The most efficient materials are far too expensive to produce fuel at a price that can compete with gasoline. In this new method, researchers combined cheap, oxide-based materials to split water into hydrogen and oxygen gases using solar energy with a solar-to-hydrogen conversion efficiency of 1.7 percent - the highest reported for any oxide-based photoelectrode system.

"In order to make commercially viable devices for solar fuel production, the material and the processing costs should be reduced significantly while achieving a high solar-to-fuel conversion efficiency," explained Kyoung-Shin Choi, a chemistry professor at the University of Wisconsin-Madison.

Choi created solar cells from an inorganic compound called bismuth vanadate using electro-deposition - the same process employed to make gold-plated jewellery or surface-coat car bodies - to boost the compound's surface area to a remarkable 32 square metres for each gram.

"Without fancy equipment, high temperature or high pressure, we made a nanoporous semiconductor of very tiny particles that have a high surface area," added Choi.

More surface area means more contact area with water, and, therefore, more efficient water splitting.

"Since no one catalyst can make a good interface with both the semiconductor and the water that is our reactant, we choose to split that work into two parts," noted Choi.

“The iron oxide makes a good junction with bismuth vanadate and the nickel oxide makes a good catalytic interface with water. So we use them together,” he added.

This resulted in the construction of an inexpensive all oxide-based photoelectrode system with a record high efficiency, claimed the study published in the journal Science.