Using a simple solar cell and a photo anode made of a metal
oxide, HZB and TU Delft scientists have
successfully stored nearly five percent of solar energy chemically in the form
of hydrogen. This is a major feat as the design of the solar cell is much
simpler than that of the high-efficiency triple-junction cells based on
amorphous silicon or expensive III-V semiconductors that are traditionally used
for this purpose. The photo anode, which is made from the metal oxide bismuth
vanadate (BiVO4) to which a small amount of tungsten atoms was added, was
sprayed onto a piece of conducting glass and coated with an inexpensive cobalt
phosphate catalyst. “Basically, we combined the best of both worlds,” explains
Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels: “We
start with a chemically stable, low cost metal oxide, add a really good but
simple silicon-based thin film solar cell, and – voilà – we’ve just created a
cost-effective, highly stable, and highly efficient solar fuel device.”