In hydrogen production, the anodic oxygen evolution reaction (OER) limits the energy conversion efficiency and also impacts stability in proton-exchange membrane water electrolyzers. Widely used Ir-based catalysts suffer from insufficient activity, while more active Ru-based catalysts tend to dissolve under OER conditions. This has been associated with the participation of lattice oxygen (lattice oxygen oxidation mechanism (LOM)), which may lead to the collapse of the crystal structure and accelerate the leaching of active Ru species, leading to low operating stability. Here we develop Sr–Ru–Ir ternary oxide electrocatalysts that achieve high OER activity and stability in acidic electrolyte. The catalysts achieve an overpotential of 190 mV at 10 mA cm–2 and the overpotential remains below 225 mV following 1,500 h of operation. X-ray absorption spectroscopy and 18O isotope-labeled online mass spectroscopy studies reveal that the participation of lattice oxygen during OER was suppressed by interactions in the Ru–O–Ir local structure, offering a picture of how stability was improved. The electronic structure of active Ru sites was modulated by Sr and Ir, optimizing the binding energetics of OER oxo-intermediates.

No abstract

No abstract

No abstract

No abstract

Among various organic cathode materials, CO group-enriched structures have attracted wide attention worldwide. However, small organic molecules have long suffered from dissolving in electrolytes during charge–discharge cycles. π-Conjugated microporous polymers (CMPs) become one solution to address this issue. However, the synthesis strategy for CMPs with rich CO groups and stable backbones remains a challenge. In this study, a novel CMP enriched with CO units was synthesized through a highly efficient Diels–Alder reaction. The as-prepared CMP exhibited a fused carbon backbone and a semiconductive characteristic with a band gap of 1.4 eV. When used as an organic electrode material in LIBs, the insoluble and robust fused structure caused such CMPs to exhibit remarkable cycling stability (a 96.1% capacity retention at 0.2 A g–1 after 200 cycles and a 94.8% capacity retention at 1 A g–1 after 1500 cycles), superior lithium-ion diffusion coefficient (5.30 × 10–11 cm2 s–1), and excellent rate capability (95.8 mAh g–1 at 1 A g–1). This study provided a novel synthetic method for fabricating quinone-enriched fused CMPs, which can be used as LIB cathode materials.

In the past few years, great progress has been made in nonprecious metal catalysts, which hold the potential as alternative materials to replace platinum in proton exchange membrane fuel cells. One type of nonprecious metal catalyst, Fe− N−C, has displayed similar catalytic activity as platinum in rotating disk electrode tests; however, rapid degradation of Fe−N−C catalyst-based fuel cells is always observed, which limits its practical application. Although considerable research has been devoted to study the degradation of the catalyst itself, rather less attention has been paid to the membrane electrode assembly that makes the mechanism of fuel cell degradation remain unclear. In this work, a high-performance Fe−N−C catalyst-based membrane electrolyte assembly is prepared and used to study its degradation mechanism. The fuel cell performs with an initial peak power density as high as 1.1 W cm −2 but suffers a current loss of 52% at 0.4 V over 20 h only. The experimental and DFT calculation results indicate that Fe at active sites of catalysts is attacked by hydroxyl free radicals decomposed from H 2 O 2 , which is further leached out, causing an increase in activity loss. The ionomer of the catalyst layer and the membrane is further contaminated by the leached Fe ions, which results in an enlarged membrane resistance and cathode catalyst layer proton conduction resistance, greatly influencing the cell performance. In addition, it has been assumed in previous studies that the quick performance loss of Fe−N−C-based fuel cells is caused by water flooding within the catalyst layer, which is proved to be incorrect in our study through a dry-out experiment.

has a large dipole moment of 1.08 D. [2] By contrast, naphthalene, which only contains two fused six-membered rings, has a dipole moment of 0 D. Azulene, which was discovered and named by Piesse in 1863, has attracted considerable interest since its discovery in petroleum exploitation. [3] In 1937, Plattner and Pfau published their pioneering report on the synthesis of azulene. [4] However, their method was not practical due to its low azulene yield. In the 1950s, Ziegler and Hafner formulated a highly efficient and practical method for synthesizing azulene and its derivatives. [5] Because azulene is difficult to synthesize and has a low natural abundance, research on azulene-based molecules and materials is less advanced relative to research on its isomer. Direct functionalization of 1-and/ or 3-positions is a common and effective method of producing azulene derivatives. However, direct functionalization of other positions is much harder, e.g., bromination of 6-and 1,3-positions, [6] nucleophilic addition to obtain 6-subsituted azulene, [7] borylation at 2-position, [8] arylation at the 2-position, [9] and so on. The electron distribution in the front-line molecular orbitals (MOs) must usually be considered when functionalizing azulene. Because of resonance delocalization, the oddnumbered position of azulene, which is electron-rich, easily reacts with electrophilic compounds. Among the odd-numbered azulene varieties, 1-and 3-azulene have the highest activity. [10] By Azulene has a considerably larger dipole moment than its isomer naphthalene; it also has unique physicochemical properties, including different reactivities on five-and seven-membered rings, a dark color, a narrow gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital, and stimulus response. Although azulene was discovered more than 100 years ago, the use of azulene-based derivatives can be traced back to five centuries ago. Due to its unusual structure, azulene-based molecules and materials are widely used in various fields. However, studies on azulene-based materials have long been hindered by difficulties in the synthesis. Considerably fewer studies have been conducted on azulene-based derivatives than on naphthalene-based derivatives. This perspective paper mainly introduces recent reports on the synthesis of azulene-based aromatic molecules, conjugated polymers, and coordination polymers, in addition to azulene-based frameworks. The structure-property relationship, optoelectronic applications, and energy-related applications of azulene-based derivatives are reviewed, including their use in near-infrared absorption, organic field-effect transistors, organic solar cells, and microsupercapacitors.