| Author: | Zhang, Hao |
| Title: | An investigation of structure-activity correlations of some Cu-based electrocatalysts |
| Advisors: | Lo, Benedict (ABCT) Mok, Kam-wah (ABCT) |
| Degree: | Ph.D. |
| Year: | 2025 |
| Subject: | Catalysts Electrocatalysis Carbon dioxide mitigation Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Applied Biology and Chemical Technology |
| Pages: | viii, 194 pages : color illustrations |
| Language: | English |
| Abstract: | The efficient conversion and storage of renewable energy and CO2 into chemical bonds via electrochemical catalysis present a promising avenue for addressing environmental concerns and tackling the prevailing energy crisis. Extended efforts have been dedicated to designing catalysts with higher selectivity of target products. In upgrading the electrocatalyst, precise synthesis heavily relies on unveiling the structure-performance relationship. This thesis focuses on deciphering the intricate structure-performance relationship of electrochemical catalysts. To gain profound insights into the catalyst evolution under operating conditions, we have established a multi-modal operando characterization system, comprising operando powder X-ray diffraction (PXRD), Raman spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. This integrated approach enables the simultaneous monitoring of structural transformations, compositional changes, and the dynamic behaviour of adsorbates and intermediates within the catalytic system. In Chapter 1, we used an electrochemical CO2 reduction reaction over Cu-based nanocatalysts as a model to discuss the recent advances in the use of operando characterization techniques. Chapter 2 describes the chemical materials and characterization techniques used in this thesis. In Chapter 3, we successfully transmitted the electrochemical operando PXRD reactor from design drawings to practical applications. In a comparative study of CuO-based electrocatalysts, we found that the addition of the secondary metal affects the reduction rate of Cu2+. The correlation study between operando PXRD and catalysis performance revealed that Cu0 is the major active site for C2H4 formation. In Chapter 4, we investigated the Cu+/Cu0 synergy by studying the correlations between the structure of the electrocatalysts and the electrochemical carbon dioxide (eCO2RR) activity. By conducting a series of multi-modal operando studies, the dynamic changes in the bulk (by operando PXRD), surface/sub-surface (by operando Raman spectroscopy), and interface properties (by operando Fourier-transform infrared spectroscopy) concerning the catalysis performance have been revealed. Chapter 5 reports a theory-guided discovery of second metal-decorated Cu-based nanoalloys (Cu-M) for urea electrosynthesis. The substantially enhanced selectivity of the Cu-M catalyst can be attributed to the ability of the doping metal to modulate the binding energy of the *CO and *NO2 on the catalyst surface, as evidenced by operando Raman and operando FTIR investigations. In brief, this thesis presents a promising avenue for the design of catalytic materials with superior properties guided by deep investigation of the structure-performance relationship with the use of operando techniques for mechanism validation. |
| Rights: | All rights reserved |
| Access: | open access |
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