ポリオックスメタラートクラスターを組み込んだ高エントロピーオキシード サブ-1 nm ナノワイヤ
Junli Liu1, Yuqi Li2, Zhao Chen2
1Engineering Research Center of Advanced Rare Earth Materials, Department of Chemistry, Tsinghua University, Beijing100084, China.
Journal of the American Chemical Society
|December 8, 2022
まとめ
研究者らは,ポリオキシメタラートクラスターを使用して,サブ-1ナノメートルの高エントロピー酸化物 (HEO) ナノワイヤを作成する新しい方法を開発しました. これらのHEOナノワイヤは,ナトリウムイオン電池の陽極として優れた性能を示し,安定性と容量を向上させています.
科学分野:
- 材料科学
- ナノテクノロジー
- 電気化学
背景:
- 高エントロピーの酸化物 (HEO) は独特の特性を持っていますが,ナノスケールでの測定は依然として困難です.
- サブ1ナノメートルのスケールの材料は性能が向上しますが,正確な制御で合成することは困難です.
研究 の 目的:
- 構成と形状を制御できる高エントロピー酸化ナノワイヤ (HEO-SNWs) を合成するための汎用戦略を開発する.
- これらの新しいHEO材料をナトリウムイオン電池の陽極として適用することを調査する.
主な方法:
- ポリオックスメタラート (POM) クラスターを模板として利用し,複数の不混合金属酸化物を1nm以下のナノワイヤに組み込みました.
- 金属酸化物とPOM種の柔軟な調節で温和な条件 (140 °C) で合成されたHEO-POM SNWs.
- ナイオン電池におけるアノドとしてのHEO-POM SNWの電気化学性能を評価した.
主要な成果:
- HEO-POM SNWsの多様な範囲をsub-1 nmスケールで成功裏に合成しました.
- ナイオン電池で優れた電気化学的性質を証明し,金属酸化物種が増えると性能が向上する.
- 優れた安定性と長いサイクル寿命を達成し,10Cで5000サイクル後に約92%の容量を保持します.
結論:
- 開発されたPOMテンプレート戦略は,1nm以下のHEOsの容易かつ制御可能な合成を可能にします.
- HEO-POM SNWは,ナトリウムイオン電池の高性能アノド材料として大きな可能性を秘めている.
- この研究は,軽度な条件下でナノスケールHEOの設計と準備に関する新しい洞察を提供します.
関連する概念動画
02:58Properties of Transition Metals
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
02:21Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.