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Water splitting with silicon p-i-n superlattices suspended in solution
Taylor S Teitsworth1, David J Hill1, Samantha R Litvin1
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Nature
|February 9, 2023
Summary
Researchers developed silicon nanowire (SiNW) particle suspension reactors for efficient photoelectrochemical water splitting. These SiNWs generate high photovoltage, enabling hydrogen fuel production using sunlight.
Area of Science:
- Materials Science
- Renewable Energy
- Nanotechnology
Background:
- Photoelectrochemical (PEC) water splitting for hydrogen fuel production has been researched for 50 years but hasn't become widespread.
- Standard silicon (Si) p-n junctions are unsuitable for water splitting due to insufficient photovoltage.
- Particle suspension reactors (PSRs) offer a potentially low-cost alternative to planar PEC systems.
Purpose of the Study:
- To develop efficient silicon-based particle suspension reactors for water splitting.
- To overcome the limitations of traditional planar PEC devices and standard Si junctions.
- To explore the potential of multijunction silicon nanowires (SiNWs) in PSRs.
Main Methods:
- Synthesized multijunction SiNWs with p-type-intrinsic-n-type (p-i-n) superlattices.
- Co-functionalized SiNWs with oxygen and hydrogen evolution co-catalysts via spatioselective photoelectrodeposition.
- Investigated water splitting performance under 1 sun illumination and across various wavelengths.
Main Results:
- Achieved tunable photovoltages exceeding 10 V under 1 sun illumination using p-i-n SiNWs.
- Enabled water splitting at infrared wavelengths up to approximately 1,050 nm.
- Demonstrated that photonic characteristics of SiNWs dictate hydrogen generation efficiency and spectral dependence.
Conclusions:
- Multijunction SiNWs integrated into PSRs offer a novel approach for water-splitting reactors.
- This design leverages the photonic advantages of tunable geometry and the material benefits of silicon.
- Further development is needed to improve initial energy conversion efficiencies for widespread adoption.
