Aspects of the Photodimerization Mechanism of 2,4-Dichlorocinnamic Acid Studied by Kinetic Photocrystallography

Photoinduced structural variations in single crystals of 2,4-dichloro-trans-cinnamic acid (C9H6Cl2O2, DiClCA) have been investigated using X-ray diffraction (photocrystallography) and optical spectroscopic methods. During UV irradiation, which initiates the irreversible dimerization reaction, a loss of the long-range order of the reactant single crystal was found, i.e., that the dimerization is a heterogeneous one. This unexpected result emphasizes the still-existing problem of predicting changes or of remaining periodicity during chemical reactions in the solid state. On the basis of the experimental results, we propose a qualitative kinetic reaction scheme for DiClCA heterogeneous dimerization reaction

Phase Behaviour of CoC12-MnC12 Mixed Crystals

Thermal properties of CoCl2, MnCl2 and their mixed crystals are investigated by means of temperature dependent neutron powder diffraction and time-resolved small angle neutron scattering. The coefficients of thermal expansion of these crystals have been determined as a function of temperature. The temperature-induced structural variations can be explained by distortions of CoCl5/MnCl6 octahedra and changes in Co/Mn-Cl bond lengths. CoCl2 and MnCl2 form homogeneous solid solutions in the entire temperature range between the solidus and 50 K. There is no indication of any miscibility gap as predicted from thermodynamic calculations

Few-layer black phosphorus and boron-doped graphene based heteroelectrocatalyst for enhanced hydrogen evolution

Research interest in two-dimensional (2D) materials has grown exponentially across various fields over the past few years. In particular, 2D phosphorene, the single- or few-layered analogue of semiconducting black phosphorus (BP), holds specific promise for advanced catalysis reactions including electrocatalytic hydrogen (H2) production. However, bare phosphorene nanosheets suffer from poor electrical conductivity, limited catalytic sites and instability under ambient conditions. Herein, we integrate ultrathin few-layer BP (FL-BP) nanosheets with boron-doped graphene (BG) to form a novel metal-free 2D/2D heteroelectrocatalyst for the hydrogen evolution reaction (HER) in acidic media. Our newly designed electrocatalyst (FL-BP@BG) shows remarkably enhanced HER activity with a low overpotential of 385.9 mV at 10 mA cm−2, while exhibiting a low charge transfer resistance of only 5.5 Ω in H2SO4\ua0electrolyte. In addition, the FL-BP@BG catalyst shows an outstanding stability over 500 continuous cycles, demonstrating that hybridizing FL-BP with BG is an efficient strategy to construct stable BP based electrocatalyst. This work paves the way for emerging 2D materials for advanced catalysis systems