Title Page
Contents
Abstract 9
1. Introduction 10
2. Experimental 13
2.1. Synthesis of Zn-Co-ZIF 13
2.2. Synthesis of Zn-Co-S@NSC 14
2.3. Physical characterization 14
2.4. Electrochemical characterization 15
2.5. Density functional theory (DFT) calculations 17
3. Results and discussion 19
3.1. Synthesis and characterization of Zn-Co-S@NSC 19
3.2. Electrochemical measurements 29
4. Conclusions 39
5. References 40
Table 1. Atomic percentages of Zn, Co, S, N and C for Zn-Co-S@NSC, Zn-... 27
Table 2. Comparison of the ORR activity for several recently reported... 32
Figure 1. Model surface structures for (a) ZnS(llO), (b) CoZnS-terminated... 18
Figure 2. XRD patterns of Zn-ZIF, Zn-Co-ZIF and Co-ZIF. SEM images of... 20
Figure 3. (a) XRD pattern, (b) SEM image, (c) low-magnification TEM, (d)... 21
Figure 4. (a) Raman spectra of Co-S@NSC, Zn-S@NSC, and Zn-Co-... 23
Figure 5. (a) XPS survey spectrum of Zn-Co-S@NSC. High-resolution XPS... 26
Figure 6. Electrochemical assessments of the prepared samples. (a) CV... 30
Figure 7. Rotating disk voltammograms of (a) Zn-S@NSC and (b) Co-... 34
Figure 8. The Gibbs free energy change of the ORR at the equilibrium and... 37
Scheme 1. Schematic illustration of preparation of Zn-Co-S@NSC. 19