SCIENCE CHINA Materials, Volume 61, Issue 6: 895-904(2018) https://doi.org/10.1007/s40843-017-9237-2

A dual-electrolyte system for photoelectrochemical hydrogen generation using CuInS2-In2O3-TiO2 nanotube array thin film

More info
  • ReceivedNov 7, 2017
  • AcceptedFeb 26, 2018
  • PublishedApr 4, 2018


The utilization of Na2S/Na2SO3 mixture as the electrolyte solution to stabilize sulfide anode in a photoelectrochemical cell for hydrogen evolution generally compromises the current-to-hydrogen efficiency (ηcurrent) of the system. Here, the employment of a dual-electrolyte system, that is, Na2S/Na2SO3 mixture and pH-neutral Na2SO4 as the respective electrolyte solutions in the anode and cathode chambers of a water splitting cell is demonstrated to suppress the photocorrosion of CuInS2-In2O3-TiO2 nanotube (CIS-In2O3-TNT) heterostructure, while simultaneously boosts the ηcurrent. Although n-type CIS and In2O3 nanoparticles can be easily formed on TNT array via facile pulse-assisted electrodeposition method, conformal deposition of the nanoparticles homogeneously on the nanotubes wall with preservation of the TNT hollow structure is shown to be essential for achieving efficient charge generation and separation within the heterostructure. In comparison to Na2S/Na2SO3 solution as the sole electrolyte in both the anode and cathode chambers, introduction of dual electrolyte is shown to not only enhance the photostability of the CIS-In2O3-TNT anode, but also lead to near-unity ηcurrent as opposed to the merely 20% ηcurrent of the single-electrolyte system.

Funded by

the Australian Research Council(DP170102895)


This work was supported by the Australian Research Council (DP170102895). We thank the UNSW Mark Wainwright Analytical Centre for providing access to all analytical facilities.

Interest statement

The authors declare no conflict of interest.

Contributions statement

Ng C and Yun JH fabricated the electrodes and conducted the photoelectrochemical measurements. Tan HL and Wu H performed characterizations on the samples. Amal R and Ng YH supervised this work. All authors analyzed the data and completed the paper.

Author information

Charlene Ng is currently an Alexander von Humboldt Postdoctoral Fellow at Leibniz-Institut für Polymerforschung Dresden. She received her PhD in Chemical Engineering from UNSW Australia and was awarded for a 3-year OCE Postdoctoral Fellowship from Year 2014--2017 at the Commonwealth Scientific and Industrial Research Organization in Melbourne, Australia. Her primary research interests are aimed at addressing challenges associated with the conversion of solar energy into chemical fuels.

Yun Hau Ng received his PhD from Osaka University in 2009. After a brief research visit to the University of Notre Dame, he joined UNSW with the Australian Postdoctoral Fellowship (APD) in 2011. He is currently a senior lecturer in the School of Chemical Engineering at UNSW. His research is focused on the development of novel photoactive semiconductors (particles and thin films) for solar energy conversion.


[1] Fujishima A, Honda K. Electrochemical photolysis of water at a semiconductor electrode. Nature, 1972, 238: 37-38 CrossRef ADS Google Scholar

[2] Guo J, Zhou H, Ouyang S, et al. An Ag3PO4/nitridized Sr2 Nb2O7 composite photocatalyst with adjustable band structures for efficient elimination of gaseous organic pollutants under visible light irradiation. Nanoscale, 2014, 6: 7303-7311 CrossRef PubMed ADS Google Scholar

[3] Yun JH, Ng YH, Huang S, et al. Wrapping the walls of n-TiO2 nanotubes with p-CuInS2 nanoparticles using pulsed-electrodeposition for improved heterojunction photoelectrodes. Chem Commun, 2011, 47: 11288-11290 CrossRef PubMed Google Scholar

[4] Fujishima A, Rao TN, Tryk DA. Titanium dioxide photocatalysis. J Photochem Photobiol C-Photochem Rev, 2000, 1: 1-21 CrossRef Google Scholar

[5] Wang H, You T, Shi W, et al. Au/TiO2/Au as a plasmonic coupling photocatalyst. J Phys Chem C, 2012, 116: 6490-6494 CrossRef Google Scholar

[6] Tang Y, Traveerungroj P, Tan HL, et al. Scaffolding an ultrathin CdS layer on a ZnO nanorod array using pulsed electrodeposition for improved photocharge transport under visible light illumination. J Mater Chem A, 2015, 3: 19582-19587 CrossRef Google Scholar

[7] Selloni A. Anatase shows its reactive side. Nat Mater, 2008, 7: 613-615 CrossRef PubMed ADS Google Scholar

[8] Pan J, Liu G, Lu GQM, et al. On the true photoreactivity order of {001}, {010}, and {101} facets of anatase TiO2 crystals. Angew Chem Int Ed, 2011, 50: 2133-2137 CrossRef PubMed Google Scholar

[9] Kazmerski LL, Ayyagari MS, Sanborn GA. CuInS2 thin films: Preparation and properties. J Appl Phys, 1975, 46: 4865-4869 CrossRef ADS Google Scholar

[10] Tang Y, Wang P, Yun JH, et al. Frequency-regulated pulsed electrodeposition of CuInS2 on ZnO nanorod arrays as visible light photoanodes. J Mater Chem A, 2015, 3: 15876-15881 CrossRef Google Scholar

[11] Minoura H, Tsuiki M. Anodic reactions of several reducing agents on illuminated cadmium sulfide electrode. Electrochim Acta, 1978, 23: 1377-1382 CrossRef Google Scholar

[12] Reber JF, Meier K. Photochemical production of hydrogen with zinc sulfide suspensions. J Phys Chem, 1984, 88: 5903-5913 CrossRef Google Scholar

[13] Buehler N, Meier K, Reber JF. Photochemical hydrogen production with cadmium sulfide suspensions. J Phys Chem, 1984, 88: 3261-3268 CrossRef Google Scholar

[14] Yun JH, Ng YH, Ye C, et al. Sodium fluoride-assisted modulation of anodized TiO2 nanotube for dye-sensitized solar cells application. ACS Appl Mater Interfaces, 2011, 3: 1585-1593 CrossRef PubMed Google Scholar

[15] Boiko M, Medvedkin G. Thermal oxidation of CuInSe2: Experiment and physico-chemical model. Sol Energy Mater Sol Cells, 1996, 41-42: 307-314 CrossRef Google Scholar

[16] Dirnstorfer I, Hofmann DM, Meister D, et al. Postgrowth thermal treatment of CuIn(Ga)Se2: Characterization of doping levels in In-rich thin films. J Appl Phys, 1999, 85: 1423-1428 CrossRef ADS Google Scholar

[17] Asenjo B, Chaparro AM, Gutiérrez MT, et al. Quartz crystal microbalance study of the growth of indium(III) sulphide films from a chemical solution. Electrochim Acta, 2004, 49: 737-744 CrossRef Google Scholar

[18] Shankar K, Bandara J, Paulose M, et al. Highly efficient solar cells using TiO2 nanotube arrays sensitized with a donor-antenna dye. Nano Lett, 2008, 8: 1654-1659 CrossRef PubMed ADS Google Scholar

[19] Jiang Z, Tang Y, Tay Q, et al. Understanding the role of nanostructures for efficient hydrogen generation on immobilized photocatalysts. Adv Energy Mater, 2013, 3: 1368-1380 CrossRef Google Scholar

[20] Ma Y. Synthesis of TiO2 nanotubes film and its light scattering property. Chin Sci Bull, 2005, 50: 1985 CrossRef Google Scholar

[21] Unnikrishnan EK, Kumar SD, Maiti B. Permeation of inorganic anions through Nafion ionomer membrane. J Membrane Sci, 1997, 137: 133-137 CrossRef Google Scholar

[22] Danielsson LG, Yang X. Transport of low molecular weight anions through a Nafion ionomer membrane: application to kraft cooking liquors. Anal Chem, 2000, 72: 1564-1568 CrossRef Google Scholar

  • Figure 1

    XRD spectra of CIS-In2O3-TNT1 and TNT1 anodized for 1 h.

  • Figure 2

    SEM images of (a) CIS-In2O3-TNT1, (b) CIS-In2O3-TNT3, (c) CIS-In2O3-TNT7 and (d) UV-vis diffuse reflectance spectra of the CIS-In2O3-TNT heterostructures. The inset in (a) presents the SEM image of TNT1.

  • Figure 3

    (a) Amperometric photocurrent densities of CIS-In2O3 and CIS-In2O3-TNT arrays with different lengths of TNT arrays under visible light irradiation (λ>435 nm) in Na2S/Na2SO3 electrolyte solution. (b) Schematic diagram on energy band gap and different photoexcited electron pathways within the CIS-In2O3-TNT composite photoelectrode. (c) Photocurrent density comparison of the TNT arrays and CIS-In2O3-TNT electrodes with different lengths under UV illumination.

  • Figure 4

    (a) Current-to-hydrogen efficiency of CIS-In2O3-TNT1 array in Na2S/Na2SO3 & Na2SO4 dual electrolyte and Na2S/Na2SO3 electrolyte in a two-electrode photoelectrochemical water splitting system for H2 generation, (b) photocurrent of CIS-In2O3-TNT1 array in Na2S/Na2SO3 & Na2SO4 dual electrolyte system and Na2SO4 electrolyte, (c) schematic diagram of the photoelectrochemical H2 generation reactor featuring dual-electrolyte system and (d) photoelectrochemical H2 evolution of CIS-In2O3-TNT1 array in Na2S/Na2SO3 & Na2SO4 dual-electrolyte system.

Copyright 2020 Science China Press Co., Ltd. 《中国科学》杂志社有限责任公司 版权所有