Development of core-shell nanostructured corrosion-resistant photoanodes for hydrogen generation
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Abstract
Efficient and economical photoanodes used in photoelectrochemical cells (PEC)
to produce hydrogen gas by water decomposition using sunlight must both absorb a
large portion of incident solar radiation and be stable in alkaline or acidic electrolytic
solutions. While smaller bandgaps are necessary to efficiently absorb visible light,
only large bandgap materials that absorb primarily UV radiation are known to be
stable in photoelectrochemical cells. A promising method of increasing the absorption
of photoanodes while retaining corrosion resistance is to create heterostructured
materials that feature a low-bandgap material encapsulated by a corrosion-resistant
metal oxide layer.
In this work, two methods of fabricating heterostructured photoanodes through
electrospray deposition of particles and post-deposition sintering were investigated.
In the first method, layered photoanodes were fabricated using a needle-to-plane
electrode geometry. A layer of low-bandgap TiSi2 particles was deposited onto a
titanium substrate followed by a second layer of TiO2 nanoparticles. The structure
was then sintered at 600◦C for 3 hours to promote TiSi2 interparticle necks and
TiO2 densification. In the second method, sintered core-shell particles were produced
using a novel three-electrode electrospray mixing device consisting of two opposing,
oppositely energized hypodermic needle electrodes and a planar ground electrode.
The core-shell structure was verified by encapsulating larger, 2.92μm polystyrene latex
spheres with smaller 0.96μm spheres and examining the structure under an optical [TRUNCATED]
Description
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