Hydrogen Production

1. Computational screening of two
dimensional materials for hydrogen
evolution reactions
Presented by:
MUHAMMAD IRSHAD KHAN
Supervisor Co-Supervisor
Prof. Dr. Syed Zafar Ilyas Dr. Abdul Jalil
Department of Physics
Allama Iqbal Open University Islamabad

2. Outline
 Introduction
 Literature Review
 Statement of Problems
 Aims and Objectives
 Research Methodology

3. 1
Energy system
Energy recourses and production
Renewable Energy recourses and production Non-Renewable Energy recourses and production
Energy from hydrogen production
 Because pure hydrogen does not occur
naturally .on the earth in large quantities ,
it takes a substantial amount of energy in
its industrial production.
 Based on source of energy , there are
different way to the production of
hydrogen.
48.2
30
18
0.8
natural
gas
oil
Coil
other
Hydrogen production method
Fossil fuel and biomass
Thermochemical
process
Electrolysis
Solar hydrogen
production
Biological production
Wind
Hydropower Natural gas
Solar Biomass
Oil Coal
Nuclear

4. Introduction
 Hydrogen is widely consider to be the
fuel in the powering of nonpolluting
vehicles, domestic heating, and aircrafts.
 The abundant supply of water and
sunlight offers us an affordable
alternative source to produce hydrogen
apart from fossil fuels and biomass.
 Photo-electrochemical(PEC) water
splitting is one of the potential
techniques for clean solar hydrogen
production and has been utilized I small
to large scale hydrogen generators.
 In 1972, Honda and Fujishima first
investigated water splitting using a single
TiO2 crystal as a photo-anode and Pt as a
cathode..
Relative
Emission
of
Carbon
Combustion
Engen
using
gasoline
Fuel
cell
using
gasoline
fuel
cell
using
hydrogen
from
natural
gar
Hydrogen
electric
internal
combustion
engine
using
gasoline
Fuel
cell
using
hydrogen
from
hydroelectric
0.5
1.0
1.5
2.0
Source
sunlight
e.g photovoltaic e.g photoelectrolysis
Fuell cells /electrolysis
H2O
H2 H2
Electricity
prime carrier
Hydrogen
Storage & fuel
2

5. Working principle (Photo-electrochemical (PEC)
 In 1972, Honda and Fujishima first investigated
water splitting using a single TiO2 crystal as a
photo-anode and Pt as a cathode
 There are three options for the arrangement of
photon-electodes in the assembly of PECs
 Photo-anode made of n-type semiconductor
and cathode made of metal.
 Photo-anode made of n-type semiconductor
and photo-cathode made of p-type
semiconductor.
 Photo-cathode made of p-type
semiconductor and anode made of metal.
Cathode
Photo-Anode
R
V
H+
Na2SO4
e-
ƕν
2H+ + 2e- H2 H20 + 2h+ 2H+ +½ O2
3
 Water photo-electrolysis using a PEC involves several processes within photo electrodes and at the
photo-electrode/electrolyte interface , including;
 light-induced intrinsic ionization of the semiconducting material, resulting in the formation of
electronic charge carriers; 2ɧʋ 2e- +2h+
where; ɧ is Planck's constant , ʋ is the frequency , e-
is the election , h+ is the hole.
 Oxidation of water at the photo-anode by holes;
2h+
+ H2O ½ O2 + 2H+
 Transport of H+ ions from the photo-anode to the cathode through the electrolyte
transport of electrons from photo-anode to the cathode the external circuit;
 Reduction of hydrogen ions at the cathode by electrons.

6. PEC Cell structure
PEC cell structure
Single photo-electrode PEC system
I Bio- photo-electrode PEC system
Hybrid photo-electrode PEC system
II
4
III
I. Single photo-electrode PEC system
 The single photo-electrode PEC system, similar to that reported by fujishima and
Honda in 1972, is equipped with one photo-electrode while the second electrode is
not light-sensitive (mostly metals)
II. Bio-photo-electrode PEC system
 The bi-photo-electrode PEC system is based on the use of semiconducting materials
as both photo-electrode.
 In this case n- and p- type materials are used as the photo-anode and photo-cathode,
respectively.
 The advantages of such system is that the photo-voltages are generated on both
electrodes, resulting , in consequences , in the formation of an overall photo-voltage
that is sufficient for water decomposition without the application of a bias.

7. 5
p- Type
n- Type
Si-CELL
ƕν
ƕν
Waterproof coating
ƕν ≥ 3eV
TiO2 Thin Film
III. Hybrid photo-electrode (HPE)
 The structure of the HPE, involving the
metal contact, Si photovoltaic cell,
photo-anode of TiO2, and aqueous
electrolyte.
 In this structure , only the TiO2 layer is
exposed to the aqueous environment ,
while the Si solar cell froms a sublayer
that is not in contact with the electrolyte.
 The Si solar cell is used to generate a
photo-voltage that can be used as an
internal electrical bias. Consequently ,
this type of HPE cell is expected to
exhibit intrinsic (spontaneous )
performance in the absence of an
external bias.
 The electrochemical chain incorporated
within the HPE is shown in the figure.
V
H2O +2h+ 2H++ ½ O2 2H++ 2e- H2
p-Si
e-
H2O+MX
TiO2
e-
e-
e- H+
ƕν ƕν
ƕν
1 2 3 4 6
5
O2
H2
ƕν
n-Si
M M
Metal Electrode

8. The materials used for photo-electrodes satisfy several specific functional requirements with
respect to semiconducting and electrochemical properties.
Although these properties have been identified , it is difficult to process materials such that
all requirements are satisfied.
Key functional properties of photo-electrodes 6
1. Band gap
2.Schottky barrier
φB
Metal Semicon
EC
EV
EF
E
3 Gibbs free energy
The band gap should be small for photo-electrodes. The band gap values should be in
between the 0.8 to 1.5eV for the good photo catalytic activity.
• Thermodynamic parameters, namely, the change of Gibbs free
energy (ΔG) and the change of enthalpy (ΔH)
• Basically, the closer the ΔGH* value to zero, the higher the activity of the catalyst will be
ΔGH∗ = ΔEH∗ + ΔEZPE − TΔS

9. 7
Literature Review
 The GeI2/C2N vdW heterostructure showed an inherent type-II
indirect bandgap energy of 2.02 eV and excellent visible light
absorption, which were significantly improved compared to those
of the monolayers.
 The charge density difference revealed that about 0.263 electrons
were transferred from the C2N to GeI2 monolayer, and the
potential drop at the interface was estimated to be 7.16 eV.
Energy Adv., 2022, 1, 146–158
Enhancing the photocatalytic hydrogen generation performance and strain regulation of
the vertical GeI2/C2N van der Waals heterostructure: insights from first-principles study

10.  Wei, Y., Gao et al (2022) [1] , reported that the calculated Gibbs free energy for B7P2
monolayer (∆GH* ) is 0.06 eV, which is comparable or even better than that of Pt catalyst
(∆GH* ¼ 0.09 eV).
 Opoku, F et al (2022) [2], studied that The GeI2/C2N vdW heterostructure showed an
bandgap energy of 2.02 eV and excellent visible light absorption, which were significantly
improved compared to those of the monolayers. Moreover, the GeI2/C2N vdW
heterostructure band edges precisely straddled the water redox potential energies for pH
values ranging from 0 to 9,allowing it to meet the conditions for spontaneous water splitting.
 Yin, Q et al (2022), [3] reported that the AuSe/SnSe heterostructure has maximum solar-to-
hydrogen conversion efficiency could attain 32.95% if a suitable biaxial strain is applied.
 Jakhar, M et al (2021), [4] suggested that the effect of pH in overall water splitting are
summarized to improve the existing problems for a photocatalytic catalytic reaction such as
overcoming large overpotential to trigger the water-splitting reactions without using
cocatalysts.

11. Literature Review 18
 Demissie et al (2022) [5] reported that Two-dimensional (2D) gallium selenide (GaSe) are
exhibit almost thermoneutral hydrogen adsorption free energy ΔGH and small
bandgaps (2.09–2.21 eV), making them promising materials to perform an efficient
HER.
 Chen, H et al, (2022) [6] Reported that the modified g-C3N4 by copolymerizing
urea and diaminodiphenyl sulfone can promote the effective separation of
photogenerated electrons and holes, and simultaneously significantly increase the
fluorescence lifetime of g-C3N4.
 Cao et al, (2022) [7] reported that the small bandgap of the 2D WSeTe/XS2 direct
Z-scheme heterojunctions enables it to obtain a wide light absorption range and
also the built-in electric field from WSeTe to XS2 changes the charge transfer mode
of the heterojunction and improves the separation efficiency of photo-generated
carriers.
 Zhang et al (2022) [8] reported that noble metal doping can enhance the
electrocatalytic performance of the monolayer MoS2

12. Statement of Problems 13
 The problem associated with photocatalysis is high band gap for hydrogen
evolution reaction (i.e. 3.03 eV for ZnO ).
 The rate of charge carrier mobilities for photocatalysis in hydrogen evolution
reaction is not faster.
 The variable behavior of electrodes (some time acidic and some time basic )
upon pH value on solutions.
 Existence of Strong van der Waals (vdW)force between interlayer.
 The narrow-band-gap semiconductors (1.0–0.35eV) can utilize visible light
photons, but they also suffer from the fast recombination of photoinduced
charge carriers, which drastically decreases their photocatalytic efficiency.
 Low adsorption efficiency of the hydrogen.
 The active sites, surface defects, and compositions of electrocatalysts should be
optimized for better performance.

13. Aims and objective 14
 To reduced the band gap of photoelectrodes by using 2D Materials.
 To increased the charge mobility of the photo catalysis.
 To set the Gibbs free energy values for possible bandgap .
 The effect of pH in overall water splitting are summarized to improve
the existing problems for a photocatalytic catalytic reaction.
 The effects of the interlayer distance on the geometrical structures
and electronic properties can be reduced by using 2D Materials.
 The narrow-band-gap semiconductors (1.0–0.35eV) can utilize visible
light photons, but they also suffer from the fast recombination of
photoinduced charge carriers, which drastically decreases their
photocatalytic efficiency.
 To increases the hydrogen adsorption efficiency.

14. Research Methods 14

16. Purposed 2D materials 14
Host materials ZnO ,TiO2 2D Materials Bandgap(eV)

17. Frame Work
Search of 2D materials
Dynamical and thermodynamical Stability
Electronic properties
Band Edge Diagram for Photocatalysis
Calculations of Gibbs Free Energy (∆G)
Optical properties
14

18. 1. Wei, Y., Gao, F., Huang, H., & Jiang, G. (2022). Two-dimensional B7P2: Dual-purpose
functional material for hydrogen evolution reaction/hydrogen storage. International Journal
of Hydrogen Energy, 47(13), 8338-8347.
2. Opoku, F., Oppong, S. O. B., Asare-Donkor, N. K., Akoto, O., & Adimado, A. A. (2022).
Enhancing the photocatalytic hydrogen generation performance and strain regulation of
the vertical GeI 2/C 2 N van der Waals heterostructure: insights from first-principles
study. Energy Advances, 1(3), 146-158.
3. Yin, Q. K., Yang, C. L., Wang, M. S., & Ma, X. G. (2022). Two-dimensional AuSe/SnSe
heterostructure for solar photocatalytic hydrogen evolution reaction with Z-scheme. Solar
Energy Materials and Solar Cells, 247, 111940.
4. Jakhar, M., Kumar, A., Ahluwalia, P. K., Tankeshwar, K., & Pandey, R. (2022). Engineering
2D Materials for Photocatalytic Water-Splitting from a Theoretical
Perspective. Materials, 15(6), 2221.
References 18

19. References 18
5. Demissie, E. G., Tang, W. K., & Siu, C. K. (2022). Structure–Property Relationship of
Oxygen-Doped Two-Dimensional Gallium Selenide for Hydrogen Evolution Reaction
Revealed from Density Functional Theory. ACS Applied Energy Materials.
6. Chen, H., Fan, Y., Fan, Z., Xu, H., Cui, D., Xue, C., & Zhang, W. (2022). Electronic tuning of g-
C3N4 via competitive coordination to stimulate high-efficiently photocatalytic for hydrogen
evolution. Journal of Alloys and Compounds, 891, 162027.
7. Cao, J., Zhang, X., Zhao, S., Wang, S., & Cui, J. (2022). Mechanism of photocatalytic water
splitting of 2D WSeTe/XS2 (X= Hf, Sn, Zr) van der Waals heterojunctions under the
interaction of vertical intrinsic electric and built-in electric field. Applied Surface
Science, 599, 154012.
8.Zhang, Z., Chen, K., Zhao, Q., Huang, M., & Ouyang, X. (2021). Electrocatalytic and
photocatalytic performance of noble metal doped monolayer MoS2 in the hydrogen
evolution reaction: a first principles study. Nano Materials Science, 3(1), 89-94.

20. 38

21. 2D Materials 35
Materials Bandgap Charge Mobility
ZnO 3.32eV
GeC 2.21eV
ZnO/g-GeC 2.73eV
WSe2 1.92eV
ZnO/WSe2 2.03eV 103cm2V-1S-1
WS2 1.98eV
ZnO/WS2 2.09eV
MoS2 1.91eV
ZnO/MoS2 2.06eV
ZnO/WSSe2 2.13