinduced heterointerfacial charge transfer can greatly hinder the recombination process of charge-carrier in photocatalysts. In this work, we fabricated copper species nanocrystals/TiO₂ multi-hetero-junction photocatalysts through in situ reduction of CuO nanocrystals in CuO/TiO₂ electrospun nanofibers by a hydrothermal method assisted by glucose. By changing the concentration of glucose, the composition ratio of copper species nanocrystals, including CuO, Cu₂O, and Cu, can be adjusted in multi-hetero-junction nanofibers. Upon simulated sunlight irradiation, the optimal copper species nanocrystals/TiO₂ multi-hetero-junction nanofibers exhibited an H₂ evolution rate of ∼10.04 μmol h^–1, a 17.3 times increase over that of bare TiO₂ nanofibers (∼0.57 μmol h^–1)

Au/Pt Nanoparticle-Decorated TiO₂ Nanofibers with Plasmon-Enhanced Photocatalytic Activities for Solar-to-Fuel Conversion

We present the fabrication of TiO₂ nanofibers codecorated with Au and Pt nanoparticles through facile electrospinning. The Au and Pt nanoparticles with sizes of 5–12 nm are well-dispersed in the TiO₂ nanofibers as evidenced by electron microscopic analyses. The present design of Au/Pt codecoration in the TiO₂ nanofibers leads to remarkably enhanced photocatalytic activities on both hydrogen generation and CO₂ reduction. This great enhancement is attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au nanoparticles, which significantly improves charge separation of photoexcited TiO₂. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities of semiconductors initiated by UV-light to more effectively utilize the whole solar spectrum for energy conversion

Thermally Induced Reversible Double Phase Transitions in an Organic–Inorganic Hybrid Iodoplumbate C₄H₁₂NPbI₃ with Symmetry Breaking

A one-dimensional (1D) organic–inorganic hybrid iodoplumbate crystal (<b>1</b>, C₄H₁₂NPbI₃, TMAPbI₃) can undergo two reversible phase transitions as the temperature decreases. Its dynamic phase-transition behaviors were carefully studied by dielectric measurements, thermal analysis, and variable-temperature crystallographic studies. These results indicate that the phase transitions possess a disorder–order feature with a noncentrosymmetrical intermediate phase structure. Due to the existence of the ordered motion and reorientation of the C₄H₁₂N⁺ cation, <b>1</b> undergoes two phase transitions: the first one from space group <i>P</i>6₃/<i>m</i> at room temperature to <i>Pm</i> at 163 K with symmetry breaking, and the second one from space group <i>Pm</i> at 163 K to <i>P</i>6₁ at 142 K with partial symmetry restoration. Our results indicate that there is an existence of a transitional structure with a low symmetry space group during the disorder–order-type phase transitions, which can provide us valuable information to deeply understand the disorder–order phase transition in organic–inorganic hybrids

Thermally Induced Reversible Double Phase Transitions in an Organic–Inorganic Hybrid Iodoplumbate C₄H₁₂NPbI₃ with Symmetry Breaking

A one-dimensional (1D) organic–inorganic hybrid iodoplumbate crystal (<b>1</b>, C₄H₁₂NPbI₃, TMAPbI₃) can undergo two reversible phase transitions as the temperature decreases. Its dynamic phase-transition behaviors were carefully studied by dielectric measurements, thermal analysis, and variable-temperature crystallographic studies. These results indicate that the phase transitions possess a disorder–order feature with a noncentrosymmetrical intermediate phase structure. Due to the existence of the ordered motion and reorientation of the C₄H₁₂N⁺ cation, <b>1</b> undergoes two phase transitions: the first one from space group <i>P</i>6₃/<i>m</i> at room temperature to <i>Pm</i> at 163 K with symmetry breaking, and the second one from space group <i>Pm</i> at 163 K to <i>P</i>6₁ at 142 K with partial symmetry restoration. Our results indicate that there is an existence of a transitional structure with a low symmetry space group during the disorder–order-type phase transitions, which can provide us valuable information to deeply understand the disorder–order phase transition in organic–inorganic hybrids

Thermally Induced Reversible Double Phase Transitions in an Organic–Inorganic Hybrid Iodoplumbate C₄H₁₂NPbI₃ with Symmetry Breaking

A one-dimensional (1D) organic–inorganic hybrid iodoplumbate crystal (<b>1</b>, C₄H₁₂NPbI₃, TMAPbI₃) can undergo two reversible phase transitions as the temperature decreases. Its dynamic phase-transition behaviors were carefully studied by dielectric measurements, thermal analysis, and variable-temperature crystallographic studies. These results indicate that the phase transitions possess a disorder–order feature with a noncentrosymmetrical intermediate phase structure. Due to the existence of the ordered motion and reorientation of the C₄H₁₂N⁺ cation, <b>1</b> undergoes two phase transitions: the first one from space group <i>P</i>6₃/<i>m</i> at room temperature to <i>Pm</i> at 163 K with symmetry breaking, and the second one from space group <i>Pm</i> at 163 K to <i>P</i>6₁ at 142 K with partial symmetry restoration. Our results indicate that there is an existence of a transitional structure with a low symmetry space group during the disorder–order-type phase transitions, which can provide us valuable information to deeply understand the disorder–order phase transition in organic–inorganic hybrids

Au@TiO₂–CdS Ternary Nanostructures for Efficient Visible-Light-Driven Hydrogen Generation

We report a new type of Au@TiO₂–CdS ternary nanostructure by decorating CdS nanoparticles onto Au@TiO₂ core–shell structures. In comparison to that of binary structures such as CdS–TiO₂ and Au@TiO₂, these ternary nanostructures exhibit a remarkably high photocatalytic H₂-generation rate under visible-light irradiation. The enhanced photocatalytic activity is attributed to the unique ternary design, which builds up a transfer path for the photoexcited electrons of CdS to the core Au particles via the TiO₂ nanocrystal bridge and thus effectively suppresses the electron-hole recombination on the CdS photocatalyst. This internal electron-transfer pathway (CdS → TiO₂→ Au) eliminates the need for the postdeposition of the metal cocatalyst because the core Au nanoparticles can act as the interior active catalyst for proton reduction toward hydrogen evolution. We believe that our work demonstrates a promising way for the rational design of metal–semiconductor hybrid photocatalysts that can achieve a high photocatalytic efficiency for use in solar fuels production

Specific activities of WT and point mutants of DndA measured using in vitro cysteine desulfurase activity assay.

<p>Assays were performed for five times, and the average values of specific activities along with standard deviations of the measurements were shown.</p

Crystal structure of DndA from <i>Streptomyces lividans</i>.

<p>(<b>A</b>) <b>Overall structure of the DndA dimer.</b> The structure is viewed perpendicular to the two-fold axis of the dimer. The two protomers are shown in magenta and green, respectively. Their bound PLP cofactors are presented as sticks, with carbon atoms yellow, nitrogen atoms blue, oxygen atoms red, and phosphorus atoms orange. (<b>B</b>) <b>Structure of a protomer of DndA.</b> α helices are shown in cyan, β sheets are shown in magenta, and loops are shown in pink. PLP and its covalently linked Lys200 of DndA, as well as the catalytic Cys327 (mutated to serine in our study), are shown in stick representation.</p

The binding site of PLP on DndA.

<p>(<b>A</b>) <b>PLP is located in a deep surface pocket on DndA.</b> The two protomers of DndA are shown in surface representation, with only one PLP shown in stick representation. The protomer of DndA harboring this PLP is colored in light grey, whereas the other protomer is colored in dark grey. Blue, red, yellow, and orange represent nitrogen, oxygen, carbon, and phosphorus atoms, respectively. (<b>B</b>) <b>The interaction interface between PLP and DndA.</b> DndA is shown in grey, with carbon atoms of its side chains and PLP shown in green. Blue, red, and orange represent nitrogen, oxygen, and phosphorus atoms, respectively. Hydrogen bonds are represented by magenta dashed lines. The orange circle indicates the presumable location of the carboxylate group of the L-cysteine substrate.</p

Structural comparison of DndA with related cysteine desulfurases/selenocysteine lyase.

<p>(<b>A</b>) Structural superimposition of DndA (red), IscS (green, PDB code 1P3W), NifS (cyan, PDB code 1ECX), CsdB (magenta, PDB code 1C0N), and SufS (blue, PDB code 1T3I). Their bound PLP's are shown as sticks. (<b>B</b>) In DndA, the active site Cys327 is located on a β strand, and its distance from PLP is ∼16 Å. In IscS (<b>C</b>) and NifS (<b>D</b>), the active site cysteines are located on relatively long loops, and are not visible in the crystal structure. Visible residues closest to the catalytic cysteines on the primary sequence are no less than 9 Å from PLP. In CsdB (<b>E</b>) and SufS (<b>F</b>), the active site cysteines are located on relatively short loops, and are ∼7 Å from PLP.</p