Sérgio Ribeiro Teixeira

Novembro de 2019

O IF em Revista

2

Application of nanomaterials in

photochemical hydrogen production

from water splittingProfs. Sherdil Khan e Durão

IF-UFRGS

sherdil.khan@ufrgs.br

srgrbrtxr@gmail.com

Outlines

1. Importance of renewable energy.

2. Hydrogen as a clean fuel and artificial photosynthesis.

3. Nanomaterials applied in solar hydrogen production

3

Energy production has consequences!

Serious and combined efforts are must!

Country Emissions percentages of CO2 (2016)

Global Greenhouse Gas Emissions by Gashttps://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data

(1)Electricity generation(2) Industrial processes(3)Transportation Fuels

20-200 ys in oceans

1000 ys others

(1)Agriculture byproducts(2)Fossil fuels and distribution(3)Waste disposal & treatment 12 years

Short lived

(1)Agricultural byproducts(2)Land use & biomass burning(3) Industrial process

114 years

Os HFC são refrigerantes inofensivos para o ozonio,eficientes energeticamente e geralmente de baixatoxicidade e não inflamáveis. Porém, os gasesfluorados têm um GWP (Potenc. Aquec. Global)relativamente alto, contribuindo assim para oaquecimento global, quando libertados naatmosfera.

https://climateactiontracker.org/global/temperatures/

2100 Warming Projections and combined efforts

Is Brazil a renewable energy consuming country?

Total primary energy consumption in Brazil

20172013

www.euanmearns.com www.eia.gov

Compared to Germany the sunniest region receives a solar radiation

index that is 40% lower than that of the least sunny region in Brazil.

Thin films and nanostructure fabrication lab (L3FNano)

10

L3FNano

Physical & Chemical Synthesis

Hydrogen Production via Water Splitting

Super

Hydrophobic

Surfaces

CO2

Reduction

11

Energy density(kJ/g) Energy Density (KWh/gallon)

CO2 (lb/gallon)

Hydrogen as a clean fuel

12

Hydrogen as a fuel

Hydrogen is a green fuel if and only if it is produced by a renewable source.

Targets: 2019-2033

5 kg CO2/kg of H2

https://www.prnewswire.com

2018: hydrogen stations operational worldwide = 337

2033: over three thousand six hundred hydrogen fueling stations

1313

Potential >1.23V

H2O

H2

e-

Electrolyte

ELECTROLYSIS

H2O

O2

~0.4 V

PHOTO

Anode Cathode

h+

H2O

O2

Light

VB

CB

h+

e-

Fujishima, A. & Honda, K. - Nature - (1972).

Water Oxidation

Ox: 1.23 V/RHE

Water Reduction

Red: 0 V/RHE

Kenichi HondaAkira Fujishima

Then a new idea comes up!

NHE or SHE

14

V

Oxygen Hydrogen Electron Hole

(WE)

Pt (CE)

Ag/AgCl

(RE)

H2O

WE: 2H2O O2 + 4H+ +4e-

H2O2

CE: 4H+ + 4e- 2H2

hʋ+ -

Reversed bias

SC (n-type)

Photoelectrochemical Hydrogen Production

15

Photocatalytic Hydrogen Production

BC

BV

Semicondutor

hν

h+

e-

Água

Water Splitting

H20

H2

Redução do

H+ (H+/H2)

Oxidação

da água

(OH-/H2O)

E

0

+ 1,23

E (V)

- 0,41

+ 0,82

PH = 0 PH = 7

NHE

1,23 V

16Leung, D. Y. C. et al. - ChemSusChem – 2010 – pág - 681-694.

1 p/Solução idealmol.dm-3

Standard Hydrogen Electrode 2 H+(aq) + 2 e- → H2(g) at 25 °C.

BC

BV

Semicondutor

hν

h+

e-

H20

H2

fs-psns-µs µs-ms

Água

Tempos

17Leung, D. Y. C. et al. - ChemSusChem – 2010 – pág - 681-694.

BC

BV

Semicondutor

hν

h+

e-

H20

H2

Tempos

>< <

Água

Adicionando Agente de Sacrifício

+ Agente de Sacrifício

C2H6O - Etanol

C3H8O3 - Glicerol

CH4O - Metanol

Rufino M. Navarro Yerga, et al – ChemSusChem – 2009 - pág - 471-485

Leung, D. Y. C. et al. - ChemSusChem – 2010 – pág - 681-694.18

BC

BV

Semicondutor

hν

h+

e-

Subramanian, V., et al - J. Am. Chem. Soc. – 2004 – pág - 4943-4950.

NPs

Nanoparticulas

Metálicas

Estruturas com elevada

área superficial

E

H20

H2

Mohamed, A. E. et al Energy & Environmental Science – 2011 – pág - 1065-1086.19

NANOESTRUTURAS

Filmes Finos

Nanopartículas

Nanofios

Nanotubos

20Z. Xing, X. Zong, J.Pan, L.Wang, 2013, 104, 125

PhotoelectrolysisPhotolysis

PEM

Ag NP+Castor Oil

caprylic/capric

triglyceride (CCT) oils

NOVO MÉTODO DE RECOBRIMENTO DE SUBSTRATOS EM PÓ COMNANOPARTÍCIULAS: APLICAÇÃO EM CATÁLISE E NANOPARTÍCULASMAGNÉTICAS

Figura 1.1: Gráfico apresentando a evolução de

artigos sobre catálise e nanopartículas desde 2000 a

2012; dados coletados do ISI 01/02/2013.

Figura 3.17: Sistema de vibração; 1- copo de alumínio repuxado; 2-

conector do sinal elétrico; 3a- molas superior e inferior; 3b- porca e contra

porca de regulagem; 4- bobina eletromagnética; 5- Batente superior; 6 -

Aranha de sustentação.

(a) Alumínio; (b) Cobre e (c) Oxigênio.

These functional over-layers on magnetic

supports can be detrimental to catalytic

activity, since multipoint covalent

attachments may promote rigidification

of the molecular structure of the

immobilized enzyme.

Modification

of NP surface

lipase from

Pseudomonas

cepacia

TEM (a) and AFM (b) images of the lipase after Ni deposition. HRTEM

of one of these Ni NP (c). 1.1 mg of Ni by 1 g of Lipase.

28

UV-Vis of Ta3N5 NTs samples

Sample: 800°C – 3h

Eg≈2.06 eV

Eg≈3.7 eV

Species such as Tantalum (Ta4+)

creating surface defects acting

as recombination centers

Remaining Oxigen atoms

which give rise to density

of states inside the band gap.

29

PEC performace of Ta3N5 NTs samples

0 V vs V Ag/AgCl (pH, 7.5) = 0.64 V vs RHE

0.6 V vs Ag/AgCl = 1.23 V vs RHE 25-fold

[Fe(CN)6]-3/-4

Sherdil Khan

30

Anderson Mauricio Thais Hameed Rogério Ariadne

SérgioSherdil

Fernanda João Erhon

Lamai- IQ-UFRGS

No of Publications in this area (2010-2019)

Publications by year

www.webofknowledge.com

From Brazil (2.4%) (1)USP

(2)UNESP

(3)UNICAMP

(4)UFRGS

www.webofknowledge.com

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