Facile Approach for Synthesizing High-Performance MnO/C Electrodes from Rice Husk.

Pyrolysis is an effective way to convert biomass into biofuel while obtaining highly porous active carbon materials. In this study, a facile approach, involving hydrothermal and pyrolysis steps, is described for preparing hybrid metal oxide nanoparticle-embedded porous hard carbon matrices (MnO/C) from the biowaste rice husk and organometallic precursors. It was found that the pyrolysis/calcination temperature had a strong influence over the microstructure, especially over the porosity, but also over the carbon content and crystallinity of the nanocomposites; hence, the electrical properties can be controlled. Galvanostatic measurements showed that the nanocomposite obtained at 600 °C exhibited the highest charge/discharge capacity and best stability, delivering an initial discharge capacity of 1104 mA·h·g-1 at a current density of 200 mA·g-1, and retaining a value of 830 mA·h·g-1 after 200 cycles, suggesting excellent cycle stability. A discharge capacity of 581 mA·h·g-1 was obtained even at a current density as high as 2400 mA·g-1, demonstrating superb rate capability. This outstanding electrochemical performance, ascribed to high electrochemical activity of the embedded MnO nanoparticles enhanced by electrical conductivity provided through the high surface area of the active porous carbon support, is discussed in relation to the microstructure of the nanocomposite.

Aqua-{tris-[(1H-benzimidazol-2-yl-κN)meth-yl]amine}-zinc 5-(dimethyl-amino)-naphthalene-1-sulfonate perchlorate 2.5-hydrate.

In the title compound, [Zn(C(24)H(21)N(7))(H(2)O)](C(12)H(12)NO(3)S)(ClO(4))·2.5H(2)O, the Zn(II) ion is in a distorted trigonal-bipyramidal coordination geometry. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds connect the components into a two-dimensional network parallel to (001). In addition, there are weak C-H⋯O hydrogen bonds.

(Nitrato-κO){N,N,N',N'-tetra-kis-[(1H-benzimidazol-2-yl-κN)meth-yl]cyclo-hexane-1,2-diamine}-lead(II) hemiaqua-{N,N,N',N'-tetra-kis-[(1H-benzimidazol-2-yl-κN)meth-yl]cyclo-hexane-1,2-diamine}-lead(II) trinitrate dihydrate.

In the title compound, [Pb(NO(3))(C(38)H(38)N(10))][Pb(C(38)H(38)N(10))(H(2)O)(0.5)](NO(3))(3)·2H(2)O, both Pb(II) ions are coordinated in a distorted trigonal-prismatic environment by a hexa-dentate N,N,N',N'-tetra-kis-[(1H-benzimidazol-2-yl)meth-yl]cyclo-hex-ane-1,2-diamine ligand. A nitrate and a half-occupancy water ligand form long coordination bonds to the Pb(II) ions capping the trigonal-prismatic environment. In the crystal, the components are linked by N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional network. C-H⋯O inter-actions also occur.

4-[1-(4-Hy-droxy-3-meth-oxy-benz-yl)-1H-benzimidazol-2-yl]-2-meth-oxy-phenol.

In the title mol-ecule, C(22)H(20)N(2)O(4), the dihedral angles between the benzimidazole ring system and the benzene rings are 44.26 (2) and 82.91 (2)°. Intra-molecular O-H⋯O hydrogen bonds occur. In the crystal, O-H⋯N and O-H⋯O hydrogen bonds connect the mol-ecules into a two-dimension network parallel to (10[Formula: see text]) and weak inter-molecular C-H⋯O hydrogen bonds complete the formation of a three-dimensional network.

Dichlorido[tris-(benzimidazol-2-ylmeth-yl)amine]-indium(III) chloride ethanol solvate dihydrate.

In the title complex, [InCl(2)(C(24)H(21)N(7))]Cl·C(2)H(5)OH·2H(2)O, the In(III) ion is coordinated by four N atoms from the tris-(benz-imidazol-2-ylmeth-yl)amine (NTB) ligand and two Cl atoms in a distorted octa-hedral environment. In the crystal structure, inter-molecular N-H⋯O, O-H⋯O, O-H⋯Cl and weak C-H⋯Cl hydrogen bonds connect the cations, anions and solvent mol-ecules into a three-dimensional network. The ethanol solvent mol-ecule is disordered over two sites with refined occupancies of 0.54 (2) and 0.46 (2).

8-Quinolyl 5-(dimethyl-amino)-naphthalene-1-sulfonate.

In the title compound, C(21)H(18)N(2)O(3)S, the dihedral angle between the naphthalene and quinoline ring systems is 55.53 (2)°, and the torsion angle involving the connecting C-S-O-C atoms is 87.60 (3)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds connect mol-ecules into chains along [100] and there are π-π stacking inter-actions between pairs of chains with a centroid-centroid distance of 3.5485 (15) Å.

[N,N,N',N'-Tetra-kis(benzimidazol-2-yl-meth-yl)ethane-1,2-diamine]copper(II) sulfate monohydrate.

In the title compound, [Cu(C(34)H(32)N(10))]SO(4)·H(2)O, the Cu(II) ion is coordinated by six N atoms of a hexa-dentate N,N,N',N'-tetra-kis(benzimidazol-2-ylmeth-yl)ethane-1,2-diamine (EDTB) ligand, in a distorted octa-hedral environment. In the crystal structure, inter-molecular N-H⋯O and weak C-H⋯O hydrogen bonds connect the cations, anions and water mol-ecules into a three-dimensional network. The O atoms of the anion are disordered over two sites with refined occupancies of 0.711 (2) and 0.289 (2).

5-(Dimethyl-ammonio)naphthalene-1-sulfonate dihydrate.

There are two formula units in the asymmetric unit of the title compound, C(12)H(13)NO(3)S·2H(2)O. In the crystal structure, mol-ecules are linked by inter-molecular O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds, forming a three-dimensional network.

[N,N,N',N'-Tetra-kis(benzimidazol-2-yl-meth-yl)cyclo-hexane-1,2-diamine]-nickel(II) dinitrate dihydrate.

In the title compound, [Ni(C(38)H(38)N(10))](NO(3))(2)·2H(2)O, the Ni(II) ion is located on a crystallographic twofold rotation axis and is in a distorted octa-hedral coordination environment. The crystal structure is stablized by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds, and weak C-H⋯π inter-actions. The O atoms of the unique nitrate ion are disordered over two sites with occupancies of 0.63 (1) and 0.37 (1). In addition, the O atom of the unique solvent water mol-ecule is disorded over two sites with equal occupancies.