Given that surfactants can control the shape and size of micro‐/nanoparticles, they should be able to direct the growth of bulk crystals. This Minireview summarizes recent developments in the ...application of surfactants for the preparation of new crystalline inorganic materials, including chalcogenides, metal–organic frameworks, and zeolite analogues. The roles of surfactants in different reaction systems are discussed.
Multifaceted media: Since surfactants can control the shape and size of micro‐/nanoparticles, they are also able to direct the growth of bulk crystals. Recent developments in the use of surfactants in the preparation of crystalline inorganic materials, including chalcogenides, metal–organic frameworks, and zeolite analogues, are summarized in this Minireview.
Two‐dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are ...mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal–organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared‐layer framework. When the 3D pillared‐layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal–organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm−2 and a turnover frequency as high as 30 s−1 at an overpotential of 300 mV.
MOF slicing: A pillared‐layer metal–organic framework (MOF), in which the catechol functionalized pillars can be oxidized and removed in an electrochemical process, gives ultrathin nanosheets (2 nm). These are efficient electrocatalysts for water oxidation at pH 13 with a low overpotential and high turnover frequency (TOF).
Inserting polymers into a crystalline inorganic matrix to understand the structure, position, and the structure–property relationships of the resulting composites is important for designing new ...inorganic‐organic materials and tuning their properties. Single crystals of polymer‐chalcogenide composites were successfully prepared by trapping polyethyleneglycol within a selenidostannate matrix under surfactant‐thermal conditions. This work might provide a new strategy for preparing novel crystalline polymer‐inorganic composites through encapsulating polymer chains within inorganic matrices.
Common thread: Inserting a polymer into a crystalline inorganic matrix to understand its structure, position, and the structure–property relationships of the resulting composites is important for designing new inorganic–organic materials and tuning their properties. Single crystals of polymer‐chalcogenide composites were isolated by trapping polyethyleneglycol within a selenidostannate matrix under surfactant‐thermal conditions.
Separating ethene (C2H4) from ethane (C2H6) is of paramount importance and difficulty. Here we show that C2H4 can be efficiently purified by trapping the inert C2H6 in a judiciously designed ...metal-organic framework. Under ambient conditions, passing a typical cracked gas mixture (15:1 C2H4/C2H6) through 1 litre of this C2H6 selective adsorbent directly produces 56 litres of C2H4 with 99.95%+ purity (required by the C2H4 polymerization reactor) at the outlet, with a single breakthrough operation, while other C2H6 selective materials can only produce ca. ⩽ litre, and conventional C2H4 selective adsorbents require at least four adsorption-desorption cycles to achieve the same C2H4 purity. Single-crystal X-ray diffraction and computational simulation studies showed that the exceptional C2H6 selectivity arises from the proper positioning of multiple electronegative and electropositive functional groups on the ultramicroporous pore surface, which form multiple C-H···N hydrogen bonds with C2H6 instead of the more polar competitor C2H4.
The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two‐step nonlinear optical (NLO) switch with genuine ...“off–on–off” second harmonic generation (SHG) conversion between one NLO‐active state and two NLO‐inactive states.
Conventional adsorbents preferentially adsorb the small, high-polarity, and unsaturated 1,3-butadiene molecule over the other C₄ hydrocarbons from which it must be separated. We show from ...single-crystal x-ray diffraction and computational simulation that a hydrophilic metal-organic framework, Zn₂(btm)₂, where H₂btm is bis(5-methyl-1H-1,2,4-triazol-3-yl)methane, has quasi-discrete pores that can induce conformational changes in the flexible guest molecules, weakening 1,3-butadiene adsorption through a large bending energy penalty. In a breakthrough operation at ambient temperature and pressure, this guest conformation–controlling adsorbent eluted 1,3-butadiene first, then butane, butene, and isobutene. Thus, 1,3-butadiene can be efficiently purified (≥99.5%) while avoiding high-temperature conditions that can lead to its undesirable polymerization.
Zinc‐ion batteries (ZIBs) have been extensively investigated and discussed as promising energy storage devices in recent years owing to their low cost, high energy density, inherent safety, and low ...environmental impact. Nevertheless, several challenges remain that need to be prioritized before realizing the widespread application of ZIBs. In particular, the development of zinc anodes has been hindered by many challenges, such as inevitable zinc dendrites, corrosion passivation, and the hydrogen evolution reaction (HER), which have severely limited the practical application of high‐performance ZIBs. This review starts with a systematic discussion of the origins of zinc dendrites, corrosion passivation, and the HER, as well as their effects on battery performance. Subsequently, we discuss solutions to the above problems to protect the zinc anode, including the improvement of zinc anode materials, modification of the anode–electrolyte interface, and optimization of the electrolyte. In particular, this review emphasizes design strategies to protect zinc anodes from an integrated perspective with broad interest rather than a view with limited focus. In the final section, comments and perspectives are provided for the future design of high‐performance zinc anodes.
A systematic and detailed summary of the research progress on zinc ion battery anodes is presented, including the causes of zinc dendrites, corrosion passivation and hydrogen evolution reaction on zinc anodes along with the existing strategies. Perspectives are provided for the future design of high‐performance zinc anodes.
Switching materials in channels of nonlinear optics (NLOs) are of particular interest in NLO material science. Numerous crystalline NLO switches based on structural phase transition have emerged, but ...most of them reveal a single‐step switch between two different second‐harmonic‐generation (SHG) states, and only very rare cases involve three or more SHG states. Herein, we report a new organic‐inorganic hybrid salt, (Me3NNH2)2CdI4, which is an unprecedented case of a reversible three‐step NLO switch between SHG‐silent, ‐medium, ‐low, and ‐high states, with high contrasts of 25.5/4.3/9.2 in a temperature range of 213–303 K. By using the combined techniques of variable‐temperature X‐ray single‐crystal structural analyses, dielectric constants, solid‐state 13C nuclear magnetic resonance spectroscopy, and Hirshfeld surface analyses, we disclose that this four‐state switchable SHG behavior is highly associated with the stepwise‐changed molecular dynamics of the polar organic cations. This finding demonstrates well the complexity of molecular dynamics in simple hybrid salts and their potential in designing new advanced multistep switching materials.
A new simple hybrid salt has been synthesized that exhibits reversible multistep phase transitions and an unprecedented thermally induced three‐step “silent‐medium‐low‐high” second‐harmonic‐generation switching behavior. This behavior arises from complex and stepwise molecular dynamic changes of the polar organic cations.
Ge‐based hybrid perovskite materials have demonstrated great potential for second harmonic generation (SHG) due to the geometry and lone‐pair induced non‐centrosymmetric structures. Here, we report a ...new family of hybrid 3D Ge‐based bromide perovskites AGeBr3, A=CH3NH3 (MA), CH(NH2)2 (FA), Cs and FAGe0.5Sn0.5Br3, crystallizing in polar space groups. These compounds exhibit tunable SHG responses, where MAGeBr3 shows the strongest SHG intensity (5×potassium dihydrogen phosphate, KDP). Structural and theoretical analysis indicate the high SHG efficiency is attributed to the displacement of Ge2+ along 111 direction and the relatively strong interactions between lone pair electrons of Ge2+ and polar MA cations along the c‐axis. This work provides new structural insights for designing and fine‐tuning the SHG properties in hybrid metal halide materials.
A new family of non‐centrosymmetric hybrid Ge‐based bromide perovskites are reported, showing second harmonic generation (SHG) responses. The largest SHG signal from CH3NH3GeBr3 is likely due to the perferable alignment of the polar cation with the lone pair electrons of Ge2+ along the 111 direction.
A new perovskite‐like coordination polymer (CH3)2NH2Cd(N3)3 is reported which undergoes a reversible ferroelastic phase transition. This transition is due to varied modes of motion of the (CH3)2NH2+ ...guest accompanied by a synergistic deformation of the Cd(N3)3− framework. The unusual two‐staged switchable dielectric relaxation reveals the molecular dynamics of the polar cation guest, which are well controlled by the variable confined space of the host framework. As the material switches from the ferroelastic phase to the paraelastic phase, a remarkable increase of the rotational energy barrier is detected. As a result, upon heating at low temperature, this compound shows a notable change from a low to a high dielectric state in the ferroelastic phase. This thermoresponsive host–guest system may serve as a model compound for the development of sensitive thermoresponsive dielectric materials and may be key to understanding and modulating molecular/ionic dynamics of guest molecules in confined space.
Flexible frameworks: A perovskite‐like coordination polymer (CH3)2NH2Cd(N3)3 undergoes a ferroelastic‐to‐paraelastic phase transition as a result of the motion of the guest cation within the host framework (see picture), which itself undergoes a simultaneous deformation. This material acts as a thermoresponsive dielectric system owing to the well‐controlled guest molecular dynamics in the confined space.
PDF
