APPLICATIONS OF TECHNOLOGY:
- Hydrogen production
- Artificial photosynthesis
- Semiconductor fabrication equipment manufacturers
- High mobility electrons and holes
- Spontaneous H2O dissociation
- D-4 architecture
A team of Berkeley Lab researchers led by Wladyslaw Walukiewicz has designed a novel photoelectrochemical cell (PEC) for production of hydrogen gas through spontaneous solar light-induced water splitting. The production of fuels through artificial photosynthesis is a strategic goal, but this technology offers in the near term an alternative to conventional hydrogen production, a $100 billion industry that currently relies on expensive and energy inefficient steam reforming of petroleum.
The Berkeley Lab team has developed a novel PEC architecture using two crystalline forms of a cadmium / zinc-oxide alloy (CdxZn1-xO). The design exploits the dramatically different electrical and optical behaviors of these crystals in their hexagonal and cubic forms, as it combines a direct-gap semiconductor layer that strongly absorbs solar photons with an indirect-gap layer that exhibits a long hole lifetime, which is needed to build a practical water splitting device. These layers are fabricated in a tandem configuration with conventional n/p Si photovoltaic cell that provides additional bias to drive the spontaneous water dissociation reaction. This architectural concept is called D-4, because it uses four photons to split each molecule of water.
The goal of artificial photosynthesis is to produce hydrogen or hydrocarbon fuels from water directly from sunlight. PECs are promising candidates for artificial photosynthesis because they have the potential to generate highly mobile electrons and holes. An abundance of these mobile charges can be harnessed within the same device to split hydrogen from water through electrolysis. There is no industrial technology today using solar light for water splitting. However, the Berkeley Lab team has shown that this novel design has the potential to produce hydrogen in an inexpensive and environmentally friendly manner.
DEVELOPMENT STAGE: Early stage
STATUS: Patent pending. Available for licensing or collaborative research.
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REFERENCE NUMBER: IB-2013-136