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Although anion‐exchange membranes (AEMs) are commonly used in fuel cells and water electrolyzers, their widespread commercialization is hindered by problems such as low anion conductivity and durability. Moreover, the development of high‐performance AEMs remains complex and time consuming. Here, we address these challenges by proposing an innovative approach for the efficient design and screening of AEM polymers using unsupervised machine learning. Our model, which combines principal component analysis with uniform manifold approximation and projection, generates an intuitive map that clusters AEM polymers based on structural similarities without any predefined knowledge regarding anion conductivity or other experimentally derived variables. As a powerful navigation tool, this map provides insights into promising main‐chain structures, such as poly(arylene alkylene)s with consistently high conductivity and polyolefins with exceptional performance depending on the substituent. Furthermore, assisted by key molecular descriptors, inverse analysis with this model allows targeted design and property prediction before synthesis, which will significantly accelerate the discovery of novel AEM polymers. This work represents a paradigm shift not only in AEM research but also generally in materials research, moving from black‐box predictions toward interpretable guidelines that foster collaboration between researchers and machine learning for efficient and informed material development. [ABSTRACT FROM AUTHOR]

The article titled "Cover Feature: Unsupervised Machine Learning-Derived Anion-Exchange Membrane Polymers Map: A Guideline for Polymers Exploration and Design" in the journal ChemElectroChem presents a visual map that summarizes the relationship between the chemical structure and anion conductivity of anion exchange membranes (AEMs). This map helps researchers identify regions with high-performing AEMs and design new polymer structures with superior conductivity. By studying the positions of well-performing AEMs on the map, researchers can gain insights into tailoring new AEM structures for optimized performance. The article provides more information on this topic and is authored by Tsuyohiko Fujigaya, Koichiro Kato, and their colleagues. [Extracted from the article]

Local chemical functionalization is used for defect doping of single‐walled carbon nanotubes (SWNTs), to develop near‐infrared photoluminescence (NIR PL) properties. We report the multistep wavelength shifting of the NIR PL of SWNTs through chemical reactions at local doped sites tethered to an arylaldehyde group. The PL wavelength of the doped SWNTs is modulated based on imine chemistry. This involves the imine formation of aldehyde groups with added arylamines, imine dissociation reaction, exchange reaction of bound arylamines in the imine, and the Kabachnik–Fields reaction of imine groups using diisopropyl phosphite. Using doped sites as a localized chemical reaction platform can exploit the versatile molecularly driven functionality of carbon nanotubes and related nanomaterials. A near‐infrared photoluminescent nanomaterial with versatile emission is reported. Chemical reaction at local doped sites of single‐walled carbon nanotubes shifts the emission to longer or shorter wavelengths, according to different chemical pathways. The doped sites allow for multiple chemical reactions, and realize the response based on dynamic imine bond formation and its further modification using the Kabachnik–Fields reaction. [ABSTRACT FROM AUTHOR]

Abstract: Doped semiconducting single‐walled carbon nanotubes (SWNTs) through local chemical functionalization (lf‐SWNTs) show fascinating photoluminescence (PL) that appears with a longer wavelength and enhanced quantum yield compared to the original PL of non‐modified SWNTs. In this study, we introduce an azacrown ether moiety at the doped sites of lf‐SWNTs (CR‐lf‐SWNTs), and observe selective PL wavelength shifts depending on different interaction modes of silver ion inclusion and protonation of the amino group in the ring. Interestingly, their different values of the wavelength shifts show a clear correlation with calculated electron density of the nitrogen atom in the azacrown moiety in case of the inclusion form and the protonated form. This newly‐observed responsiveness based on molecular interactions is expected to create doped sites that can versatilely control the PL functions based on molecular systems. [ABSTRACT FROM AUTHOR]

The development of synthetic methods of copper nanoparticles (Cu-NPs) on conductive supports is very challenging and receives much attention. Here, we describe a novel technique to grow stable and uniform metallic Cu-NPs homogeneously on the surface of pristine multiwalled carbon nanotube (MWNTs) catalyst support physically functionalized with a pyridine-based polybenzimidazole (PyPBI) polymer that acts as a ligand to capture the Cu-NPs. Cu-metal nanoparticles with a particle size of 5.0±0.5 nm were obtained on the surface of MWNTs with homogenous and uniform distribution. The newly prepared Cu-NPs show a remarkably enhanced air stability and electrical conductivity, compared to the current state of the art Cu-NPs, over 20 days and 500 potential cycles, respectively, with a limited degradation rate of Cu-metallic state. The PyPBI polymer plays an essential role in the stability of Cu-NPs on the surface of MWNTs through coordination with PyPBI, suppressing the Cu-degradation process, which usually decreases the Cu application efficiency. Accordingly, the prospects of applications of the present Cu-NPs composite are excellent. [ABSTRACT FROM AUTHOR]

We describe a method to control the size of platinum nanoparticles (Pt-NPs) on poly[2,2′-(2,6-pyridine)-5,5′-bibenzimidazole] (PyPBI)-wrapped pristine multi-walled carbon nanotubes (MWNTs) without changing the loading amount by adding various concentrations of sodium hydroxide (NaOH) to the ethylene glycol aqueous solutions. The Pt-NP sizes decreased from 3.8±0.4 to 1.7±0.1 nm with increasing NaOH concentrations. The mass activity of the oxygen reduction reaction was 224 mA mgPt−1 for the electrocatalyst with 3 nm Pt-NPs, in which the power density reached 350 mW cm−2, which was 1.4 times higher than that of the electrocatalyst synthesized without NaOH (250 mW cm−2) at 120 °C and without any extra humidification. The electrocatalyst synthesized from a small amount of additional NaOH (0.5 m m) in the starting solution shows an enhanced performance and similar Pt stability. More importantly, the Pt-NP size showed no effect on the Pt stability owing to the use of the PyPBI. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphitic structures (N-GSs) are promising and cheap catalyst candidates for the oxygen reduction reaction (ORR). In this paper, we describe, first, the synthesis of single-walled carbon nanotubes (SWNTs) coated by a N-GS (SWNT/N-GS) and, second, the dramatic enhancement in the activity of the ORR by using this catalyst relative to that observed for the analogue composite composed of multiwalled carbon nanotubes (MWNTs) coated by a N-GS (i.e., MWNT/N-GS). Scanning electron microscopy and gas-adsorption experiments revealed that the SWNT/N-GS formed a bundled structure and that superior gas adsorption behavior originated from this groove structure. It is assumed that the grooves of the bundled SWNT/N-GS dramatically enhance the activity of the ORR owing to superior O2 adsorption on the grooves. [ABSTRACT FROM AUTHOR]

The development of a low-cost and high-performance fuel cell is a strong social demand. Anion-exchange membrane fuel cells (AEMFCs) have recently emerged as an alternative technology to conventional fuel cells that use a proton-exchange membrane as they enable the use of cheaper metals than platinum. An AEMFC exhibiting a maximum power density of 241 mW cm−2 based on a palladium-based electrocatalyst has been developed. The polybenzimidazole-wrapped carbon nanotubes were used to anchor the palladium nanoparticles, and the material was doped using KOH to form an ideal triple-phase boundary structure around the palladium. The observed maximum power density is the highest among previously reported AEMFCs using palladium as the metal catalyst. [ABSTRACT FROM AUTHOR]

The development of a high-performance, durable, and less expensive membrane electrode assembly (MEA) composed of a polymer electrolyte membrane and electrocatalysts is important for developing fuel cells. Herein, we described the design and fabrication of an electrocatalyst with carbon black, polybenzimidazole doped with poly(vinylphosphonic acid) (PVPA), and platinum nanoparticles as an electron-conducting support material, an electrolyte, and a metal catalyst, respectively. Most importantly, we used PVPA in place of phosphoric acid, which is a widely used acid dopant, as the acid dopant for both the electrocatalyst and the polymer electrolyte membrane. We reported that the use of PVPA is crucial for the high performance of the MEA because it prevented the leaching of acid molecules from the MEA, which led to high durability compared to that of the phosphoric acid-doped MEAs. [ABSTRACT FROM AUTHOR]

All coated up: Platinum nanoparticles loaded on multiwalled carbon nanotubes (MWNTs) are coated with pyridine‐containing polybenzimidazole (PyPBI). Interestingly, although a slight decrease in the accessibility of methanol is observed after coating, the methanol oxidation activity of Pt dramatically improves after coating with PyPBI. [ABSTRACT FROM AUTHOR]

Review: 227 refs. [ABSTRACT FROM AUTHOR]