Frank E. Osterloh , University of California (Davis)
The goal of this project is to test and develop novel materials for photocatalytic conversion of cellulosic biomass into gaseous fuels. This reaction converts abundant photochemical energy (sunlight) and residues from the forest and food industries (wheat straw and wood chips) into usable fuels, incl. hydrogen, and potentially methane and ethane. Impact of Research
Work Tasks Completed: After nanostructured Cu2O, CuO, V2O5, CuSe proved not suitable for photocatalytic biomass conversion (see 2010 progress report), the project focused on VO2, WO3 and TiO2, using methanol and glucose as biomass models.
1. In the hands of my student Andy Frame (Ph.D. in Dec 2010), VO2 had shown photocatalytic H2 production ability from glucose and methanol under visible irradiation (see 2010 progress report). But after Andy graduated in December, we could not reproduce hydrogen evolution from this material, even after I assigned another student (Sarah Gee, M.S. June 2011) to specifically retest the material under various conditions (pH, concentration, UV versus visible irradiation). The publication of this data has to await clarification of the issue, hopefully in early 2012, with support from another funding source.
2. Both, WO3 and TiO2 were found to have photocatalytic activity for glucose oxidation under UV and visible irradiation. While H2 did produce hydrogen from an irradiated catalyst suspension, WO3 did not because its conduction band is not sufficiently reducing. Thus, to extract the photochemical energy from these catalysts, films of TiO2 and WO3 were made on gold electrodes and illuminated in aqueous glucose solution. In connection with a platinum –air electrode these films produced electrical power equivalent to 1.7 % (0.19%) power conversion based on the incident irradiation (395 nm light from a Light Emitting Diode, LED). Under sunlight, 0.5 % (0.09%) of the sunlight was converted into electricity (not fuel). Under these conditions, 84% (19% in the case of WO3) of the power was produced by glucose oxidation. A publication on this material is in preparation.
In summary, this project did not result in any new catalysts for the conversion of cellulose into gaseous fuels, but established photoelectrochemical oxidation as a new method to extract usable energy (electricity) from biomass (glucose from cellulose) suspended in water. Impact on Career
1. While being supported on this project, I was promoted to Full Professor in July 2011. Impact on Students
1. The work on V2O5/VO2 was part of a dissertation for F. Andrew Frame, who graduated in December of 2010 with a Ph.D. in chemistry.
2. The work on Cu2O, CuO2, and Cu2Se was integrated into the M.S. thesis of Sarah Gee, who graduated with a M.S. degree in June of 2011.
3. The work on WO3 and TiO2 will be part of Ms. Rachel Chamousis’ dissertation (expected graduation) in Fall of 2013.
4. The project also impacted the following graduate students: Jorie Fields, who was responsible for the preparation of nanoscale catalysts particles, Erwin Sabio, who obtained electron microscopy images, and Jing Zhao, who carried out optical measurements.