Single-Site Ni-Grafted TiO2 with Diverse Coordination Environments for Visible-Light Hydrogen Production.

Solar hydrogen production at a high efficiency holds the significant importance in the age of energy crisis, while the micro-environment manipulation of active sites on photocatalysts plays a profound role in enhancing the catalytic performance. In this work, a series of well-defined single-site Ni-grafted TiO2 photocatalysts with unique and specific coordination environments, 2,2'-bipyridine-Ni-O-TiO2 (T-Ni Bpy) and 2-Phenylpyridine-Ni-O-TiO2 (T-Ni Phpy), were constructed with the methods of surface organometallic chemistry combined with surface ligand exchange for visible-light-induced photocatalytic hydrogen evolution reaction (HER). A prominent rate of 33.82 µmol ⋅ g-1 ⋅ h-1 and a turnover frequency of 0.451 h-1 for Ni are achieved over the optimal catalyst T-Ni Bpy for HER, 260-fold higher than those of Ni-O-TiO2 . Fewer electrons trapped oxygen vacancies and a larger portion of long-lived photogenerated electrons (>3 ns, ~52.9 %), which were demonstrated by the electron paramagnetic resonance and femtosecond transient IR absorption, correspond to the photocatalytic HER activity over the T-Ni Bpy. The number of long-lived free electrons injected from the Ni photoabsorber to the conduction band of TiO2 is one of the determining factors for achieving the excellent HER activity.

Bis(5-chloro-salicylato-κO)bis-(1,10-phenanthroline-κN,N')cadmium(II).

In the title complex, [Cd(C(7)H(4)ClO(3))(2)(C(12)H(8)N(2))(2)], the Cd atom is coordinated by two 5-chloro-salicylate ligands and two 1,10-phenanthroline ligands, displaying a distorted octa-hedral coordination geometry. The crystal structure is stabilized by O-H⋯O and C-H⋯O hydrogen bonds and π-π inter-actions between the 1,10-phenanthroline ligands and 5-chloro-salicylate ligands, with a centroid-centroid distance between neighbouring aromatic rings of 3.730 (1) Å.

Bis(2,2'-bipyridine-κN,N')(3,5-dinitro-2-oxidobenzoato-κO,O)cobalt(II).

In the title compound, [Co(C(7)H(2)N(2)O(7))(C(10)H(8)N(2))(2)], the Co(II) atom is coordinated by four N atoms from two 2,2'-bipyridine ligands and two O atoms from a 3,5-dinitro-2-oxidobenzoate ligand, displaying a distorted octa-hedral coordination geometry. The crystal structure involves C-H⋯O hydrogen bonds between the 2,2'-bipyridine ligands and the carboxyl-ate and NO(2) groups of the 3,5-dinitro-2-oxidobenzoate ligand.

Petrophysical characterization of high-rank coal by nuclear magnetic resonance: a case study of the Baijiao coal reservoir, SW China.

To better apply nuclear magnetic resonance (NMR) to evaluate the petrophysical characterization of high-rank coal, six anthracite samples from the Baijiao coal reservoir were measured by NMR. The porosity, T 2 cutoff value, permeability and pore type were analysed using the transverse relaxation time (T 2) spectrum before and after centrifugation. The results show that the T 2 spectrum of water-saturated anthracite can be divided into a discontinuous and continuous trimodal distribution. According to the connectivity among pores, three T 2 spectrum peaks were identified at the relaxation times of 0.01-1.7 ms, 1.7-65 ms and greater than 65 ms, which correspond to the micropores (less than 100 nm), mesopores (100-1000 nm) and macropores (greater than 1000 nm), respectively. Based on the T 2 cutoff value, we divided the T 2 spectrum into two parts: bound fluid and free fluid. By comparing two classic permeability models, we proposed a permeability model to calculate the permeability of anthracite. This result demonstrates that NMR has great significance to the exploration of coal reservoirs and to the understanding of the development of coalbed methane.