Exploratory Projects

Research Areas & Activities Solar Energy Biomass Energy Hydrogen Advanced Combustion CO₂ Capture CO₂ Storage Advanced Materials & Catalysts Advanced Coal Advanced Transportation Other Renewables Integrated Assessment Advanced Nuclear Energy Energy Distribution & Infrastructures Geoengineering All Activities Analysis Activities Technical Reports

Research

GCEP provides funding for research activities of an exploratory nature that test the feasibility and application of potential step-out ideas. These activities focus on novel approaches and innovative concepts associated with technologies that may permit reductions in greenhouse gas emissions on a global scale. While exploratory activities are limited to $100K and a one-year performance period, the preliminary analysis results may support the submission of a detailed proposal. The current activities are listed below. Please also see Completed Exploratory Projects.

Current Exploratory Projects Development of an Immobilized Enzyme System for Lignocellulosic Biomass Saccharification

Investigator
Richard Zare, Department of Chemistry, Stanford University

Electrocatalytic Water Oxidation to Dioxygen in Molecular PdII/IV Coordination Environment

Investigator
Dmitry Yandulov, Department of Chemistry, Stanford University

Geological Sequestration of CO₂ – An Exploratory Study of the Mechanisms and Kinetics of CO₂ Reaction with Mg-Silicates

Investigators
Gordon Brown, Dennis K. Bird, Kate Maher and Wendy Mao, Geo & Environmental Science, Stanford University

A possible strategy for geological sequestration of CO₂ is in the reaction of CO₂ and Mg silicates. Mg silicates are present in the form of picrites and serpentinites which are abundant and thermodynamically convenient rocks to form Mg-carbonates. This exploratory project focuses on the mechanism and kinetics of CO₂(and H₂O) interactions with both serpentinites and picrites, as well as in individual serpentine minerals and individual minerals found in picritic basalts. This investigation will focus on 1) changes in the surface chemistry of these minerals following carbonation reactions, 2) molecular-level characterization of the reaction products, and 3) kinetic studies of these surface carbonation reactions using stable isotopes as tracers. Results from the project may open pathways to enhance reaction kinetics of CO₂ with these minerals such that costs can be reduced at scale.

Multijunction Nanowire Solar Cells for Inexpensive and Highly Efficient Photoelectricity: Enabling Methods

Investigator
Paul McIntyre, Materials Science & Engineering, Stanford University

This exploratory program aims at investigating a novel multijunction solar cell design to address the high fabrication costs of traditional multijunction devices, which use expensive-to-grow, high-quality semiconductor single crystals. The proposed design uses vertical semiconductor nanowire arrays grown on inexpensive polycrystalline germanium substrates, and takes advantage of the elastic dilatation property of nanowires that can relax misfit trains and allows the growth of high-quality nanowire heterojunctions with no dislocations. The program focuses on three enabling methods required for nanowire multijunction solar cells: 1) catalysis of Ge nanowire growth using inexpensive metal catalysts which, unlike the standard Au catalyst, do not produce deep carrier traps in the Ge bandgap; 2) nucleation and growth of dense, vertical Ge nanowire arrays on (111)-oriented polycrystalline Ge thin films on inexpensive glass substrates; and 3) formation of heterostructure GaAs/Ge nanowires by continuous, locally catalyzed deposition on Ge wires using Ga and As precursors.

Nanostructured MoS₂ and WS₂ for the Solar Production of Hydrogen

Investigator
Thomas Jaramillo, Chemical Engineering, Stanford University

Hydrogen production from photoelectrochemical (PEC) water splitting has been extensively investigated in the last few decades following the first experimental demonstrations using TiO₂-based photoanodes. The realization of efficient and cost-effective PEC systems requires the identification of material candidates with the following properties: optimal bandgap for improved solar absorption; band edges aligned with the energy levels required for the redox water splitting reaction; sufficient carrier mobility for the photogenerated charges to reach the electrode/water interface before recombination; stability against corrosion; optimal catalytic properties for H₂ and O₂ evolution; and low cost. This exploratory program aims at investigating the potential of nanostructured earth-abundant, non-toxic dichalcogenide semiconductors (molybdenum and tungsten disulfides) where bulk and surface properties could be tailored independently to satisfy the above criteria by controlling their nanostructure.

Spectroscopic Characterization of Multi-Exciton Generation Efficiency in Nano-Structured Materials

Investigators
Kelly Gaffney, SLAC; Yi Cui and Mike McGehee, Materials Science & Engineering, Stanford University

This exploratory project aims at implementing a novel time-resolved spectroscopic diagnostic technique to validate recent experimental estimates of the efficiency of multiple exciton generation (MEG) in semiconductor nanoparticles following the absorption of a single high-energy photon. As opposed to traditional transient absorption measurements performed at the band gap energy, the proposed experiment uses the excited-state absorption as a signature of multiple exciton generation. This approach avoids using questionable assumptions, such as the weak interaction between multiple excitons within a quantum dot, in interpreting the results.