Electrocatalysis

The electrocatalysis is a branch of heterogeneous catalysis , through which the activation energy of electrochemical reaction is decreased. It allows high currents with low overvoltages in electrochemical processes . Well-known electrocatalysts are platinum and its metal alloys, for example for use in fuel cells .

Fuel cell

A hydrogen - fuel cell has the following half-reactions of:

Anode :

${\displaystyle \mathrm {2\ H_{2}\to 4\ H^{+}+4\ e^{-}} }$
Oxidation / electron donation

Cathode :

${\displaystyle \mathrm {O_{2}+4\ H^{+}+4\ e^{-}\to 2\ H_{2}O} }$
Reduction / electron uptake

Overall reaction:

${\displaystyle \mathrm {2\ H_{2}+O_{2}\to 2\ H_{2}O} }$
Redox reaction / cell reaction

Theoretically, such a fuel cell can have an efficiency of 83% at 25 ° C. In comparison, an internal combustion engine that is operated at 500 ° C. has a maximum theoretical efficiency of 53%. The efficiency achieved when generating electrical energy by means of a fuel cell is in practice higher than that of internal combustion engines , but the theoretically possible efficiency is not achieved. However, the efficiency is improved by using an electrocatalyst.

Web links

• Katharina Krischer: Electrocatalysis, a key to improving electrochemical energy converters. In: The current newsreel of the GDCh. Retrieved July 7, 2017.

literature

• Michael Bron: Physical Chemistry 2008 . In: News from chemistry . tape 57 , no. 3 , 2009, p. 287-296 , doi : 10.1002 / nadc.200960748 .

Individual evidence

1. ↑ Fuel Cells: Fuel Cell Efficiency. World Energy Council , archived from the original on February 9, 2014 ; accessed on July 7, 2017 (English).