User talk:Chzz/electrocatalyst

An electrocatalyst is a catalyst that participates in electrochemical reaction.

Catalyst materials modify and increase the rate of chemical reactions without being consumed in the process. In a reaction involving an electrical current, the reaction often requires extra energy. For example, if hydrogen and oxygen are mixed, no reaction will occur, and the result is a mixed gas. If the correct electrocatalyst is added, the chemicals can react to produce water. This can be used in a fuel cell, to burn hydrogen and oxygen in a controlled manner, and produce electricity through the efficient electrolysis of water.

The extra energy required to overcome kinetic barriers is usually described in terms of low faradayic efficiency and high overpotentials. Like other catalysts, an electrocatalyst lowers the activation energy for a reaction without altering the reaction equilibrium. Furthermore there is often more then one possible reaction at the surface of an electrode. For example, during the electrolysis of water, the anode can oxidize water through a two electron process to hydrogen peroxide or a four electron process to oxygen. The presence of a electrocatalysts could facilitate either of the reaction pathways. .

An electrocatalyst can be heterogeneous such as a platinum surface or nanoparticles, or homogeneous like a coordination complex or enzyme.

Ethanol fuel cells
An electrocatalyst of platinum and rhodium on carbon backed tin-dioxide nanoparticles can break carbon bonds at room temperature with only carbon dioxide as a by-product, so that ethanol can be oxidised into the necessary hydrogen ions and electrons required to create electricity. .

Each half-cell of an electrochemical cell requires an electrocatalys specific to its half-reaction.