在高温基固体氧化物电化学电池上对水电解和电氧化的机械研究
Chunjuan Zhang1, Yi Yu, Michael E Grass
1Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
Journal of the American Chemical Society
|July 5, 2013
概括
这项研究使用环境压力X射线光电子谱学 (APXPS) 来研究水分和氧化的电极. 它揭示了共享的速度限制步骤和表面二极极层,这对于理解电催化非常重要.
科学领域:
- 材料科学 材料科学 材料科学
- 电化学 电化学 电化学
- 表面科学是一门学科.
背景情况:
- 固体氧化物电化学电池 (SOC) 对于能量转化至关重要.
- 了解 (CeO2-x) 电极机制是有效催化剂的关键.
- 电催化反应,如水分裂和氧化,需要详细的机械洞察.
研究的目的:
- 为了阐明电催化水分裂和电氧化在电极上的机制.
- 为了研究表面中间体的作用和气体-固体界面上的电荷分离.
- 在前进和反向反应中识别速度限制步骤.
主要方法:
- 环境压力X射线光电子谱学 (APXPS) 在~700°C.
- 使用单面固体氧化物电化学电池 (SOC).
- 在现场XPS与DFT计算相结合.
主要成果:
- 观察到表面中间体 (OH(-) 和Ce(3+)) 的暂时积累.
- 证明电荷分离仅在电化学活跃区域.
- 确定了水电解和氧化两种常见的限速电荷转移步骤.
- 在水电解过程中揭示了OH(-) 和O(2-) 的表面电位的0.25 eV差异.
- 在氧化过程中显示OH(-) 和O(2-) 表面度的显著变化.
结论:
- 同样的电荷转移步骤是限制水电解和电氧化的速度.
- 一个诱导的表面二极管层,作为一个电化学双层,在气体-固体界面形成.
- 潜在的分离源于Ce-OH键的偏振减少,这是由于Ce(3+) 表面度的增加造成的.
更多相关视频
10:52Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
12:12On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method
Published on: March 16, 2018
相关概念视频
Batteries and Fuel Cells
A battery is a galvanic cell that is used as a source of electrical power for specific applications. Modern batteries exist in a multitude of forms to accommodate various applications, from tiny button batteries such as those that power wristwatches to the very large batteries used to supply backup energy to municipal power grids. Some batteries are designed for single-use applications and cannot be recharged (primary cells), while others are based on conveniently reversible cell reactions that...
Electrolysis
In a galvanic cell, the electrical work is done by a redox system on its surroundings as electrons produced by the spontaneous redox reactions are transferred through an external circuit. Alternatively, an external circuit does work on a redox system by imposing a voltage sufficient to drive an otherwise nonspontaneous reaction in a process known as electrolysis. For instance, recharging a battery involves the use of an external power source to drive the spontaneous (discharge) cell reaction in...
Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
Electrochemical Cells
Electrochemical cells are systems that convert chemical energy into electrical energy or use electrical energy to drive chemical reactions. They consist of two electrodes in contact with an electrolyte, where redox reactions enable electron transfer. Most electrochemical cells include two half-cells connected by an external wire for electron flow and a salt bridge for ion flow. The salt bridge contains an electrolyte solution and maintains charge neutrality by allowing ions—not electrons—to...
Concentration Cells
A concentration cell is an electrochemical cell in which the emf arises from a difference in concentration of a species between two half-cells. Unlike galvanic cells, where electrical energy comes from a chemical reaction, the driving force here is the transfer of matter from a region of higher concentration to lower concentration. The overall process is therefore physical in nature. A classic illustration is a cell made of two chlorine electrodes operating at different chlorine gas...
Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
