Publication Date
2023
Document Type
Dissertation/Thesis
First Advisor
Cheng, Yingwen Y.
Degree Name
Ph.D. (Doctor of Philosophy)
Legacy Department
Department of Chemistry and Biochemistry
Abstract
Electrocatalysis has played significant roles in energy conversion and environmental applications. This dissertation focusses on electrocatalytic performance of Chevrel phase material and building up relationship between structure with durability and activity.The dissertation mainly contains four parts. In chapter 2, the Ni2Mo6S8 catalyst exhibited in producing hydrogen peroxide with an outstanding selectivity of nearly 98%, derived from the combined ligand and ensemble effects of Ni, coupled with the strategic placement of Ni, Mo, and S in the active structure of the catalyst. Those synergistic effect results in a remarkable turnover frequency (TOF) of 30 s-1, leading to a hydrogen peroxide synthesis rate of around 90 mmol·gcat-1·h-1. Chapter 3 illustrates Fe2Mo6S8 catalysts serving as an effective electrocatalyst for the targeted electrochemical transformation of nitrogen to ammonia. Remarkably, it exhibited stable Faradaic efficiencies of up to 12.5% at a potential of −0.20 V versus RHE and produced ammonia at a rate of 70 mg·gcat−1·h-1. Within the Fe2Mo6S8 structure, the Fe/Mo sites act as key regions for nitrogen molecule adsorption and activation, while the S sites enhanced by Fe generate reactive Had* intermediate. In Chapter 4, we present a novel Co2Mo6S8 Chevrel phase catalyst, inspired by Mo-S active sites in natural nitrate reductases, which employs a multi-site binding mechanism to effectively convert nitrate to ammonia. The spatial organization of the active sites enhances the kinetic coupling, preventing unwanted N−N interactions, leading to impressive ammonia yields of 941.0 mmol·gcat−1·h−1 in neutral solutions. Chapter 5 delves into a series of Chevrel phase Ni2Mo6T8 catalysts, differentiated only by their chalcogenide anions. The study revealed that the transition from sulfide to telluride anions curbs competing reactions, driving superior ammonia formation. Notably, the Ni2Mo6Te8 variant displayed exceptional efficiency (99.4%) and turnover rates (21.5 s-1) and showcased enhanced durability, owing to its resistance against electrolyte cation intercalation.
Recommended Citation
Xia, Fan, "Chevrel Phase Materials for Electrocatalytic Chemical Conversion" (2023). Graduate Research Theses & Dissertations. 7862.
https://huskiecommons.lib.niu.edu/allgraduate-thesesdissertations/7862
Extent
155 pages
Language
en
Publisher
Northern Illinois University
Rights Statement
In Copyright
Rights Statement 2
NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.
Media Type
Text
