Picosecond time-resolved x-ray photoemission spectroscopy provides real-time electron distributions of donors and acceptors in a prototypical bipyridyl-ZnO hybrid light harvesting system. The measurements show that photo-injected electrons remain localized within the defect-rich surface region of the nanoporous ZnO substrate, revealing a challenge for the extraction of free charge carriers. Read more »
Direct Observation of Surface-Bound Intermediates During Methanol Oxidation on Platinum Under Alkaline Conditions
A comprehensive mechanism for the methanol oxidation reaction (MOR) in alkaline media is presented, and it is shown that the MOR proceeds via two different pathways (via COad or H3C–Oad intermediates). The latter dominates the overall MOR current, suggesting that the H3C–Oad oxidation could be a viable pathway to accelerate the MOR in alkaline systems. Read more »
Strategies for Reducing Platinum Waste in Fuel Cells
Industry and university researchers used the ALS to explore why the platinum used as a catalyst in hydrogen fuel cells degrades unevenly. The resulting knowledge has enabled the development of simple, effective strategies to reduce the waste of precious catalyst material, lowering the costs associated with a promising green technology. Read more »
A Split-Screen View of Solar-Cell Crystallization
Researchers simultaneously monitored both the structure and function of a photovoltaic material as it crystallized from solution. The work raises the prospect of rationally tuning materials for optimal performance in photovoltaics and other light-manipulating devices, including light-emitting diodes, detectors, and lasers. Read more »
New Technique Paves the Way for Perfect Perovskites
A new solar material, organic-inorganic halide perovskites, could one day help the U.S. achieve its solar ambitions and decarbonize the power grid. A recent study reports that manufacturing could be aided by a new instrument that uses invisible x-ray light and visible laser light to probe a perovskite material’s crystal structure and optical properties as it is synthesized. Read more »
3D View Reveals Shadow Effect after Rapid Battery Charging
Using 3D x-ray microtomography, researchers measured the lithiation levels of particles in Li-ion battery electrodes during charging. At faster charging rates, lithium metal accumulated on the electrode surface and created a “shadow effect,” a region of poor lithiation in the electrode at some distance away from the lithium plating. Read more »
Exquisitely Selective CO2 Reduction on Silver
Researchers electrochemically reduced CO2 to CO with nearly perfect selectivity over other products by adding an organic compound to the surface of a silver electrode. With theoretical analyses and ALS data, the work revealed the key role of the microenvironment in promoting the conversion of CO2, a greenhouse gas, into useful products. Read more »
Coulombically-stabilized oxygen hole polarons enable fully reversible oxygen redox
We investigate oxygen redox in layered Na2−xMn3O7, a positive electrode material with ordered Mn vacancies. Our results establish a complete picture of redox energetics by highlighting the role of coulombic interactions across several atomic distances and suggest avenues to stabilize highly oxidized oxygen for applications in energy storage and beyond. Read more »
A Multiscale Picture of Oxygen Loss in Battery Electrodes
In lithium-ion batteries, oxygen atoms leak out of electrode particles as the lithium moves back and forth between electrodes. Now, researchers have measured this process at multiple length scales, showing how the oxygen loss changes the electrode’s structure and chemistry, gradually reducing the amount of energy it can store. Read more »
New Tools Link Catalytic Activity to Nanoscale Transformations
Transitioning to a clean hydrogen economy will require cheaper, more efficient ways to split water molecules. To address bottlenecks in the water-splitting process, researchers developed a suite of advanced tools, including a liquid flow cell that enables electrochemical studies of catalysts under working conditions. Read more »
- « Previous Page
- 1
- …
- 3
- 4
- 5
- 6
- 7
- …
- 14
- Next Page »