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In pursuit of universal access to clean water, photocatalytic water remediation using metal–organic frameworks (MOFs) emerges as a strong alternative to the current wastewater treatment methods. In this study, we explore a unique Ti-based MOF comprised of 2D secondary-building units (SBUs) connected via biphenyl dicarboxylic acid (H2bpdc) ligands – denoted as COK-47 – as a visible-light-driven photocatalyst for organic dye degradation. Synthesized via a recently developed microwave-assisted method, COK-47 exhibits high hydrolytic stability, demonstrates a strong dye uptake, and shows noteworthy dye-degradation performance under UV, visible, and solar light, outperforming benchmark TiO2 and MIL-125-Ti photocatalysts. Due to its nanocrystalline structure and surface termination with organic linkers, COK-47 exhibits selective degradation of cationic pollutants while remaining inert towards anionic dyes, thus highlighting its potential for selective oxidation reactions. Mechanistic studies reveal the involvement of superoxide radicals in the degradation process and emphasize the need to minimize the recombination of photogenerated electron–hole pairs to achieve optimal performance. Post-catalytic studies further confirm the high stability and reusability of COK-47, making it a promising photocatalyst for water purification, organic transformation, and water splitting reactions under visible light. [ABSTRACT FROM AUTHOR]

We report two Ni12 multicubane topologies enclosed in the polyanions [Ni12(OH)9(WO4)3(PO4)(B-α-PW9O34)3]21−{Ni12W30} and [Ni12(OH)9(HPO4)3(PO4)(B-α-PW9O34)(A-α-PW9O34)2]21−{Ni12W27} that magnetically behave as Ni12 units clearly distinguishing them from typical Ni4 cubanes as shown by magnetic studies together with high field and frequency electron paramagnetic resonance (HFEPR). Beyond the unprecedented static properties, {Ni12W30} shows the unusual coexistence of slow relaxation of the magnetization and a diamagnetic ground state (S = 0), providing the unique opportunity of studying the essentially elusive magnetic relaxation behavior in excited states. The cubane-topology dependent activity of {Ni12W30} and {Ni12W27} as homogeneous HER photocatalysts unveils the structural key features significant for the design of photocatalysts with efficient charge utilization exemplified by high quantum yields (QY) of 10.42% and 8.36% for {Ni12W30} and {Ni12W27}, respectively. [ABSTRACT FROM AUTHOR]

Various types of imperfections/defects in metal halide perovskite (MHP) light-absorbing layers and/or at relevant interfaces have indelible effects on perovskite solar cells (PSCs) in terms of performance, stability, and scalability. So far, some effective defect-passivation strategies and agents have successfully been applied to reduce defects in MHPs to improve film quality and device properties for future commercialized long-term stable large-scale PSCs. Characterization methods play an important role in clarifying the mechanistic understanding of defect passivation in MHPs, allowing the development of more efficient passivation strategies. Therefore, new advanced measurements of defect passivation, especially some in situ techniques that are different from conventional characterization tools, were reviewed in this paper aiming to provide useful guidelines for further continuously promoting MHP and PSC research. [ABSTRACT FROM AUTHOR]

The design of active and selective co-catalysts constitutes one of the major challenges in developing heterogeneous photocatalysts for energy conversion applications. This work provides a comprehensive insight into thermally induced bottom-up generation and transformation of a series of promising Cu-based co-catalysts. We demonstrate that the volcano-type HER profile as a function of calcination temperature is independent of the type of the Cu precursor but is affected by changes in oxidation state and location of the copper species. Supported by DFT modeling, our data suggest that low temperature (<200 °C) treatments facilitate electronic communication between the Cu species and TiO2, which allows for a more efficient charge utilization and maximum HER rates. In contrast, higher temperatures (>200 °C) do not affect the Cu oxidation state, but induce a gradual, temperature-dependent surface-to-bulk diffusion of Cu, which results in interstitial, tetra-coordinated Cu+ species. The disappearance of Cu from the surface and the introduction of new defect states is associated with a drop in HER performance. This work examines electronic and structural effects that are in control of the photocatalytic activity and can be transferred to other systems for further advancing photocatalysis. [ABSTRACT FROM AUTHOR]

B2O3 doped (0.5–15 mol%) ordered mesoporous bioactive glasses (MBG) with the composition 80% SiO2–15% CaO–5% P2O5 were synthesized via a sol–gel based evaporation-induced self-assembly process using the block-copolymer P123 as a structure directing agent and characterized by biokinetic, mechanical and structural investigations. Nitrogen physisorption isotherms and electron microscopy indicate no detrimental effect of B2O3 on the ordered hexagonal pore structure. Boron incorporation increases both the bulk modulus and hardness of the glasses. In vitro bioactivity tests reveal a rapid initial release of Ca2+ and PO43− ions, followed by formation of hydroxyapatite carbonate within a few hours. Contrary to the tight incorporation of Al in Al-doped MBGs, the rapid release of borate species into simulated-body-fluid suggests loosely bound species localized at the internal surfaces of the mesopores. 29Si, 11B, 31P, and 1H solid state NMR spectroscopy reveal that the majority of the borate is present as anionic BO4/2− species. The need for charge compensation leads to an increase in the average degree of polymerization of the phosphate species for high boron contents. 11B{31P} rotational echo double resonance NMR results reveal the absence of B–O–P linkages. This structural model explains the rapid release of borate and the enhanced dissolution kinetics of the Ca2+ and phosphate species. [ABSTRACT FROM AUTHOR]

Here we report a systematic study of a series of non-noble-metal co-catalysts based on Co, Mn, Ni and Fe oxides that were prepared by wet impregnation of the corresponding acetylacetonate precursors onto a model TiO2 substrate, followed by their oxidative decomposition. We analyze thermal evolution of the impregnated M(acac)x–TiO2 composites with a combination of analytical methods and reveal strong differences in the precursor decomposition onsets and the resulting product composition, compared to the case of pure M(acac)x precursors. Consequent electron microscopy analyses of the resulting MOx–TiO2 composites indicate the presence of small (1–5 nm) amorphous MOx nanoparticles that are homogeneously distributed on the surface of the substrate TiO2. Complementing Raman and photoluminescence (PL) spectra confirm pronounced effects of MOx deposition on the state of TiO2 substrate and suggest strong electronic communication between the components. The composites obtained at 350 °C were further tested towards sacrificial hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) demonstrating the dynamic nature of the NiOx–TiO2 photocatalyst whose Ni0 active HER sites were generated in situ upon light exposure. In contrast, FeOx–TiO2, CoOx–TiO2, and NiOx–TiO2 were all active towards OER, featuring water oxidation ability in descending order, while XPS data of the samples after reaction indicate that partial oxidation of M species takes place during the course of the photocatalytic experiment. This work provides detailed insights on the wet chemistry-based preparation of MOx co-catalysts decorating oxide nanopowders including optimization of the thermal treatment, potential substrate effects and synergy as well as further prospects in photocatalysis. [ABSTRACT FROM AUTHOR]

Hierarchical hollow microspheres (HHMSs) constitute a very popular class of materials for use as drug-delivery carriers, photocatalysts and electrode materials in batteries, owing to their large, porous surface area and mechanical integrity during intercalation reactions. Here, we used a template- and additive-free hydrothermal route to prepare an unusually shaped SnO2 material that comprises a hollow spherical morphology with uniform diameters and very thin petal-like nano-sheets grown perpendicularly on the sphere's surface, resembling a “chestnut cupule”. We thoroughly investigated the formation mechanism by 119Sn Mössbauer spectroscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy. Key to this process is the ultrasonic pre-treatment of an aqueous SnCl2 solution, followed by Ostwald “inside-out” ripening upon hydrothermal processing. This unique morphology has greatly improved the storage capacity and cycling performance of SnO2 as an anode material for lithium and sodium ion batteries compared with conventional SnO2 materials. [ABSTRACT FROM AUTHOR]

We present a material and device based study on the fabrication of mesoporous TiO2and its integration into dye-sensitized solar cells. Poly(isoprene-block-ethyleneoxide) (PI-b-PEO) copolymers were used as structure directing agents for the sol–gel based synthesis of nanoporous monolithic TiO2which was subsequently ground down to small particles and processed into a paste. The TiO2synthesis and the formation of tens of micrometre thick films from the paste is a scalable approach for the manufacture of dye sensitised solar cells (DSCs). In this study, we followed the self-assembly of the material through the various processing stages of DSC manufacture. Since this approach enables high annealing temperatures while maintaining porosity, excellent crystallinity was achieved. Internal TiO2structures ranging from the nanometre to micrometre scale combine a high internal surface area with the strong scattering of light, which results in high light absorption and an excellent full-sun power conversion efficiency of up to 6.4% in a robust, 3 μm thick dye-sensitized solar cell. [ABSTRACT FROM AUTHOR]

Correction for 'Elucidating the formation and active state of Cu co-catalysts for photocatalytic hydrogen evolution' by Jasmin S. Schubert et al., J. Mater. Chem. A, 2021, DOI: 10.1039/d1ta05561e. [ABSTRACT FROM AUTHOR]

Single-crystalline sillenite-type bismuth titanate nanowires with photocatalytic properties have been synthesized viaa simple solution-phase synthesis route. [ABSTRACT FROM AUTHOR]

We report two Ni 12 multicubane topologies enclosed in the polyanions [Ni 12 (OH) 9 (WO 4 ) 3 (PO 4 )(B-α-PW 9 O 34 ) 3 ] 21- {Ni 12 W 30 } and [Ni 12 (OH) 9 (HPO 4 ) 3 (PO 4 )(B-α-PW 9 O 34 )(A-α-PW 9 O 34 ) 2 ] 21- {Ni 12 W 27 } that magnetically behave as Ni 12 units clearly distinguishing them from typical Ni 4 cubanes as shown by magnetic studies together with high field and frequency electron paramagnetic resonance (HFEPR). Beyond the unprecedented static properties, {Ni 12 W 30 } shows the unusual coexistence of slow relaxation of the magnetization and a diamagnetic ground state ( S = 0), providing the unique opportunity of studying the essentially elusive magnetic relaxation behavior in excited states. The cubane-topology dependent activity of {Ni 12 W 30 } and {Ni 12 W 27 } as homogeneous HER photocatalysts unveils the structural key features significant for the design of photocatalysts with efficient charge utilization exemplified by high quantum yields (QY) of 10.42% and 8.36% for {Ni 12 W 30 } and {Ni 12 W 27 }, respectively., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Nanocrystalline silicon nanoparticles with a median crystallite size of 3-4 nm and several crystalline phases and defects ( e.g. twin boundary) were produced by femtosecond laser processing of a SiO 2 /Si target in various organic fluids. Furthermore, a nanoscaled amorphous oxide layer and a few atomic layers of a graphite shell were detected in ethanol and 2-butanol correspondingly. The ultrafast laser pulses may manipulate nanostructures at the atomic level and generate a high density of defects; this may be correlated with significant thermal stresses on nanoparticles and rapid condensation of primary nanoparticles with high cooling rates. Size distribution width and a polydispersity index slightly increased with increasing laser fluence in ethanol. In 2-butanol, the maximum ablation volume was observed. The specific ablation rates in 2-butanol and ethanol were approximately five times higher than n -hexane. The lowest ablation efficiency in n -hexane can be associated with femtosecond laser-induced photolysis and pyrolysis of solvent molecules, as total energy deposition on the material may be reduced due to the formation of carbonaceous products. The roughened zones (average roughness of ∼400 nm) in circumferences of the ablated craters in 2-butanol may be related to a correlation between the erosive power of the vapour bubble collapse and higher pressure at the bubble wall in relatively high dynamic viscosity fluids. Furthermore, sputtering of a pristine surface by releasing nanoparticles from the collective collapse of up-flow vapour bubbles can also contribute to the generation of roughened regions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We used polyisoprene-block-ethyleneoxide copolymers as structure-directing agents to synthesise well-ordered and highly-crystalline mesoporous WO(3) architectures that possess improved photocatalytic properties due to enhanced dye-adsorption in absence of diffusion limitation.

Single-crystalline sillenite-type bismuth titanate nanowires with photocatalytic properties have been synthesized via a simple solution-phase synthesis route.

Zirconia doped with low-valent cations (e.g. Y3+ or Ca2+) exhibits an exceptionally high ionic conductivity, making them ideal candidates for various electrochemical applications including solid oxide fuel cells (SOFC) and oxygen sensors. It is nevertheless important to study the undoped, monoclinic ZrO2 as a model system to construct a comprehensive picture of the electrical behaviour. In pure zirconia a residual number of anion vacancies remains because of contaminants in the material as well as the thermodynamic disorder equilibrium, but electronic conduction may also contribute to the observed conductivity. Reduction of zirconia in hydrogen leads to the adsorption of hydrogen and to the formation of oxygen vacancies, with their concentration affected by various parameters (e.g. reduction temperature and time, surface area, and water vapour pressure). However, there is still little known about the reactivities of defect species and their effect on the ionic and electronic conduction. Thus, we applied electrochemical impedance spectroscopy to investigate the electric performance of pure monoclinic zirconia with different surface areas in both oxidizing and reducing atmospheres. A novel equivalent circuit model including parallel ionic and electronic conduction has previously been developed for titania and is used herein to decouple the conduction processes. The concentration of defects and their formation energies were measured using volumetric oxygen titration and temperature programmed oxidation/desorption.

We present a novel method to produce pure rutile nanotubes using a sacrificial carbon nanotube template.