Subscriber access provided by TUFTS UNIV
Letter
Boosting Photoelectrochemical Water Oxidation Activity and Stability of Mo-doped BiVO4 through the Uniform Assembly Coating of NiFe-Phenolic Networks Yanmei Shi, Yifu Yu, Yu Yu, Yi Huang, Bohang Zhao, and Bin Zhang ACS Energy Lett., Just Accepted Manuscript • Publication Date (Web): 20 Jun 2018 Downloaded from http://pubs.acs.org on June 20, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
Boosting Photoelectrochemical Water Oxidation Activity and Stability of Mo-doped BiVO4 through the Uniform Assembly Coating of NiFe-Phenolic Networks Yanmei Shi, Yifu Yu, Yu Yu, Yi Huang, Bohang Zhao, and Bin Zhang* Department of Chemistry, School of Science, and Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China AUTHOR INFORMATION Corresponding Author *E-mail:
[email protected]
ACS Paragon Plus Environment
1
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 20
ABSTRACT. Photocorrosion is a key factor that greatly hinders the stability of the photoanodes. Depositing appropriate cocatalysts can effectively protect the semiconductors from the photocorrosion, as well as improve the photoelectrochemical (PEC) activity. However, the formation of cocatalysts is mostly under island growth, making the semiconductors partially unprotected, thus leading to a poor stability. Herein, we demonstrate the complex assembly film composed of phenolic ligands (tannic acid) coordinated with Ni and Fe ions as a robust cocatalyst (TANF) for Mo-doped BiVO4 (Mo:BiVO4@TANF) towards PEC water oxidation. The photocurrent density of Mo:BiVO4@TANF at 1.23 V vs. reversible hydrogen electrode (RHE) reaches a value of 5.10±0.13 mA cm-2. Furthermore, because the complete coverage of TANF film can effectively protect the semiconductor from photocorrosion, 92 % photocurrent of the integrated photoanode retains after operating at harsh 1.23 V vs. RHE for 3 h. The outstanding activity and stability of the integrated photoanode surpass many existing cocatalysts such as ferrihydrite (Fh) and cobalt phosphate (Co-Pi). And the TANF cocatalyts can be also applied to other semiconductors (non-doped BiVO4 and TiO2), indicating the TANF to be a promising cocatalyst alternative for solar energy conversion.
TOC GRAPHICS
ACS Paragon Plus Environment
2
Page 3 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
Photoelectrochemical (PEC) overall water splitting is a promising approach to harvest and store solar energy as renewable and clean fuels.1-7 In general, the PEC process can be divided to three steps: (i) the light-absorption of semiconductor to produce electron-hole pairs, (ii) the separation and migration of the photogenerated charges, and (iii) the surface reaction initiated by the photogenerated charges.8-12 The overall PEC efficiency is determined by all the three steps. Specially, bismuth vanadate (BiVO4) is considered to be a good model photoanode for PEC water oxidation.13-22 The suitable bandgap of BiVO4 makes step (i) easy to happen. After Modoping, the conductivity of BiVO4 can be greatly improved.23-24 As a result, the charge transfer of Mo:BiVO4 is facilitated, leading to a high charge separation rate (step ii). To further increase the PEC efficiency of Mo:BiVO4 photoanode, efforts should be carried on the step (iii), which is promoted by the deposition of appropriate oxygen evolution cocatalysts (OECs).25-27 OECs can effectively lower the activation energy of the surface oxygen evolution reaction or passivate the surface charge recombination centers of the semiconductors,28-29 so that the PEC activity can be greatly improved. Many efforts have been made in the searching for the adequate OECs for Mo:BiVO4, such as cobalt phosphate (Co-Pi),30-31 cobalt borate (Co-Bi),32 NiOOH and/or FeOOH,33 and ferrihydrite (Fh).34-35 However, even with the assistance of the state-of-theart OEC, the photocurrent density of photoanodes with single BiVO4 as light absorber only attain ~5 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE),36 which is still much smaller than the theoretical value (7.6 mA cm-2).37 On the other hand, OECs can also improve the stability of the photoanodes. By blocking the direct contact between semiconductors and the electrolyte, OECs can effectively protect the semiconductors from photocorrosion.38 However, many conventional strategies always produce OECs with island distribution on the semiconductors,39-40 leaving the semiconductors partially
ACS Paragon Plus Environment
3
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 20
exposed to the electrolyte, thus leading to a poor stability. Notably, although some OECs are reported to be very stable at low current density, their durability at high photocurrent density are seldom studied, even if the latter is more significant in practical application. Therefore, the fabrication of highly active OECs with large-photocurrent stability in the form of uniform and intact film, is highly desirable. Herein, we present a low-cost OEC film composed of a phenolic ligand (tannic acid, TA) and NiFe ions (together denoted as TANF) on porous Mo-doped BiVO4 as integrated photoanode (denoted as Mo:BiVO4@TANF) towards PEC water oxidation. The integrated photoanode can attain a photocurrent density of 5.10±0.13 mA cm-2 at 1.23 V vs. RHE. Moreover, the integrated photoanode also performs outstanding stability at high current density, mainly originating from the complete protection provided by the intact TANF film. And the TANF film can be extended to many other n-type semiconductors as well. Firstly, porous Mo:BiVO4 is synthesized according to the reported method (See more in the experimental section and Figure S1 in the Supporting Information).41 Then, TANF film is coated by simply mixing TA with metal ions (Ni2+ and Fe3+) in the weak alkaline solution with the presence of porous Mo:BiVO4 for appropriate time. Previous reports have shown that TA, which is a kind of natural polyphenol, can rapidly coordinate with diverse metal ions to form an assembly layer of uniform and thin film (Figure S2).42-43 And the large amounts of adjacent phenolic groups in TA molecules perform strong attachment on various substrates due to the strong coordination bonding or hydrogen bonding with the substrate atoms.44-46 Consequently, the TA-metal complex assembly film form easily on different substrates. Different from many traditional cocatalysts with island growth (Figure 1a), the TANF consists of two-dimensional networks by connecting TA molecules with metal ions, resulting in a thin layer of intact and
ACS Paragon Plus Environment
4
Page 5 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
uniform film on the surface of the Mo:BiVO4 (Figure 1b). Scanning electron microscopy (SEM) images (Figure S3) display no obvious change after the deposition of TANF film, whereas a thin amorphous layer appears to completely cover the surface of crystalline Mo:BiVO4 from
ACS Paragon Plus Environment
5
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 6 of 20
Figure 1. (a, b) Schematic illustrations of the growth procedure for (a) island growth of traditional cocatalysts and (b) coating of TANF on the surface of the semiconductor. (c, d) TEM images of (c) Mo:BiVO4 and (d) Mo:BiVO4@TANF. (e, f) HRTEM images of (e) Mo:BiVO4 and (f) Mo:BiVO4@TANF.
transmission electron microscopy (TEM) images and high resolution TEM images (HRTEM) (Figure 1c-f and Figure S4). The disappearance of the VO2+/VO2+ redox peaks in cyclic scans of Mo:BiVO4 after the coating of TANF further indicates the complete coverage of TANF on the surface of Mo:BiVO4 (Figure S5). The thickness of the intact amorphous layer is about 5.3±0.7 nm (Figure 1f). The scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS) elemental mapping images indicate the existence of Bi, V, Mo, O, C, Ni and Fe elements in the sample of Mo:BiVO4@TANF (Figure S6). Among these elements, it is clearly seen that Bi, V and Mo uniformly distribute in the area of Mo:BiVO4 (within the white dotted circle), whereas C, O, Fe and Ni, especially for C and O with high content in TANF, can be found both inside and outside the white dotted circle. All the aforementioned results indicate that after the deposition of TANF, the crystalline Mo:BiVO4 nanoparticles are covered with a layer of amorphous TANF film. The PEC activity of the samples is measured in 0.5 M borate buffer (pH=8.5) in a standard three-electrode system. The samples supported by fluorine-doped tin oxide (FTO) glass are backilluminated by a 300 W Xe lamp equipped with the AM 1.5G filter with the light intensity calibrated to 100 mW cm-2 on the surface of the sample. The sole TANF without semiconductor shows no photocurrent (Figure 2a and Figure S7), reflecting that TANF is not photoactive. The photocurrent density of the as-prepared BiVO4 at 1.23 V vs. RHE is about 1.31±0.15 mA cm-2,
ACS Paragon Plus Environment
6
Page 7 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
which is comparable with the previous reports.41 After Mo-doping and the deposition of TANF, the photocurrent density of Mo:BiVO4@TANF is measured to be 5.10±0.13 mA cm-2 at 1.23 V vs. RHE, which is much larger than that of the uncoated Mo:BiVO4 (2.89±0.05 mA cm-2) and non-doped BiVO4. Compared TANF with the traditional Co-Pi cocatalyst, the up-to-date Fh
Figure 2. (a) LSV curves of Mo:BiVO4@TANF, Mo:BiVO4, BiVO4 and TANF under back-side illumination. (b) Comparison of photocurrent density collected from Mo:BiVO4 decorated with different OECs at 1.23 V vs. RHE under illumination. Data from Mo:BiVO4 and BiVO4 are shown as comparison. (c) LSV curves of Mo:BiVO4@TANF, Mo:BiVO4, BiVO4 and TANF under chopped illumination. (d) ABPE of Mo:BiVO4@TANF, Mo:BiVO4 and BiVO4 calculated from (a).
ACS Paragon Plus Environment
7
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 8 of 20
cocatalyst and many other OECs (Figure 2b, Figure S8 and Table S1), the novel Mo:BiVO4@TANF film performs the highest photocurrent density. And the photoresponse of the Mo:BiVO4@TANF is fast and reproducible under chopped illumination (Figure 2c). The applied bias photon to current efficiency (ABPE) is calculated from the LSV curves in Figure 2a. The maximum ABPE of Mo:BiVO4@TANF is found to be 1.56 % at 0.72 V vs. RHE (Figure 2d), demonstrating a high photoconversion efficiency of TANF. Besides, the incident photon to current efficiencies (IPCE) of Mo:BiVO4@TANF, Mo:BiVO4 and BiVO4 are also examined. As shown in Figure S9a, the IPCE of Mo:BiVO4@TANF acquired at 1.23 V vs. RHE is as high as ~95 % in the wavelength range of 365-475 nm, which is much higher than that of Mo:BiVO4 and BiVO4. The photocurrent densities obtained by integrating the corresponding IPCEs with the AM 1.5G spectrum match well with the measured values in Figure 2a (Figure S9b), reflecting the consistency of our light source with the AM 1.5G spectrum.47-48 After the addition of sulfite as the hole scavenger, the photocurrent density of Mo:BiVO4@TANF can further increase to 6.10 mA cm-2 (Figure 3a). In consideration of the similar bandgaps of BiVO4 and Mo:BiVO4 (Figure S10), this value is further close to the theoretical limitation of BiVO4 (7.6 mA cm-2).37 The bare Mo:BiVO4 also displays a high current density of 6.09 mA cm-2 in the presence of sulfite. Compared with the non-doped BiVO4, it can be found that the charge separation efficiency can be largely improved by Mo-doping,24 and then slightly promoted by TANF (Figure 3b). The impressive contribution of TANF is the enhancement of the charge injection efficiency (Figure 3c). The charge injection efficiency is dramatically increased from 47 % to 86 % at 1.23 V vs. RHE, reflecting that TANF can greatly facilitate the surface water oxidation process. Moreover, the electrochemical impedance spectrum (EIS) at open circuit potential of Mo:BiVO4@TANF presents the lowest charge
ACS Paragon Plus Environment
8
Page 9 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
transfer resistance (Figure 3d), indicating that TANF can greatly facilitate the charge transfer of the surface water oxidation reaction. The Mo:BiVO4@TANF composite photoanode also performs a nearly 100 % Faradic efficiency (Figure S11a). Additionally, the linear part of the Mott-Schottky plots of Mo:BiVO4@TANF shows the gentlest slope and the most negative flatband potential (Figure S11b). The positive slopes in the Mott-Schottky plots represent the typical feature of n-type semiconductor for all the tested photoanodes. And the gentle slope of Mo:BiVO4@TANF means the coating of TANF can obviously increase the density of the carriers in the semiconductors.49-50 Besides, the more negative flatband potential reflects more negative potential of the photo-generated electron for cathode reaction, making the whole PEC cell more efficient.37 All the above results reveal TANF to be a highly efficient OEC.
ACS Paragon Plus Environment
9
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 10 of 20
Figure 3. (a) LSV curves of Mo:BiVO4@TANF, Mo:BiVO4 and BiVO4 with (dotted) and without (solid) the addition of Na2SO3 in 0.5 M borate buffer. (b) Charge separation efficiency and (c) charge injection efficiency of Mo:BiVO4@TANF, Mo:BiVO4 and BiVO4. (d) EIS spectra of Mo:BiVO4@TANF, Mo:BiVO4 and BiVO4 collected at the open circuit potential.
With the prominent PEC activity, it is time to estimate the stability of Mo:BiVO4@TANF. BiVO4 is known for easy photocorrosion, which is caused by photo-induced electrochemical dissolution of V5+ in BiVO4.38, 51 So a qualified OEC should possess the capability of continuous separation BiVO4 and electrolyte during the whole measurement, especially at high current density. As shown in Figure 4a, the photocurrent density of Mo:BiVO4@TANF can preserve 92 % of the initial value after tested at 1.23 V vs. RHE for 3 h in 0.5 M borate buffer (pH=8.5). The stability measurements of Co-Pi and Fh cocatalysts in the same conditions are also shown here for comparison. Severe photocurrent loss of these two cocatalysts is found in this figure, in which the photocurrent densities of Mo:BiVO4@Co-Pi and Mo:BiVO4@Fh after 3-h test decrease to only 21 % and 60 % of the initial value, respectively. Compared with the stability of the cocatalysts themselves, it can be found that TANF and Fh perform good stability, while CoPi shows an obvious decay in the first one hour, then kept stable in the following test (Figure S12). The stability difference between Mo:BiVO4@TANF and Mo:BiVO4@Fh may originate from the coverage of the OECs, which is determined by the growth mode of the cocatalysts. The Fh nanoparticles grow selectively on the surface of the Mo:BiVO4, which is the typical island growth (Figure 4b). In this way, part of the Mo:BiVO4 is exposed to the electrolyte, thus leading to easy photocorrosion of the semiconductor and consequent poor PEC stability. A similar island-growth mode can be found for Co-Pi as well (Figure 4c). As for TANF (Figure 4d and
ACS Paragon Plus Environment
10
Page 11 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
Figure S4), the uniform TANF film can avoid the direct contact between the Mo:BiVO4 and the electrolyte, so that the loss of V5+ can be suppressed,38 thus remarkably promoting the stability of Mo:BiVO4@TANF. It should be mentioned that the deposition of Co-Pi with low coverage and poor stability can still slightly improve the stability of the bare Mo:BiVO4. The reason may be that the deposited Co-Pi can facilitate the consumption of the photogenerated hole, thus partly suppressing the photocorrosion of the semiconductor.38
Figure 4. (a) j-t curves of different OECs deposited on Mo:BiVO4 and bare Mo:BiVO4 at harsh 1.23 V vs. RHE under illumination for 3 h in 0.5 M borate buffer (pH=8.5). (b-d) TEM images of Mo:BiVO4 decorated with different OECs, (b) Fh, (c) Co-Pi, and (d) TANF. The insets in (b-d) are the illustrations of the corresponding growth mode of the cocatalysts.
ACS Paragon Plus Environment
11
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 12 of 20
The TANF assembly film can be successfully extended to other n-type semiconductors for PEC water oxidation as well. For example, with the deposition of TANF, the photocurrent density of non-doped BiVO4@TANF at 1.23 V vs. RHE is increased to 4.28 mA cm-2 (Figure S13a), which is 3.3 times larger than the original BiVO4. And the stability of the BiVO4@TANF photoanode is also dramatically enhanced with the aid of TANF (Figure S13b). Moreover, when depositing TANF onto rutile TiO2 nanorod arrays (Figure S14), both the PEC activity and stability perform remarkably improvements (Figure S15). The photocurrent density of TiO2@TANF is raised to 1.69 mA cm-2 at 1.23 V vs. RHE, and 94 % current is retained after tested at 1.23 V vs. RHE for as long as 12 h. These results indicate that the TANF film can easily form and function well on diverse semiconductors as outstanding PEC water oxidation cocatalyst, making TANF to be promising cocatalyst alternative in practical applications in future. In summary, we have presented the TANF complex assembly film coating as a highly active and stable OEC for Mo:BiVO4 and other n-type semiconductors. The Mo:BiVO4@TANF integrated photoanode performs the impressive photocurrent density of as high as 5.10±0.13 mA cm-2 at 1.23 V vs. RHE. This remarkable result is attributed to the dramatic enhancement of charge injection efficiency and charge separation efficiency caused by TANF and Mo-doping, respectively. The Mo:BiVO4@TANF also demonstrates excellent stability. 92 % of the photocurrent density of Mo:BiVO4@TANF is maintained after 3-h stability test at harsh operating potential of 1.23 V vs. RHE, mainly resulting from both the rapid consumption of the interfacial charge and the complete protection provided by the intact TANF film. And the TANF film can be also applied to other n-type semiconductors for enhanced PEC activity and stability. The remarkable improvements of both activity and superior stability qualify TANF as an ideal
ACS Paragon Plus Environment
12
Page 13 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
OEC, opening new opportunities to develop technologically and economically viable catalysts for many other photoelectrochemically induced conversions. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: XXXX. Additional material characterizations, additional electrocatalytic and photoelectrocatalytic measurements, and the enhancements of TANF for non-doped BiVO4 and rutile TiO2 (PDF) AUTHOR INFORMATION Corresponding Author *E-mail:
[email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT We acknowledge the financial support from the National Natural Science Foundation of China (No. 21422104) and the Natural Science Foundation of Tianjin City (No. 17JCJQJC44700 and No. 16JCZDJC30600). This work is dedicated to the memory of Professor Helmuth Möhwald. REFERENCES (1)
Zou, Z.; Ye, J.; Sayama, K.; Arakawa, H. Direct Splitting of Water under Visible Light Irradiation with an Oxide Semiconductor Photocatalyst. Nature 2001, 414, 625-627.
ACS Paragon Plus Environment
13
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(2)
Page 14 of 20
Cho, I. S.; Lee, C. H.; Feng, Y.; Logar, M.; Rao, P. M.; Cai, L.; Kim, D. R.; Sinclair, R.; Zheng, X. Codoping Titanium Dioxide Nanowires with Tungsten and Carbon for Enhanced Photoelectrochemical Performance. Nature Commun. 2013, 4, 1723.
(3)
Sambur, J. B.; Chen, T.-Y.; Choudhary, E.; Chen, G.; Nissen, E. J.; Thomas, E. M.; Zou, N.; Chen, P. Sub-Particle Reaction and Photocurrent Mapping to Optimize CatalystModified Photoanodes. Nature 2016, 530, 77-80.
(4)
Youngblood, W. J.; Lee, S.-H. A.; Kobayashi, Y.; Hernandez-Pagan, E. A.; Hoertz, P. G.; Moore, T. A.; Moore, A. L.; Gust, D.; Mallouk, T. E. Photoassisted Overall Water Splitting in a Visible Light-Absorbing Dye-Sensitized Photoelectrochemical Cell. J. Am. Chem. Soc. 2009, 131, 926-927.
(5)
Swierk, J. R.; Méndez-Hernández, D. D.; McCool, N. S.; Liddell, P.; Terazono, Y.; Pahk, I.; Tomlin, J. J.; Oster, N. V.; Moore, T. A.; Moore, A. L., et al. Metal-Free Organic Sensitizers for Use in Water-Splitting Dye-Sensitized Photoelectrochemical Cells. Proc. Natl. Acad. Sci. USA 2015, 112, 1681-1686.
(6)
Hou, Y.; Zuo, F.; Dagg, A. P.; Liu, J.; Feng, P. Branched WO3 Nanosheet Array with Layered C3N4 Heterojunctions and CoOx Nanoparticles as a Flexible Photoanode for Efficient Photoelectrochemical Water Oxidation. Adv. Mater. 2014, 26, 5043-5049.
(7)
Peerakiatkhajohn, P.; Yun, J.-H.; Chen, H.; Lyu, M.; Butburee, T.; Wang, L. Stable Hematite Nanosheet Photoanodes for Enhanced Photoelectrochemical Water Splitting. Adv. Mater. 2016, 28, 6405-6410.
(8)
Ran, J.; Zhang, J.; Yu, J.; Jaroniecc, M.; Qiao, S. Z. Earth-Abundant Cocatalysts for Semiconductor-Based Photocatalytic Water Splitting. Chem. Soc. Rev. 2014, 43, 77877812.
ACS Paragon Plus Environment
14
Page 15 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
(9)
Warren, S. C.; Voïtchovsky, K.; Dotan, H.; Leroy, C. M.; Cornuz, M.; Stellacci, F.; Hébert, C.; Rothschild, A.; Grätzel, M. Identifying Champion Nanostructures for Solar Water-Splitting. Nature Mater. 2013, 12, 842-849.
(10)
Wang, Q.; Hisatomi, T.; Jia, Q.; Tokudome, H.; Zhong, M.; Wang, C.; Pan, Z.; Takata, T.; Nakabayashi, M.; Shibata, N., et al. Scalable Water Splitting on Particulate Photocatalyst Sheets with a Solar-to-Hydrogen Energy Conversion Efficiency Exceeding 1%. Nature Mater. 2016, 15, 611-615.
(11)
Kuang, Y.; Yamada, T.; Domen, K. Surface and Interface Engineering for Photoelectrochemical Water Oxidation. Joule 2017, 1, 290-305.
(12)
Pihosh, Y.; Turkevych, I.; Mawatari, K.; Uemura, J.; Kazoe, Y.; Kosar, S.; Makita, K.; Sugaya, T.; Matsui, T.; Fujita, D., et al. Photocatalytic Generation of Hydrogen by CoreShell WO3/BiVO4 Nanorods with Ultimate Water Splitting Efficiency. Sci. Rep. 2015, 5, 11141.
(13)
Chang, X.; Wang, T.; Zhang, P.; Zhang, J.; Li, A.; Gong, J. Enhanced Surface Reaction Kinetics and Charge Separation of p–n Heterojunction Co3O4/BiVO4 Photoanodes. J. Am. Chem. Soc. 2015, 137, 8356-8359.
(14)
Zhong, M.; Hisatomi, T.; Kuang, Y.; Zhao, J.; Liu, M.; Iwase, A.; Jia, Q.; Nishiyama, H.; Minegishi, T.; Nakabayashi, M., et al. Surface Modification of CoOx Loaded BiVO4 Photoanodes with Ultrathinp-Type NiO Layers for Improved Solar Water Oxidation. J. Am. Chem. Soc. 2015, 137, 5053-5060.
(15)
Ye, K.-H.; Wang, Z.; Gu, J.; Xiao, S.; Yuan, Y.; Zhu, Y.; Zhang, Y.; Mai, W.; Yang, S. Carbon Quantum Dots as a Visible Light Sensitizer to Significantly Increase the Solar
ACS Paragon Plus Environment
15
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 16 of 20
Water Splitting Performance of Bismuth Vanadate Photoanodes. Energy Environ. Sci. 2017, 10, 772-779. (16)
Qiu, Y.; Liu, W.; Chen, W.; Zhou, G.; Hsu, P.-C.; Zhang, R.; Liang, Z.; Fan, S.; Zhang, Y.; Cui, Y. Efficient Solar-Driven Water Splitting by Nanocone BiVO4-Perovskite Tandem Cells. Sci. Adv. 2016, 2, e1501764.
(17)
Luo, W.; Yang, Z.; Li, Z.; Zhang, J.; Liu, J.; Zhao, Z.; Wang, Z.; Yan, S.; Yu, T.; Zou, Z. Solar Hydrogen Generation from Seawater with a Modified BiVO4 Photoanode. Energy Environ. Sci. 2011, 4, 4046-4051.
(18)
Rao, P. M.; Cai, L.; Liu, C.; Cho, I. S.; Lee, C. H.; Weisse, J. M.; Yang, P.; Zheng, X. Simultaneously Efficient Light Absorption and Charge Separation in WO3/BiVO4 Core/Shell Nanowire Photoanode for Photoelectrochemical Water Oxidation. Nano Lett. 2014, 14, 1099-1105.
(19)
Loiudice, A.; Ma, J.; Drisdell, W. S.; Mattox, T. M.; Cooper, J. K.; Thao, T.; Giannini, C.; Yano, J.; Wang, L. W.; Sharp, I. D., et al. Bandgap Tunability in Sb-Alloyed BiVO4 Quaternary Oxides as Visible Light Absorbers for Solar Fuel Applications. Adv. Mater. 2015, 27, 6733-6740.
(20)
Han, H. S.; Shin, S.; Kim, D. H.; Ik Jae Park; Kim, J. S.; Huang, P.-S.; Lee, J.-K.; Cho, I. S.; Zheng, X. Boosting the Solar Water Oxidation Performance of a BiVO4 Photoanode by Crystallographic Orientation Control. Energy Environ. Sci. 2018, 11, 1299-1306.
(21)
Wang, S.; Chen, P.; Bai, Y.; Yun, J.-H.; Liu, G.; Wang, L. New BiVO4 Dual Photoanodes with Enriched Oxygen Vacancies for Efficient Solar-Driven Water Splitting. Adv. Mater. 2018, 30, 1800486.
ACS Paragon Plus Environment
16
Page 17 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
(22)
Kuang, Y.; Jia, Q.; Nishiyama, H.; Yamada, T.; Kudo, A.; Domen, K. A FrontIlluminated Nanostructured Transparent BiVO4 Photoanode for >2% Efficient Water Splitting. Adv. Energy Mater. 2016, 6, 1501645.
(23)
Huang, Z. F.; Pan, L.; Zou, J. J.; Zhang, X.; Wang, L. Nanostructured Bismuth VanadateBased Materials for Solar-Energy-Driven Water Oxidation: A Review on Recent Progress. Nanoscale 2014, 6, 14044-14063.
(24)
Parmar, K. P.; Kang, H. J.; Bist, A.; Dua, P.; Jang, J. S.; Lee, J. S. Photocatalytic and Photoelectrochemical
Water
Oxidation
Over
Metal-doped
Monoclinic
BiVO4
Photoanodes. ChemSusChem 2012, 5, 1926-1934. (25)
Huang, Y.; Yu, Y.; Xin, Y.; Meng, N.; Yu, Y.; Zhang, B. Promoting Charge Carrier Utilization by Integrating Layered Double Hydroxide Nanosheet Arrays with Porous BiVO4 Photoanode for Efficient Photoelectrochemical Water Splitting. Sci. China Mater. 2017, 60, 193-207.
(26)
Kim, J. H.; Jo, Y.; Kim, J. H.; Jang, J. W.; Kang, H. J.; Lee, Y. H.; Kim, D. S.; Jun, Y.; Lee, J. S. Wireless Solar Water Splitting Device with Robust Cobalt-Catalyzed, Dualdoped BiVO4 Photoanode and Perovskite Solar Cell in Tandem: A Dual Absorber Artificial Leaf. ACS Nano 2015, 9, 11820-11829.
(27)
Wang, L.; Han, D.; Ni, S.; Ma, W.; Wang, W.; Niu, L. Photoelectrochemical Device Based on Mo-doped BiVO4 Enables Smart Analysis of the Global Antioxidant Capacity in Food. Chem. Sci. 2015, 6, 6632-6638.
(28)
Ding, C.; Shi, J.; Wang, Z.; Li, C. Photoelectrocatalytic Water Splitting: Significance of Cocatalysts, Electrolyte, and Interfaces. ACS Catal. 2017, 7, 675-688.
ACS Paragon Plus Environment
17
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(29)
Page 18 of 20
Zachäus, C.; Abdi, F. F.; Peter, L. M.; van de Krol, R. Photocurrent of BiVO4 is limited by surface recombination, not surface catalysis. Chem. Sci. 2017, 8, 3712-3719.
(30)
Zhong, D. K.; Choi, S.; Gamelin, D. R. Near-Complete Suppression of Surface Recombination in Solar Photoelectrolysis by “Co-Pi” Catalyst-Modified W:BiVO4. J. Am. Chem. Soc. 2011, 133, 18370-18377.
(31)
Pilli, S. K.; Furtak, T. E.; Brown, L. D.; Deutsch, T. G.; Turner, J. A.; Herring, A. M. Cobalt-Phosphate (Co-Pi) Catalyst Modified Mo-doped BiVO4 Photoelectrodes for Solar Water Oxidation. Energy Environ. Sci. 2011, 4, 5028-5034.
(32)
Wang, S.; Chen, P.; Yun, J.-H.; Hu, Y.; Wang, L. An Electrochemically Treated BiVO4 Photoanode for Efficient Photoelectrochemical Water Splitting. Angew. Chem. Int. Ed. 2017, 56, 8500-8504.
(33)
Kim, J. Y.; Youn, D. H.; Kang, K.; Lee, J. S. Highly Conformal Deposition of an Ultrathin FeOOH Layer on a Hematite Nanostructure for Efficient Solar Water Splitting. Angew. Chem. Int. Ed. 2016, 55, 10854-10858.
(34)
Yu, F.; Li, F.; Yao, T.; Du, J.; Liang, Y.; Wang, Y.; Han, H.; Sun, L. Fabrication and Kinetic Study of a Ferrihydrite-Modified BiVO4 Photoanode. ACS Catal. 2017, 7, 18681874.
(35)
Liu, G.; Shi, J.; Zhang, F.; Chen, Z.; Han, J.; Ding, C.; Chen, S.; Wang, Z.; Han, H.; Li, C. A Tantalum Nitride Photoanode Modified with a Hole-Storage Layer for Highly Stable Solar Water Splitting. Angew. Chem. Int. Ed. 2014, 53, 7295-7299.
(36)
Wang, Y.; Li, F.; Zhou, X.; Yu, F.; Du, J.; Bai, L.; Sun, L. Highly Efficient Photoelectrochemical Water Splitting with an Immobilized Molecular Co4O4 Cubane Catalyst. Angew. Chem. Int. Ed. 2017, 56, 6911-6915.
ACS Paragon Plus Environment
18
Page 19 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
(37)
Park, Y.; McDonald, K. J.; Choi, K.-S. Progress in Bismuth Vanadate Photoanodes for Use in Solar Water Oxidation. Chem. Soc. Rev. 2013, 42, 2321-2337.
(38)
Lee, D. K.; Choi, K.-S. Enhancing Long-Term Photostability of BiVO4 Photoanodes for Solar Water Splitting by Tuning Electrolyte Composition. Nature Energy 2017, 3, 53-60.
(39)
Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Bisquert, J.; Hamann, T. W. Photoelectrochemical and Impedance Spectroscopic Investigation of Water Oxidation with “Co–Pi”-Coated Hematite Electrodes. J. Am. Chem. Soc. 2012, 134, 16693-16700.
(40)
Steinmiller, E. M. P.; Choi, K. S. Photochemical Deposition of Cobalt-Based Oxygen Evolving Catalyst on a Semiconductor Photoanode for Solar Oxygen Production. Proc. Natl. Acad. Sci. USA 2009, 106, 20633-20636.
(41)
Kim, T. W.; Choi, K.-S. Nanoporous BiVO4 Photoanodes with Dual-Layer Oxygen Evolution Catalysts for Solar Water Splitting. Science 2014, 343, 990-994.
(42)
Ejima, H.; Richardson, J. J.; Liang, K.; Best, J. P.; van Koeverden, M. P.; Such, G. K.; Cui, J.; Caruso, F. One-Step Assembly of Coordination Complexes for Versatile Film and Particle Engineering. Science 2013, 341, 154-157.
(43)
Guo, J.; Ping, Y.; Ejima, H.; Alt, K.; Meissner, M.; Richardson, J. J.; Yan, Y.; Peter, K.; von Elverfeldt, D.; Hagemeyer, C. E., et al. Engineering Multifunctional Capsules Through the Assembly of Metal-Phenolic Networks. Angew. Chem. Int. Ed. 2014, 53, 5546-5551.
(44)
Chen, L. X.; Liu, T.; Thurnauer, M. C.; Csencsits, R.; Rajh, T. Fe2O3 Nanoparticle Structures Investigated by X-ray Absorption Near-edge Structure, Surface Modifications, and Model Calculations. J. Phys. Chem. B 2002, 106, 8539-8546.
ACS Paragon Plus Environment
19
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(45)
Page 20 of 20
Anderson, T. H.; Yu, J.; Estrada, A.; Hammer, M. U.; Waite, J. H.; Israelachvili, J. N. The Contribution of DOPA to Substrate–Peptide Adhesion and Internal Cohesion of Mussel-Inspired Synthetic Peptide Films. Adv. Funct. Mater. 2010, 20, 4196-4205.
(46)
Ye, Q.; Zhou, F.; Liu, W. Bioinspired Catecholic Chemistry for Surface Modification. Chem. Soc. Rev. 2011, 40, 4244.
(47)
Döscher, H.; Young, J. L.; Geisz, J. F.; Turner, J. A.; Deutsch, T. G. Solar-to-Hydrogen Efficiency: Shining Light on Photoelectrochemical Device Performance. Energy Environ. Sci. 2016, 9, 74-80.
(48)
Seaman, C. H. Calibration of Solar Cells by the Reference Cell Method-The Spectral Mismatch Problem. Sol. Energy 1982, 29, 291-298.
(49)
Wang, Y.; Zhang, Y.-Y.; Tang, J.; Wu, H.; Xu, M.; Peng, Z.; Gong, X.-G.; Zheng, G. Simultaneous Etching and Doping of TiO2 Nanowire Arrays for Enhanced Photoelectrochemical Performance. ACS Nano 2013, 7, 9375-9383.
(50)
Ning, F.; Shao, M.; Xu, S.; Fu, Y.; Zhang, R.; Wei, M.; Evans, D. G.; Duan, X. TiO2/Graphene/NiFe-Layered Double Hydroxide Nanorod Array Photoanodes for Efficient Photoelectrochemical Water Splitting. Energy Environ. Sci. 2016, 9, 2633-2643.
(51)
Kuang, Y.; Jia, Q.; Ma, G.; Hisatomi, T.; Minegishi, T.; Nishiyama, H.; Nakabayashi, M.; Shibata, N.; Yamada, T.; Kudo, A., et al. Ultrastable Low-Bias Water Splitting Photoanodes via Photocorrosion Inhibition and in situ Catalyst Regeneration. Nature Energy 2016, 2, 16191.
ACS Paragon Plus Environment
20
