Vitamin D receptor gene polymorphisms, bioavailable 25-hydroxyvitamin D, and hepatocellular carcinoma survival.

BACKGROUND: Little is known about the role of vitamin D receptor polymorphisms and their interaction with vitamin D status in hepatocellular carcinoma (HCC) prognosis. METHODS: We evaluated the association of TaqI, BsmI, Cdx-2, and ApaI polymorphisms, individually and in combination, with liver cancer-specific (LCSS) and overall survival (OS) among 967 patients with newly diagnosed HCC. Subsequently, we examined whether these polymorphisms modified the association between serum bioavailable 25-hydroxyvitamin D (25OHD) concentrations and survival. Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: During a median follow-up of 1017 days, 393 deaths occurred, with 360 attributed to HCC. Having TaqI G allele (HRper allele = 1.30, 95% CI = 1.08 to 1.57) or BsmI T allele (HRper allele = 1.41, 95% CI = 1.01 to 1.99) was associated with worse LCSS. Carrying increasing numbers of protective alleles was associated with superior LCSS (HR6-8 vs 0-3 = 0.52, 95% CI = 0.34 to 0.80). The inverse association of bioavailable 25OHD with LCSS was only significant in patients with TaqI AA (HRQuartile 4 vs Quartile 1 = 0.63, 95% CI = 0.44 to 0.92), BsmI CC (HRQuartile 4 vs Quartile 1 = 0.62, 95% CI = 0.44 to 0.88), and 6 to 8 protective alleles (HRQuartile 4 vs Quartile 1 = 0.45, 95% CI = 0.23 to 0.87). Similar associations were observed for OS. CONCLUSIONS: Patients carrying wild-type TaqI, BsmI, or more protective alleles had improved survival and might benefit from optimizing bioavailable 25OHD status.

Reticular chemistry guided precise construction of zirconium-pentacarboxylate frameworks with 5-connected Zr6 clusters.

Zirconium-based metal-organic frameworks (Zr-MOFs) have been extensively studied due to their very rich structural chemistry. The combination of nearly unlimited carboxylic acid-based linkers and Zr6 clusters with multiple connectivities has led to diverse structures and specific properties of resultant Zr-MOFs. Herein, we demonstrate the successful use of reticular chemistry to construct two novel Zr-MOFs, HIAM-4040 and HIAM-4040-OH, with zfu topology. Based on a thorough structural analysis of (4,4)-connected lvt-type Zr-tetracarboxylate frameworks and a judicious linker design, we have obtained the first example of a Zr-pentacarboxylate framework featuring unprecedented 5-connected organic linkers and 5-connected Zr6 clusters. Compared with HIAM-4040, a larger Stokes shift is achieved in HIAM-4040-OH via hydroxyl group induced excited-state intramolecular proton transfer (ESIPT). HIAM-4040-OH exhibits high chemical and thermal stability and is used for HClO detection in aqueous solution with excellent sensitivity and selectivity.

Porphyrin conjugated polymer/Pt-loaded graphite carbon nitride nanocomposites for efficient charge separation and broadband responsive H2evolution.

An efficient broadband responsive two-dimensional (2D) heterometallic Zn-/Co-porphyrin conjugated polymer (ZnCoP-F CP) with its Co-porphyrin bridging unit bearing two perfluorophenyls is coupled with 2.0 wt% Pt-loaded graphite carbon nitride (PCN) to fabricate a novel 2D/2D nanocomposite (ZnCoP-F/PCN). The resultant ZnCoP-F/PCN composite with an optimal mass ratio exhibits broadband (UV-vis-NIR) responsive H2evolution reaction (HER) activity up to 432µmol h-1, 5.2 and 2.8 times higher than that of the ZnCoP-F CP (83µmol h-1) and PCN (151µmol h-1) alone, respectively. Furthermore, the ZnCoP-F/PCN displays excellent apparent quantum yields (AQY) of 18.2%, 18.3%, 17.6%, 16.5%, 13.9%, 8.7%, 5.1%, 4.3%, 1.9%, 0.95% and 0.62% at 350, 380, 420, 450, 500, 550, 600, 700, 785, 850 and 950 nm, which are also higher than that of ZnCoP-F CP illuminated at the respective monochromatic light. The enhanced broadband responsive HER performance of ZnCoP-F/PCN can be attributed to the easily assembled ZnCoP-F CP and PCN nanosheets through strongπ-πstacking interaction, which can facilitate the fast charge transfer from ZnCoP-F CP to PCN for HER. This work opens a new pathway to fabricate porphyrin polymer-based nanocomposite for more efficiently converting solar radiation and water into H2.

Hydrogen-Bond Regulation of the Microenvironment of Ni(II)-Porphyrin Bifunctional Electrocatalysts for Efficient Overall Water Splitting.

Accurately regulating the microenvironment around active sites is an important approach for boosting the overall water splitting performance of bifunctional electrocatalysts, which can drive both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in the same electrolyte. Herein, pseudo-pyridine-substituted Ni(II)-porphyrins (o-NiTPyP, m-NiTPyP, and p-NiTPyP) with pseudo-pyridine N-atoms located at the ortho-, meta-, or para-position are prepared and used as model catalysts for alkaline water splitting. Experimental and theoretical results reveal that the pseudo-pyridine N-atom positions can regulate the microenvironment around the active sites and the adsorption free energy of H-donating substances by affecting the H-bonding interaction and the NNiN bond angles of active sites, and thus those pseudo-pyridine-substituted Ni(II)-porphyrins deliver better electrocatalytic activity than the Ni(II)-tetraphenylporphyrin (NiTPP) without pseudo-pyridine N-atoms. Among them, m-NiTPyP on carbon nanotubes delivers the lowest overpotentials of 267 and 138 mV at 10 mA cm-2 for the OER and HER, respectively. Specifically, m-NiTPyP as bifunctional electrocatalyst in an alkaline electrolyzer requires only 1.62 V to drive efficient overall water splitting at 10 mA cm-2 while remaining durable. This work proposes a new H-bond-regulating approach of the microenvironment of electrocatalysts for effectively boosting the overall water splitting activity and deeply understanding its related mechanism.

Structural Regulation of Coupled Phthalocyanine-Porphyrin Covalent Organic Frameworks to Highly Active and Selective Electrocatalytic CO2 Reduction.

Covalent organic frameworks (COFs) have been applied as potential electrocatalysts for CO2 reduction reaction (CO2 RR) due to their adjustable architecture and porous feature. Herein, tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine cobalt(II) (CoTAPc) are used as nodes to couple with 5,15-di(4-aminophenyl)-10,20-diphenylporphyrin (DAPor) or 5,15,10,20-tetrayl(4-aminophenyl)porphyrin (TAPor) via imidization reaction to fabricate novel coupled phthalocyanine-porphyrin Type 1:2 (CoPc-2H2 Por) or Type 1:1 (CoPc-H2 Por) COFs. Electrocatalytic CO2 RR experiments show that both Type 1:2 and Type 1:1 COFs exhibit the maximum Faraday efficiency over 90% with high stability, while the Type 1:2 COF (CoPc-2H2 Por) delivers lower overpotential, higher current density, and CO selectivity than Type 1:1 COF (CoPc-H2 Por) and CoPc monomer. Theoretical and experimental results reveal that the better CO2 RR activity of CoPc-2H2 Por than CoPc-H2 Por can be attributed to its larger pore size and conjugate structure, which then cause more efficient electron transfer, adsorption/activation of CO2 , faster mass transfer, and reaction kinetics. This work provides a new idea in the structural design of COF-based electrocatalyst for efficient CO2 RR.

Brookite TiO2 Nanoparticles Decorated with Ag/MnOx Dual Cocatalysts for Remarkably Boosted Photocatalytic Performance of the CO2 Reduction Reaction.

The solar-driven CO2 reduction reaction (CO2RR) for producing chemical fuels is considered to be a promising approach to dealing with the growing energy crisis and greenhouse effect. Herein, novel Ag/MnOx dual-cocatalyst-decorated brookite titania (BT) nanoparticles with remarkably boosted photocatalytic CO2RR performance are prepared through a facile photodeposition method. The resultant xAg-BT-yMn composite with optimal cocatalyst content delivers amazing CO/CH4 yields of 31.70/129.98 µmol g-1 with an overall photoactivity of 1103.28 µmol g-1 h-1, 11.98 times higher than that of the BT nanoparticles alone. Further investigations demonstrate that the dual cocatalysts decorating the BT nanoparticles not only effectively retard the photoinduced charge recombination but also significantly vary the surface chemical feature to promote the adsorption/activation of the reactants (CO2/H2O). In addition, the Ag nanoparticles can broaden the spectral response region, while the MnOx cocatalyst can promote the CH4 product selectivity and the water oxidation reaction. The synergistic effect of Ag/MnOx dual cocatalysts on the BT nanoparticles renders a remarkably boosted CO2RR performance, which provides a simple yet general synthesis strategy for brookite titania-based photocatalysts with high-performance solar-driven CO2 conversion.

Electron-Rich Pincer Ligand-Coupled Cobalt Porphyrin Polymer with Single-Atom Sites for Efficient (Photo)Electrocatalytic CO2 Reduction at Ultralow Overpotential.

Porphyrin and phthalocyanine complexes bearing single-atom catalytic sites (M-N4 ) have been explored as promising electrocatalysts for CO2 reduction reaction (CO2 RR), whose activity can be improved by regulating the ligands and/or the metal centers. Moreover, their photosensitive features also provide the possibility for highly efficient photoelectrocatalytic CO2 RR. Herein, a novel N'NN'-pincer-ligand (N3 )-coupled cobalt porphyrin (CoPor-N3 ) polymer is developed for realizing efficient (photo)electrocatalytic CO2 RR. The unraveled electronic structure and (photo)electrocatalytic features suggest that a synergistic effect between the electron-rich N3 ligands and the Co-N4 single-atom sites in the CoPor-N3 polymer results in the Co centers attaining more electrons, which is beneficial to facilitating the electron transfer to CO2 for the activation and reduction processes. As expected, the resultant CoPor-N3 polymer delivers a good long-term durability and high CO faradaic efficiency (96%) at an ultralow overpotential (0.39 V), which outperforms the CoPor alone and most porphyrin-/phthalocyanine-based electrocatalysts reported so far. Moreover, the photosensitivity of CoPor units can further reduce the overpotential to 0.34 V with a CO faradaic efficiency over 90% under light illumination. The present findings offer a new approach to constructing porphyrin-based photosensitive electrocatalysts with high-efficiency photoelectrocatalytic CO2 RR.

Filling metal-organic framework mesopores with TiO2 for CO2 photoreduction.

Metal-organic frameworks (MOFs)1-3 are known for their specific interactions with gas molecules4,5; this, combined with their rich and ordered porosity, makes them promising candidates for the photocatalytic conversion of gas molecules to useful products6. However, attempts to use MOFs or MOF-based composites for CO2 photoreduction6-13 usually result in far lower CO2 conversion efficiency than that obtained from state-of-the-art solid-state or molecular catalysts14-18, even when facilitated by sacrificial reagents. Here we create 'molecular compartments' inside MOF crystals by growing TiO2 inside different pores of a chromium terephthalate-based MOF (MIL-101) and its derivatives. This allows for synergy between the light-absorbing/electron-generating TiO2 units and the catalytic metal clusters in the backbones of MOFs, and therefore facilitates photocatalytic CO2 reduction, concurrent with production of O2. An apparent quantum efficiency for CO2 photoreduction of 11.3 per cent at a wavelength of 350 nanometres is observed in a composite that consists of 42 per cent TiO2 in a MIL-101 derivative, namely, 42%-TiO2-in-MIL-101-Cr-NO2. TiO2 units in one type of compartment in this composite are estimated to be 44 times more active than those in the other type, underlining the role of precise positioning of TiO2 in this system.

Direct Z-Scheme 2D/2D Photocatalyst Based on Ultrathin g-C3N4 and WO3 Nanosheets for Efficient Visible-Light-Driven H2 Generation.

Ultrathin two-dimensional (2D) nanomaterials can not only boost the interfacial charge migration and separation but also provide abundant reactive sites for the photocatalytic H2 generation. Herein, a kind of direct Z-scheme 2D/2D hybrid nanomaterial is fabricated by post-annealing atomically ultrathin Pt-loaded g-C3N4 nanosheets (Pt-CN NSs) with a thickness of ∼4.0 nm and hydrogen-treated WO3 nanosheets (HWO NSs) with a thickness of ∼2.6 nm. The strong affinity existing between the two types of nanosheets with few-layer stacking results in the formation of atomically ultrathin 2D/2D hybrid nanomaterials (Pt-CN/HWO) with intimate interfacial contact in which the strong electronic interaction and efficient charge separation lead to a direct Z-scheme electron flowing from HWO NSs to CN NSs and then to the Pt cocatalyst for catalyzing the H2 generation reaction. After optimizing the component ratio, the corresponding Pt-CN/HWO hybrid nanomaterial delivers a significantly boosted photocatalytic H2 generation activity, up to 6.2 times as high as that of the Pt-CN/WO composite containing Pt-CN NSs and WO3 nanoplates (WO NPs) without hydrogen treatment. This result reveals that the atomically ultrathin nanosheets in the 2D/2D hybrid nanomaterials can not only deliver strong electronic interaction to promote the Z-scheme mechanism for maintaining the high reduction ability of g-C3N4 and high oxidation ability of WO3 but also alleviate the charge recombination, therefore resulting in the excellent photocatalytic H2 generation performance.

Porous hypercrosslinked polymer-TiO2-graphene composite photocatalysts for visible-light-driven CO2 conversion.

Significant efforts have been devoted to develop efficient visible-light-driven photocatalysts for the conversion of CO2 to chemical fuels. The photocatalytic efficiency for this transformation largely depends on CO2 adsorption and diffusion. However, the CO2 adsorption on the surface of photocatalysts is generally low due to their low specific surface area and the lack of matched pores. Here we report a well-defined porous hypercrosslinked polymer-TiO2-graphene composite structure with relatively high surface area i.e., 988 m2 g-1 and CO2 uptake capacity i.e., 12.87 wt%. This composite shows high photocatalytic performance especially for CH4 production, i.e., 27.62 µmol g-1 h-1, under mild reaction conditions without the use of sacrificial reagents or precious metal co-catalysts. The enhanced CO2 reactivity can be ascribed to their improved CO2 adsorption and diffusion, visible-light absorption, and photo-generated charge separation efficiency. This strategy provides new insights into the combination of microporous organic polymers with photocatalysts for solar-to-fuel conversion.

Improved photovoltaic performance of perovskite solar cells based on three-dimensional rutile TiO2 nanodendrite array film.

In order to explore high performance and stable perovskite solar cells (PSCs), the design and optimization of electron transport layer (ETL) have been paid more and more attention. Vertically oriented, one-dimensional (1D) TiO2 nanostructured array films are considered superior ETLs because of their rapid electron transporting property and open pore architectures. In this study, a three-dimensional (3D) rutile TiO2 nanodendrite array (RTNDA) film containing 1D trunks and branches was fabricated through second hydrothermal treatment of 1D rutile TiO2 nanorod array (RTNRA) film hydrothermally grown on a fluorine tin oxide (FTO) conductive glass. The resulting 3D-RTNDA film not only facilitates close contact with mixed-ion perovskite (Cs0.05(FA0.83MA0.17)0.95Pb(I0.9Br0.1)3) film, but also promotes the formation of a perovskite layer with larger crystal grain sizes. Both can efficiently retard the interface charge recombination, and thus result in a significantly improved power conversion efficiency (PCE) of 18.0%, improved by 20% as compared to that (15.0%) of the device fabricated with the 1D-RTNRA film. Spectroscopic, electrochemical and photoelectrochemical measurements indicate that the improved photovolatic performance can be mainly ascribed to the largely suppressed hysteresis effect, the increased open-circuit voltage and fill factor stemming from the more effective hole blocking and electron transport. The results presented here demonstrate that 3D-RTNDA film with 3D rutile TiO2 hierarchical nanoarchitecture is a promising ETL selection in designing high-performance PSCs.

Drastically enhanced visible light-driven H2 evolution by anchoring TiO2 nanoparticles on molecularly grafted carbon nitride nanosheets via a multiple modification strategy.

The development of graphitic carbon nitride (CN) based photocatalysts towards efficient visible light-driven H2 evolution is highly desired for solar energy conversion. It is well-known that bulk CN materials possess three intrinsic problems, namely, high charge recombination loss, low specific surface area, and limited sunlight harvesting range. To simultaneously overcome the abovementioned drawbacks of CN, we report an innovative multiple modification strategy, involving molecular grafting of the CN network, exfoliation to ultrathin nanosheets, and hybridization with TiO2 photocatalysts. The visible light utilization ability, specific surface area, and charge separation efficiency of the CN materials improved accordingly. As expected, the TiO2/CNX-NS heterojunction photocatalyst exhibited remarkably enhanced visible light-driven H2 production rate of 138.4 µmol h-1, which was about 4.6 times higher than that of pristine CN. The excellent photocatalytic performance under visible light confirmed the successful improvement in the corresponding drawbacks of CN by each modification. In this study, we propose the possibility of combining multiple modifications in the same system to synthesize an excellent visible light-driven photocatalyst for solar-to-fuel conversion.

Highly Efficient Photocatalytic Hydrogen Evolution by ReS2 via a Two-Electron Catalytic Reaction.

Highly efficient photocatalytic hydrogen evolution (PHE) is highly desirable for addressing the global energy crisis and environmental problems. Although much attention has been given to electron-hole separation, ridding photocatalysts of poor efficiency remains challenging. Here, a two-electron catalytic reaction is developed by utilizing the distinct trion behavior of ReS2 and the efficient reduction of two H+ (2H+ + 2e- → H2 ) is realized. Due to the monolayer-like structure of the catalyst, the free electrons in ReS2 can be captured by the tightly bound excitons to form trions consisting of two electrons and one hole. These trions can migrate to the surface and participate in the two-electron reaction at the abundant active sites. As expected, such a two-electron catalytic reaction endows ReS2 with a PHE rate of 13 mmol g-1 h-1 under visible light irradiation. Meanwhile, this reaction allows the typically poor PHE efficiency of pure transition metal dichalcogenides to be overcome. The proposed two-electron catalytic reaction provides a new approach to the design of photocatalysts for PHE.

Growth of a sea urchin-like rutile TiO2 hierarchical microsphere film on Ti foil for a quasi-solid-state dye-sensitized solar cell.

A sea urchin-like rutile TiO2 microsphere (RMS) film was fabricated on Ti foil via a hydrothermal process. The resulting rutile TiO2 hierarchical microspheres with a diameter of 5-6 µm are composed of nanorods with a diameter of ∼200 nm and a length of 1-2 µm. The sea urchin-like hierarchical structure leads to the Ti foil-based RMS film possessing much better light-scattering capability in the visible region than the bare Ti foil. By using it as an underlayer of a nanosized anatase TiO2 film (bTPP3) derived from a commercially available paste (TPP3), the corresponding bilayer Ti foil-based quasi-solid-state dye-sensitized solar cell (DSSC) only gives a conversion efficiency of 4.05%, much lower than the single bTPP3 film-based one on Ti foil (5.97%). By spin-coating a diluted TPP3 paste (sTPP3) on the RMS film prior to scraping the bTPP3 film, the resulting RMS/sTPP3/bTPP3 film-based DSSC achieves a significantly enhanced efficiency (7.27%). The electrochemical impedance spectra (EIS) show that the RMS/sTPP3/bTPP3 film possesses better electron transport capability and longer electron lifetime than the bTPP3 film. This work not only provides the first example of directly growing rutile TiO2 hierarchically structured microsphere film on Ti foil suitable for replacing the rigid, heavy and expensive transparent conductive oxide (TCO) glass substrate to serve as a light-scattering underlayer of Ti foil-based quasi-solid-state DSSCs, but also paves a new route to develop Ti foil-based flexible DSSCs with high efficiency, low cost and a wide application field through optimizing the composition and structure of the photoanode.

Oxidant-free synthesis of benzimidazoles from alcohols and aromatic diamines catalysed by new Ru(ii)-PNS(O) pincer complexes.

Benzimidazoles are chemically and pharmaceutically important, and an environmentally benign synthetic method based on acceptorless dehydrogenative condensation of primary alcohols and benzene-1,2-diamine is developed in this work. Three Ru(ii) hydride complexes [RuHCl(CO)(PNS(O))] (containing two isomers 1a and 1b) and [RuHCl(CO)(PPh3)(SNCNHC)]PF6 (2) based on two new quinoline-based ligands 2-(diphenylphosphanylmethyl)-8-phenylsulfinylquinoline (PNS(O)) and 1-mesityl-3-(8-phenylthioquinolyl-2-methyl)-2-imidazole carbene (SNCNHC) are prepared and fully characterized. These complexes catalyse the condensation of benzyl alcohol and benzene-1,2-diamine to 2-phenylbenzimidazole with the liberation of H2, and the catalytic activity follows the order: 1a ≈ 1b > 2. When 0.2 mol% of 1a and 2 mol% of NaBPh4 were used, various 2-functionalized benzimidazoles were obtained in good yields (70-85%) and high turnover numbers (TONs ∼ 425). This homogeneous system does not need oxidants or stoichiometric strong bases (KOH or KOtBu, etc.) that are normally used in the reported homogeneous systems, and thus is a greener process.

One-Pot Synthesis of Cu-Nanocluster-Decorated Brookite TiO2 Quasi-Nanocubes for Enhanced Activity and Selectivity of CO2 Photoreduction to CH4.

A new kind of metallic Cu-loaded brookite TiO2 composite, in which Cu nanoclusters with a small size of 1-3 nm are decorated on brookite TiO2 quasi nanocube (BTN) surfaces (hereafter referred to as Cu-BTN), is synthesized via a one-pot hydrothermal process and then used as photocatalyst for CO2 reduction. It was found that the decoration of Cu nanoclusters on BTN surfaces can improve the activity and selectivity of CO2 photoreduction to CH4 , and 1.5 % Cu-BTN gives a maximum overall photocatalytic activity (150.9 µmol g-1 h-1 ) for CO/CH4 production, which is ≈11.4 and ≈3.3 times higher than those of pristine BTN (13.2 µmol g-1 h-1 ) and Ag-BTN (45.2 µmol g-1 h-1 ). Moreover, the resultant Cu-BTN products can promote the selective generation of CH4 as compared to CO due to the number of surface oxygen vacancies and the CO2 /H2 O adsorption behavior, which differs from that of the pristine BTN. The present results demonstrate that brookite TiO2 would be a potential effective photocatalyst for CO2 photoreduction, and that Cu nanoclusters can act as an inexpensive and efficient co-catalyst alternative to the commonly used noble metals to improve the photoactivity and selectivity for CO2 reduction to CH4 .

Syntheses of asymmetric zinc porphyrins bearing different pseudo-pyridine substituents and their photosensitization for visible-light-driven H2 production activity.

A series of asymmetric zinc porphyrin (ZnPy) derivatives bearing different external substituents were synthesized and used to sensitize Pt-loaded graphitic carbon nitride (Pt/g-C3N4) for photocatalytic H2 production. Among them, ZnPy-1 has one benzoic acid and three phenyls as peripheral substituents, while ZnPy-2, ZnPy-3, and ZnPy-4 contain one benzoic acid and three pseudo-pyridines with different N-atom positions. The experimental results indicate that the pseudo-pyridine substitution for the phenyls in ZnPy-1 lead to enhanced photosensitization with an order of ZnPy-1 < ZnPy-2 < ZnPy-3 < ZnPy-4 under visible light (λ > 420 nm) irradiation. ZnPy-4-sensitized Pt/g-C3N4 (ZnPy-4-Pt/g-C3N4) exhibits the best average H2 production activity of 524 µmol h-1 with an extremely high turnover number (TON) of 11 089 h-1, which is much higher than that (328 µmol h-1) of ZnPy-2-Pt/g-C3N4 with a TON of 6942 h-1. Also, ZnPy-4-Pt/g-C3N4 shows a much higher apparent quantum yield (AQY) of 32.3% than that (11.5%) of ZnPy-2-Pt/g-C3N4 under 420 nm monochromatic light irradiation. The different N-atom positions in the pseudo-pyridines result in different interactions of the ZnPy dyes with a sacrificial reagent, which then strongly influences the photoactivity for H2 production. The present results demonstrate the molecular engineering aspect of ZnPy dyes in which fine-tuning of molecular structures is crucial for improving the photocatalytic H2 production activity of dye-sensitized semiconductors.

Preparation of Single-Crystalline AgIn5S8 Octahedrons with Exposed {111} Facets and Its Visible-Light-Responsive Photocatalytic H2 Production Activity.

Although AgIn5S8 as one kind of ternary chalcogenides has been extensively investigated due to its band-edge positions meeting the thermodynamic requirement for water photosplitting, very little attention has been focused on the crystallinity and facet effects of AgIn5S8 on its photocatalytic activity. Herein, a facile hydrothermal route was developed to fabricate regular single-crystalline AgIn5S8 octahedrons with only {111} facets exposed. Also, the effects of the hydrothermal reaction conditions on the composition, crystal phase, crystallinity, and morphology of the obtained AgxInyS(x+3y/2) products (hereafter denoted as AIS-x, where x represents the pH value of the reaction solution) were investigated, and it was found that the accurately released S2- ions from the thermal decomposition of thioacetamide (TAA) is the central factor for the nucleation and growth of the AgIn5S8 octahedrons. The experimental results indicate that the resultant regular AgIn5S8 octahedrons (AIS-10.6) exhibit the best photocatalytic activity for H2 production among those AgxInyS(x+3y/2) products, and the higher crystallinity and fewer defects of the AgIn5S8 octahedrons compared to the other AgxInyS(x+3y/2) products can retard the photogenerated charge recombination, while those indium atoms with higher density in the exposed {111} facets might be beneficial for the photocatalytic H2 production reaction by acting as active sites to promote the charge separation and transfer processes. The results presented here provide new insights into the significance of crystallinity and exposed facets in the visible-light-responsive activity of AgIn5S8, thus paving new ways into the design and synthesis of high-performance, cost-effective AgIn5S8 photocatalysts for H2 production.

Preparation of brookite TiO2 nanoparticles with small sizes and the improved photovoltaic performance of brookite-based dye-sensitized solar cells.

Brookite TiO2 nanoparticles with small sizes (hereafter denoted as BTP particles) were synthesized through the hydrothermal treatment of TiCl4 solution with Pb(NO3)2 as an additive. The obtained BTP particles have a large specific surface area (∼122.2 m2 g-1) and relatively uniform particle sizes (∼10 nm) with the coexistence of a small quantity of nanorods with a length of ∼100 nm. When used as a photoanode material for dye-sensitized solar cells (DSSCs), the BTP particles show a much higher dye-loading content than the brookite TiO2 quasi nanocubes (denoted as BTN particles) with a mean size of ∼50 nm and a specific surface area of ∼34.2 m2 g-1 that were prepared through a similar hydrothermal process but without the addition of Pb(NO3)2. The fabricated BTP film-based solar cell with an optimized film thickness gives a conversion efficiency up to 6.36% with a 74% improvement when compared to the BTN film-based one (3.65%) under AM 1.5G one sun irradiation, while the corresponding bilayer brookite-based solar cell by using brookite TiO2 submicrometer particles as an overlayer of the BTP film displays a significantly enhanced efficiency of 7.64%. Both of them exceed the current record (5.97%) for the conversion efficiency of pure brookite-based DSSCs reported in the literature. The present results not only demonstrate a really simple synthesis of brookite TiO2 nanoparticles with both high phase purity and a large surface area, but also offer an efficient approach to improve the photovoltaic performance of brookite-based solar cells by offsetting brookite's inherent shortages such as lower dye-loading and poor conductivity as compared to anatase.