Conductive One-Dimensional Coordination Polymers with Tunable Selectivity for the Oxygen Reduction Reaction

Lattice Strained Induced Spin Regulation in Co-N/S Coordination-Framework Enhanced Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is the bottleneck of metal-air batteries and fuel cells. Strain regulation can change the geometry and adjust the surface charge distribution of catalysts, which is a powerful strategy to optimize the ORR activity. The introduction of controlled strain to the material is still difficult to achieve. Herein, we present a temperature-pressure-induced strategy to achieve the controlled lattice strain for metal coordination polymers. Through the systematic study of the strain effect on ORR performance, the relationship between geometric and electronic effects is further understood and confirmed. The strained Co-DABDT (DABDT=2,5-diaminobenzene-1,4-dithiol) with 2 % lattice compression exhibits a superior half-wave potential of 0.81 V. Theoretical analysis reveals that the lattice strain changes spin-charge densities around S atoms for Co-DABDT, and then regulates the hydrogen bond interaction with intermediates to promote the ORR catalytic process. This work helps to understand the catalytic mechanism from the atomic level.

Spin-Magnetic Effect of d-π Conjugation Polymer Enhanced O-H Cleavage in Water Oxidation

A deep understanding of the mechanism for the spin-magnetic effect on O-H cleavage is crucial for the development of new catalysts for water oxidation. Herein, we designed and synthesized the crystalline Fe-DABDT and Co-DABDT (DABDT = 2,5-diaminobenzene-1,4-dithiol) and optimized an effective magnetic moment to explore the role of the spin-magnetic effect in the regulation of water oxidation activity. It can be found that the OER activity of the catalyst is positively correlated with its effective magnetic moment. Under the external magnetic field, Fe-DABDT with more spin single electrons has a stronger spin-magnetic response to water oxidation than Fe/Co-DABDT and Co-DABDT. The increase in OER current of Fe-DABDT is nearly 2 times higher than that of Co-DABDT. Experimental and density functional theory studies show that magnetized Fe sites could realize nucleophilic reaction, accelerate the polarization of electron spin states, and promote the polar decomposition of O-H and the formation of the O-O bond. This study provides mechanistic insight into the spin-magnetic effect of oxygen evolution reaction and further understanding of the spin origin of catalytic activity, which is expected to improve the energy efficiency of hydrogen production.

Cobalt-based conjugated coordination polymers with tunable dimensions for electrochemical sensing of p-nitrophenol

Using planar π-conjugated 2,5-diamino-1,4-benzenedithiol as organic ligand, Co-based conjugated coordination polymers (CoCCPs) with different morphology were prepared through controlling the injection rate of Co2+. When the injection rate decreases from 1.00 to 0.25 mL min-1, the obtained CoCCPs change from 2D nanosheets to quasi-1D nanorods. It is found that the different-shaped CoCCPs exhibit varying electrochemical sensing performance. The prepared CoCCPs-1 with quasi-1D nanowires and porous network structure possesses larger active area, faster electron transfer and higher accumulation ability. Moreover, the CoCCPs-1 is more active for the oxidation of p-nitrophenol (PNP), and greatly enhances its oxidation signal. Based on the morphology-tuned sensing performance of CoCCPs, a highly-sensitive electrochemical sensor has been developed for PNP, with detection limit of 0.00986 μM (9.86 nM). It was used in the analysis of wastewater samples, and the results is validated by other instrumental method.

The crystal structure and oxygen reduction reaction of Ni(II)-complex templated borate-sulfate and borate

Three nickel borate compounds, [Ni(1-MI)₆]·[B(OH)₃]₄·SO₄ (1-MI = 1-methylimidazole) (1), [Ni(H₂O)₃(1-MI)₃]·[B₅O₆(OH)₄]₂ (2) and [Ni(DMA3)]·[B₆O₇(OH)₆]·3.5H₂O (DMA3 = N,N-dimethylethylenediamine) (3), have been synthesized. It is noteworthy that the structures of 1 and 2 can be adjusted by varying the ratio of amine. Compound 3 has shown an unexpected example of unique water clusters in its structure. The three frameworks exhibit different interlinkage modes, resulting in channels varying in their size and shape. These compounds have been characterized by FTIR, UV-vis and PXRD. In addition, 1, 2, and 3 exhibited different wide band gaps (4.4 eV for 1, 4.5 eV for 2 and 4.4 eV for 3), and ORR activities with a half-wave potential of 0.78 V for 1, 0.74 V for 2 and 0.79 V for 3.