Doctoral Dissertations
Date of Award
5-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Mechanical Engineering
Major Professor
Feng-Yuan Zhang
Committee Members
David A. Cullen, Peng Zhao, Zhiqiang Xie
Abstract
Hydrogen, the future energy carrier, has gained extensive attention due to its advantages of high energy density, low weight, and zero-carbon emission. So far, hydrogen has been widely used in various fields including transportation, oil upgrading, metal refining, etc. Most hydrogen is currently produced from fossil fuels, which can cause serious environmental problems. Water electrolysis was proposed to produce clean hydrogen with carbon-free emission and only byproduct of oxygen. Among various water electrolyzer devices, the proton exchange membrane electrolyzer cell (PEMEC) shows great potential to produce green hydrogen by integrating renewable sources (solar, wind, etc.) due to its advantages of high energy efficiency, high energy density, fast charging and discharging, compact system design and easily scale up/down. However, the high capital cost hinders the large-scale application and commercialization of the PEMEC, which is mainly due to platinum group metal (PGM)-based electrocatalysts/electrodes with scarcity and high price of PGMs. Hence, it is significant to develop novel and advanced electrocatalysts/electrodes with high material utilization and low cost to cut down the capital cost and then speed up the wide application of the PEMEC.
The main achievements of this dissertation are as follows: (a) Bifunctional NiFeW nanosheet fabrication via facile electrodeposition for alkaline water splitting. (b) Impacts of W-doping concentration on NiFe morphology and performance for water splitting. (c) High-performance Ir-integrated electrode for the PEMEC with high current operation capacity. (d) Highly porous Ir with fine honeycomb nanostructures and improved reaction kinetics for the PEMEC. (e) Nanoporous Ir nanosheets with abundant nanopores and edges for the PEMEC, showing impressive performances and far exceeding the 2026 DOE targets. (f) Ultrathin Pt-NS with a thickness of about 4 nm as a cathode electrode for the PEMEC, achieving more than 99-fold catalyst savings and 237-fold higher catalyst utilization. This research provides guidance for the development of novel and advanced electrocatalysts/electrodes for water electrolyzers and other energy storage devices. Furthermore, the novel and advanced electrocatalyst/electrode designs with high material utilization and easy scalability could boost the commercialization and the industrial application of the PEMEC, and thus accelerate renewable energy evolution.
Recommended Citation
Ding, Lei, "Tunable Catalysts and Electrodes with High Material Utilization and Durability for Hydrogen Production. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/10113
Movie S1. The bubble dynamics of the dense Ir CCLGDL at a current density of 200 mA/cm2.
Movie S2.mp4 (66862 kB)
Movie S2. The bubble dynamics of the HC Ir CCLGDL at a current density of 200 mA/cm2.
Movie S3.mp4 (4736 kB)
Movie S3. The bubble dynamics of the dense Ir CCLGDL at 1.85 V.
Movie S4.mp4 (4712 kB)
Movie S4. The bubble dynamics of the HC Ir CCLGDL at 1.85 V.
Movie S5.mp4 (26320 kB)
Movie S5. The bubble dynamics of the Pt-NS electrode at a current density of 200 mA/cm2.
Movie S6.mp4 (26368 kB)
Movie S6. The bubble dynamics of the PtNP electrode at a current density of 200 mA/cm2.
Included in
Electro-Mechanical Systems Commons, Energy Systems Commons, Structural Materials Commons