空结构的Pt-Rh电催化剂对完成乙醇电氧化的封闭效应
Kyeong-Ho Kim1,2, Gustavo M Hobold1, Katherine J Steinberg1
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
ACS nano
|July 10, 2023
概括
优化电催化剂附近的局部pH值可以增强燃料电池的乙醇氧化反应 (EOR). 微调电极多孔性与-空心球通过管理氧化物吸附,提高了活动和耐用性.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 能源转换 能源转换
背景情况:
- 氧化吸附 (OHads) 阻碍了直接乙醇燃料电池中的乙醇氧化反应 (EOR) C-C 键裂变.
- 优化OHads覆盖面对于完全的乙醇氧化 (C1通路) 和燃料电池耐用性至关重要.
- 局部pH操纵为管理OHads提供了替代低性电解质的替代方案.
研究的目的:
- 研究电极多孔性和Pt-Rh空心球体催化剂特性对局部pH和EOR性能的影响.
- 为了提高直接乙醇燃料电池的C1路径选择性和耐用性.
主要方法:
- 制造具有不同颗粒大小 (250和350纳米) 和质量负载的Pt-Rh空心球体电催化剂.
- 调节电极的多孔性,通过影响H+释放和OH-质量传输来控制局部pH.
- 乙醇氧化反应活性的电化学表征,C1通路法拉代的效率和耐久性.
主要成果:
- Pt0.5Rh0.5空洞球体 (250 nm) 实现了高活性 (1629 A gPtRh-1),比最先进的二进制催化剂高50%左右.
- 使用较小颗粒大小增加的质量负荷导致耐用性增加2倍,C1通路FE增加38.3%.
- 更多孔的电极创造了局部酸性环境,优化了OH覆盖面,并促进了所需的C1路径.
结论:
- 微调电极孔隙与Pt-Rh空洞球体有效地操纵局部pH,以改善EOR.
- 这一策略增强了C1路径的选择性,并显著提高了燃料电池的耐用性.
- 利用当地的pH波动为推进直接乙醇燃料电池技术提供了一个有希望的途径.
相关概念视频
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.4K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.4K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.2K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
12.2K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.0K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.8K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
7.8K
02:23Alcohols from Carbonyl Compounds: Reduction
10.5K
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
10.5K
02:57Sharpless Epoxidation
4.1K
The conversion of allylic alcohols into epoxides using the chiral catalyst was discovered by K. Barry Sharpless and is known as Sharpless epoxidation. The use of a chiral catalyst enables the formation of one enantiomer of the product in excess. This chiral catalyst is mainly a chiral complex of titanium tetraisopropoxide and tartrate ester (specific stereoisomer). The stereoisomer used in the chiral catalyst dictates the formation of the enantiomer of the product. In other words, the use of...
4.1K