New standard for green hydrogen technology set by Rice U engineers - ScienceDaily -

New standard for green hydrogen technology set by Rice U engineers – ScienceDaily

Rice University engineers can convert sunlight into hydrogen with record efficiency thanks to a device that combines next-generation halide perovskite semiconductors and electrocatalysts into a single rugged, cost-effective and scalable device.

The new technology is an important step forward for clean energy and can serve as a platform for a wide range of chemical reactions that use solar-powered electricity to convert raw materials into fuel.

The lab of chemical and biomolecular engineer Aditya Mohite has built an integrated photoreactor using an anti-corrosion barrier that insulates the semiconductor from water without impeding electron transfer. According to a study published in Nature Communicationsthe device achieved an efficiency of converting 20.8% of solar energy into hydrogen.

“Using sunlight as an energy source to manufacture chemicals is one of the biggest hurdles to the clean energy economy,” said Austin Fair, PhD student in chemical and biomolecular engineering and one of the study’s lead authors. “Our goal is to build economically viable platforms that can generate solar-derived fuels. Here, we designed a system that absorbs light and complements the electrochemical chemistry of water splitting on its surface.”

The device is known as a photoelectrochemical cell because the absorption of light, its conversion into electricity, and the use of electricity to power a chemical reaction all occur in the same device. So far, the use of photovoltaic technology to produce green hydrogen has been hampered by the low efficiency and high cost of semiconductors.

“All devices of this type produce green hydrogen using only sunlight and water, but our devices are exceptional because they are record-breaking and use very cheap semiconductors,” Fehr said.

Mohit’s lab and collaborators created the device by turning highly competitive solar cells into a reactor that can use harvested energy to split water into oxygen and hydrogen. The challenge they had to overcome was that halide perovskite is very unstable in water and the coating used to insulate the semiconductor ended up either disrupting or damaging its function.

“Over the past two years, we’ve gone back and forth trying different materials and technologies,” said Michael Wong, a chemical engineer at Rice and a co-author of the study.

After lengthy experiments failed to yield the desired result, the researchers finally came up with a solution that worked.

“Our main insight was that you need two layers on the barrier, one to keep out the water and one to make good electrical contact between the perovskite layers and the protective layer,” Fehr said. “Our results are the highest efficiencies for photovoltaic cells without a solar concentrator, and the best overall for those using halide perovskite semiconductors.

“It’s a first in a field that has historically been dominated by expensive semiconductors, and it may represent a path to commercial viability for this type of device for the first time ever,” Fehr said.

The researchers showed that their barrier design works with different interactions and with different semiconductors, making it applicable across many systems.

“We hope that such systems can serve as a platform to drive a wide range of electrons for fuel formation reactions using abundant feedstocks with only sunlight as the energy input,” Mohit said.

“With further improvements in stability and range, this technology could unlock the hydrogen economy and change the way humans make things from fossil fuels to solar fuels,” Fehr added.

Rice graduate students Ayush Agrawal and Faiz Mandani are lead authors of the study along with Fehr. The work was also authored in part by the National Renewable Energy Laboratory, which is operated by the Alliance for Sustainable Energy LLC for the Department of Energy under Contract DE-AC36-08GO28308.

Mohiti is associate professor of chemical and biomolecular engineering and faculty director of the Rice Engineering Initiative for Energy Transition and Sustainability, or REINVENTS. Wong is the Tina and Sunit Patel Professor of Molecular Nanotechnology, Chair and Professor of Chemical and Biomolecular Engineering, Professor of Chemistry, Materials Science and Nanotechnology, as well as Civil and Environmental Engineering.

The research was supported by the Department of Energy (DE-EE0008843), Sarin Energy Corporation and the Rice Joint Equipment Authority.