(418g) Titanium Supported Iron Oxide for Photo-Electrochemical Hydrogen Production

The
total global energy consumption today is about 14 TW and is expected to double
by the year 2050. There is a heavy dependency on fossil fuels to meet this
energy demand, which contributes significantly to global CO₂
emissions. Hydrogen is a clean energy carrier, which could supply future energy
demand whilst minimising CO₂ emissions, provided that the hydrogen
is produced in a clean and sustainable process such as by photo-electrolysis.

Photo-electrolysis
offers a potentially elegant solution to the capture of solar energy by
directly facilitating the splitting of water to produce hydrogen and oxygen. The
feasibility of this process is well established and much work is devoted to
finding and developing improved photo anodes for oxygen evolution.

The
current state of the art for photo-electrolysis systems is restricted to small,
lab-scale, photo-electrochemical cells which cannot produce useful quantities of
hydrogen. In order to scale up photo-electrochemical systems the photo-electrodes
need to be deposited onto larger electrode areas. Conventional support electrodes
are ITO (indium doped tin oxide) or FTO (fluorine doped tin oxide) substrates. Our
previous work has shown that the use of fluorine-dope tin oxide (FTO) substrates
would result in a large lateral potential drop, rendering most of the exposed
photo electrode surface area inactive for the photo oxidation/reduction of
water. This can be avoided if a more conductive substrate such as stainless
steel or titanium is employed.

In this
paper we will present and compare our results of the photo-activity of Fe₂O₃
deposited by spray pyrolysis onto both, FTO and titanium substrates (Figure 1).
We will show that the control of the metal oxide interface layer is crucial in
achieving high photocurrents in the case of titanium substrates.

Figure
1:    Cyclic
voltamogram of Fe₂O₃ deposited onto TEC-8 FTO and
titanium substrate under

42 Wm^-2
white light illumination