Molecular artificial photosynthesis

Abstract

The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research has been devoted to this topic recently. Nature has been using sunlight as the primary energy input to oxidise water and generate carbohydrates (solar fuel) for over a billion years. Inspired, but not constrained, by nature, artificial systems can be designed to capture light and oxidise water and reduce protons or other organic compounds to generate useful chemical fuels. This tutorial review covers the primary topics that need to be understood and mastered in order to come up with practical solutions for the generation of solar fuels. These topics are: the fundamentals of light capturing and conversion, water oxidation catalysis, proton and CO2 reduction catalysis and the combination of all of these for the construction of complete cells for the generation of solar fuels.

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

“…This work presents a photoanode for solar water splitting involving a molecular catalyst 6 and elucidates the dynamical details of the catalytic mechanism of the first water oxidation step. For the first time the proton and the electron dynamics is followed during the catalytic process, unambiguously showing the PCET nature of this reaction.…”

“…The design of artificial solar energy conversion devices 5 aims at applying essential fundamental principles governing natural photosynthesis, while aiming for dedicated solar to fuel conversions, which allows using a much simpler structure. [6][7][8][9][10][11][12] A photoelectrochemical solar fuel cell device combines the functions of light harvesting, charge separation and catalysis. [13][14][15] In the last decade several systems have been proposed employing either metal oxide nanoparticles 8,[16][17][18][19][20][21][22][23][24] or molecular complexes 8,[25][26][27][28] as water oxidation catalyst (WOC).…”

CO2 Reduction: From the Electrochemical to Photochemical Approach

“…Yet it is highly challenging (if not impossible) for a single‐component photocatalyst to simultaneously meet all these criteria. In nature, photosynthesis takes place in two individual but well concerted steps in photosystems I and II that harvest 700 and 680 nm photons, respectively 214, 215. The sites for oxygen evolution and CO 2 fixation are also spatially separated.…”

Tracking the Structural and Electronic Configurations of a Cobalt Proton Reduction Catalyst in Water

“…In this context, the use of molecular cobalt-based catalysts, stabilized by nitrogen donor ligands, has proven to be a good alternative given the high turnover numbers and stability achieved under catalytic conditions. [4][5][6][7][8][9] The catalyst precursor [LCo III Cl 2 ] + (L = macrocyclic ligand) in Scheme 1 belongs to this family of HEC and has been used in electrochemical as well as photochemical catalysis showing excellent results. [10][11][12][13][14] In contrast to many other molecular HEC that are active only in organic solvents, complex [LCo III Cl 2 ] + works in pure aqueous conditions showing remarkable stability over a period of several hours.…”