Researchers from the Stanford University have developed a new way to make hydrogen fuel from water and also improve grid-scale batteries.


In order to improve hydrogen production, the Stanford engineer Yi Cui and colleagues created microscopic arrays featuring thousands of silicon nanocones, each about 600nm tall.

Stanford Institute for Materials and Energy Sciences principal investigator Cui said that the nanocone structures have validated promising light-trapping capability over a broad range of wavelengths.

During an experiment, the researchers placed the nanocone arrays on a thin film of bismuth vanadate, which is said to be an inexpensive compound capable of absorbing sunlight and generate modest amounts of electricity.

The researchers then deposited the two layers on a solar cell made of promising photovoltaic material perovskite.

The three-layer tandem device, upon submerging, started splitting water at a solar-to-hydrogen conversion efficiency of 6.2%.

The result also matches with the theoretical maximum rate for a bismuth vanadate cell, the researchers said.

Chi said: "The tandem solar cell continued generating hydrogen for more than 10 hours, an indication of good stability.

"Although the efficiency we demonstrated was only 6.2%, our tandem device has room for significant improvement in the future."

Additionally, the researchers developed a new battery design for grid-scale storage.

The battery features zinc and nickel electrodes separated by a plastic insulator and wrapped a carbon insulator around the edges of the zinc electrode.

Toyota Central R&D Labs visiting scientist Shougo Higashi said: "With our design, zinc ions are reduced and deposited on the exposed back surface of the zinc electrode during charging.

"Therefore, even if zinc dendrites form, they will grow away from the nickel electrode and will not short the battery."

During testing, the team demonstrated the stability of the battery by charging and discharging it more than 800 times without shorting.
Cui added:"Our design is very simple and could be applied to a wide range of metal batteries.".

Image: Stanford engineers created arrays of silicon nanocones to improve solar cells performance. Photo: courtesy of Wei Chen and Yongcai Qiu/Stanford University.