Bis[hexa­amminecobalt(III)] penta­chloride nitrate

The title compound, [Co(NH3)6]2Cl5(NO3), was obtained under hydro­thermal conditions. The asymmetric unit contains three Co3+ ions, one lying on an inversion center and the other two located at 2/m positions. All Co3+ ions are six-coordinated by NH3 mol­ecules, forming [Co(NH3)6]3+ octahedra, with Co—N distances in the range 1.945 (4)–1.967 (3) Å. The nitrate N atom and one of the O atoms lie at a mirror plane. Among the Cl− anions, one lies in a general position, one on a twofold axis and two on a mirror plane. N—H⋯O and N—H⋯Cl hydrogen bonds link the cations and anions into a three-dimensional network

catena-Poly[[[triaqua­copper(II)]-μ-2,2′-bipyridine-3,3′-dicarboxyl­ato-κ3 N,N′:O] monohydrate]

The title compound, {[Cu(C12H6N2O4)(H2O)3]·H2O}n, was synthesized under hydro­thermal conditions. The Cu2+ ion is six-coordinated by three water O atoms, and two N atoms and one O atom of the 2,2′-bipyridine-3,3′-dicarboxyl­ate bridging ligand in a sligthly distorted octa­hedral environment. The 2,2-bipyridine-3,3′-dicarboxyl­ate bridges link the Cu2+ ions into chains along the b-axis direction. These chains are further linked by O—H⋯O hydrogen bonds involving the water solvent mol­ecules, forming a three-dimensional framework

Tris(2,2′-bi-1H-imidazole-κ2 N 3,N 3′)cobalt(II) hydrogen phosphate

The title compound, [Co(C6H6N4)3]HPO4, was synthesized under hydro­thermal conditions. In the cation, the CoII atom is octa­hedrally coordinated by six N atoms from three 2,2′-bi-1H-imidazole ligands [Co—N bond lengths are in the range 2.084 (5)–2.133 (6) Å]. Inter­molecular N—H⋯O hydrogen bonds form an extensive hydrogen-bonding network, which links cations and anions into a three-dimensional crystal structure

catena-Poly[[gallium(III)-bis[μ-D/l-tartrato(2−)]-gallium(III)-di-μ-hydroxido] dihydrate]

In the title compound, {[Ga2(C4H4O6)2(OH)2]·2H2O}n, the GaIII atom is located on a twofold rotation axis and is six-coordinated by two O atoms from bridging hydroxide groups and four O atoms from two symmetry-related tartrate units in a slightly distorted octahedral environment. Each tartrate unit binds to two GaIII atoms as a bis-chelating bridging ligand by two pairs of hydroxide groups and an O atom of a carboxylate group. The GaIII atoms are linked by two bridging hydroxide groups located on mirror planes. In this way a chain along the c axis is formed. Free water molecules on mirror planes are located between the chains and hold them together through hydrogen-bonding interactions, with O...O distances in the range 2.509 (3)–3.179 (5) Å

Tris[hexaamminecobalt(III)] bis[trioxalatocobaltate(II)] chloride dodecahydrate

The title compound, [CoIII(NH3)6]3[CoII(C2O4)3]2Cl·12H2O, was synthesized under hydrothermal conditions. The asymmetric unit comprises two [Co(NH3)6]3+ cations, one located on a threefold axis and the other on a site of symmetry -3, a [Co(C2O4)3]4+ anion, located on a threefold axis, one sixth of a chloride anion [disordered over two sites, one threefold (site occupancy = 0.5) and the other -3 (site occupancy (0.25)] and two water molecules. Both CoIII centers are six-coordinated by NH3 molecules, forming [Co(NH3)6]3+ octahedra, with Co—N distances in the range 1.958 (2)–1.977 (3) Å. The title structure gives the first example of the [Co(C2O4)3]4− anion, with the distorted octahedral environment of CoII center formed by six O atoms from three oxalate residues. The Co—O bond lengths are 2.0817 (18) to 2.0979 (18) Å. Multiple N—H...O, N—H...Cl and O—H...O hydrogen bonds link the cations, anions and water molecules into a three-dimensional network

Highly Selective Gas Sensor Based on Litchi-like g-C₃N₄/In₂O₃ for Rapid Detection of H₂

Hydrogen (H2) has gradually become a substitute for traditional energy, but its potential danger cannot be ignored. In this study, litchi-like g-C3N4/In2O3 composites were synthesized by a hydrothermal method and used to develop H2 sensors. The morphology characteristics and chemical composition of the samples were characterized to analyze the gas-sensing properties. Meanwhile, a series of sensors were tested to evaluate the gas-sensing performance. Among these sensors, the sensor based on the 3 wt% g-C3N4/In2O3 (the mass ratio of g-C3N4 to In2O3 is 3:100) showeds good response properties to H2, exhibiting fast response/recovery time and excellent selectivity to H2. The improvement in the gas-sensing performance may be related to the special morphology, the oxygen state and the g-C3N4/In2O3 heterojunction. To sum up, a sensor based on 3 wt% g-C3N4/In2O3 exhibits preeminent performance for H2 with high sensitivity, fast response, and excellent selectivity

Controllable Synthesis of Sheet-Flower ZnO for Low Temperature NO₂ Sensor

ZnO is a wide band gap semiconductor metal oxide that not only has excellent electrical properties but also shows excellent gas-sensitive properties and is a promising material for the development of NO2 sensors. However, the current ZnO-based gas sensors usually operate at high temperatures, which greatly increases the energy consumption of the sensors and is not conducive to practical applications. Therefore, there is a need to improve the gas sensitivity and practicality of ZnO-based gas sensors. In this study, three-dimensional sheet-flower ZnO was successfully synthesized at 60 °C by a simple water bath method and modulated by different malic acid concentrations. The phase formation, surface morphology, and elemental composition of the prepared samples were studied by various characterization techniques. The gas sensor based on sheet-flower ZnO has a high response value to NO2 without any modification. The optimal operating temperature is 125 °C, and the response value to 1 ppm NO2 is 125. At the same time, the sensor also has a lower detection limit (100 ppb), good selectivity, and good stability, showing excellent sensing performance. In the future, water bath-based methods are expected to prepare other metal oxide materials with unique structures