Homogeneous photocatalytic CO2 conversion

Scope of this topic and related important content

The content of this topic page covers information on homogeneous approaches that are relevant for the reduction of CO₂. Currently, the information on this page is limited to information on the conversion of CO₂ to CO, CH₄ and CHOOH, further extension of the content is planned in the future. To get the right context and preceding information, reading the higher level topics CO2 conversion and Photocatalytic CO2 conversion might be helpful.

Distinction from other articles within the topic Photocatalytic CO2 conversion

Photocatalytic CO2 conversion can be formally divided into processes using homogeneous catalysis or heterogeneous catalysis for the conversion of the starting material CO₂. In this article, we focus on the homogeneous catalysis which involves a catalyst that is in the same phase (usually liquid or gas) as the reactants. In this case, the catalyst and the reactants are well-mixed and form a single phase throughout the reaction. The catalyst interacts directly with the reactants, forming an intermediate complex, which then undergoes a reaction to form the desired products. Homogeneous catalysis often involves the use of transition metal complexes or organocatalysts. One advantage of homogeneous catalysis is that the catalyst can be precisely tuned and controlled to promote specific reactions. Reviews for further reading focusing on homogeneous photocatalytic CO₂ conversion are available.[CoC12]

The related topic Heterogeneous photocatalytic CO2 conversion refers to reactions that involve a catalyst that is in a different phase (typically solid) from the reactants. The reactants are in a different phase (liquid or gas) and come into contact with the solid catalyst, which is usually in the form of a powder or a material such as a modified surface or material in general. The reactants adsorb onto the surface of the catalyst, where the catalytic reaction occurs. For further information, please see chapter heterogeneous photocatalytic CO₂ conversion and literature links therein.

Important aspects of homogeneous photocatalytic CO₂ conversion

In comparison to heterogeneous photocatalytic CO₂ conversion, homogeneous processes usually benefit from a uniform distribution of the catalyst in the reaction medium, faster reaction rates due to better contact between the catalyst and reactants, and a simpler reactor design due to the application of the catalyst in solution. In heterogeneous systems, the catalyst often needs to be immobilized on a support material.

Summary of selected scientific progress

Table of all experiments that have a turnover number >100 for one of the products CO, CH₂, HCOOH, H₂ or MeOH. This table is sorted by catalyst.

TON CO, CH4, HCOOH, H2, MeOH >100, sorted by catalyst