Direct Synthesis of Highly Designable Hybrid Metal Hydroxide Nanosheets by Using Tripodal Ligands as One‐Size‐Fits‐All Modifiers

Abstract

How did the collaborationo nt his project start?This work is ac ollaboration between two research groups in Waseda University (Kuroda-Shimojima-Wada Laboratory,w ith an interest in the synthesis of inorganic solids from molecular precursors) and the University of To kyo (Mizuno-Yamaguchi Laboratory, with an interest in the catalysis of metal oxide cluster compounds like polyoxometalates). The collaboration started when one of the authors (Y.K.) moved between these groups. During many discussions, we came to the idea that several polyoxometalates can be regarded as building blocks of inorganic solids, and techniques developed specially for the chemical design of polyoxometalates can also be applied to inorganic solids like brucite-type layered metal hydroxides. Thus, we succeeded in establishing the novel synthetic concept of hybrid metal hydroxide nanosheets by combining the chemistries of layered metal hydroxides and polyoxometalates.What is the most significant result of this study?The modification reaction developed in this study can be applied to aw ide range of materials, in terms of constituent metallic elements of metal hydroxide nanosheets and those of surface functional groups. Because tripodal ligands have flexible tridentate binding sites, they can adjust their conformations to metal hydroxide nanosheets with different lattice constants;t his is expressed by the phrase "one-size-fits-all modifier" in the title. What was the inspiration for this cover design?The cover design was inspired by the Japanese Sushi culture. We enjoy various fishes in as tandardized style, in which as lice of af ish is placed on av inegared rice ball. In this study,w ec an provide various metal hydroxide nanosheets in as tandardized method. The future goal of this study will be the production of designed nanosheets which satisfy the demands of functional devices, in the same way as aS ushi master makes flavored Sushi that fits the customer's taste.Invited for the cover of this issue is the group of Yoshiyuki Kuroda and Kazuyuki Kuroda at the Waseda University in Tokyo. The image depicts how the production of diverse metal hydroxide nanosheets can be standardized in the same way as Sushi. Read the full text of the article at

Tunable Method for the Preparation of Layered Double Hydroxide Nanoparticles and Mesoporous Mixed Metal Oxide Electrocatalysts for the Oxygen Evolution Reaction

“…All samples were analyzed using selected area electron diffraction (SAED), and the results exhibited diffuse diffraction rings assignable to the corresponding LDHs, a behavior that is expected due to the samples being composed of randomly distributed stacks of nanoparticles (Figure S1a–c). It is worth noting that previous electron diffraction results for LDHNPs prepared in a similar fashion also showed diffuse diffraction rings, with distinct hexagonal features being observed only for isolated LDH nanosheets . This observation of the SAED results strongly suggests that the synthesized NiX LDHNPs also consist of brucite-like layers, with the turbostratic structure arising from the random stacking of nanosheets.…”

“…The powder material was characterized using XRD. The XRD patterns showed broad features that are typical of LDH materials modified with Tris–NH 2 (Figure a–c), indicating that both Co and Fe are incorporated in the structure and form a single phase . The features observed in the XRD patterns can be assigned to the pseudo-hexagonal lattice of turbostratic layered metal hydroxides.…”

“…It is worth noting that previous electron diffraction results for LDHNPs prepared in a similar fashion also showed diffuse diffraction rings, with distinct hexagonal features being observed only for isolated LDH nanosheets. 55 This observation of the SAED results strongly suggests that the synthesized NiX LDHNPs also consist of brucite-like layers, with the turbostratic structure arising from the random stacking of nanosheets.…”

“…The XRD patterns showed broad features that are typical of LDH materials modified with Tris−NH 2 (Figure 1a−c), indicating that both Co and Fe are incorporated in the structure and form a single phase. 55 The features observed in the XRD patterns can be assigned to the pseudo-hexagonal lattice of turbostratic layered metal hydroxides. It is worth mentioning that the broadness of the (100) and (110) diffraction peaks is related to the small particle size, while the broad asymmetric feature in the 33°< 2θ < 45°range is attributed to the stacking disorder of the LDHNPs.…”

“…In LDHs, a fraction of the divalent metallic cations can be substituted by trivalent metallic cations; this substitution changes the physical properties of the material, such as the layer charge and anion exchange ability . Moreover, LDH materials have been used as building blocks in the preparation of porous materials and, if the size of the LDH particles is controlled, large surface area electrocatalysts can be successfully prepared. , Controlling the size of LDH materials can be a challenge, but one can achieve that in a variety of ways, such as by using carbon-based substrates and ultrasonication. − In an alternative method, the particle size can be controlled by using organic ligands, such as tris­(hydroxymethyl)­aminomethane (Tris–NH 2 ), a tridentate molecule that limits crystal growth through binding to the outer layers of the particle. − The benefits of this method are the use of water as a solvent, the lower thermal treatment temperature requirement (below 100 °C), and the few reagents required. In fact, Tris–NH 2 -modified LDH nanoparticles (LDHNPs) have been successfully employed as precursors for the preparation of mesoporous materials with a large surface area .…”