REVIEW | doi:10.20944/preprints202210.0388.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: oxygen evolution reaction; water electrolysis; iridium-based catalysts; engineering strategy; acidic OER
Online: 25 October 2022 (10:56:06 CEST)
Proton exchange membrane water electrolyzers (PEMWEs) for water electrolysis have received tremendous attention due to their immediate response, high proton conductivity, low ohmic losses and gas crossover rate. However, design high activity, economical and long-term durable electrocatalysts in an acidic environment is still the bottleneck to realize the large-scale commercialization of PEMWEs. Iridium-based materials represent one of the most promising classes of oxygen evolution reaction (OER) catalysts due to their intrinsic stability in acid media over ruthenium-based counterparts. However, only a few innovative approaches have been developed to synthesizing iridium-based catalysts (IBCs) in the past decade, mainly due to achieving high activity may deteriorate the stability of IBCs. Accordingly, various engineering strategies of optimizing IBCs have been proposed to address this issue, including doping engineering, morphology engineering, crystal phase engineering and support engineering. Herein, a critical overview focusing on various synthesis and modulation strategies of IBCs is presented, based on an in-depth understanding of the relationship between electronic structures, charge redistribution and activity as well as stability of the electrocatalysts. In addition, the unprecedented achievements in PEMWEs are summarized. The reaction mechanisms and future perspectives are critically discussed to inspire more rational design of IBCs toward practical applications.
ARTICLE | doi:10.20944/preprints202306.0837.v1
Subject: Biology And Life Sciences, Insect Science Keywords: New taxon; morphological characteristics; ITS2; Medicago sativa
Online: 12 June 2023 (13:16:07 CEST)
Three new species of the Sequester group of Pteromalus (Habrocytus) (Hymenoptera: Pteromalidae: Pteromalinae), Pteromalus (Habrocytus) boleensis Yan et Li sp. nov., Pteromalus (Habrocytus) longepedicelus Yan et Li sp. nov., and Pteromalus (Habrocytus) robustus Yan et Li sp. nov. are described and illustrated based on adult morphology and molecular data from Xinjiang, China. The DNA barcodes (ITS2) of Pteromalus (Habrocytus) boleensis sp. nov. and Pteromalus (Habrocytus) robustus sp. nov. have been generated and compared with all existing sequences of the Sequester species group. The results of morphological taxonomy and molecular identification are consistent. A key to all known species of the Sequester group in the world is provided.
REVIEW | doi:10.20944/preprints202211.0444.v1
Subject: Chemistry And Materials Science, Electrochemistry Keywords: Density functional theory; Descriptor; Carbon-based materials; Electrocatalysis; Low dimension
Online: 23 November 2022 (11:04:03 CET)
Low-dimensional carbon-based (LDC) materials have attracted extensive research attentions in electrocatalysis because of their unique advantages such as structural diversity, low cost, and chemical tolerance. They have been widely used in a broad range of electrochemical reactions to relief environmental pollution and energy crisis. Typical examples include hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR). Traditional “trial and error” strategies seriously slowed down the rational design of electrocatalysts for these important applications. Recent studies show that the combination of density functional theory (DFT) calculations and experimental research is capable of accurately predicting the structures of electrocatalysts, thus could reveal the catalytic mechanisms. Herein, current well-recognized collaboration methods of theory and practice are reviewed. The history of modern DFT, commonly used calculation methods, and basic functionals are briefly summarized. Special attention is paid to descriptors that are widely accepted as a bridge links the structure and activity, and the breakthroughs for high-volume accurate prediction of electrocatalysts. Importantly, correlating multiple descriptors are used to systematically describe the complicated interfacial electrocatalytic processes of LDC catalysts. In addition, machine learning and high-throughput simulations are crucial in assisting the discovery of new multiple descriptors and reaction mechanisms. This review will guide the further development of LDC electrocatalysts for extended applications from the aspect of DFT computations.
ARTICLE | doi:10.20944/preprints202308.1077.v1
Subject: Chemistry And Materials Science, Paper, Wood And Textiles Keywords: waterborne acrylic paint; painting process; drying time; film properties
Online: 15 August 2023 (07:09:23 CEST)
Herein, bamboo-laminated lumber for furniture was coated with waterborne acrylic paint. The effects of different painting techniques and quantities on the drying rate, smoothness, hardness, adhesion and wear resistance of the paint film were investigated. Then, the thermal properties of the paint were analysed using thermogravimetry and differential scanning calorimeter to examine the film-forming mechanism. The results showed that painting technique had no effect on the drying time, flatness, hardness and adhesion of the paint film, but it influenced the wear resistance. Herein, the films’ flatness showed little variation with different painting methods (one-layer primer one-layer topcoat, one-layer primer two-layer topcoat, two-layer primer one-layer topcoat and two-layer primer two-layer topcoat). The drying time for primer surfaces/solids was 8min/8.5 min, while it was 6.5/7 min for topcoats. The paint films exhibited grade B hardness and grade 0 adhesion and the better wear resistance when using one-layer primer one-layer topcoat at 51.24 mg·100 r−1. The amount of paint applied significantly affected the drying time and flatness of the paint film. As the quantity increased, the drying time of the paint’s surfaces and solids also increased, whereas the film’s flatness initially increased before decreasing. The film’s optimal adhesion, hardness and wear resistance values were grade 0, grade B and 51.24 mg·100 r−1, respectively, when 80 g/m2 of paint was applied. Thermal analysis of the primer and topcoat showed that water decomposition occurred at 100℃ and thermal decomposition of organic components occurred at 350℃. The primer and topcoat exhibited the same weight loss, but primer’s thermal loss rate was higher than that of topcoat. Consequently, the topcoat displayed better thermal stability than the primer.