Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials: Energy Applications of Nanostructures
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division, ACerS Engineering Ceramics Division
Program Organizers: Haitao Zhang, University of North Carolina at Charlotte; Gurpreet Singh, Kansas State University; Kathy Lu, Virginia Tech; Edward Gorzkowski, Naval Research Laboratory ; Jian Shi, Rensselaer Polytechnic Institute; Kejie Zhao, Purdue University ; Michael Naguib , Tulane University; Sanjay Mathur, University of Cologne
Tuesday 2:00 PM
November 3, 2020
Room: Virtual Meeting Room 26
Location: MS&T Virtual
Session Chair: Sanjay Mathur, University of Cologne; Haitao Zhang, UNC Charlotte
2:00 PM Invited
Panchromatic Light Absorption in CdSe/CdS Coated SnO2 Nanowires for Solar-fuel Conversion: Salim Caliskan1; Jung-Kun Lee1; 1University of Pittsburgh
In the solar-fuel conversion process, the low charge collection efficiency and thermalization loss of a photoelectrode are common problems which limit the photoelectrochemical (PEC) performance. To address this problem, different sequential coating methods were employed to sensitize SnO2 nanowires (NWs) and Sb-SnO2 NWs and the effect of the sequential coating sequence and NW electric conductivity on PEC performance was examined. In comparison to the traditional radial sequential coating (RSC), longitudinal sequential coating (LSC) increased the photocurrent density of coated NWs by 30 %. Since high energy and low energy photons are absorbed by different parts of NWs, the improvement of the photocurrent is attributed to higher conversion rate and low thermalization loss of high energy photons to electricity in LSC NWs. Our recent study shows that the sequential coating of different bandgap sensitizers along the longitudinal direction on highly conductive NWs paves a way toward highly efficient solar-fuel conversion.
2:30 PM
Control Over Structure and Chemistry Across Multiple Lengthscales in Fe-Si-Ge-Based Thermoelectrics: Naiming Liu1; Mona Zebarjadi1; Jerrold Floro1; 1University of Virginia
We synthesized FeSi2 – SiGe nanocomposites via React/Transform Spark Plasma Sintering, in which eutectoid decomposition, Ge alloying, doping and sintering efficiently occurred in a single process. This produced hierarchical structuring with a percolated DC network coexisting with discrete nanoscale inclusions, embedded in the FeSi2 matrix. This partially decouples thermal and electrical transport. Alloy chemistry was crucial to improving properties: Ge increases phonon scattering while reducing the DC bandgap; selective doping of both phases provides the requisite carrier concentration, while minor additions of Cu and Sb accelerate eutectoid decomposition, and reduce sintering temperatures, respectively. Hall measurements show that the electron mobilities are 25 times higher than similar materials produced using typical powder processing. The maximum thermoelectric figure of merit ZT of ~0.67 at 973K is a record for this system. Since the nanocomposite is primarily Fe and Si, it is non-toxic, eco-friendly, and the components are relatively abundant and inexpensive.