Apr 26 2017
(Credit: New Jersey Institute of Technology)
There has been extensive ongoing research to minimize our reliance on fossil fuels, including highly efficacious production of gaseous hydrogen fuel by disintegrating water into hydrogen and oxygen using solar energy.
In the recent past, Yong Yan—an assistant professor in the Department of Chemistry and Environmental Science at the New Jersey Institute of Technology—has reported a major advancement in the basic science, crucial for achieving this aim, in an article published in the Nature Energy journal. Yong Yan is the lead author of the article.
The article titled “Multiple exciton generation for photoelectrochemical hydrogen evolution reactions with quantum yields exceeding 100%” describes the analytical research performed by Yan in cooperation with collaborators from the National Renewable Energy Laboratory, the Colorado School of Mines, and San Diego State University. Mainly, the researchers developed a quantum dot photoelectrochemical cell with the ability to catalytically attain quantum efficiency for hydrogen gas production that surpassed 100%. An efficiency of 114% was reported in their experiments.
Quantum dots are very small semiconductor particles measuring just a few nanometers in size—where 1 nm is one-billionth of a meter. In the device developed by the researchers, semiconductor materials such as copper indium gallium arsenide and silicon were replaced by lead sulfide quantum dots, providing the benefit that the photoelectrochemical device will have the ability to convert a major portion of the solar spectrum into useful energy.
The reported device has the potential to produce two or more electrons by absorbing just one and visible solar photon, by means of a process called multiple exciton generation (MEG). The electrons are further used to reduce water to produce hydrogen gas. While globally many researchers are working toward attaining quantum efficiency closer to 100% for generating solar hydrogen, Yan’s success in directly surpassing this number is a remarkable basic advancement. This obviously shows that the photoelectrochemical cell design reported by Yan is highly efficient when compared to a quantum dot solar cell with regard to quantum yield.
Yan became part of the NJIT faculty in the year 2016 and reiterates that this development is at the basic solar science level, and also that the advancement with regard to quantum yield is not in correspondence with a considerable increase in the utmost solar-to-hydrogen conversion efficacy. However, the drastic increase in quantum yield achieved by means of a distinctive lead sulfide quantum dot photoelectrochemical device is a significant advancement in many ways, and is a result of Yan’s long-term involvement in renewable sources of energy, specifically in innovative use of solar energy.
In the case of Yan, the study described in Nature Energy concluded at NJIT after his earlier role as a postdoc at Princeton University and at the U.S. Department of Energy’s National Renewable Energy Laboratory in Colorado. The accomplishment of the cutting-edge technology was feasible due to the partial funding provided by NJIT and the Department of Energy.
These results do present the possibility of generating more energy more efficiently with such a solar-capture device in the future. This could also lead to a fundamental change in the entire process of producing hydrogen fuel. We can now obtain hydrogen fuel from water by using electricity supplied by conventional power plants that consume fossil fuels. But by building on the basic step of achieving such high quantum efficiency for solar hydrogen generation, we could make the process of producing a ‘green’ fuel much greener as well.
Yong Yan, Assistant Professor, Department of Chemistry and Environmental Science, New Jersey Institute of Technology