Energy Conversion in Natural and Artificial Photosynthesis

Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil-fuel dependence has severe consequences, including energy security issues and greenhouse gas emissions. The consequences of fossil-fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and in artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices, including photoelectrochemical cells, for solar energy conversion.

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► Solar energy conversion uses light harvesting, charge separation, catalysis, and photoprotection
► Nature uses large antenna, but fewer light-harvesting units are optimal for artificial systems
► Natural photosystems rapidly separate charges to avoid recombination
► Nature uses abundant Mn for water oxidation catalysis, but the best artificial catalysts use Ru or Ir
► Photoprotection in artificial systems may increase the useful life of solar devices