Defense presentation

1. SynthesisAnd Characterization Of Cu Based
ZIF-8 Catalysts For Electro-catalytic CO2
Reduction
AWAIS AHMAD
REG # 206139
DEPARTMENT OF ENERGY SYSTEMS ENGINEERING
U.S.-PAKISTAN CENTRE FOR ADVANCED STUDIES IN ENERGY (USPCAS-E)
NATIONAL UNIVERSITY OF SCIENCES AND TECHNOLOGY (NUST), ISLAMABAD

2. Supervisor
Dr. Naseem Iqbal (Associate Professor)
USPCAS-E NUST
GEC Members
Dr. Rabia Liaquat (USPCAS-E NUST)
Dr. Nadia Shehzad (USPCAS-E NUST)
Dr. Sehar Shakir (USPCAS-E NUST)
Guidance And Examination
Committee

3.  Introduction
 Problem Statement
 Objectives
 Literature Review
 Synthesis Methodology
 Characterization
 CO2 Electroreduction Cell Setup
 Electrochemical results & Product analysis
 Conclusions and Recommendations
 Acknowledgements
 Publications
 References
Outline

4.  Current world energy consumption is
highly dependent upon fossil fuels.
 Fossil fuels result in escalated greenhouse
gas emission (CO2)
 CO2 concentration in the atmosphere has
increased from 280 to 400 ppm
 How to effectively reduce the atmospheric
CO2 level?
Atmospheric CO2 concentration and corresponding
global average temperatures since the 19th century.
Introduction

5. CO2 mitigation Techniques
Various strategies are implemented to mitigate CO2 emissions
 Improving combustion engine efficiecny.
 Carbon capture and storage technology
 Artificial photosynthesis
 Photocatalysis
 Electrocatalysis
 Photoelectrocatalysis
Overall schematic of carbon
capture and storage concept

6.  A process for converting carbon dioxide into useful products like
hydrocarbons.
 Requires the use of a catalytic material on working electrode.
 Carbon dioxide is bubbled through the electrolyte in an electro-chemical
cell.
 Catalytic material will adsorb CO2 and reduce it by doing its hydrogenation
through water.
Schematic diagram of electrochemical reduction
of CO2 and possible applications of fuel product
Electrocatalytic CO2
reduction

7. Schematic of CO2 electroreduction cell Reaction mechanism schematic
Process Mechanism

8. CO2 Reduction Catalyst:
Previously employed heterogeneous catalyst include:
 Metals
1. Noble metals Pt, Pd, Au, Ag
2. Transition metals (Cu, Zn, Fe)
 Metal oxides ( ZnO, CuO)
 Metal chalcogenides i.e, MoS2
 Metal Organic Frameworks: consist of metal ions and organic linkers. These
are crystalline porous materials.
 ZIF: Subclass of MOFs, having metal ions and imidazolate ligands (ZIF-8,
ZIF-67)

9. Sr.
No
Research Title Authors &
year of
publication
Journal Remarks
1 Zinc Imidazolate Metal–Organic
Frameworks (ZIF-8) for
Electrochemical Reduction of CO2
to CO
Yulin Wang,
2017
ChemPhysC
hem
(Special
Issue)
ZIF-8 (Zn imidazole MOF) using Zinc sulpahte
precursor as catalyst was used with 0.5m NaCl
aqueous solution electrolyte to achieve CO
69.8% Faradaic Efficiency
2 Metal-Organic-Framework-
Mediated Nitrogen-Doped Carbon
for
CO2 Electrochemical Reduction
Riming Wang,
2018
ACS Appl.
Mater.
Interfaces
ZIF-8 derived Nitrogen doped carbon structure
was synthesized to reduce CO2 in 0.1M KHCO3
to achieve CO faradaic efficieny of 78% with
current density of f −1.1 mA cm-2
3 Cu2+-doped zeolitic imidazolate
frameworks (ZIF-8): Efficient and
stable catalysts for cycloadditions
and condensation reactions
Aleksandra
Schejn, 2015
Catalysis
Science &
Technology
Cu doped ZIF-8 material was synthesized with
various copper dopings. Cu5%/ZIF-8 crystals
showed high catalytic activity in the synthesis of
quinolines using 2-aminobenzophenone as
starting material.
4 Cubic Cu2O on nitrogen-doped
carbon shell for electro-catalytic
CO2 reduction to
C2H4
Hui Ning, 2019 Carbon Cu2O/N-doped carbon shell was used a catalyst
in 0.1M KHCO3 to achieve FE of C2H4 (24.7%)
with stable current density of around 10 mA cm-2
Literature Review

10. Literature Review
Sr.
No.
Research Title Authors & year
of publication
Journal Remarks
5 Selective electroreduction of
carbon dioxide to methanol
on copper selenide
nanocatalysts
Dexin Yang, 2019 Nature
Communications
Copper based selenide catalysts were used
to achieve very effective results for CO2
electroreduction to methanol. The current
density can be as high as 41.5 mA cm-2
with a Faradaic efficiency of 77.6% at a
low overpotential of 285 mV.
6. Electrochemical Reduction of
CO2 Using Copper Single-
Crystal Surfaces:
Effects of CO* Coverage on
the Selective Formation of
Ethylene
Yun Huang, 2017 ACS Catalysis Cu(100) and Cu(111) surfaces favored the
formation of C2H4 and, CH4 respectively,
Cu(100), −0.85 V, CH4 −19 μA cm-2
7. Electrocatalytic reduction of
carbon dioxide over reduced
nanoporous
zinc oxide
Xiaole Jiang, 2016 Electrochemical
Communications
A maximum CO Faradaic efficiency of
92.0% and CO current density of
15.1 mA cm-2 was achieved at −1.66 V (vs.
Ag/AgCl), which are much higher than
those over commercial Zn foil (55.5%, 3.3
mA cm-2)

11.  In this work we need to improve current density of catalyst as well as the
selectivity of the product from CO to methane through electroreduction.
Problem Statement

12. Materials Selected
 ZIF-8 is being selected because
• Large specific surface area.
• Tunable porosity and good stability
 Cu precursor is being selected because
• Selectivity towards hydrocarbons like methanol, ethanol, ethane etc.
• Good current density, faradaic efficiency
 Final Material: Cu doped ZIF-8

13. Preparation of Cu doped ZIF-8 materials
by solvothermal process with various
copper doping percentages.
Characterization of the materials by XRD,
SEM, EDX, TGA, BET and FTIR
techniques.
Use of the materials as catalyst for
electrocatalytic CO2 reduction by
performing electrochemcial workstation
techniques.
Product analysis of the gas products formed
to check effectiveness of our catalyst for
CO2 conversion.
Objectives of Research

14. Steps:
 Two solutions A & B are formed in methanol solvent:
 Mixing of solution in the presence of N2 atmosphere for 90min.
 Precipitate was centrifuged, washed and separated
 The final precipitate powder is dried in vacuum to obtain catalysts Cu10%ZIF-8,
Cu20%ZIF-8, and Cu30%ZIF-8.
Schematic Diagram for synthesis of Cu-doped ZIF-8
Synthesis Methodology

15.  ZIF-8 and Cu-doped ZIF-8 sample
patterns are similar
 Cu-ZIF-8 has body-centered cubic
crystal lattice symmetry as in ZIF-
8
 Crystallite size was found to
increase from 31.7 nm to 41.62 nm
with increasing Cu. Scherrer
equation:
Particle Size = (0.9 x λ)/ (d cosθ)
Characterization:
X-Ray Diffraction

16.  Images show rhombic
dodecahedral cubic structure
for all samples.
 Cu-doping does not alter the
crystal morphology of the Zn-
imidazole framework.
SEM images of a) ZIF-8, b) Cu10%ZIF-8, c) Cu20% ZIF-8 and d)
Cu30% ZIF-8
Scanning Electron
Microscopy

17.  All the Cu-doped ZIF-8 samples
have Cu, Zn, C, N and O elements.
 Carbon has the highest content in all
the samples.
Weight % Atomic %
Elements C N O Zn Cu C N O Zn Cu
ZIF-8 47.79
5
36.35 3.235 10.09 - 54.185 40.79 2.845 2.175 -
Cu10%ZIF-
8
46.56 34.90 6.80 11.48 0.26 55.60 38.76 6.10 2.53 0.06
Cu20%ZIF-
8
46.49 29.90 4.42 18.70 0.50 59.20 32.03 4.20 4.45 0.12
Cu30%ZIF-
8
46.89 30.5 2.53 19.85 1.02
5
60.03 33.70 2.05 4.78 0.25
Energy Dispersive
X-ray

18.  The Cu10%ZIF-8 sample shows
thermal stability up to 430 °C.
 From 430 °C to 542°C the sharp
weight loss of 60-65% for
Cu10%ZIF-8
 Higher Cu percentage catalysts of
Cu20%ZIF-8 and Cu30%ZIF-8 have
more thermal stability.
 The final residue of high copper
catalyst is less.
Thermogravimetric Analysis

19.  Isotherms were of
type I.
 The BJH pore size
distribution for
Cu-ZIF-8 samples
is in the range of
1.8-2.32 nm.
 Dual micro and
mesoporous nature
of Cu doped ZIF-8
samples.
Brunauer-emmett-teller (BET) Surface
Area And Pore Size Distribution

20. Material BET Surface Area
(m2 g-1)
Micropore
Size (nm)
Micropore
Volume (cm3 g-1)
ZIF-8 1620 0.99 0.80
Cu10%ZIF-8 1967 0.96 0.95
Cu20%ZIF-8 1772 0.977 0.88
Cu30%ZIF-8 1238 0.98 0.60
BET Data Table

21.  ZIF-8, Cu10%ZIF-8, Cu20%ZIF-8,
and Cu30%ZIF-8 all have the
similar responses and functional
groups.
Fourier Transform Infrared
Spectroscopy (FT-IR)

22. CO2 Electroreduction Cell
Setup
 Two compartments electrochemical
H-cell
 Glass fritz
 Three electrode system
 Working electrode(glassy carbon +
coated catalyst)
 Reference electrode (Ag/AgCl)and
counter electrode (Pt wire)
 0.1M KHCO3 aqueous electrolyte
 Gas inlet for CO2 intake and outlet to
collect gas products
Electrochemical H-cell in-process image

23. Working Electrode
Formation
Catalyst Ink
formation
• 25mg catalyst,
1000mL ethanol,
40uL nafion
• Sonicated and
vortex mixed
Coating on
Electrode
• Using pipette
• 4 layers of 3mL
ink were formed
Drying the
ink
• Dried in air or in
oven

24.  Initially N2 was purged followed by CO2 purge
 Linear sweep voltammetry measurements were taken (-0.9 to -2.1V
vs. Ag/AgCl.
 Bulk electrolysis experiment (-1.2 V to -1.6 V vs. Ag/AgCl)
 Each experiment (20min)
 Gas was collected for GC analysis.
 Faradaic efficiency is calculated as:
Electrochemical Testing
 Where n is 2 for CO, H2, and 8 for CH4
 F is Faraday’s constant

25.  Cu30%ZIF-8 showed the
highest current density
of -40 mA cm-2 at -2.1 V.
 Cu10%ZIF-8 gives higher
current density of 18.3
mA cm-2 then
 Cu20%ZIF-8 value of
13.7 mA cm-2
LSV comparison of N2 and CO2 saturated 0.1 M KHCO3 electrolytes
Linear Sweep Voltammetry
Results:

26.  H2, methane and CO
were detected.
 Cu20%ZIF-8 catalyst
giving the least H2
faradaic efficiency of
80%.
 Cu10%ZIF-8 shows the
highest CO formation
performance of 62.26%
at -1.5 V vs. Ag/AgCl
 Cu30%ZIF-8 achieves
the faradaic efficiency
of 35.21% at -1.6 V vs.
Ag/AgCl
Total current density and Faradaic efficiency results
Constant Potential Electrolysis/
Product analysis Results

27.  The line is relatively more stable at -
1.2 V vs. Ag/AgCl potential.
 High partial current densities on
Cu30%ZIF-8
Constant Potential Electrolysis/
Product Analysis Results

28.  Copper doping in ZIF-8 improved the selectivity from CO to methane as
well as current density.
 Cu10%ZIF-8 and Cu20%ZIF-8 give increased surface area of 1967m2 g-1 and
1772m2 g-1 respectively compared to ZIF-8 1620m2 g-1
 Cu30%ZIF-8 gives the highest CH4 faradaic efficiency of 35.21% at -1.6 V vs.
Ag/AgCl with a current density of -40 mA cm-2
 Increasing the copper molar percentage the selectivity for methane increases.
 The morphology, surface area, and proper accessibility of active metal
catalytic sites play a key role in achieving high catalytic efficiency.
Conclusion

29.  Use of online gas chromatography for gas analysis to get more accurate
product faradaic efficiency results.
 Use of Nafion membrane in place of glass fritz to improve the ions flow.
 Employing continuous cell with gas diffusion electrode to get better
electroreduction results.
 Further research in cheap active metal based MOF materials.
 Liquid product analysis through proper techniques is recommended.
Future Recommendations

30.  USPCAS-E, NUST
 Principal
 HoD ESE
 Supervisor: Dr. Naseem Iqbal
 GEC Members
 Dr. Rabia Liaquat
 Dr. Sehar Shakir
 Dr. Nadia Shehzad
 Lab Engineers (Especially Naveed, Ali Abdullah, Asghar Ali,
Qamar Ud Din, Hassan, Aamir)
 Family (Parents, Brother and Sisters)
 Friends ( Especially Ahmed Hassan, Abdul Wahab, Azeem
Sarwar, Usman Ali, Arslan Raza, Ahmed Qayyum, Nisar, Sheraz)
Acknowledgements

31.  Awais Ahmad, Naseem Iqbal, Tayyaba Noor, Ahmed Hassan, Usman Ali Khan, Abdul
Wahab Qureshi, Muhammad Arslan Raza, Sheeraz Ashraf. “Cu-doped Zeolite
Imidazole Framework (ZIF-8) for Effective Electrocatalytic CO2 Reduction”.
Journal of CO2 utilization (First Revision).
 Abdul Wahab, Naseem Iqbal, Tayyaba Noor, Sheeraz Ashraf, Muhammad Arslan
Raza, Awais Ahmad and Usman Ali Khan, “Thermally reduced mesoporous
manganese MOF @reduced graphene oxide nanocomposite as bifunctional
electrocatalyst for oxygen reduction and evolution”. RSC Advances, 2020, 10,
27728–27742, DOI: 10.1039/d0ra04193a
Publications

33. References
1. Jinghua Wu, Yang Huang, Wen Ye, and Yanguang Li*, CO2 Reduction: From the
Electrochemical to Photochemical Approach, Adv. Sci. 2017, 4, 1700194, DOI:
10.1002/advs.201700194
2. Aleksandra Schejn,a Abdelhay Aboulaich,b Lavinia Balan,c Véronique Falk,a Jacques Lalevée,c
Ghouti Medjahdi,d Lionel Aranda,d Kevin Mozet,a Raphaël Schneider*a, Cu2+-doped zeolitic
imidazolate frameworks (ZIF-8): Efficient and stable catalysts for cycloadditions and
condensation reactions, Catalysis Science & Technology, 2015, DOI: 10.1039/b000000x
3. Yulin Wang,[a] Pengfei Hou,[a, b] Zhuo Wang,* [a] and Peng Kang*[a, b], Zinc Imidazolate
Metal–Organic Frameworks (ZIF-8) for Electrochemical Reduction of CO2 to CO,
ChemPhysChem 2017, 18, 3142 – 3147, DOI: 10.1002/cphc.201700716
4. Jiaquan Li, Yunbing Hou, Pengtao Wang, and Bo Yang, A Review of Carbon Capture and Storage
Project Investment and Operational Decision-Making Based on Bibliometrics, Energies (2019),
12, 23, 2-2.
5. Lau, L. C.; Lee, K. T.; Mohamed, A. R. Global Warming Mitigation and Renewabl Energy Policy
Development from the Kyoto Protocol to the Copenhagen Accord—A Comment. Renew. Sustain.
Energy Rev. 2012.
6. Hui Ning, Xiaoshan Wang, Wenhang Wang, Qinhu Mao, Zhongxue Yang, Qingshan Zhao, Yan
Song, Mingbo Wu, Cubic Cu2O on nitrogen-doped carbon shell for electrocatalytic CO2
reduction to C2H4, CARBON, 2019.
7. Dexin Yang1,2, Qinggong Zhu1,2, Chunjun Chen1,2, Huizhen Liu1,2, Zhimin Liu1,2, Zhijuan
Zhao1 , Xiaoyu Zhang1 , Shoujie Liu3 & Buxing Han1,2, Selective electroreduction of carbon
dioxide to methanol on copper selenide nanocatalysts, Nature communications, 2019.
8. Riming Wang,†,§ Xiaohui Sun,†,§ Samy Ould-Chikh,‡ Dmitrii Osadchii,† Fan Bai,†
Freek Kapteijn,† and Jorge Gascon, Metal-Organic-Framework-Mediated Nitrogen-
Doped Carbon for CO2 Electrochemical Reduction, ACS Appl. Mater. Interfaces
2018, 10, 14751−14758.