A new method of water splitting could facilitate easier solar energy harvesting and storage, shows researchers from Binghamton University.
According to Associate Professor of Physics Louis Piper, “The key idea is to generate a solar fuel: hydrogen gas, which can be burnt to release energy on demand without releasing carbon dioxide. For water splitting, we use visible light to generate photo-excited negative electrons and positive holes that are then separated in order to catalyze water into oxygen and hydrogen gases. Storing gases is more straightforward (and cheaper) than employing battery setups, so this approach has the benefit of clean energy harvesting and storage.”
The scientists determined that doping into vanadium pentoxide nanowires raises the highest filled energy levels for more efficient hole transfer from the quantum dots to nanowires, i.e., separation of the photo-excited electrons and holes.
“If you don’t dope, then there is a buildup of positive holes that corrode the quantum dots (referred to as photo-corrosion),” said Piper. “Using computation and chemical intuition, we predicted doping with Sn2+ ions would result in excellent energy alignment and efficient charge separation. We saw a tenfold increase in the amount of solar-harvested hydrogen we obtained.”
The is now working to enhance the hydrogen gas evolution by decorating the quantum dots with platinum.