Cathodic shift of a photo-potential on a Ta3N5photoanode by post-heating a TiO2passivation layer

Liu, Jie; Luo, Wenjun; Zhu, Kaijian; Wen, Xin; Xiu, Fei; Yuan, Jiajie; Zou, Zhigang; Huang, Wei

doi:10.1039/c7ra04647b

Cited by 9 publications

(6 citation statements)

References 43 publications

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“…3,13 So far, Ta 3 N 5 photoanodes have been fabricated by nitridation of oxide layers, 14−16 particle transfer, 17 magnetron sputtering, 18,19 and flux coating. 20 In addition, there have been attempts to improve the PEC performances, such as controlling the Ta 3 N 5 structure, 16,21−23 doping Ta 3 N 5 , 24−26 modifying the Ta 3 N 5 surface with co-catalysts and a passivation layer, 21,27,28 and introducing a hole-blocking layer. 29 cm −2 at 1.23 V vs a reversible hydrogen electrode (hereafter abbreviated as V RHE ) under simulated AM 1.5G solar-light irradiation.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In addition to possessing a band gap that is suitable for water splitting, the narrowness of its band gap (2.1 eV) allows for the absorption of visible light with wavelength of up to 600 nm. , So far, Ta 3 N 5 photoanodes have been fabricated by nitridation of oxide layers, − particle transfer, magnetron sputtering, , and flux coating . In addition, there have been attempts to improve the PEC performances, such as controlling the Ta 3 N 5 structure, ,− doping Ta 3 N 5 , − modifying the Ta 3 N 5 surface with co-catalysts and a passivation layer, ,, and introducing a hole-blocking layer . Li et al reported that a Ta 3 N 5 photoanode fabricated by nitridation of NaTaO 3 on the surface of a Ta substrate exhibited a photocurrent of 12.1 mA·cm –2 at 1.23 V vs a reversible hydrogen electrode (hereafter abbreviated as V RHE ) under simulated AM 1.5G solar-light irradiation .…”

Section: Introductionmentioning

confidence: 99%

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Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere

Suzuki

Yanai

Yamada

et al. 2018

ACS Appl. Energy Mater.

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Photoelectrochemical (PEC) water splitting is an attractive technique to convert solar energy into chemical fuels of hydrogen and oxygen. Here, we report novel fabrication of Ta 3 N 5 photoanodes using flux method. Layers of Ta 3 N 5 with thickness of several hundred nanometers were grown on the surface of a Ta substrate by using a NaCl− Na 2 CO 3 mixed flux for the crystal growth. The Ta substrate surface was dissolved by the heated and subsequently evaporated particles of NaCl−Na 2 CO 3 in a flow of NH 3 , and Ta 3 N 5 crystals were formed upon cooling. Analysis of the cross-sectional structure showed that the interface between the Ta 3 N 5 film and the Ta substrate had few voids. In addition, the Ta 3 N 5 film consisted of two layersa sparse upper layer and a dense lower layerat a holding temperature of 900 °C, which can be attributed to variations in the evaporation behavior of the flux under different fabrication conditions. When assynthesized Ta 3 N 5 crystal film was modified using Co−Pi as the co-catalyst, it exhibited an anodic photocurrent of 6.5 mA•cm −2 at 1.23 V vs a reversible hydrogen electrode. We also studied the formation process of the Ta 3 N 5 crystal film and the role of NaCl and Na 2 CO 3 used as the mixed flux by changing the holding temperature, holding time, and NaCl/Na 2 CO 3 mixing ratio. Our results revealed that the thickness and structure of the Ta 3 N 5 crystal film were controlled by these fabrication parameters.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere

Suzuki

Yanai

Yamada

et al. 2018

ACS Appl. Energy Mater.

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“…In open circuit condition, under illumination electrons accumulate within the film and shift the Fermi level to negative potential thereby resulting in a cathodic shift of OCP. This cathodic shift is the prime characteristic of material with n‐type nature . The maximum photo potential (i. e. Voc Light −Voc Dark ) has been observed for Ag−Au‐ZNRs based photo‐anode among all the synthesized photo‐anodes.…”

Section: Resultsmentioning

confidence: 83%

“…The OCP measurements can be used to understand the intricate nature of all the synthesized photo-anodes. [12] OCP is measured as a function of time under light ON and OFF conditions and the same are plotted for all the synthesized photo-anodes in Figure 6.…”

Section: Resultsmentioning

confidence: 99%

Ag−Au‐Bimetal Incorporated ZnO‐Nanorods Photo‐Anodes for Efficient Photoelectrochemical Splitting of Water

et al. 2018

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Plasmonic Ag−Au/ZnO nanorods (ZNRs) based photo‐anodes were synthesized using a simple electrochemical route and were then evaluated for photoelectrochemical (PEC) activity. The amalgamation of Ag and Au nanoclusters broadens the UV‐Vis light absorption in the range of 400 nm to 650 nm. Ag−Au/ZNRs photo‐anodes had shown photocurrent density of ∼1.4 mA cm−2, at a bias of 0.75 V/SCE, which is ∼3.1 times of bare ZNRs photo‐anode. Bi‐metallic Ag−Au/ZNRs based photo‐anode shows the maximum photo‐conversion efficiency of 0.77 % at 0.5 V/SCE, under one sun illumination. Formation of hot electrons in Ag−Au/ZNRs photo‐anodes can be partly held responsible for the enhanced PEC activity. Au/Ag core/shell morphology evolves when a thin layer of Ag is loaded on Au nanoparticles. For an in‐depth analysis on Ag−Au incorporated ZNRs based photo‐anodes and its PEC activity, a detailed characterization was carried out using physico‐chemical, spectral and microscopy techniques. The analysis shows that Au in direct contact with ZnO interacts mainly with oxygen vacancies present on surface of ZnO and Ag interacts with Au for an effective electron‐hole segregation process at their interface and electron storage occurs in metal nanoparticles. The results suggest bi‐metal incorporated ZNRs based photo‐anodes can be a prospective candidate for PEC water splitting application.

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“…[15,18,27] There are several strategies to negatively shift the onset potential for the OER, e.g., cation doping of Ta 3 N 5 , [28][29][30][31][32] precious morphology design of Ta 3 N 5 , [33] and conjugation of Ta 3 N 5 with other materials. Especially, there are a lot of studies of the conjugation of Ta 3 N 5 with GaN, [32,34,35] ferrihydrite coating, [36] TiO 2 coating, [37] Ni(OH) x /MoO 3 bilayer coating, [38] and Cu 2 O coating [39] for cathodic shift of the onset potential. Nurlaela et al achieved band structure tuning in a GaN surface layer by Mg doping to obtain an onset potential below 0 V versus RHE.…”

Section: Introductionmentioning

confidence: 99%

Design Predictions of n–n Heterojunction Based Photoanode for Efficient Unbiased Overall Solar Water Splitting

et al. 2021

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There are multiple requirements for maximizing the efficiency of photoelectrochemical overall water splitting using a single n‐type semiconducting photoanode. Many visible‐light‐responsive photoanode materials have been developed but overall water splitting by such materials without external bias has hardly been demonstrated. Herein, the aim is to scale the impact of performance improvement by an n–n heterojunction photoanode comprising an n‐type thin modification surface layer over an n‐type photon absorber, using a finite element method. For the n‐type photon absorber, the semiconductor properties are initially set to those of a well‐studied visible–light‐absorbing Ta3N5, and key properties are varied. It is demonstrated that an appropriate donor density and thickness of the thin surface layer induce adequate energy band bending in the photon absorber, resulting in a dramatic reduction of the onset potential of the photoanode. Thus, even though the quality of the photoanode is poor (e.g., the donor density is high (≈1 × 1019 cm−3)), the optimized surface layer enables the n–n heterojunction photoanode to facilitate bias‐free solar water splitting. These exhaustive investigations could provide design guidelines for obtaining effective photoanodes using an n‐type surface modification layer, such as cocatalysts and hole collection layers.

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Cathodic shift of a photo-potential on a Ta₃N₅photoanode by post-heating a TiO₂passivation layer

Abstract: A 90 mV cathodic shift of photo-potential of a Ta3N5photoanode is achieved by increasing the conductivity of a TiO2passivation layer.

Cited by 9 publications

References 43 publications

Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere

Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere

Ag−Au‐Bimetal Incorporated ZnO‐Nanorods Photo‐Anodes for Efficient Photoelectrochemical Splitting of Water

Design Predictions of n–n Heterojunction Based Photoanode for Efficient Unbiased Overall Solar Water Splitting

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Cathodic shift of a photo-potential on a Ta3N5photoanode by post-heating a TiO2passivation layer

Abstract: A 90 mV cathodic shift of photo-potential of a Ta3N5photoanode is achieved by increasing the conductivity of a TiO2passivation layer.

Cited by 9 publications

References 43 publications

Ta3N5 Photoanodes Fabricated by Providing NaCl–Na2CO3 Evaporants to Tantalum Substrate Surface under NH3 Atmosphere

Ta3N5 Photoanodes Fabricated by Providing NaCl–Na2CO3 Evaporants to Tantalum Substrate Surface under NH3 Atmosphere

Ag−Au‐Bimetal Incorporated ZnO‐Nanorods Photo‐Anodes for Efficient Photoelectrochemical Splitting of Water

Design Predictions of n–n Heterojunction Based Photoanode for Efficient Unbiased Overall Solar Water Splitting

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Cathodic shift of a photo-potential on a Ta₃N₅photoanode by post-heating a TiO₂passivation layer

Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere

Ta₃N₅ Photoanodes Fabricated by Providing NaCl–Na₂CO₃ Evaporants to Tantalum Substrate Surface under NH₃ Atmosphere