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Photochargeable multilayer membrane device composed of CdS film and prussian blue battery
Elrriro‘hmic” *era. “0, Prmted I” Great antal”
35. No
I. pp B-293.
,990
00134686/w I3 oo+o.oo ;T, 1989 Per~amon Press plc
SHORT COMMUNICATION PHOTOCHARGEABLE MULTILAYER MEMBRANE DEVICE COMPOSED OF CdS FILM AND PRUSSIAN BLUE BATTERY MASAO KANEKO and TOKUO OKADA
The Institute of Physical and Chemical Research, Solar Energy Research Group, Wako, Saitama 351-01, Japan HIDEKI MINOURA, TAKASHI SUGIURA and YASUSADA UENO Gifu University, Faculty of Engineering, Yanagido I-1, Gifu 501-l 1, Japan (Received 13 February 1989; in revised form 4 April 1989)
INTRODUCTION Photoenergy conversion and storage are attracting attention not only in solar energy utilization but also in photodevices which are important for the future socalled photonics (photoelectronics). Photoinduced charge separation and the following accumulation of the separated charges are typical processes in photoenergy/information conversion and storage. These processes are generally carried out in different systems or phases respectively to result in a whole achievement. If they are combined to realize in one device, it must be of much value for the development of photodevices. Such a device is capable of photocharge and dark-discharge, and would open a new field in photoenergy and information conversion/storage. Some systems for photocharge and dark-discharge have been reported that are composed of liquidjunction semiconductor and redox electrolyte present in solution[l-51. A new concept is now proposed to realize photocharge and dark-discharge by a multifunctional solid state device, which must be of great use for practical application. The present authors have designed a multilayer membrane device for photocharge and dark-discharge so that each layer bears a function such as photoinduced charge separation, accumulation of positive/negative charges, separation of reactants. As for the membrane materials, polymer is most suited for practical use[6]. As a charge storage material, Prussian Blue (PB) which is a high molecular and polynuclear mixedvalent iron cyanide complex was chosen in the present paper. Electrochemical behavior of PB has been well characterized by Neff and Itaya et aI.[7-91. This complex, whose composition is represented by Fe:’ [Fe”(CN),]:-, has three kinds of reversible redox states, so that it can store both positive and negative charges. PB batteries were reported by NefllO], Kanekorll, 123, and Honda et al.[13] in which two PB films were utilized for an anode and a cathode. A multilayer PB polymer battery
(PB/Nafion/PB) has been fabricated, and its reaction characteristics have been studied electrochemically and spectrophotometrically by the present authors[12]. Photoreaction of PB film coated on TiO, has been studied in aqueous electrolyte solution[14], but this system uses only ultraviolet light and dark-discharge has not been reported. In the present paper, a multilayer solid type photochargeable device driven by visible light irradiation will be reported which is composed of n-CdS semiconductor film and trilayered PB battery membranes.
EXPERIMENTAL n-CdS film was coated on a NESA glass by a chemical spray deposition method as reported by Ueno et al.[ 151. PB was coated on the top of the CdS film and on a NESA glass by the reductive electrodeposition method[7-91 at 20 PA cm-’ under galvanostatic condition in an aqueous mixture of 10 mM K3[Fe(CN)6], 10 mM FeCl, and 10 mM HCl. A photochargeable multilayer device was fabricated by sandwiching a Nafion film (173 pm thickness) adsorbing aqueous electrolyte (0.5 M KNO, and 10 mM HNO,) with a PB-coated CdS film/NESA and a PB-coated NESA. For obtaining a device capable of discharge in the dark after photocharge, a comb-type Au electrode was attached on the PB membrane coated on CdS by vapor deposition before sandwiching. The cell composition shown in Fig. 1 is: NESA/CdS/PB/comb-type
Au/Naiion/PB/NESA.
The area of the effective cell surface was about 0.20 cm2. The irradiation was made with visible light (40&800 nm) from the reverse side of the NESA glass on which CdS is coated. A 500 W xenon lamp was used after passing the light through cut-off filters (Toshiba VY-42 and IRQ-80). The light intensity was 74 mW cm-‘. 291
M KANEKO
et al
V
NESA
Fig
1 Photochargeable
deuce
RESULTS AND DISCUSSION The charge and discharge reactlons of a multllayer PB battery are shown by Scheme 1, where PB has a Fe3+j2+ state, BG 1s Berlin Green (Fe3+“+), and PW 1s Prussian White (Fe2 ‘I2 + )
,
I
PosItwe
electrode,
Charge
PB m
0
BG
4
20
10 Charge/mC cm-2
Discharge
Negative
electrode,
PB 7
Charge
PW
Dwcharge
Scheme
l3g 2 Charge/discharge characterlstlcs of the PB/Au/ Nafion/PB/NESA secondary battery of the photochargeable device
1
The charge/discharge characterlstlcs of an NESA/PB/Nafion/PB/NESA battery has been reported[12] The cell of Fig 1 constitutes a PB battery when the Au and the counter NESA electrodes are connected The charge/dncharge characterlstlcs of this battery (PB/Au/Nafion/PB/NESA) 1s shown m Fig 2 Although the discharge/charge ratio (73%) was worse than an NESA/PB/Nafion/PBjNESA battery (90%)[12], the cycle could be carried out repeatedly The photochemrcal conversIon characterlstlcs of the naked CdS used m the present device were, V,, 0 34 4 V, J,, ca 70 PA cmm2, FF ca 0 4 and quantum efficiency 8% and energy conversIon efficiency 0 5% under 480 nm monochromatic hght lrradlatlon when dipped m an aqueous polysulfide solution (1 M NaOH, 1 MNa,S, 1 M S)[lS] In this polysulfide solution, the CdS photoanode gave stable photocurrents of 0 6 mAcme2, and no evidence of CdS corrosion was observed after the passage of 15 C The current changes mduced by swltchmg on and off the lrradlatlon of the photochargeable device composed of NESA/CdS/PB/Au/Nafion/PB/NESA were shown m Fig 3 On lrradlatlon, anodlc photocurrent flaws with the first strong spike followed by constant photocurrents, and, during the photoelectrochemlcal process, the color of the PB faded mdlcatmg that chargmg of PB occurs After passing 1 29 mC charges for 7 mm (correspondmg to 65% of the coated PB amount), the lrradlatlon was cut off On swltchmg off the Irradiation, the current returns to zero, and the
Photocharge Light on
t
0
Fig 3 Photocharge
’ I----
5 Time/min
0
and dark-discharge chargeable device
5
of the photo-
charged state could be maintained while the circuit was kept open When the device was short-circuited m the dark, reverse discharge current flows with the first strong cathodic spike followed by a gradual decay, after which the PB color returns back to orlgmal blue The discharge amounted to 0 47 mC for 5 mm which 1s 36% of the photocharged amount These photocharge and dark discharge cycles could be repeated reversibly many times at least for a few hours After a few hours,
Photochargeable multllayer membrane device degradation of the current was observed Reactlon of PB with Au electrode was visually observable after detachmg the sandwich structure of the device, but no change was observed at the CdS/PB Interface Degradation of the device seems to come prlmarlly from the side reaction of PB and Au electrode rather than CdS photocorroslon itself A photochargeable device could thus be fabricated by utlhzmg multdayer membrane system composed of Prussian Blue battery and CdS film
REFERENCES 1 J Manassen, G Hodes and D Cahen, J electrochem Sot 124, 532 (1977) 2 G Betz, H Trlbutsch and S Flechter, J electrochem Sot 131, 640 (1984)
293
3 H J Gernten, W Ruppel and P Wurfel, J electrochem Sot 131, 2037 (1984) 4 Y Yonezawa, M Okal, M Ishmo and H Hada, Bull them Sot Jpn 56, 2873 (1983) 5 S Kanda and R W Murray, Bull them Sot Jpn 58, 3010 (1985) 6 M Kaneko and A Yamada, Adu Pofym SCI 55,1(1984) 7 K Itava and V D Neff. Act Chem Res 19. 162 (19861 8 V D Neff, J electrochem Sot 125, 886 (1958) ’ 9 K Itaya, T Ataka and S Toshlma, J Am them Sot 104, 4767 (1982) 10 V D Neff, J electrochem Sot 132, 1382 (1985) 11 M Kaneko, J Polymer Scr , Polymer Lett 24,435 (1986) 12 M Kaneko and T Okada, J electroanal Chem 255,45 (1988) 13 K Honda, J Ochlal and H Hayashl, J them Sot , them Commun 168 (1986) 14 K Itaya, I Uchlda, S Toshlma and R M De La Rue, J electrochem Sot 131, 2086 (1984) 15 M Tsulkl, H Mmoura, T Nakamura and Y Ueno, J appl Electrochem 8, 523 (1978)
35. No
I. pp B-293.
,990
00134686/w I3 oo+o.oo ;T, 1989 Per~amon Press plc
SHORT COMMUNICATION PHOTOCHARGEABLE MULTILAYER MEMBRANE DEVICE COMPOSED OF CdS FILM AND PRUSSIAN BLUE BATTERY MASAO KANEKO and TOKUO OKADA
The Institute of Physical and Chemical Research, Solar Energy Research Group, Wako, Saitama 351-01, Japan HIDEKI MINOURA, TAKASHI SUGIURA and YASUSADA UENO Gifu University, Faculty of Engineering, Yanagido I-1, Gifu 501-l 1, Japan (Received 13 February 1989; in revised form 4 April 1989)
INTRODUCTION Photoenergy conversion and storage are attracting attention not only in solar energy utilization but also in photodevices which are important for the future socalled photonics (photoelectronics). Photoinduced charge separation and the following accumulation of the separated charges are typical processes in photoenergy/information conversion and storage. These processes are generally carried out in different systems or phases respectively to result in a whole achievement. If they are combined to realize in one device, it must be of much value for the development of photodevices. Such a device is capable of photocharge and dark-discharge, and would open a new field in photoenergy and information conversion/storage. Some systems for photocharge and dark-discharge have been reported that are composed of liquidjunction semiconductor and redox electrolyte present in solution[l-51. A new concept is now proposed to realize photocharge and dark-discharge by a multifunctional solid state device, which must be of great use for practical application. The present authors have designed a multilayer membrane device for photocharge and dark-discharge so that each layer bears a function such as photoinduced charge separation, accumulation of positive/negative charges, separation of reactants. As for the membrane materials, polymer is most suited for practical use[6]. As a charge storage material, Prussian Blue (PB) which is a high molecular and polynuclear mixedvalent iron cyanide complex was chosen in the present paper. Electrochemical behavior of PB has been well characterized by Neff and Itaya et aI.[7-91. This complex, whose composition is represented by Fe:’ [Fe”(CN),]:-, has three kinds of reversible redox states, so that it can store both positive and negative charges. PB batteries were reported by NefllO], Kanekorll, 123, and Honda et al.[13] in which two PB films were utilized for an anode and a cathode. A multilayer PB polymer battery
(PB/Nafion/PB) has been fabricated, and its reaction characteristics have been studied electrochemically and spectrophotometrically by the present authors[12]. Photoreaction of PB film coated on TiO, has been studied in aqueous electrolyte solution[14], but this system uses only ultraviolet light and dark-discharge has not been reported. In the present paper, a multilayer solid type photochargeable device driven by visible light irradiation will be reported which is composed of n-CdS semiconductor film and trilayered PB battery membranes.
EXPERIMENTAL n-CdS film was coated on a NESA glass by a chemical spray deposition method as reported by Ueno et al.[ 151. PB was coated on the top of the CdS film and on a NESA glass by the reductive electrodeposition method[7-91 at 20 PA cm-’ under galvanostatic condition in an aqueous mixture of 10 mM K3[Fe(CN)6], 10 mM FeCl, and 10 mM HCl. A photochargeable multilayer device was fabricated by sandwiching a Nafion film (173 pm thickness) adsorbing aqueous electrolyte (0.5 M KNO, and 10 mM HNO,) with a PB-coated CdS film/NESA and a PB-coated NESA. For obtaining a device capable of discharge in the dark after photocharge, a comb-type Au electrode was attached on the PB membrane coated on CdS by vapor deposition before sandwiching. The cell composition shown in Fig. 1 is: NESA/CdS/PB/comb-type
Au/Naiion/PB/NESA.
The area of the effective cell surface was about 0.20 cm2. The irradiation was made with visible light (40&800 nm) from the reverse side of the NESA glass on which CdS is coated. A 500 W xenon lamp was used after passing the light through cut-off filters (Toshiba VY-42 and IRQ-80). The light intensity was 74 mW cm-‘. 291
M KANEKO
et al
V
NESA
Fig
1 Photochargeable
deuce
RESULTS AND DISCUSSION The charge and discharge reactlons of a multllayer PB battery are shown by Scheme 1, where PB has a Fe3+j2+ state, BG 1s Berlin Green (Fe3+“+), and PW 1s Prussian White (Fe2 ‘I2 + )
,
I
PosItwe
electrode,
Charge
PB m
0
BG
4
20
10 Charge/mC cm-2
Discharge
Negative
electrode,
PB 7
Charge
PW
Dwcharge
Scheme
l3g 2 Charge/discharge characterlstlcs of the PB/Au/ Nafion/PB/NESA secondary battery of the photochargeable device
1
The charge/discharge characterlstlcs of an NESA/PB/Nafion/PB/NESA battery has been reported[12] The cell of Fig 1 constitutes a PB battery when the Au and the counter NESA electrodes are connected The charge/dncharge characterlstlcs of this battery (PB/Au/Nafion/PB/NESA) 1s shown m Fig 2 Although the discharge/charge ratio (73%) was worse than an NESA/PB/Nafion/PBjNESA battery (90%)[12], the cycle could be carried out repeatedly The photochemrcal conversIon characterlstlcs of the naked CdS used m the present device were, V,, 0 34 4 V, J,, ca 70 PA cmm2, FF ca 0 4 and quantum efficiency 8% and energy conversIon efficiency 0 5% under 480 nm monochromatic hght lrradlatlon when dipped m an aqueous polysulfide solution (1 M NaOH, 1 MNa,S, 1 M S)[lS] In this polysulfide solution, the CdS photoanode gave stable photocurrents of 0 6 mAcme2, and no evidence of CdS corrosion was observed after the passage of 15 C The current changes mduced by swltchmg on and off the lrradlatlon of the photochargeable device composed of NESA/CdS/PB/Au/Nafion/PB/NESA were shown m Fig 3 On lrradlatlon, anodlc photocurrent flaws with the first strong spike followed by constant photocurrents, and, during the photoelectrochemlcal process, the color of the PB faded mdlcatmg that chargmg of PB occurs After passing 1 29 mC charges for 7 mm (correspondmg to 65% of the coated PB amount), the lrradlatlon was cut off On swltchmg off the Irradiation, the current returns to zero, and the
Photocharge Light on
t
0
Fig 3 Photocharge
’ I----
5 Time/min
0
and dark-discharge chargeable device
5
of the photo-
charged state could be maintained while the circuit was kept open When the device was short-circuited m the dark, reverse discharge current flows with the first strong cathodic spike followed by a gradual decay, after which the PB color returns back to orlgmal blue The discharge amounted to 0 47 mC for 5 mm which 1s 36% of the photocharged amount These photocharge and dark discharge cycles could be repeated reversibly many times at least for a few hours After a few hours,
Photochargeable multllayer membrane device degradation of the current was observed Reactlon of PB with Au electrode was visually observable after detachmg the sandwich structure of the device, but no change was observed at the CdS/PB Interface Degradation of the device seems to come prlmarlly from the side reaction of PB and Au electrode rather than CdS photocorroslon itself A photochargeable device could thus be fabricated by utlhzmg multdayer membrane system composed of Prussian Blue battery and CdS film
REFERENCES 1 J Manassen, G Hodes and D Cahen, J electrochem Sot 124, 532 (1977) 2 G Betz, H Trlbutsch and S Flechter, J electrochem Sot 131, 640 (1984)
293
3 H J Gernten, W Ruppel and P Wurfel, J electrochem Sot 131, 2037 (1984) 4 Y Yonezawa, M Okal, M Ishmo and H Hada, Bull them Sot Jpn 56, 2873 (1983) 5 S Kanda and R W Murray, Bull them Sot Jpn 58, 3010 (1985) 6 M Kaneko and A Yamada, Adu Pofym SCI 55,1(1984) 7 K Itava and V D Neff. Act Chem Res 19. 162 (19861 8 V D Neff, J electrochem Sot 125, 886 (1958) ’ 9 K Itaya, T Ataka and S Toshlma, J Am them Sot 104, 4767 (1982) 10 V D Neff, J electrochem Sot 132, 1382 (1985) 11 M Kaneko, J Polymer Scr , Polymer Lett 24,435 (1986) 12 M Kaneko and T Okada, J electroanal Chem 255,45 (1988) 13 K Honda, J Ochlal and H Hayashl, J them Sot , them Commun 168 (1986) 14 K Itaya, I Uchlda, S Toshlma and R M De La Rue, J electrochem Sot 131, 2086 (1984) 15 M Tsulkl, H Mmoura, T Nakamura and Y Ueno, J appl Electrochem 8, 523 (1978)