Preparation of Iron-an Nitrogen-Codoped Carbon Nanotubes

Presentation

1. Presenter: En , Ku ( 顧恩 ) Advisor: Dr. Ren-Xuan Yang Date: 2022/05/05 Sustainable Resource and Environmental Nanomaterials Lab Institute of Environmental Engineering and Management National Taipei University of Technology

2. Outline Introduction Materials and Methods Results and discussion Conclusions

3. 3 Introduction

4. 4 Purpose: To prepare Fe-CNTs from the catalytic pyrolysis of polypropylene, using alumina loaded with iron. To perform co-pyrolysis of the produced Fe-CNTs with melamine to obtain the final Fe-N-CNTs catalysts. To evaluate the performance of the Fe-N-CNTs catalysts with an electrochemical workstation, compared to 20% Pt/C. Introduction CNT:Carbon nanotubes

5. 5 Materials and Methods

6. 6 Materials and Methods(1/3) Fe based catalyst was prepared with an impregnation method and γ- Al 2 O 3 was used as the support. Fe(NO 3 ) 3 ·9H 2 O (7.21g) was dissolved into 20 ml absolute ethyl alcohol, and 10.00 g of γ- Al 2 O 3 was added to ensure that the initial Fe loading was 10 wt.%. Then, the mixed solution was stirred for 4h at 50 o C with a magnetic stirrer, then dried in an oven at 105 o C overnight, and followed by calcination at 800 o C for 2h under air atmosphere with a heating rate of 10 o C min -1 . The catalyst was crushed and sieved to size smaller than 0.1 mm, which was labeled as Fe- Al 2 O 3 . For the synthesis of Fe-Al 2 O 3

7. 7 Materials and Methods(2/3) 0.5g Fe-Al 2 O 3 1g Plastic 800 o C 20 o C /min 500 o C 10 o C /min Ar Fe-Al 2 O 3 ( 0.5 g ) was put into a quartz holder on the lower stage and 1 g plastic was put into another quartz holder on the upper stage. The lower stage was firstly preheated to the catalytic temperature of 800 o C with a heating rate of 20 o C min -1 . Then, the upper stage was heated to 500 o C at 10 o C min -1 and was kept isothermal for 10 min. The reactions took place under an argon atmosphere. At the end of the reactor system, ethanol was used to absorb the volatile organic matter. They used distilled water for washing, until the ph value of filtrate was close to neutral. Finally, the residue from filtering was dried at 105 o C in an oven for 12 h, the obtained product was then labeled as Fe-CNT. For the synthesis of Fe-CNT

8. 8 Materials and Methods(3/3) Ar 0.2g Fe-CNT + 1g C 3 H 6 N 6 Fe-CNT (0.2 g) and 1g of melamine were mixed uniformly and heated in quartz holder. At 750 o , 800 o C , 850 o C and 900 o C for 2h with Ar purging at a heating rate of 20 o C min -1 . The generated carbon powder was labeled as Fe-N-CNT X . For the synthesis of Fe-N-CNTs

9. 9 Results and Discussion

10. 10 Results and Discussion(1/9) SEM image of Fe-N-CNT850. TEM image of Fe-N-CNT850 with encapsulated Fe nanoparticles. HRTEM image showing the presence of Fe nanoparticles. HRTEM image showing the presence of Fe 3 C. HAADF-STEM cross-sectional compositional profiles. TEM-EDX images with elemental mapping of C, N, and Fe.

11. 11 Results and Discussion(2/9) The X-ray diffraction (XRD) spectra. The full spectra of Fe-CNTs and Fe-N-CNTs display distinctive peaks of C and O.

12. 12 Results and Discussion(3/9) N 1s XPS spectrum. Fe 2p XPS spectrum.

13. 13 Based on the XPS diagrams and the fitted peaks the mass percentages of the carbon nitrogen and iron were calculated. The initial Fe-CNT has a higher content of carbon, while the co-pyrolysis with melamine seems to enrich the carbon nanotube with hydrogen and water. Results and Discussion(4/9) 13

14. 14 Results and Discussion(5/9) The different rotation rates LSVs and K−L plots of Fe-N-CNT850. The current density increased with increasing rotational speed. Corresponding K-L plots at different potentials fitted curves are linear. A. LSV curves of Fe-N-CNT850 at different rotation rates. B. Corresponding K–L plots of Fe-N-CNT850 at different potentials. C. Electron transfer number (n) of Fe-N-CNT850 catalyst.

15. 15 Results and Discussion(6/9) N2 adsorption–desorption isotherms and pore distribution. e)

16. 16 Results and Discussion(7/9) The surface area passing from a temperature of 750 o C to a temperature of 900 o C. This corresponds also to a reduction of the average diameter of pores and also to a reduction in the total volume of the pores (Vt).

17. 17 Results and Discussion(8/9) Raman spectra of all samples The number of disordered and defective sites in the carbon structure can be estimated by the relative peak intensity ratio (ID/IG) of the D to G bands. 2670 cm -1 1340 cm -1 1580 cm -1

18. 18 Their behavior is compared with that of 20% Pt/C. All the electrocatalysts result to have a peak about 0.8 V which corresponds to the reduction reaction, as reported for other tests performed with similar carbonaceous material. Results and Discussion(9/9)

19. 19 Conclusions

20. 20 Conclusions One-dimensional tubular Fe and N codoped carbon-based materials (Fe-N-CNTs) through the catalytic pyrolysis of waste plastics. The optimized Fe-N-CNT850 catalyst displayed better catalytic activity than the pristine Fe-CNTs. Fe-N-CNT850 also showed a higher limiting-current density than Fe-CNTs. Furthermore, Fe-N-CNT850 revealed remarkable electrocatalytic activities compared with 20 % Pt/C. The significantly enhanced performance of Fe-N-CNT850 was also manifested in its better stability and anti-poisoning properties. Electrocatalysts synthesized by catalytic pyrolysis of waste plastics provide a new preparation route and the development of cost-effective electrocatalysts.

21. 21 Thank you!