A PEC cell based on CuO nanophotocatalysts . (courtesy of Chia-Ying Chiang)

1. Biological Templates for Anti Reflective PEC ApplicationsSheryl Ehrman, University of Maryland College Park, DMR 0806610 Outcome: Researchers at University of Maryland have created a 3D biological templated current collector with improved solar energy harvesting ability. Tobacco mosaic virus (TMV1cys), a rod like virus, 300 nm long and 18 nm wide, was used as the template. Earth abundant, non toxic copper oxide was used as the photoactive catalyst. Impact: Such films will potentially enable efficient absorption of solar energy, using the energy to split water and generate hydrogen, a renewable portable form of energy. Explanation:Hydrogen generation by splitting water via a photoelectrochemical (PEC) cell was studied. Combined effects of reducing charge carrier transport distance, increasing surface area and the suppression of light reflection make these virus templated surfaces ideal for photoelectrochemical applications. A PEC cell based on CuO nanophotocatalysts. (courtesy of Chia-Ying Chiang) Professor Sheryl Ehrman (left), of Department of Chemical and Biomolecular Engineering at the University of Maryland led the team, which developed the virus templated CuO electrode. Other team members pictured include undergraduate student KosiAroh, middle and Chia Ying Chiang, right. Courtesy of Faye Levine

2. Biological Templates for Anti Reflective PEC ApplicationsSheryl Ehrman, University of Maryland College Park, DMR 0806610 The best performing films had a photocurrent density of 3.15 mA/cm2 at a bias voltage of -0.55 V vs. Ag/AgCl (shown in figure at right). These films were made using a virus concentration of 10-3 mg/mL, which corresponded to an average distance of 500 nm between virus current collectors. Nickel and copper oxide were subsequently coated onto the virus, and the virus was removed by heat treatment, leaving the conductive, photoactive rods. The highest photocurrent density found in this sample might be due to the shortened charge carrier transport distance of less than or equal to 500 nm, which was shown to be the optimal thickness for intrinsic porous CuO samples. PEC performance of CuO deposited on plain substrates for the sputter deposition time of 5 min, 15min and 30 min along with a 15 min CuO deposition on TMV1cys patterned substrate. (courtesy of S. Ehrman)

3. Biological Templates for Anti Reflective PEC ApplicationsSheryl Ehrman, University of Maryland College Park, DMR 0806610 An integrated education and outreach effort of this project includes the design and construction of a “semiconductor photocatalyst hydrogen generator,” a copper oxide thin film deposited on a 3D current collecting substrate, which serves as a photoelectrode. The hydrogen generator has been developed and sequentially improved by graduate student Chia-Ying Chiang, REU undergraduate student Jillian Epstein, and UMD student KosiAroh, in collaboration with faculty from other disciplines: Prof. Munday from Electrical and Computer Engineering and Prof. Culver from Plant Science and Landscape Architecture. This devicehas been used as demonstration tool in open house and other outreach events. From top to down: Jillian Epstein, Chia-Ying Chiang, (courtesy of Faye Levine )Dr. Ehrman, in blue shirt, with middle school students (courtesy of Donna Hammer)