Solar to Chemical Energy Conversion

Volume 32 of the series Lecture Notes in Energy pp 249-260


Photoelectrochemical Approach for Water Splitting

  • Joel W. AgerAffiliated withJoint Center for Artificial Photosynthesis and Materials Sciences Division, Lawrence Berkeley National Laboratory and Materials Science and Engineering, University of California Email author 

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The splitting of liquid water into hydrogen and water via photoelectrochemical (PEC) approaches is described. If sunlight is used as the illumination source, the overall process provides a means to convert solar power into chemical energy. PEC water splitting is the direct coupling of the following processes: (1) absorption of solar light in a material and the creation of electrons and holes, (2) transport of electrons and holes to the absorber/water interface, and (3) evolution of hydrogen from the electrons and oxygen from the holes, often with the assistance of catalysts. The distinctions between this process and the related approach of coupling photovoltaic (PV) elements to hydrogen evolution (HER) and oxygen evolution (OER) catalysts will be discussed. The history of research on PEC water splitting dating back to its discovery in the early 1970s is summarized. The basic design principles of PEC water splitting device, with an emphasis on the type and number of PV absorbing elements are discussed and state of the art demonstrations are summarized.