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The effect of pressure on the spin-transition properties of the 2D coordination polymer {Fe(phpy)2[Ni(CN)4]} is reported. The study has been carried out by means of variable-temperature (10-310 K) magnetic susceptibility measurements at applied pressures of 105 Pa to 1.0 GPa and spectroscopic studies in the visible region at room temperature (105 Pa-3.0 GPa). As the pressure is increased, the characteristic temperature of the spin transition is displaced to higher temperatures and the thermal hysteresis loop disappears. A cooperative first-order spin transition characterized by a piezo-hysteresis loop about 0.3 GPa wide was observed at 293 K. [ABSTRACT FROM AUTHOR]

Hydrogen energy is an abundant, clean, sustainable and environmentally friendly renewable energy source. Therefore, the production of hydrogen by photocatalytically splitting water on semiconductors has been considered in recent years as a promising and sustainable strategy for converting solar energy into chemical energy to replace conventional energy sources and to solve the growing problem of environmental pollution and the global energy crisis. However, highly efficient solar‐driven photocatalytic hydrogen production remains a huge challenge due to the poor visible light response of available photocatalytic materials and the low efficiency of separation and transfer of photogenerated electron‐hole pairs. In the present work, organic heterojunction structures based on bacteriochlorophyll (BChl) and chlorophyll (Chl) molecules were introduced and used for solar‐driven photocatalytic hydrogen production from water under visible light. Also, noble metal‐free photocatalyst was successfully constructed on Ti3C2Tx nanosheets by simple successive deposition of Chl and BChl, which was used for the photocatalytic splitting water to hydrogen evolution reaction (HER). The results show that the optimal BChl@Chl@Ti3C2Tx composite has a high HER performance with 114 μmol/h/gcat, which is much higher than the BChl@Ti3C2Tx and Chl@Ti3C2Tx composites. [ABSTRACT FROM AUTHOR]

In this work, a novel multiferroic‐like nanocomposite is designed and obtained using the high‐pressure torsion (HPT) method. The crystal structure, phase composition, morphology, ferromagnetic (FM), and ferroelectric (FE) properties of the initial powders and ferroelectric/ferromagnetic nanocomposites are studied comprehensively. The initial powders and their composite show the perovskite and spinel crystalline phases for the FE and FM fractions, respectively. After HPT, the particle sizes of the initial powders are decreased significantly. It is shown that the novel nanocomposite consists of exchange‐interacting FE and FM phases and demonstrates improved magnetic and electrical properties in low fields at room temperature. A giant increase in residual polarization with an increase in external high‐pressure is found in new composite. The obtained results make it possible to consider the novel nanocomposite as a new functional material for its use both in electronic devices for monitoring ultra‐high‐pressure and in integrated circuits of high‐speed computing nanosystems with low switching energy. The HPT method is a promising method for obtaining new heterophase nanosystems. [ABSTRACT FROM AUTHOR]

The thermal spin-crossover behaviour, photoexcitation and subsequent relaxation, as well as the pressure-induced spin-crossover behaviour at 298 K are discussed for the non-porous two-dimensional Hofmann-like coordination polymer [Fe(3-Clpy)2Pd(CN)4] ( 1). The title compound undergoes a two-step, cooperative thermal-induced SCO with critical temperatures Tc1↓ = 159.6 K and Tc1↑ = 164.5 K for the first step and Tc2↓ = 141.4 K and Tc2↑ = 148.4 K for the second step. Irradiation of the low-spin state with green light (514 nm) at 10 K induced the photoexcitation of around 60 % of the iron(II) centres to the high-spin state (LIESST effect). The subsequent cooperative relaxation processes were recorded at several temperatures and analysed. The effect of cooperativity on the photoexcitation was investigated by the LITH (light-induced thermal hysteresis) procedure. At 300 K, the coordination polymer 1 underwent a cooperative spin-crossover transition at around 0.6 GPa. The thermodynamic analysis of the pressure-induced SCO transition afforded the enthalpy and cooperativity parameters Δ HHL( p) = 22.01 kJ mol-1 and Γ( p) = 7.47 kJ mol-1, consistent with previous results. [ABSTRACT FROM AUTHOR]