Efficiency Enhancement of Carbon Nitride Photoelectrochemical Cells via Tailored Monomers Design

Bian, Juncao; Xi, Lifei; Huang, Chao; Lange, Kathrin M.; Qi, Fei; Shalom, Menny

doi:10.1002/aenm.201600263

Cited by 123 publications

(128 citation statements)

References 37 publications

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“…In a typical PEC, the photoanode is composed of a light harvester attached to a wide band gap semiconductor (i.e., TiO 2 , ZnO) that serves as electrons acceptor layer while the holes are transferred to the counter electrode through the electrolyte solution. [18][19][20][21][22] The PEC operation is considered to be more complicated compared to the photocatalysis process due be extracted by the redox electrolyte (path 3). [4,5] Particularly, in the photoanode, excited states electrons of the light harvester must be injected into the conduction band of a wide band gap semiconductor prior their self-recombination (either radiatively or nonradiatively).…”

Section: Doi: 101002/admi201600265mentioning

confidence: 99%

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

Albero

Barea

et al. 2016

Adv Materials Inter

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to the necessity to establish a direct contact between the active materials (C 3 N 4 ) and the wide band gap semiconductor and the need of interparticle charge migration to the electrode. [23][24][25] Lately, we have succeeded to sensitize TiO 2 with C 3 N 4 by in situ deposition method that resulted in the formation of direct chemical bond between the TiO 2 and the C 3 N 4 . The intimate contact between TiO 2 and C 3 N 4 led to the absorption extension to longer wavelengths due to creation of new energy transfer paths between the materials. Moreover, the TiO 2 /C 3 N 4 system exhibited promising photocurrent densities in the presence of polysulfide as the redox electrolyte. [26] However, in comparison to the theoretical current densities the performances of this system are still low. In order to improve the cell performance, the understanding of the charge transfer reactions that limit the PEC efficiency, especially in the photoanode, is highly desired.Herein, we studied the charge recombination process between C 3 N 4 and mesoporous TiO 2 in a photoelectrode configuration using laser transient absorption spectroscopy (L-TAS). In addition, we determined the electron injection rate from the C 3 N 4 excited states to the TiO 2 conduction band by steady state and time resolved photoluminescence. Finally, the hole extraction kinetics using various liquid electrolytes and solid state hole conductors were also studied in detail. Our measurements indicate that the photoexcited electrons from C 3 N 4 can be efficiently injected to the TiO 2 conduction band, the recombination between electrons and holes from the TiO 2 conduction band and the C 3 N 4 valence band, respectively, is found to be relatively slow, thus allowing long-live charge separation. However, the hole transfer to the electrolyte was found to be the limiting process during the PEC operation. This understanding of the processes taking place within C 3 N 4 /TiO 2 photoanode can lead to the efficient C 3 N 4 -based PEC cells and photovoltaics solar cell via rational selection of hole conductor and smart electrode design.The C 3 N 4 electrodes were prepared according to our previous report. [26] Briefly, the C 3 N 4 was deposited onto mesoporous TiO 2 (which was grown on FTO glass) and nonconductive glass, respectively, by using cyanuric acid-melamine (CM) supramolecular complex as the precursor. The CM precursor was placed on top of TiO 2 electrodes or glass, totally covering the substrates and afterward the system was heated to 550 °C under nitrogen atmosphere (see also Figures S1 and S2, Supporting Information). After that the electrodes were fully characterized by a range of techniques. [26]

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Section: Doi: 101002/admi201600265mentioning

confidence: 99%

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

Albero

Barea

et al. 2016

Adv Materials Inter

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“…[85] Der In-situ-Gastransportmechanismus erlaubt eine vollständige Beschichtung des mesoporçsen TiO 2 -Films durch Erhitzen von pulverfçrmigen Vorstufen, die nur mit der Oberfläche des Films in Kontakt stehen. [53,86,87] Die Kondensation eines supramolekularen Komplexes wurde auch zwischen zwei Elektroden unter einer inerten Atmosphäre durchgeführt. B. Fehlen von sogenannten Pinholes,d.h.…”

Section: Wachstumsverfahrenunclassified

“…Durch die Addition eines C-reichen Moleküls (z. [86] [38,39,113] Dieser Effekt führte zu einer Verdopplung des Photostroms von 3a uf 6 mAcm À2 .…”

Section: Lichtabsorptionunclassified

“…[125,126] Die Ty p-II-Energiebandanpassung kann auch durch Abscheiden von zwei oder mehr CN-Schichten mit unterschiedlichen Bandlücken erreicht werden. [86] Die neuen C=C-Bindungen innerhalb der CN-Struktur wirken sich synergistisch positiv aus,u nd zwar im Wesentlichen hinsichtlich einer verbesserten Elektronenleitfähigkeit und einer Rotverschiebung des Absorptionsbeginns.E in weiteres Verfahren zur Umgehung der schlechten Elektronenleitfähigkeit ist die bereits erwähnte Hybridisierung von CN mit leitfähigen Materialien, die als Leitungspfade dienen. [55] Eine der Haupteinschränkungen der CN-PEC-Leistung ist die schlechte elektronische Leitfähigkeit der CN-Schicht.…”

Section: Angewandte Chemieunclassified

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Kohlenstoffnitridmaterialien für photochemische Zellen zur Wasserspaltung

et al. 2019

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Graphitische Kohlenstoffnitridmaterialien (CN) sind aufgrund ihrer einstellbaren Bandlücke, geeigneten Energiebandposition, hohen Stabilität unter harschen chemischen Bedingungen und geringen Kosten interessante Photokatalysatoren und heterogene Katalysatoren für zahlreiche Reaktionen. Allerdings befindet sich die Nutzung von CN in photoelektrochemischen (PEC) und photoelektronischen Bauelementen noch in einem frühen Stadium, da die Abscheidung einer hochwertigen und homogenen CN‐Schicht auf Substraten, die breite Bandlücke, die schlechte Ladungstrennungseffizienz sowie die geringe elektronische Leitfähigkeit noch Schwierigkeiten bereiten. In diesem Kurzaufsatz diskutieren wir Synthesewege zur Herstellung verschiedener Strukturen von CN auf Substraten und deren grundlegende photophysikalische Eigenschaften und photoelektrochemische Aktivität. Wir beschreiben die wesentlichsten Herausforderungen bei der Einbindung von CN in PEC‐Zellen sowie mögliche Wege zur Überwindung der bestehenden Beschränkungen zur Integration von CN‐Materialien in PEC und andere photoelektronische Bauelemente.

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“…

sunlight is sufficient to supply the ≈18 TW of energy required to meet our current global energy needs [2] and sustain our soci ety's projected energy demands (≈80 TW to carry society through the end of this century). Numerous strategies to harvest solar energy have been proposed and studied, such as photovoltaics, [5] water splitting, [6][7][8][9] and artificial photosynthesis of organic molecules. Numerous strategies to harvest solar energy have been proposed and studied, such as photovoltaics, [5] water splitting, [6][7][8][9] and artificial photosynthesis of organic molecules.

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confidence: 99%

Dual Protection Layer Strategy to Increase Photoelectrode–Catalyst Interfacial Stability: A Case Study on Black Silicon Photoelectrodes

Yang

Aguiar

Fairchild

et al. 2019

Adv Materials Inter

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sunlight is sufficient to supply the ≈18 TW of energy required to meet our current global energy needs [2] and sustain our soci ety's projected energy demands (≈80 TW to carry society through the end of this century). [1][2][3][4] This enormous potential within solar energy systems has aroused great interest in the scientific commu nity. Numerous strategies to harvest solar energy have been proposed and studied, such as photovoltaics, [5] water splitting, [6][7][8][9] and artificial photosynthesis of organic molecules. [10] Of particular interest to this group is photoelectrochemical (PEC) hydrogen production, by means of photo induced electrochemical conversion. PEC systems prove to be promising and prac tical due to hydrogen's abilities as a clean chemical fuel that can be stored, trans ferred, and redistributed to meet our ever increasing energy demands.A key component of PEC systems is the presence of an efficient photoabsorber able to instantly and effectively absorb and convert solar irradiation into electrical energy. Silicon (Si) has been widely inves tigated and employed in PEC systems due to its high abundance and low cost. [11,12] Its narrow bandgap of 1.12 eV suggests that Si is suitable to absorb a wide wave length range, making it advantageous in comparison with other semiconductor materials. Si's bandgap is slightly lower than overall water splitting energetics (1.23 eV), while its conduction Photoelectrode degradation under harsh solution conditions continues to be a major hurdle for long-term operation and large-scale implementation of solar fuel conversion. In this study, a dual-layer TiO 2 protection strategy is presented to improve the interfacial durability between nanoporous black silicon and photocatalysts. Nanoporous silicon photocathodes decorated with catalysts are passivated twice, providing an intermediate TiO 2 layer between the substrate and catalyst and an additional TiO 2 layer on top of the catalysts. Atomic layer deposition of TiO 2 ensures uniform coverage of both the nanoporous silicon substrate and the catalysts.After 24 h of electrolysis at pH = 0.3, unprotected photocathodes layered with platinum and molybdenum sulfide retain only 30% and 20% of their photocurrent, respectively. At the same pH, photocathodes layered with TiO 2 experience an increase in photocurrent retention: 85% for platinum-coated photocathodes and 91% for molybdenum sulfide-coated photocathodes. Under alkaline conditions, unprotected photocathodes experience a 95% loss in photocurrent within the first 4 h of electrolysis. In contrast, TiO 2 -protected photocathodes maintain 70% of their photocurrent during 12 h of electrolysis. This approach is quite general and may be employed as a protection strategy for a variety of photoabsorber-catalyst interfaces under both acidic and basic electrolyte conditions.

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Efficiency Enhancement of Carbon Nitride Photoelectrochemical Cells via Tailored Monomers Design

Cited by 123 publications

References 37 publications

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

Toward Efficient Carbon Nitride Photoelectrochemical Cells: Understanding Charge Transfer Processes

Kohlenstoffnitridmaterialien für photochemische Zellen zur Wasserspaltung

Dual Protection Layer Strategy to Increase Photoelectrode–Catalyst Interfacial Stability: A Case Study on Black Silicon Photoelectrodes

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