Institut de Chimie Moléculaire et des Matériaux d'Orsay

Laboratoire de Chimie Inorganique - LCI

Artificial Photosynthesis

Ally Aukauloo, Marie Sircoglou
Stéphanie Cherdo (Ph.D. candidate), Christian Herrero (post-doc), Allison Tebo (visiting Ph.D. student)

Artificial Photosynthesis

Photosynthesis is the natural process where water is the fuel to fix carbon dioxide in the form of energy rich synthons and providing O2 as byproduct. Performing such reactions at a lab level and implementing these metal complexes for the production of a solar based fuel is our target. We are developing molecular based complexes that can replicate the main events in natural photosynthesis for the development of the so-called artifical photosynthesis.

Nature’s secrets!

During photosynthesis, absorption of light initiates a series of energy and electron transfer processes that lead to the oxidation of water (1) in order to produce reducing equivalents that can then drive the reduction of either CO2 into higher carbohydrates (2), or protons intoH2(3):


(1) 2 H2O + 4 hν → O2 + 4 H+ + 4 e-
(2) n CO2 + 2n e- + 2n H+ → (CH2O)n + n/2 O2
(3) 2 H+ + 2 e-→ H2

Photosystem II is the enzyme responsible for the photo-oxidation of water. It is often conceptualized as being made up of two parts:

  • a photochemical charge separating device which produces a reductant and a strong oxidant species on opposite sides of the membrane
  • a catalytic device (Oxygen Evolving Complex, OEC) in which the oxidizing power is accumulated in a cluster of high valence manganese ions.


Towards An Artificial Construct for photooxidation of water.

A molecular system designed to mimic the reactions leading to water oxidation should be capable of efficient absorption of visible light and conversion of this energy into a chemical potential through charge accumulation processes. The energy accumulated should then be transferred via catalytic chemical reactions into a fuel where it is stored in the form of chemical bonds. This system should therefore consist of a photoactive unit (PU) and a catalytic unit (CU) that, in principle, would be connected through an electron relay moiety (ER) in order synchronize fast photochemical processes, such as electron and proton transfers, with slow processes such as bond making-breaking steps, that happen during chemical reactions. One step further, grafting of designed PU-ER-CU molecules onto surfaces can allow for fast photo-induced electron transfer reactions and more importantly, the recovery of the reaction products of water splitting, H+ and e- in order to produce hydrogen fuel.


Theme 1 : Mimicking the Catalytic Unit of Photosystem II

Theme 2 : Building Photoactive unit and Electron relay

Theme 3 : Photooxidation of organic substrates using water as oxygen source

Theme 4 : Metal complexes for H2 production




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