News — Researchers at UALR -- the University of Arkansas at Little Rock -- said they have developed a process involving nanostructure that shows great promise in boosting the efficiency of titania photoanodes used to convert solar energy into hydrogen in fuel cells.
Hydrogen, the third most abundant element on earth's surface, has long been recognized as the ultimate alternative to fossil fuels as an energy carrier. Automobiles using hydrogen directly or in fuel cells have already been developed, but the biggest challenge has been how to produce hydrogen using renewable sources of energy.
Scientists in Japan discovered in 1970 that semiconductor oxide photoanodes can harness the photons from solar radiation and used them to split a water molecule into hydrogen and oxygen, but process was too inefficient to be viable.
The UALR team, working with researchers at the University of Nevada, Reno, and supported by the U.S. Department of Energy and the Arkansas Science and Technology Authority (ASTA), has reported an 80 percent increase in efficiency with a new process.
The new process has been outlined in a recent study published in the journal Nanotechnology and also reported on the website .
Electrochemical methods were utilized to synthesize titania photoanodes with nanotubular structures. The photoanode surfaces were then subjected to low-pressure nitrogen plasma to modify their surface properties. The plasma treatment increased the light absorption by the photoanode surface. It also removed surface impurities that are detrimental for photoelectrochemical hydrogen production.
"The plasma treatment significantly enhanced the photo electrochemical activity of the samples," said Dr. Rajesh Sharma, assistant research professor in applied science in UALR's Donaghey College of Engineering and Information Technology (EIT). "The photocurrent density of plasma treated material was approximately 80 percent higher than that of the control electrodes."
Sharma's highly interdisciplinary research interests encompass materials science, electrostatics, and particulate technology. He developed an atmospheric pressure plasma reactor for surface modification of materials in a variety of applications.
In addition to his work on nanostructured materials for photoelectrochemical processes, he is also working on development of an electrodynamic screen for dust mitigation application for future Mars and Lunar missions.
In addition to Sharma, the project team includes Drs. Alexandru Biris, assistant professor in applied science and chief science officer of Nanotechnology Center at UALR; UALR Professor-emeritus Malay Mazumder, and UALR undergraduate student Jacob Bock of Cabot.
Team members in Nevada include Dr. Mano Misra in the Department of Chemical and Metallurgical Engineering at UNR, and graduate students Prajna P. Das and Vishal Mahajan at the UNR.
Dr. Steve Trigwell, manager of the Applied Science and Technology Laboratories at the Kennedy Space Center in Florida, also participated in the research.
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