In-situ deposition of Ag3PO4 on TiO2 nanosheets dominated by (001) facets for enhanced photocatalytic activities and recyclability

Ag₃PO₄/TiO₂ nanosheet (TNS) heterojunction photocatalysts with almost 100% exposed (001) facets were fabricated via a facile in situ growth process. The Ag₃PO₄/TNS exhibited remarkable photocatalytic activity for the degradation of rhodamine B (RhB) and it was significantly more recyclable under sunlight compared with Ag₃PO₄. The RhB degradation efficiency was 99.11% after 50 min of sunlight irradiation, and was 85.8% after three cycles. The photocatalytic degradation mechanism of RhB over the Ag₃PO₄/TNS heterojunctions is driven by both photogenerated holes (h⁺) and ·O₂⁻ radicals. This efficient and reusable Ag₃PO₄/TNS heterojunction photocatalyst is not only suitable for fundamental research but also has potential for practical applications in the energy and environmental fields. This study demonstrates that applying morphology engineering to heterojunctions is useful for developing composite photocatalysts with greatly improved properties.     

Construction of g-C3N4 nanotube/Ag3PO4 S-scheme heterojunction for enhanced photocatalytic oxygen generation

Heterojunction engineering is considered as a hopeful approach to ameliorate the separation of photogenerated carriers of photocatalysts, realizing efficient water-splitting performance. In this study, an organic-inorganic S-scheme of a one-dimensional g-C₃N₄ nanotube (TCN)/Ag₃PO₄ photocatalytic system with high photocatalytic water oxidation activity was designed by coupling g-C₃N₄ nanotubes over Ag₃PO₄ particles through a chemical coprecipitation method. The TCN/Ag₃PO₄ heterojunction demonstrated excellent photocatalytic O₂ production with an O₂ evolution rate of up to 370.2 μmol·L^?1·h^?1. X-ray photoelectron spectroscopy analysis showed that electron migration between TCN and Ag₃PO₄ led to the formation of an internal electric field pointing from TCN to Ag₃PO₄, which drove the S-scheme charge transfer mode between TCN and Ag₃PO₄. Accordingly, the TCN/Ag₃PO₄ heterojunction possessed fast charge separation and high redox ability, leading to high photoactivity and photostability. This research provides a new strategy for fabricating highly efficient inorganic-organic S-scheme photocatalysts for O₂ production.     

Synthesis,characterizations, and crystal structure of a novel 2D metal phosphonate: Na2[Cd2(H2O)3(O3PCH(OH)CO2)2] · 2H2O

A novel cadmium phosphonate compound Na₂[Cd₂(H₂O)₃(O₃PCH(OH)CO₂)₂] · 2H₂O (1) has been synthesized by hydrothermal reaction at 120 °C and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, elemental analysis and thermogravimetric analysis. The structure of compound 1 comprises CdO₆ octahedra and CdO₇ pentagonal bipyramid connected by [O₃PCH(OH)CO₂]³⁻ to form a 2D layered structure with a one-dimensional channel system and the charge-compensating Na⁺ cations being located between two adjacent layers.     

Synthesis,crystal structure,characterization and magnetic property of a new organophosphonate-based polyoxovanadate

A novel organophosphonate-based polyoxovanadate, Cs_1·5Na_3.5[H{V₃(H₂O)O₃}{O₃PC- (OH)(CH₃)PO₃}₃]·15H₂O (1) has been synthesized and further investigated by single-crystal X-ray diffraction analysis, IR spectrum, UV–vis spectroscopy, X-ray powder diffraction, thermogravimetric analysis and X-ray photoelectron spectroscopy. Single-crystal X-ray analysis reveals that compound 1 crystallizes in the triclinic space group P-1 with a = 9.506(3) Å, b = 15.150(5) Å, c = 17.915(6) Å, V = 2437.9(14) ų and Z = 2. Compound 1 exhibits a ring-shaped cluster with three branches of the 1-hydroxyethane 1, 1-diphosphonic acid [HEDP = H₂O₃P(OH)C(CH₃)PO₃H₂] ligands. Furthermore, the magnetic property of compound 1 has also been studied.     

Precipitation-induced healing of Nb2O5

Precipitation-induced stimulated-healing of Nb₂O₅ was carried out through the extrinsic addition of silver oxide nanoscale elemental inclusions to form ternary oxides at the crack site. Nb₂O₅ cylindrical pellets, 13 mm in diameter and 10 mm in length, were produced from powders using a cold isostatic press. The pellets were subsequently sintered at 1100 °C. A scratch was created in the sintered Nb₂O₅ pellets and was subsequently filled with Ag₂O. The pellets were annealed to stimulate the self-healing process. X-ray diffraction was used to explore the evolution of phases, chemical compositions, and structural properties of the sintered samples before and after the stimulated-healing process. Energy dispersive X-ray spectroscopy revealed the elemental composition in the healed region. The on-site composition of the healed sample was determined by Raman spectroscopy and was compared to the spectrum outside of the scratch. Raman spectroscopy confirmed that precipitation proceeded via the following chemical reaction which was facilitated at elevated temperature: Nb₂O₅ + Ag₂O → 2AgNbO₃. In addition, a 3D reconstructed stylus profilometry image of the crack region confirmed that healing occurred. Healing by recovering 89% of the original material strength was confirmed using the three-point bend test.     

Enhanced photodegradation activity of Rhodamine B by MgFe2O4/Ag3VO4 under visible light irradiation

MgFe₂O₄/Ag₃VO₄ composite photocatalysts were synthesized by a milling–calcining method. The results of Rhodamine B (RhB) photodegradation showed that the MgFe₂O₄/Ag₃VO₄ composite exhibited enhanced photodegradation activity under visible-light irradiation. The 0.2 wt.% MgFe₂O₄/Ag₃VO₄ calcined at 573 K exhibited the optimal photocatalytic behavior. Its maximum degradation rate was 5.4 times higher than that of Ag₃VO₄. Moreover, transient photocurrent-time was also investigated. Based on the results of the characterizations, the mechanism of enhanced photocatalytic activity is discussed.     

A novel polyoxometalate-based metal-organic compound constructed from an unprecedented [Ag8(Hpyttz)4(H2pyttz)2] cluster and an in-situ [VW12O40]3 − anion

A novel polyoxometalate (POM)-based metal-organic compound constructed from a multinuclear Ag^I cluster and Keggin-type [VW₁₂O₄₀]^3 − anion, [Ag₄(Hpyttz)₂(H₂pyttz)][HVW₁₂O₄₀]·3H₂O (1) (H₂pyttz = 5′-(pyridin-4-yl)-1H,2′H-3,3′-bi(1,2,4-triazole), was hydrothermally synthesized and characterized by IR spectroscopy, TG analysis, powder and single-crystal X-ray diffraction. In compound 1, [VW₁₂O₄₀]^3 − (VW₁₂) was in-situ transformed from [SiW₁₂O₄₀]^4 − anion. Eight Ag^I ions were connected by six Hpyttz/H₂pyttz ligands with three coordination modes forming an unprecedented [Ag₈(Hpyttz)₄(H₂pyttz)₂] cluster, which connected with six VW₁₂ anions to construct a 2-D double-layer (3,6)-connected network with {4³}₂{4⁶.6⁶.8³} topology. Moreover, the photocatalytic activity of 1 has been investigated.     

Ag3PO4 quantum dot sensitized BiPO4: A novel p–n junction Ag3PO4/BiPO4 with enhanced visible-light photocatalytic activity

Ag₃PO₄ quantum dot sensitized BiPO₄, a novel p–n junction Ag₃PO₄/BiPO₄ photocatalyst, was prepared by co-precipitation hydrothermal method and characterized by XRD, XPS, SEM, TEM, HRTEM, EDS and DRS. Ag₃PO₄/BiPO₄ exhibited much higher photocatalytic activity than Ag₃PO₄ and BiPO₄ for the degradation of methyl orange under visible light (λ > 420 nm). The enhanced photocatalytic activity of Ag₃PO₄/BiPO₄ could be mainly ascribed to the strong visible-light absorption originating from the quantum dot sensitization of Ag₃PO₄ and high efficient separation of photogenerated electron–hole pairs through Ag₃PO₄/BiPO₄ heterojunction. Moreover, O₂⁻ and OH were the main reactive species.     

Facile modified synthesis and intermediate temperature electrical properties of Sn0.95Al0.05P2O7/KSn2(PO4)3 composite electrolyte

In this study, Sn_0.95Al_0.05P₂O₇ and a novel dense Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ composite electrolytes were synthesized. The structural characterization of X–ray diffraction (XRD) and microstructual properties of scanning electron microscopy (SEM) were carried out. The XRD results indicated that an in-situ reaction between Sn_0.95Al_0.05P₂O₇ and inorganic melt salt take place to form the Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ composite. The intermediate temperature electrical properties were determined by using impedance spectroscopy, oxygen concentration cell and hydrogen concentration discharge cell. Finally, the H₂/O₂ fuel cell using the Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ as electrolyte membrane was constructed and the obtained maximum power output densities were 67.7 mW cm^?2 and 142.1 mW cm^?2 at 650 °C and 700 °C, respectively.     

Synthesis,structure of a coordination polymer: {Na2[Zn(C2O4)1.5H2PO4] · 2H2O}n

A phosphatooxalate compound {Na₂[Zn(C₂O₄)_1.5H₂PO₄] · 2H₂O}_n 1 was synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetric analysis (TGA) and fluorescent spectroscopy. X-ray single-crystal analysis revealed that its structure was a new mixed inorganic–organic ligand supramolecular framework building up through multilayer assembly.     

Synthesis,topology analysis and luminescent property of a 3D AgCN coordination polymer based on 2-tptz (2-tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazin)

The solvothermal reaction of AgCN with 2-tptz (2-tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazin) afforded a 3D coordination polymer [(AgCN)₃(2-tptz)]_n (1). It was characterized by infrared spectroscopy, elemental analysis and X-ray single-crystal analysis. The structure of this polymer features a 2D wavelike [AgCN]_n substructure constructed from 18-membered of Ag₆(CN)₆ rings and 22-membered of Ag₈(CN)₆C₂ rings. When silver?sliver interactions are taken into account, the structure of 1 exhibits a (3 · 8 · 9)(4 · 8 · 9)(3 · 4 · 8 · 9³)(3 · 8 · 9² · 10²) topological network which has not been reported for the (3, 4)-connected nets. The photoluminescent property of the present coordination polymer was also investigated.     

Photocatalytic degradation of bisphenol A by Ag3PO4 under visible light

Ag₃PO₄ catalysts exhibited excellent photocatalytic performance in the degradation and the mineralization of bisphenol A, displaying considerably higher photocatalytic activity than N–TiO₂ under visible light (λ > 420 nm). The trapping effects of different scavengers and spectrophotometric results proved that the oxidation of bisphenol A mainly occurred at photogenerated holes on the Ag₃PO₄ surface, along with a two-electron reduction of dissolved oxygen to H₂O₂.     

Synthesis of Ag3PO4–ZnO nanorod composites with high visible-light photocatalytic activity

Ag₃PO₄ nanoparticles with 50–100 nm in size distributed on the surface of ZnO nanorods with ca. 20 nm in diameter and 1–2 μm in length have been synthesized by a facile method. The Ag₃PO₄–ZnO nanorod composites had much higher photocatalytic activity toward degradation of Rhodamine B (RhB) under visible light irradiation than pure ZnO nanorods, and had better recyclability and stability than pure Ag₃PO₄ nanoparticles. The Ag₃PO₄–ZnO nanorod composite with the molar ratio of Ag₃PO₄:ZnO = 1:40 exhibited the highest photodegradation efficiency of RhB (93%), which was 1.5 times of pure ZnO nanorods.     

[Zn(H2O)4][B6O10]: An open-framework borate with acentric structure

An open-framework borate [Zn(H₂O)₄][B₆O₁₀] with acentric structure, has been successfully obtained for the first time under solvothermal conditions. It has been characterized by powder and single crystal X-ray diffraction, IR spectroscopy, diffuse-reflectance spectroscopy and thermogravimetric (TG) analyses, respectively. It crystallizes in the orthorhombic system, space group Pna2₁, a = 11.3140(6) Å, b = 11.8995(7) Å, c = 8.6140(5) Å and Z = 4. In the structure, the alternative connections between [B₃O₇] units give rise to an unprecedented 3D borate framework with 11- and 10-MR channels, in which the [Zn(H₂O)₄]²⁺ complexes are located. It has a cut-off edge below 200 nm and exhibits second harmonic generation (SHG) efficiency approximately 0.4 times that of KH₂PO₄ (KDP).     

Organic–inorganic hybrid oxides: Structure and magnetic properties of [{Cu(terpy)}2Mo6O17(H2O)(O3PCH2NH2CH2PO3)2] · H2O,a bimetallic oxide constructed from novel {Mo6O17(H2O)(O3PCH2NH2CH2PO3)2}4− clusters

The hydrothermal reaction of MoO₃, CuSO₄ · 5H₂O, 2,2′:6′:2″-terpyridine (terpy) and bis-N,N-(methylphosphonic acid) amine (H₂O₃PCH₂NHCH₂PO₃H₂) provided blue crystals of the bimetallic oxide [{Cu(terpy)}₂Mo₆O₁₇(H₂O)(O₃PCH₂NH₂CH₂PO₃)₂] · H₂O (1 · H₂O). The three-dimensional structure of 1 is constructed from {Mo₆O₁₇(H₂O)(O₃PCH₂NH₂CH₂PO₃)₂}⁴⁻ clusters linked through {Cu(terpy)}²⁺ subunits. The cluster consists of three pairs of edge-sharing {MoO₆} octahedra linked through corner-sharing interactions into a {Mo₆O₆} ring. One phosphonate ligand spans the diameter of the ring, bridging four molybdenum sites and leaving at a pendant {PO} group at each terminus. The second diphosphonate ligand exploits one {–PO₃} unit to cap the hexamolybdate ring and bridge all six molybdenum sites while the second {–PO₃} terminus bridges two molybdenum sites, leaving a pendant {PO} unit. Crystal data: C₃₄H₄₅Cu₂Mo₆N₈O₃₅P₄: monoclinic, P2₁/n, a = 11.9431(7) Å, b = 17.382(1) Å, c = 27.524(2) Å, β = 90.429(1)°, V = 5713.7(6) Å³, Z = 4, D_calc = 2.270 g cm⁻³, R₁ = 0.0466.     

Preparation of ZnIn2S4/K2La2Ti3O10 composites and their photocatalytic H2 evolution from aqueous Na2S/Na2SO3 under visible light irradiation

ZnIn₂S₄/K₂La₂Ti₃O₁₀ composite photocatalysts were synthesized via a hydrothermal route. The photocatalysts were characterized by the X-ray diffraction, scanning electron microscopy, ultraviolet–visible (UV–vis) diffuse reflection spectra and photoluminescence measurements. The UV–vis results indicated that ZnIn₂S₄/K₂La₂Ti₃O₁₀ has a strong absorption in the visible light region. The compositions of ZnIn₂S₄/K₂La₂Ti₃O₁₀ composite photocatalysts were optimized according to the photocatalytic activity for hydrogen production from aqueous Na₂S/Na₂SO₃. The composite photocatalyst loading 25 wt.% ZnIn₂S₄ exhibited the highest photocatalytic activity, the amount of H₂ production was 6.29 mmol/g after 3 h irradiation under visible light irradiation.     

Synthesis and electrochemical properties of a composite LiMn0.63Fe0.37PO4 with Li3V2(PO4)3 for lithium-ion battery cathode materials

A composite materials LiMn_0.63Fe_0.37PO₄ with Li₃V₂(PO₄)₃ can be synthesized by a sol-gel method using N,N-dimethylformamide (DMF) as a dispersing agent. The structures, characteristics of the appearance, and electrochemical properties of the composites have been studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The composites contained LiMnPO₄/C (LMP/C), LiFePO₄/C (LFP/C), and Li₃V₂(PO₄)₃/C (LVP/C) phases with a nano-sized dispersion. The TEM images showed that the composites are crystalline with a grain size of 10–50 nm. The Mn2p, V2p, and Fe2p valence states were analyzed by X-ray photoelectron spectroscopy (XPS). The incorporation of LVP and LFP with LMP effectively enhanced the electrochemical kinetics of the LMP phase by a structural modification and shortened the lithium diffusion length in LMP. The capacity of the composite 0.79LiMn_0.63Fe_0.37PO₄·0.21Li₃V₂(PO₄)₃/C remained at 152.3 mAh g⁻¹ (94.7%) after 50 cycles at a 0.05 C rate. The composite exhibited excellent reversible capacities 159.4, 150, 140.1, 133.7 and 123.6 mAh g⁻¹ at charge-discharge rates of 0.05, 0.1, 0.2, 0.5 and 1 C, respectively.     

Novel visible light-induced g-C3N4–Sb2S3/Sb4O5Cl2 composite photocatalysts for efficient degradation of methyl orange

A series of g-C₃N₄–Sb₂S₃/Sb₄O₅Cl₂ (SCL-CX) composite photocatalysts were successfully prepared via a hydrothermal method. The as-prepared materials were characterized by TM3000, powder X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and UV–vis diffuse reflectance spectra (UV–vis DRS). The obtained photocatalyst showed higher photocatalytic activity than pure g-C₃N₄, Sb₄O₅Cl₂ and Sb₂S₃/Sb₄O₅Cl₂ (SCL). The optimum photocatalytic of the composite with the mass of 170 mg g-C₃N₄ and a degradation efficiency up to 95% for methyl orange (MO) under visible light was achieved within 60 min. The enhanced photocatalytic performance could be attributed to the stronger absorption in the visible region and the more efficient electron–hole separation.     

Two new polyoxometalate-based metal-organic complexes constructed from two in-situ transformed ligands through different ways

Two new Keggin-type polyoxometalates-based metal–organic complexes: [Ag₃(L1)₃(PMo₁₂O₄₀)]·3H₂O (1) and Ag₄(L2)₂(HL2)(PW₁₂O₄₀)Na₂(μ-OH)]·1.5H₂O (2) (L1 = 1.2.4-triazole, HL2 = 4-amino-1,2,4-triazole) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction analyses, IR spectra and powder X-ray diffraction analyses. In compound 1, the [Ag₆(L1)₆] crown-shaped ring was clamped by two [PMo₁₂O₄₀]^3 − polyanions, forming a sandwich-like [Ag₆(L1)₆(PMo₁₂O₄₀)₂] unit, which was extended to a 1D supramolecular chain through hydrogen bonding interaction. Compound 2 is a 3D metal–organic framework containing the [Ag₆(L2)₄(HL2)₂] crown-shaped ring and 1D [Na₂(PW₁₂O₄₀)(μ-OH)]_n inorganic chains, which represents a novel (3,3,4,6,10-c)-connected 3D topological framework. The L1 and L2 ligands were in-situ transformed from two different N-heterocyclic amide ligands through different ways, respectively. In addition, the electrocatalytic and photocatalytic activities of the title compounds have been studied.     

Blue-violet ceramic pigments based on Co and Mg Co2−xMgxP2O7 diphosphates

Solid solutions of Co and Mg diphosphates with compositions Co_2?xMg_xP₂O₇ (x = 0, 0.1, 0.2, 0.3, 0.5, 0.7, 1.0, 1.5 and 1.8) have been prepared and characterized for the first time as alternative low-toxicity blue ceramic pigments. The compositions were prepared through the conventional coprecipitation route and calcined up to 1000 °C/2 h. Samples were characterized by thermal analysis, XRD, SEM/EDX, UV–vis-NIR spectroscopy and colour measurements (CIE-L^*a^*b^*). Isostructural Co_2?xMg_xP₂O₇ diphosphate solid solutions (monoclinic system and P21/c spatial group) formed successfully within the studied range of compositions, accompanied only by a minor quantity of residual Co or Mg orthophosphates (M₃(PO₄)₂). Interestingly, the obtained solid solutions developed nice blue-violet colourations even with high Mg doping after enamelling within double-firing (x = 1.5–1.8) and single-firing (x = 1.0–1.5) ceramic glasses. These optimal compositions containing a minimized Co amount (measured values around 7–16 wt%) could be therefore less toxic alternatives to the conventional Co₃(PO₄)₂ blue ceramic pigment.