1
|
Wengler-Rust S, Staechelin YU, Lange H, Weller H. Electron Donor-Specific Surface Interactions Promote the Photocatalytic Activity of Metal-Semiconductor Nanohybrids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401388. [PMID: 38634407 DOI: 10.1002/smll.202401388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/25/2024] [Indexed: 04/19/2024]
Abstract
In the past two decades, the application of colloidal semiconductor-metal nanoparticles (NPs) as photocatalysts for the hydrogen generation from water has been extensively studied. The present body of literature studies agrees that the photocatalytic yield strongly depends on the electron donating agent (EDA) added for scavenging the photogenerated holes. The highest reported hydrogen production rates are obtained in the presence of ionic EDAs and at high pH. The large hydrogen production rates are attributed to fast hole transfer from the NP onto the EDAs. However, the present discussions do not treat the influence of EDA-specific surface interactions. This systematic study focuses on that aspect by combining steady-state hydrogen production measurements with time-resolved and static optical spectroscopy, employing 11-mercaptoundecanoic acid-capped, Pt-tipped CdSe/CdS dot-in-rods in the presence of a large set of EDAs. Based on the experimental results, two distinct EDA groups are identified: surface-active and diffusion-limited EDAs. The largest photocatalytic efficiencies are obtained in the presence of surface-active EDAs that induce an agglomeration of the NPs. This demonstrates that the introduction of surface-active EDAs can significantly enhance the photocatalytic activity of the NPs, despite reducing their colloidal stability and inducing the formation of NP networks.
Collapse
Affiliation(s)
- Soenke Wengler-Rust
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
| | - Yannic U Staechelin
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
| | - Holger Lange
- The Hamburg Centre for Ultrafast Imaging, 22761, Hamburg, Germany
- Institut für Physik und Astronomie, Universität Potsdam, 14476, Potsdam, Germany
| | - Horst Weller
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, 22761, Hamburg, Germany
- Fraunhofer IAP-CAN, 20146, Hamburg, Germany
| |
Collapse
|
2
|
Ruan Q, Xi X, Yan B, Kong L, Jiang C, Tang J, Sun Z. Stored photoelectrons in a faradaic junction for decoupled solar hydrogen production in the dark. Chem 2023. [DOI: 10.1016/j.chempr.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
|
3
|
Wei X, Liu H, Gao S, Jia K, Wang Z, Chen J. Photocatalyst: To Be Dispersed or To Be Immobilized? The Crucial Role of Electron Transport in Photocatalytic Fixed Bed Reaction. J Phys Chem Lett 2022; 13:9642-9648. [PMID: 36214491 DOI: 10.1021/acs.jpclett.2c02581] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Photocatalytic fixed bed reactors allow a straightforward separation from the process stream and simplify the installation and operation in practical application. However, it is widely believed that the restriction on mass transport and volume activation severely slows the reaction. Here, we demonstrate that photocatalytic fixed bed reactors can deliver a superior reaction rate to the slurry suspension by rationally modulating the electronic process and the most concerning issue of mass transport occurring on a decisecond time scale does not retard the reaction. Although the long-distance transport of photogenerated electrons in porous semiconductor films toward catalytic sites encounters boundary scattering, this electronic process can be far faster than semiconductor-cocatalyst interfacial electron transfer occurring on the decisecond-second time scale. Besides, the fixed bed reaction can be freely amplified without losing photon utilization. Under irradiation provided by a 320 W Hg lamp, we realize a reaction rate of 0.262 mol/h with 65.2% quantum yield for anaerobic dehydrogenation of ethanol.
Collapse
Affiliation(s)
- Xuhui Wei
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, China
| | - Haifeng Liu
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
| | - Shugong Gao
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
| | - Kun Jia
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
| | - Zhijian Wang
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
| | - Jiazang Chen
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan030001, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, China
| |
Collapse
|
4
|
Li S, Chen K, Vähänissi V, Radevici I, Savin H, Oksanen J. Electron Injection in Metal Assisted Chemical Etching as a Fundamental Mechanism for Electroless Electricity Generation. J Phys Chem Lett 2022; 13:5648-5653. [PMID: 35708355 PMCID: PMC9234978 DOI: 10.1021/acs.jpclett.2c01302] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Metal-assisted chemical etching (MACE) is a widely applied process for fabricating Si nanostructures. As an electroless process, it does not require a counter electrode, and it is usually considered that only holes in the Si valence band contribute to the process. In this work, a charge carrier collecting p-n junction structure coated with silver nanoparticles is used to demonstrate that also electrons in the conduction band play a fundamental role in MACE, and enable an electroless chemical energy conversion process that was not previously reported. The studied structures generate electricity at a power density of 0.43 mW/cm2 during MACE. This necessitates reformulating the microscopic electrochemical description of the Si-metal-oxidant nanosystems to separately account for electron and hole injections into the conduction and valence band of Si. Our work provides new insight into the fundamentals of MACE and demonstrates a radically new route to chemical energy conversion by solar cell-inspired devices.
Collapse
Affiliation(s)
- Shengyang Li
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
| | - Kexun Chen
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Ville Vähänissi
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Ivan Radevici
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
| | - Hele Savin
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Jani Oksanen
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
| |
Collapse
|
5
|
Electrochemical Synthesis-Dependent Photoelectrochemical Properties of Tungsten Oxide Powders. CHEMENGINEERING 2022. [DOI: 10.3390/chemengineering6020031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
A rapid, facile, and environmentally benign strategy to electrochemical oxidation of metallic tungsten under pulse alternating current in an aqueous electrolyte solution was reported. Particle size, morphology, and electronic structure of the obtained WO3 nanopowders showed strong dependence on electrolyte composition (nitric, sulfuric, and oxalic acid). The use of oxalic acid as an electrolyte provides a gram-scale synthesis of WO3 nanopowders with tungsten electrochemical oxidation rate of up to 0.31 g·cm−2·h−1 that is much higher compared to the strong acids. The materials were examined as photoanodes in photoelectrochemical reforming of organic substances under solar light. WO3 synthesized in oxalic acid is shown to exhibit excellent activity towards the photoelectrochemical reforming of glucose and ethylene glycol, with photocurrents that are nearly equal to those achieved in the presence of simple alcohol such as ethanol. This work demonstrates the promise of pulse alternating current electrosynthesis in oxalic acid as an efficient and sustainable method to produce WO3 nanopowders for photoelectrochemical applications.
Collapse
|
6
|
Determination of photon-driven charge transfer efficiency: Drawbacks, accuracy and precision of different methods using Hematite as case of study. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2021.139559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
7
|
Vahidzadeh E, Zeng S, Alam KM, Kumar P, Riddell S, Chaulagain N, Gusarov S, Kobryn AE, Shankar K. Harvesting Hot Holes in Plasmon-Coupled Ultrathin Photoanodes for High-Performance Photoelectrochemical Water Splitting. ACS APPLIED MATERIALS & INTERFACES 2021; 13:42741-42752. [PMID: 34476945 DOI: 10.1021/acsami.1c10698] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The harvesting of hot carriers produced by plasmon decay to generate electricity or drive a chemical reaction enables the reduction of the thermalization losses associated with supra-band gap photons in semiconductor photoelectrochemical (PEC) cells. Through the broadband harvesting of light, hot-carrier PEC devices also produce a sensitizing effect in heterojunctions with wide-band gap metal oxide semiconductors possessing good photostability and catalytic activity but poor absorption of visible wavelength photons. There are several reports of hot electrons in Au injected over the Schottky barrier into crystalline TiO2 and subsequently utilized to drive a chemical reaction but very few reports of hot hole harvesting. In this work, we demonstrate the efficient harvesting of hot holes in Au nanoparticles (Au NPs) covered with a thin layer of amorphous TiO2 (a-TiO2). Under AM1.5G 1 sun illumination, photoanodes consisting of a single layer of ∼50 nm diameter Au NPs coated with a 10 nm shell of a-TiO2 (Au@a-TiO2) generated 2.5 mA cm-2 of photocurrent in 1 M KOH under 0.6 V external bias, rising to 3.7 mA cm-2 in the presence of a hole scavenger (methanol). The quantum yield for hot-carrier-mediated photocurrent generation was estimated to be close to unity for high-energy photons (λ < 420 nm). Au@a-TiO2 photoelectrodes produced a small positive photocurrent of 0.1 mA cm-2 even at a bias of -0.6 V indicating extraction of hot holes even at a strong negative bias. These results together with density functional theory modeling and scanning Kelvin probe force microscope data indicate fast injection of hot holes from Au NPs into a-TiO2 and light harvesting performed near-exclusively by Au NPs. For comparison, Au NPs coated with a 10 nm shell of Al2O3 (Au@Al2O3) generated 0.02 mA cm-2 of photocurrent in 1 M KOH under 0.6 V external bias. These results underscore the critical role played by a-TiO2 in the extraction of holes in Au@a-TiO2 photoanodes, which is not replicated by an ordinary dielectric shell. It is also demonstrated here that an ultrathin photoanode (<100 nm in maximum thickness) can efficiently drive sunlight-driven water splitting.
Collapse
Affiliation(s)
- Ehsan Vahidzadeh
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Sheng Zeng
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Kazi M Alam
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Pawan Kumar
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Saralyn Riddell
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Narendra Chaulagain
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Sergey Gusarov
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Alexander E Kobryn
- Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| |
Collapse
|
8
|
Xiang H, Wang Z, Chen J. Revealing and Facilitating the Rate-Determining Step for Efficient Sunlight-Driven Photocatalysis. J Phys Chem Lett 2021; 12:7665-7670. [PMID: 34351768 DOI: 10.1021/acs.jpclett.1c02101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Because of the complex composition of the apparent activation energy, the rate-determining step in a photocatalytic reaction like hydrogen evolution is still being explored even after sluggish oxygen evolution is replaced with efficient hole extraction. This issue severely limits the implementation of certain strategies like the synergistic thermal effect. Here, by developing a combined monitor method based on open-circuit potential decay, we demonstrate that semiconductor-cocatalyst interfacial electron transfer occurring on a decisecond to second time scale dominates photocatalytic hydrogen evolution. This time scale is approximately 6-12 orders of magnitude larger than the widely reported values of picoseconds to microseconds and is comparable to that predicted by Durrant et al. To improve photocatalytic hydrogen evolution, we manage to create more intermediate sites by electronically doping the semiconductor surface. This measure promotes semiconductor-cocatalyst interfacial electron transfer by charge recombination and makes the synergistic thermal effect very evident.
Collapse
Affiliation(s)
- Houkui Xiang
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhijian Wang
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
| | - Jiazang Chen
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
9
|
Jaramillo-Gutiérrez MI, Velasco-Rueda JS, Pedraza-Avella JA. Kinetic Approach by Photocurrent Measurements to the Photoelectrocatalytic Oxidation of an Anionic Surfactant Using an S,N-TiO2/Ti Electrode: Distinguishing Between Direct and Indirect Mechanisms. Top Catal 2021. [DOI: 10.1007/s11244-020-01404-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
10
|
Rafat MN, Cho KY, Jung CH, Oh WC. New modeling of 3D quaternary type BaCuZnS-graphene-TiO 2 (BCZS-G-T) composite for photosonocatalytic hydrogen evolution with scavenger effect. Photochem Photobiol Sci 2020; 19:1765-1775. [PMID: 33300540 DOI: 10.1039/d0pp00295j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the efficient evolution of hydrogen, we designed a 3D quaternary BaCuZnS-graphene-TiO2 (BCZS-G-T) composite by an ultrasonic method. Herein, we prepared a quaternary material to minimize the bandgap energy and size. We characterized the "as-prepared" composites by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and electrochemical impedance spectroscopy (EIS). The high hydrogen evolution was attributed to the 3D quaternary BCZS-G-T composite with small bandgap energy because of its high photoelectron recombination properties. In addition, we demonstrated the combination effects with photocatalytic and sonocatalytic treatments with a scavenger. This work highlights the potential application of quaternary graphene-based composites in the field of energy conversion.
Collapse
Affiliation(s)
- Md Nazmodduha Rafat
- Department of Advanced Materials Science & Engineering, Hanseo University, Seosan-si, Chungnam 356-706, Korea.
| | | | | | | |
Collapse
|
11
|
Andrade TS, Pereira MC, Lianos P. High voltage gain in photo-assisted charging of a metal-air battery. J Electroanal Chem (Lausanne) 2020. [DOI: 10.1016/j.jelechem.2020.114559] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
12
|
Photoelectrocatalytic production of hydrogen peroxide using a photo(catalytic) fuel cell. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2019.112210] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
13
|
Photoelectrocatalytic Hydrogen Peroxide Production Using Nanoparticulate WO3 as Photocatalyst and Glycerol or Ethanol as Sacrificial Agents. Processes (Basel) 2019. [DOI: 10.3390/pr8010037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Photoelectrochemical production of hydrogen peroxide was studied by using a cell functioning with a WO3 photoanode and an air breathing cathode made of carbon cloth with a hydrophobic layer of carbon black. The photoanode functioned in the absence of any sacrificial agent by water splitting, but the produced photocurrent was doubled in the presence of glycerol or ethanol. Hydrogen peroxide production was monitored in all cases, mainly in the presence of glycerol. The presence or absence of the organic fuel affected only the obtained photocurrent. The Faradaic efficiency for hydrogen peroxide production was the same in all cases, mounting up to 74%. The duplication of the photocurrent in the presence of biomass derivatives such as glycerol or ethanol and the fact that WO3 absorbed light in a substantial range of the visible spectrum promotes the presently studied system as a sustainable source of hydrogen peroxide production.
Collapse
|
14
|
Santos Andrade T, Papagiannis I, Dracopoulos V, César Pereira M, Lianos P. Visible-Light Activated Titania and Its Application to Photoelectrocatalytic Hydrogen Peroxide Production. MATERIALS 2019; 12:ma12244238. [PMID: 31861190 PMCID: PMC6947256 DOI: 10.3390/ma12244238] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 11/16/2022]
Abstract
Photoelectrochemical cells have been constructed with photoanodes based on mesoporous titania deposited on transparent electrodes and sensitized in the Visible by nanoparticulate CdS or CdS combined with CdSe. The cathode electrode was an air–breathing carbon cloth carrying nanoparticulate carbon. These cells functioned in the Photo Fuel Cell mode, i.e., without bias, simply by shining light on the photoanode. The cathode functionality was governed by a two-electron oxygen reduction, which led to formation of hydrogen peroxide. Thus, these devices were employed for photoelectrocatalytic hydrogen peroxide production. Two-compartment cells have been used, carrying different electrolytes in the photoanode and cathode compartments. Hydrogen peroxide production has been monitored by using various electrolytes in the cathode compartment. In the presence of NaHCO3, the Faradaic efficiency for hydrogen peroxide production exceeded 100% due to a catalytic effect induced by this electrolyte. Photocurrent has been generated by either a CdS/TiO2 or a CdSe/CdS/TiO2 combination, both functioning in the presence of sacrificial agents. Thus, in the first case ethanol was used as fuel, while in the second case a mixture of Na2S with Na2SO3 has been employed.
Collapse
Affiliation(s)
- Tatiana Santos Andrade
- Department of Chemical Engineering, University of Patras, 26500 Patras, Greece; (T.S.A.); (I.P.)
- Institute of Science, Engineering, and Technology, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus Mucuri, 39803–371 Teófilo Otoni, Minas Gerais, Brazil;
| | - Ioannis Papagiannis
- Department of Chemical Engineering, University of Patras, 26500 Patras, Greece; (T.S.A.); (I.P.)
| | | | - Márcio César Pereira
- Institute of Science, Engineering, and Technology, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus Mucuri, 39803–371 Teófilo Otoni, Minas Gerais, Brazil;
| | - Panagiotis Lianos
- Department of Chemical Engineering, University of Patras, 26500 Patras, Greece; (T.S.A.); (I.P.)
- Correspondence: ; Tel.: +30-2610-997513
| |
Collapse
|
15
|
Photoelectrocatalytic Hydrogen Production Using a TiO2/WO3 Bilayer Photocatalyst in the Presence of Ethanol as a Fuel. Catalysts 2019. [DOI: 10.3390/catal9120976] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Photoelectrocatalytic hydrogen production was studied by using a photoelectrochemical cell where the photoanode was made by depositing on FTO electrodes either a nanoparticulate WO3 film alone or a bilayer film made of nanoparticulate WO3 at the bottom covered with a nanoparticulate TiO2 film on the top. Both the electric current and the hydrogen produced by the photoelectrocatalysis cell substantially increased by adding the top titania layer. The presence of this layer did not affect the current-voltage characteristics of the cell (besides the increase of the current density). This was an indication that the flow of electrons in the combined semiconductor photoanode was through the WO3 layer. The increase of the current was mainly attributed to the passivation of the surface recombination sites on WO3 contributing to the limitation of charge recombination mechanisms. In addition, the top titania layer may have contributed to photon absorption by back scattering of light and thus by enhancement of light absorption by WO3. Relatively high charge densities were recorded, owing both to the improvement of the photoanode by the combined photocatalyst and to the presence of ethanol as the sacrificial agent (fuel), which affected the recorded current by “current doubling” phenomena. Hydrogen was produced under electric bias using a simple cathode electrode made of carbon paper carrying carbon black as the electrocatalyst. This electrode gave a Faradaic efficiency of 58% for hydrogen production.
Collapse
|
16
|
Halevy S, Korin E, Bettelheim A. Enhancement of photoelectrochemical organics degradation and power generation by electrodeposited coatings of g-C 3N 4 and graphene on TiO 2 nanotube arrays. NANOSCALE ADVANCES 2019; 1:4128-4136. [PMID: 36132104 PMCID: PMC9417468 DOI: 10.1039/c9na00437h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 09/15/2019] [Indexed: 06/01/2023]
Abstract
New g-C3N4 coatings obtained via electropolymerization (EP) of melamine followed by a heat treatment and graphene oxide (GO) coatings based on combining GO sheets via EP of GO phenolic groups are used to improve the performance of photoanodes composed of TiO2 nanotube arrays towards the photoelectrochemical (PEC) oxidation of methanol. This process, as examined in Na2CO3 solution (pH 11.4) for the two types of coatings and serving as a model for the degradation of an organic pollutant, demonstrates enhanced PEC performance as compared to that obtained using electrochemically reduced GO coatings. PEC oxidation currents obtained with 1 M methanol reach saturation at potentials as low as ∼-0.4 V vs. Ag/AgCl, with the highest saturation current density of ∼2.6 mA cm-2 and photon-to-current efficiency of 52% as observed for the new TiO2NTs/g-C3N4 photoanodes. Electrochemical impedance spectroscopy measurements for these photoanodes show a charge transfer resistance one order of magnitude lower than that obtained by the other types of coatings. This indicates an enhanced charge separation ability for the photogenerated electron-hole pairs and faster interfacial charge transfer between the electron donor (methanol) and acceptor (holes). It is also demonstrated that the process of organics degradation can be achieved not only via an applied potential but also in a galvanic photofuelcell with methanol and oxygen serving as the fuel and oxidant, respectively. The power densities achieved with the electrochemically prepared g-C3N4 photoanodes (∼0.5 mW cm-2) are at least one order of magnitude higher than those reported for other TiO2-based systems.
Collapse
Affiliation(s)
- Shuli Halevy
- Chemical Engineering Department, Ben Gurion University of the Negev Beer-Sheva 84105 Israel
| | - Eli Korin
- Chemical Engineering Department, Ben Gurion University of the Negev Beer-Sheva 84105 Israel
| | - Armand Bettelheim
- Chemical Engineering Department, Ben Gurion University of the Negev Beer-Sheva 84105 Israel
| |
Collapse
|
17
|
Denisov N, Yoo J, Schmuki P. Effect of different hole scavengers on the photoelectrochemical properties and photocatalytic hydrogen evolution performance of pristine and Pt-decorated TiO2 nanotubes. Electrochim Acta 2019. [DOI: 10.1016/j.electacta.2019.06.173] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
18
|
Abstract
Hydrogen and hydrogen peroxide have been photoelectrocatalytically produced by electrocatalytic reduction using simple carbon electrodes made by depositing a mesoporous carbon film on carbon cloth. Visible-light-absorbing photoanodes have been constructed by depositing mesoporous CdS/TiO2 or WO3 films on transparent fluorine-doped tin oxide (FTO) electrodes. Both produced substantial photocurrents of up to 50 mA in the case of CdS/TiO2 and 25 mA in the case of WO3 photoanodes, and resulting in the production of substantial quantities of H2 gas or aqueous H2O2. Maximum hydrogen production rate was 7.8 µmol/min, and maximum hydrogen peroxide production rate was equivalent, i.e., 7.5 µmol/min. The same reactor was employed for the production of both solar fuels, with the difference being that hydrogen was produced under anaerobic and hydrogen peroxide under aerated conditions. The present data promote the photoelectrochemical production of solar fuels by using simple inexpensive materials for the synthesis of catalysts and the construction of electrodes.
Collapse
|
19
|
Photo-effect on the electromotive force in two-compartment hydrogen peroxide-photofuel cell. Electrochem commun 2018. [DOI: 10.1016/j.elecom.2018.05.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
20
|
A Realistic Approach for Photoelectrochemical Hydrogen Production. MATERIALS 2018; 11:ma11081269. [PMID: 30042319 PMCID: PMC6117642 DOI: 10.3390/ma11081269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 07/18/2018] [Accepted: 07/20/2018] [Indexed: 11/17/2022]
Abstract
The production of hydrogen by water splitting has been a very attractive idea for several decades. However, the energy consumption that is necessary for water oxidation is too high for practical applications. On the contrary, the oxidation of organics is a much easier and less energy-demanding process. In addition, it may be used to consume organic wastes with a double environmental benefit: renewable energy production with environmental remediation. The oxidation of organics in a photoelectrochemical cell, which in that case is also referenced as a photocatalytic fuel cell, has the additional advantage of providing an alternative route for solar energy conversion. With this in mind, the present work describes a realistic choice of materials for the Pt-free photoelectrochemical production of hydrogen, by employing ethanol as a model organic fuel. The photoanode was made of a combination of titania with cadmium sulfide as the photosensitizer in order to enhance visible light absorbance. The cathode electrode was a simple carbon paper. Thus, it is shown that substantial hydrogen can be produced without electrocatalysts by simply exploiting carbon electrodes. Even though an ion transfer membrane was used in order to allow for an oxygen-free cathode environment, the electrolyte was the same in both the anode and cathode compartments. An alkaline electrolyte has been used to allow high hydroxyl concentration, thus facilitating organic fuel (photocatalytic) oxidation. Hydrogen production was then obtained by water reduction at the cathode (counter) electrode.
Collapse
|
21
|
|
22
|
Raptis D, Dracopoulos V, Lianos P. Renewable energy production by photoelectrochemical oxidation of organic wastes using WO 3 photoanodes. JOURNAL OF HAZARDOUS MATERIALS 2017; 333:259-264. [PMID: 28363147 DOI: 10.1016/j.jhazmat.2017.03.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/16/2017] [Accepted: 03/21/2017] [Indexed: 06/07/2023]
Abstract
The present work has studied renewable hydrogen production by photoelectrocatalytic degradation of model organic substances representing biomass derived organic wastes. Its purpose was to show that renewable energy can be produced by consuming wastes. The study has been carried out by employing nanoparticulate WO3 photoanodes in the presence of ethanol, glycerol or sorbitol, i.e. three substances which are among typical biomass products. In these substances, the molecular weight and the number of hydroxyl groups increases from ethanol to sorbitol. The photocurrent produced by the cell was the highest in the presence of ethanol, smaller in the case of glycerol and further decreased in the presence of sorbitol. The photocurrent was roughly the double of that produced in the absence of an organic additive thus demonstrating current doubling phenomena. Hydrogen was produced only under illumination and was monitored at two forward bias, 0.8 and 1.6V vs Ag/AgCl. Hydrogen production rates followed the same order as the photocurrent thus indicating that hydrogen production by reduction of protons mainly depends on the current flowing through the external circuit connecting photoanode with cathode. The maximum solar-to-hydrogen efficiency reached by the present system was 2.35%.
Collapse
Affiliation(s)
- Dimitrios Raptis
- Department of Chemical Engineering, University of Patras, 26500 Patras, Greece
| | | | - Panagiotis Lianos
- Department of Chemical Engineering, University of Patras, 26500 Patras, Greece.
| |
Collapse
|
23
|
Park H, Ou HH, Kim M, Kang U, Han DS, Hoffmann MR. Photocatalytic H2 production on trititanate nanotubes coupled with CdS and platinum nanoparticles under visible light: revisiting H2 production and material durability. Faraday Discuss 2017; 198:419-431. [DOI: 10.1039/c6fd00192k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photocatalytic production of molecular hydrogen (H2) on ternary composites of Pt, CdS, and sodium trititanate nanotubes (NaxH2−xTi3O7, TNTs) is examined in an aqueous 2-propanol (IPA) solution (typically 5 vol%) at a circum-neutral pH under visible light (λ > 420 nm). The H2 production rates are dependent on the Pt-loading level, and the optimum production rate in the Pt/CdS/TNTs is approximately six times higher than that in Pt/CdS/TiO2. A D2O solution containing 5 vol% IPA leads only to the production of D2 molecules, whereas increasing the IPA amount to 30 vol% leads to the production of DH molecules. This indicates that the Pt/CdS/TNTs composites enable H2 production via true water splitting under our typical experimental conditions. X-ray photoelectron spectroscopy (XPS) analyses of the as-synthesized Pt/CdS/TNTs and those used for 6 and 12 h show that metallic Pt on the CdS/TNTs is less susceptible to oxidation than Pt on CdS/TiO2. In addition, photocorrosion of CdS (i.e., sulfate formation) is significantly inhibited during the photocatalytic H2 production reactions in the Pt/CdS/TNTs because of the efficient charge transfer via the TNTs framework. The Pt/CdS/TNTs samples are thermally more stable than Pt/CdS/TiO2 and CdS/TNTs, effectively inhibiting the formation of CdO during the thermal synthesis. Detailed surface characterizations of the as-synthesized ternary composites are performed using X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and XPS.
Collapse
Affiliation(s)
- Hyunwoong Park
- School of Energy Engineering
- Kyungpook National University
- Daegu 41566
- Korea
- School of Architectural, Civil, Environmental and Energy Engineering
| | - Hsin-Hung Ou
- Linde-Robinson Laboratories
- California Institute of Technology
- Pasadena
- USA
| | - Minju Kim
- School of Energy Engineering
- Kyungpook National University
- Daegu 41566
- Korea
- School of Architectural, Civil, Environmental and Energy Engineering
| | - Unseock Kang
- School of Energy Engineering
- Kyungpook National University
- Daegu 41566
- Korea
- School of Architectural, Civil, Environmental and Energy Engineering
| | - Dong Suk Han
- Chemical Engineering Program
- Texas A&M University at Qatar
- Education City
- Doha
- Qatar
| | | |
Collapse
|
24
|
Mancilla FJ, Rojas SF, Gualdrón-Reyes AF, Carreño-Lizcano MI, Duarte LJ, Niño-Gómez ME. Improving the photoelectrocatalytic performance of boron-modified TiO2/Ti sol–gel-based electrodes for glycerol oxidation under visible illumination. RSC Adv 2016. [DOI: 10.1039/c6ra02806c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
B-TiO2 photoelectrodes showed a high photoelectrocatalytic performance under visible illumination due to efficient electron transport and charge carrier separation.
Collapse
Affiliation(s)
- Federico J. Mancilla
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
| | - Silvia F. Rojas
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
| | - Andrés F. Gualdrón-Reyes
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
| | - María I. Carreño-Lizcano
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
| | - Liseth J. Duarte
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
| | - M. E. Niño-Gómez
- Centro de Investigaciones en Catálisis – CICAT
- Universidad Industrial de Santander
- Piedecuesta
- Colombia
- Centro de Materiales y Nanociencias (CMN)
| |
Collapse
|