Year: 2021
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Cubic silicon carbide (3C-SiC) is a promising photoelectrode material for solar water splitting due to its relatively small band gap (2.36 eV) and its ideal energy band positions that straddle the water redox potentials. However, despite various coupled oxygen-evolution-reaction (OER) cocatalysts, it commonly exhibits a much smaller photocurrent (<∼1 mA cm –2 ) than the expected value (8 mA cm –2 ) from its band gap under AM1.5G 100 mW cm –2 illumination. Here, we show that a short carrier diffusion length with respect to the large light penetration depth in 3C-SiC significantly limits the charge separation, thus resulting in a small photocurrent. To overcome this drawback, this work demonstrates a facile anodization method to fabricate nanoporous 3C-SiC photoanodes coupled with Ni:FeOOH cocatalyst that evidently improve the solar water splitting performance. The optimized nanoporous 3C-SiC shows a high photocurrent density of 2.30 mA cm –2 at 1.23 V versus reversible hydrogen electrode (V RHE ) under AM1.5G 100 mW cm –2 illumination, which is 3.3 times higher than that of its planar counterpart (0.69 mA cm –2 at 1.23 V RHE ). We further demonstrate that the optimized nanoporous photoanode exhibits an enhanced light-harvesting efficiency (LHE) of over 93%, a high charge-separation efficiency (Φ sep ) of 38%, and a high charge-injection efficiency (Φ ox ) of 91% for water oxidation at 1.23 V RHE, which are significantly outperforming those its planar counterpart (LHE = 78%, Φ sep = 28%, and Φ ox = 53% at 1.23 V RHE ). All of these properties of nanoporous 3C-SiC enable a synergetic enhancement of solar water splitting performance. This work also brings insights into the design of other indirect band gap semiconductors for solar energy conversion.
Source: ACS Nano
Institution: Linköping University
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,000
Awards: Innovative Photoelectrode for Conversion of CO2 and Water into Fuels using Solar Energy, G4383173612, Oxide Semiconductors Core-Shell Nanowires for Solar Water Splitting, G712881263, Graphene-based Photoelectrode for Stable and Efficient Conversion of Solar Energy into Hydrogen Fuel, G8901559854
OpenAlex ID: W3132589079