Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Photoelectrochemical Water Splitting   for Hydrogen Production  Using Carbon Modified (CM) n-TiO 2 Chengkun Xu and Shahed ...
Reduced greenhouse gas emissions Reduced air pollution Improved energy efficiency Benefits of Hydrogen as an Energy Carrie...
Hydrogen Production Technologies Thermochemical Electrolytic Photolytic Natural Gas Steam Reforming ; 95% Coal Gasificatio...
Photoelectrochemial Water Splitting Photoanode: 2H 2 O + 4h  O 2  + 4H + Cathode:   4H +  + 4e  2H 2   Inputs: sunlight an...
Material Requirements for Photoelectrode Efficiency   The band gap  (Eg) must be at least 1.6-1.7eV, but not over 2.2 eV. ...
n-TiO 2 It is stable and Inexpensive. Drawbacks:   Large bandgap(3.0-3.2 eV) Unfavorable conduction  band edge position.  ...
Modifications of TiO 2  Bandgap Transition Metal Doping Nitrogen Doping   Carbon Doping Shahed U. M. Khan etc. SCIENCE, 29...
Synthesis of Carbon Modified (CM)-n-TiO 2  by Spray Pyrolysis Wet chemical spray pyrolysis Glucose as the carbon source Sp...
UV-Vis spectra of CM-n-TiO 2  films   Chengkun Xu and Shahed Khan, Electrochemical and Solid-State Letters,  10 (3) B56-B5...
Dependence of Photoresponse on the Carbon Doping Concentration C at% 1  0 2  0.58 3  0.94 4  2.0 Chengkun Xu and Shahed UM...
Dependence of Photoresponse on the Carbon Doping Concentration 1, 3-calcined in Ar; 3.8 at % C 2, 4-calcined in air; 2.1 a...
Monochromatic Photocurrent The photoresponse in the UV region now extends into the visible region ( bandgap reduction ). A...
Quantum Efficiency  η Chengkun Xu and Shahed UM Khan,   Electrochemical and Solid-State Letters,  10 (3) B56-B59, 2007
Bandgap Energy of CM-n-TiO 2 Chengkun Xu and Shahed UM Khan,   Electrochemical and Solid-State Letters,  10 (3) B56-B59, 2...
Schematic Diagram of Bandgap Modifications  for CM-n-TiO 2 H 2 O/H 2 O 2 /H 2 O 1.23 eV 2.63 eV 1.2 eV E C E V Intragap ba...
Explanations of Bandgap Modifications H. Kamisaka et al, J Chem. Phys. 123, 084704 (2005) Carbon doping induces several in...
Visible Light Photocatalytic degradation  of 4-chlorophenol Using CM-n-TiO 2  Nanoparticles CM-n-TiO 2  nanoparticles show...
Summary We developed a wet chemical spray pyrolytic method to  synthesize CM-n-TiO 2  films.  Increased carbon doping can ...
Upcoming SlideShare
Loading in …5
×

Photoelectrochemical Water Splitting

9,373 views

Published on

  • DOWNLOAD FULL eBOOK INTO AVAILABLE FORMAT ......................................................................................................................... ......................................................................................................................... 1.DOWNLOAD FULL. PDF eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. doc eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. PDF eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. doc eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... .............. Browse by Genre Available eBooks ......................................................................................................................... Art, Biography, Business, Chick Lit, Children's, Christian, Classics, Comics, Contemporary, CookeBOOK Crime, eeBOOK Fantasy, Fiction, Graphic Novels, Historical Fiction, History, Horror, Humor And Comedy, Manga, Memoir, Music, Mystery, Non Fiction, Paranormal, Philosophy, Poetry, Psychology, Religion, Romance, Science, Science Fiction, Self Help, Suspense, Spirituality, Sports, Thriller, Travel, Young Adult,
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • DOWNLOAD FULL eBOOK INTO AVAILABLE FORMAT ......................................................................................................................... ......................................................................................................................... 1.DOWNLOAD FULL. PDF eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. doc eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. PDF eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... 1.DOWNLOAD FULL. doc eBook here { https://tinyurl.com/y3nhqquc } ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... .............. Browse by Genre Available eBooks ......................................................................................................................... Art, Biography, Business, Chick Lit, Children's, Christian, Classics, Comics, Contemporary, CookeBOOK Crime, eeBOOK Fantasy, Fiction, Graphic Novels, Historical Fiction, History, Horror, Humor And Comedy, Manga, Memoir, Music, Mystery, Non Fiction, Paranormal, Philosophy, Poetry, Psychology, Religion, Romance, Science, Science Fiction, Self Help, Suspense, Spirituality, Sports, Thriller, Travel, Young Adult,
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • nice work
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • hello your slides are very nice plz can you send pranjalijadhao@gmail.com
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • like
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here

Photoelectrochemical Water Splitting

  1. 1. Photoelectrochemical Water Splitting for Hydrogen Production Using Carbon Modified (CM) n-TiO 2 Chengkun Xu and Shahed U. M. Khan * Duquesne University, Pittsburgh, PA [email_address] Chemistry & Biochemistry
  2. 2. Reduced greenhouse gas emissions Reduced air pollution Improved energy efficiency Benefits of Hydrogen as an Energy Carrier Use of Hydrogen as an Energy Carrier 2 H 2 + O 2 -> 2 H 2 O + Heat In combustion processes In fuel cells 2 H 2 + O 2 -> 2 H 2 O + Electricity Fuel Cell H 2 O 2 Water/ Heat
  3. 3. Hydrogen Production Technologies Thermochemical Electrolytic Photolytic Natural Gas Steam Reforming ; 95% Coal Gasification Biomass Gasification and Pyrolysis High-temperature Water Splitting Reforming of Renewable Liquid Fuels PEM Electrolyzer Alkaline Electrolyzers ; 5% Solid Oxide Electrolyzers Photobiological Photoelectrochemical
  4. 4. Photoelectrochemial Water Splitting Photoanode: 2H 2 O + 4h O 2 + 4H + Cathode: 4H + + 4e 2H 2 Inputs: sunlight and water Outputs: hydrogen and oxygen Sustainable and environmentally benign e n-type E g H 2 O O 2 Pt H 2 O H 2 h e 2H 2 O O 2 + 2H 2
  5. 5. Material Requirements for Photoelectrode Efficiency The band gap (Eg) must be at least 1.6-1.7eV, but not over 2.2 eV. Material Durability Must be stable in aqueous solution and under illumination. Oxide: stable III-V semiconductor: not stable. Energetics The Fermi energy of the semiconductor must be above the water reduction potential while the energy of the valence band edge must be below the water oxidation potential. n-type E g E C E V E F,n H 2 O/H 2 H 2 O/O 2 1.23 eV
  6. 6. n-TiO 2 It is stable and Inexpensive. Drawbacks: Large bandgap(3.0-3.2 eV) Unfavorable conduction band edge position. n-TiO 2 3.0-3.2 eV E C E V H 2 O/H 2 H 2 O/O 2 1.23 eV
  7. 7. Modifications of TiO 2 Bandgap Transition Metal Doping Nitrogen Doping Carbon Doping Shahed U. M. Khan etc. SCIENCE, 297 (2002) 2243
  8. 8. Synthesis of Carbon Modified (CM)-n-TiO 2 by Spray Pyrolysis Wet chemical spray pyrolysis Glucose as the carbon source Spray Solution: TiCl 4 + glucose in ethanol The resulting films were then calcined Ti substrate
  9. 9. UV-Vis spectra of CM-n-TiO 2 films Chengkun Xu and Shahed Khan, Electrochemical and Solid-State Letters, 10 (3) B56-B59, 2007 C at% 1 0 2 0.58 3 0.94 4 2.0
  10. 10. Dependence of Photoresponse on the Carbon Doping Concentration C at% 1 0 2 0.58 3 0.94 4 2.0 Chengkun Xu and Shahed UM Khan, Electrochemical and Solid-State Letters, 10 (3) B56-B59, 2007
  11. 11. Dependence of Photoresponse on the Carbon Doping Concentration 1, 3-calcined in Ar; 3.8 at % C 2, 4-calcined in air; 2.1 at % C 2.1 at % C 3.8 at % C Chengkun Xu and Shahed UM Khan, Electrochemistry Communications 8 (2006) 1650–1654 Mostly visible light illumination White light illumination 1, 2-illuminated with white light 3, 4-illuminated with mostly visible light
  12. 12. Monochromatic Photocurrent The photoresponse in the UV region now extends into the visible region ( bandgap reduction ). A second photoresponse in the visible region at around 600 nm noted ( new intragap band ). Chengkun Xu and Shahed UM Khan, Electrochemical and Solid-State Letters, 10 (3) B56-B59, 2007 Visible UV
  13. 13. Quantum Efficiency η Chengkun Xu and Shahed UM Khan, Electrochemical and Solid-State Letters, 10 (3) B56-B59, 2007
  14. 14. Bandgap Energy of CM-n-TiO 2 Chengkun Xu and Shahed UM Khan, Electrochemical and Solid-State Letters, 10 (3) B56-B59, 2007 Chengkun Xu and Shahed UM Khan, Electrochemistry Communications 8 (2006) 1650–1654
  15. 15. Schematic Diagram of Bandgap Modifications for CM-n-TiO 2 H 2 O/H 2 O 2 /H 2 O 1.23 eV 2.63 eV 1.2 eV E C E V Intragap band h ν h ν CM-n-TiO 2 KOH Undoped TiO 2 Carbon-doped TiO 2
  16. 16. Explanations of Bandgap Modifications H. Kamisaka et al, J Chem. Phys. 123, 084704 (2005) Carbon doping induces several intragap states. The intragap states near the valence band edge overlap with the valence band and form a new valence band and thus narrow the bandgap of TiO 2 . The states deep in the gap stand alone.
  17. 17. Visible Light Photocatalytic degradation of 4-chlorophenol Using CM-n-TiO 2 Nanoparticles CM-n-TiO 2 nanoparticles show significant visible light catalytic activity Under mostly visible light illumination P25 TiO 2 CM-n-TiO 2 Chengkun Xu and Shahed UM Khan, Applied Catalysis B: Environmental, 64 (2006), 312-317
  18. 18. Summary We developed a wet chemical spray pyrolytic method to synthesize CM-n-TiO 2 films. Increased carbon doping can be obtained by calcining the films in inert Ar atmosphere. CM-n-TiO 2 shows photoresponse in the visible region of the solar spectrum. Carbon doping of n-TiO 2 reduced its bandgap energy and introduces an intragap band within the original band gap. These modifications of n-TiO 2 bandgap extend the utilization of the solar energy to the visible region.

×