Nanoporous carbons with high surface area are achieved through direct carbonization of a commercially available zeolitic imidazolate framework (ZIF-8) without any additional carbon sources. The resultant nanoporous carbons exhibit high electrochemical capacitances in an acidic aqueous electrolyte.

Here we report a novel hard-templating strategy for the synthesis of mesoporous monocrystalline Pt nanoparticles (NPs) with uniform shapes and sizes. Mesoporous Pt NPs were successfully prepared through controlled chemical reduction using ascorbic acid by employing 3D bicontinuous mesoporous silica (KIT-6) and 2D mesoporous silica (SBA-15) as a hard template. The particle size could be controlled by changing the reduction time. Interestingly, the Pt replicas prepared from KIT-6 showed polyhedral morphology. The single crystallinity of the Pt fcc structure coherently extended over the whole particle.

The field of mesoporous metal nanoarchitectonics offers several advantages which cannot be found elsewhere. These materials have been showcasing impressive enhancements of their electrochemical properties for further implementation, compared to their micro- and macroporous counterparts. Since the last few decades, various methods have been developed to achieve narrow pore size distribution with a tunable porosity and particle morphology. While hard templates offer a reliable and intuitive approach to synthesize mesoporous metals, the complexity of the technique and the use of harmful chemicals pushed several research groups to focus in other directions. For example, soft templates (e.g., lyotropic crystals, micelles assemblies) and solution phase methods (requiring to control reduction reactions) offer more and more possibilities in terms of available compositions and morphologies. Indeed, various metal (Pt, Pd, Au, Ru, etc.) can now be synthesized as dendritic, core@shell, hollow or polyhedral nanoparticles, with single- or multicomponents, alloyed or not, with unprecedented electrochemical activity.

Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

Platinum (Pt) is widely used as battery electrodes, catalysts for chemicals, and catalysts for exhaust gas decomposition in industries. Increasing need and very limited supply of rare Pt is a serious problem in the world. Here, we propose new synthetic way for reducing the use of Pt in a catalytic system by increasing the surface area and modifying the Pt surface structure. Several types of mesoporous Pt films with different pore sizes ranging from 5 to 30 nm are prepared by electrochemical plating in aqueous surfactant solutions. The mesopore walls are composed of connected Pt nanoparticles with around 3 nm in diameter. The Pt atomic crystallinity is coherently extending across over several Pt nanoparticles, showing a large number of atomic steps, which can accelerate methanol oxidation reaction. As a result of a high surface area and unique Pt surface, our mesoporous Pt film exhibits high potentiality as a superior electrocatalyst.

Metallene with fantastic physicochemical properties is considered as a potential candidate for oxygen reduction reaction (ORR). Controlling the morphology and structure of metallene can provide a great opportunity to improve its catalytic performance. Herein, defect‐rich ultrathin porous Pd metallene (a sub‐nanometer and curved metal nanosheet) is developed by facile wet‐chemistry strategy for efficient and stable ORR electrocatalysis in alkaline electrolyte. The defect‐rich porous Pd metallene provides abundant highly active sites and vacancy defects, showing superior ORR activity of 0.892 A mgPd−1 at 0.9 V vs. the reversible hydrogen electrode. The mass activity is 5.1 and 16.8 times higher than those of commercial Pt/C and Pd/C, respectively, and maintains well after 5000 cycles. The strain effect and tunable electronic structure derived from highly curved sub‐nanometer nanosheet morphology contribute to the excellent ORR performance by the optimization of oxygen binding ability on Pd. The superior catalytic performance of Pd metallene may open an avenue to design other metallene materials for various fields.

Platinum nanoarchitectures consisting of a large number of edges and corner atoms are highly favorable for enhancing the catalytic performance and efficient utilization of platinum materials. In a recent study, we have shown that Pluronic F127 triblock copolymer can assist the formation of dendritic platinum nanoparticles (Wang, L.; Yamauchi, Y. J. Am. Chem. Soc. 2009, 131, 9152−9153). Herein, we expand this concept to produce platinum nanodendrites (PNDs) with interconnected arms by using various types of nonionic organic molecules. The PDNs with complex nanoarchitectures are produced simply by sonicating treatment of an aqueous solution containing K2PtCl4 precursor and formic acid in the presence of nonionic organic molecules without the need for any template, seed-mediated growth, and additive. As-produced PDNs were shown to be active as nanoelectrocatalysts for electro-oxidation formic acid. The investigated nonionic organic molecules include nonionic surfactants, e.g., Pluronic F127, Brij 700, Tetronic 1107, and polymer, e.g., poly(vinyl pyrrolidone) (PVP) and poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP-co-VA). The typical PNDs produced with Pluronic F127 possess platinum atomic crystalline state with large domains and show high surface area (32 m2 g−1). The proposed approach is highly favorable for facilitating the producing of PNDs in a wide range of platinum precursor concentrations. Because of its high flexibility and simple implement, the proposed approach can be considered as a very general and powerful strategy for producing PNDs with high surface area and open dendritic nanostructures for commercial devices. Furthermore, the dual roles of formic acid in synthesis of PNDs, i.e., reducing agent and structure-directing agent, are tentatively proposed based on the investigation results.

A NiRu@N–C hybrid is fabricated and tested as an efficient catalyst for the hydrogen evolution reaction in a wide pH range.