Modulating conductivity type of cuprous oxide (Cu2O) films on copper foil in aqueous solution by comproportionation

doi:10.1016/j.jmst.2019.04.009

Abstract

Abstract:

Cuprous oxide (Cu₂O) is an attractive material for photoelectrochemical (PEC) hydrogen production or photovoltaic application, because of its appropriate band gap, low material cost and non-toxic. In this paper, Cu₂O films were obtained by comproportionation in acid cupric sulfate solutions with varying concentrations of potassium nitrate. Photoelectrochemical and electrochemical experiments, such as zero-bias photocurrent responses, voltammograms, and Mott-Schottky measurements, show that the Cu₂O films grown in low (≤0.75 mol dm^-3) and high (≥1.00 mol dm^-3) nitrate ion concentrations presented n-type and p-type conductivity, respectively. Open circuit potential and polarization behavior were monitored to investigate the mechanism of modulating conductivity type. Nitrate ions consume protons in the plating solution during comproportionation with different concentrations of nitrate ions creating different pH at the Cu₂O/solution interface. This gradient leads to the transformation of Cu₂O films conductivity changing from n-type to p-type with increasing the concentration of nitrate ions in the plating solution. This method could be used to fabricate homojunction electrode on metal substrate for PEC hydrogen production or photoelectric application.

Key words: Cuprous oxide (Cu₂O), Comproportionation, Semiconductor films, Tuning conductivity, Photoelectrochemical cell

Changwei Tang, Xiaohui Ning, Jian Li, Hui-Lin Guo, Ying Yang. Modulating conductivity type of cuprous oxide (Cu₂O) films on copper foil in aqueous solution by comproportionation[J]. J. Mater. Sci. Technol., 2019, 35(8): 1570-1577.

Figures/Tables 10

Fig. 1. XRD patterns of Cu2O films grown on Cu foils by comproportionation in plating solutions with varying concentrations of KNO3.

Fig. 2. XPS survey spectra (a) and Cu LMM Auger spectra (b) of Cu2O films grown on Cu foils by comproportionation in the plating solutions with varying concentrations of KNO3.

Fig. 3. Mott-Schottky plots of Cu2O films grown by comproportionation in the plating solutions with varying concentrations of KNO3.

Table 1 Summary of conductivity types, onset potentials, flat band potentials and carrier densities of Cu2O films obtained through different fabrication methods.

Electrode	Fabrication Method	Conductivity type	Electrolyte	Onset Potential (V vs Ag/AgCl) (saturated KCl)	Flat band potential (V vs Ag/AgCl) (saturated KCl)	Carrier density (cm^-3)	Ref.
Cu/Cu₂O	Chemical oxidation + Thermal oxidation	P	0.01 M phosphate buffer saline (pH = 7.4)	-	0.056 - 0.146	3.92 × 10¹⁷ - 1.63 × 10¹⁸	[9]
ITO/Cu₂O	Electrodeposition	N	0.2 M K₂SO₄ (pH = 6)	-0.699	-0.780	-	[6]
ITO/Cu₂O	Electrodeposition	N	3 wt% NaCl (pH = 6.6)	-	-0.263 - 0.161	2.03 × 10¹⁷ - 3.68 × 10¹⁷	[12]
ITO/Cu₂O	Electrodeposition	P	3 wt % NaCl (pH = 6.6)	-	0.148 - 0.157	5.07 × 10¹⁷ - 7.98 × 10¹⁷	[12]
FTO/Cu₂O	Electrodeposition	N	3 wt % NaCl (pH = 6.6)	-	-0.312 - -0.180	6.81 × 10¹⁶ - 5.50 × 10¹⁶	[13]
FTO/Cu₂O	Electrodeposition	P	3 wt % NaCl (pH = 6.6)	-	0.190 - 0.381	1.437 × 10¹⁵ - 2.423 × 10¹⁷	[13]
Cu/Cu₂O	Comproportionation	N	0.1 M Na₂SO₄ (pH = 7)	-	0.039	7.35 × 10¹⁹	[11]
Cu/Cu₂O	Comproportionation	N	3 wt % NaCl (pH = 6.6)	^a -0.335	^a -0.556	^a 8.7 × 10¹⁸	This work
				^b -0.263	^b -0.534	^b 8.8 × 10¹⁷
				^c -0.250	^c -0.526	^c 4.9 × 10¹⁷
		P	3 wt % NaCl (pH = 6.6)	^d -0.039	^d -0.150	^d 2.1 × 10¹⁸
				^e -0.032	^e -0.141	^e 3.8 × 10¹⁸
				^f -0.022	^f -0.138	^f 9.2 × 10¹⁸

Fig. 4. Zero-bias photocurrent characterization for Cu2O films grown in the plating solutions with varying concentrations of KNO3.

Fig. 5. Voltammograms under illumination (100 mW cm-2) and dark of Cu2O films formed in the plating solutions with varying concentrations of KNO3.

Fig. 6. Growth diagrams of Cu2O films by comproportionation. (a) Cu foil was immersed in the plating solution; (b) Cu2O crystals grew as islands on the Cu subtrates; (c) a layer of Cu2O film formed and covered Cu substrate completely; (d) Cu2O film increased thickness with oxidized Cu substrate and reduced Cu2+ from the plating solution.

Fig. 7. SEM images of Cu2O films prepared by comproportionation for varying times in the plating solutions without KNO3.

Fig. 8. (a) OCPs of Cu foil in the plating solutions without KNO3 and with 2.00 mol dm-3 KNO3 for growing Cu2O film during comproportionation; (b) polarization curves of Pt foil in KNO3 solution without CuSO4 (pH=5.00). The counter eletrode was another Pt foil.

Fig. 9. Mechanism of controlling conductivity type of Cu2O film through comproportionation by changing the concentration of KNO3 in plating solutions. (a) Rich oxygen vacancies formed in Cu2O film at low concentrations of KNO3 due to the local acid environment at Cu2O/solution interface, and (b) rich copper vacancies formed in Cu2O film at high concentrations of KNO3 owing to reduction of NO3- consuming more H+, leading to a basic local environment at Cu2O/solution interface.

References

[1]	A. Paracchino, V. Laporte, K. Sivula, M. Grätzel, E. Thimsen, Nat. Mater. 10 (2011) 456-461.
[2]	L. Yu, G. Li, X. Zhang, X. Ba, G. Shi, Y. Li, P.K. Wong, J.C. Yu, Y. Yu, ACS Catal. 6 (2016) 6444-6454.
[3]	C. Yang, J. Wang, L. Mei, X. Wang, J. Mater. Sci. Technol. 30 (2014) 1124-1129.
[4]	A. El-Shaer, M.T.Y. Tadros, M. Khalifa, Nat. Sci. 13 (2015) 14-22.
[5]	W. Siripala, L.D.R.D. Perera, K.T.L. De Silva, J.K.D.S. Jayanetti, I.M. Dharmadasa, Sol. Energy Mater. Sol. Cells, 44 (1996) 251-260.
[6]	C.M. McShane, K.S. Choi, J. Am. Chem. Soc. 131 (2009) 2561-2569.
[7]	P. Wang, Y.H. Ng, R. Amal, Nanoscale 5 (2013) 2952-2958.
[8]	Y. Alajlani, F. Placido, H.O. Chu, R.D. Bold, L. Fleming, D. Gibson, Thin Solid Films 642 (2017) 45-50.
[9]	C. Li, Y. Li, J.J. Delaunay, ACS Appl. Mater. Interfaces 6 (2014) 480-486.
[10]	W. Lu, Y. Sun, H. Dai, P. Ni, S. Jiang, Y. Wang, Z. Li, Z. Li, Sensor. Actuat. B-Chem. 231 (2016) 860-866.
[11]	Z. Jin, Z. Hu, J.C. Yu, J. Wang, J. Mater. Chem. A 4 (2016) 13736-13741.
[12]	Y. Yang, J. Han, X. Ning, W. Cao, W. Xu, L. Guo, ACS Appl. Mater. Interfaces 6 (2014) 22534-22543.
[13]	J. Han, J. Chang, R. Wei, X. Ning, J. Li, Z. Li, H. Guo, Y. Yang, Int. J. Hydrogen Energy 43 (2018) 13764-13777.
[14]	C.A.N. Fernando, S.K. Wetthasinghe, Sol. Energy Mater. Sol. Cells 63 (2000) 299-308.
[15]	C.A.N. Fernando, P.H.C. de Silva, S.K. Wethasinha, I.M. Dharmadasa, T. Delsol, M.C. Simmonds, Renew. Energy 26 (2002) 521-529.
[16]	L. Ma, Y. Lin, Y. Wang, J. Li, E. Wang, M. Qiu, Y. Yu, J. Phys. Chem. C 112 (2008) 18916-18922.
[17]	W. Zhang, Y. Zhang, Z. Yang, G. Chen, G. Ma, Q. Wang, Chin. J. Chem. Eng. 24 (2016) 48-52.
[18]	L.C. Olsen, F.W. Addis, W. Miller, Sol. Energy Mater. Sol. Cells 7 (1982) 247-279.
[19]	T. Jiang, T. Xie, L. Chen, Z. Fu, D. Wang, Nanoscale 5 (2013) 2938-2944.
[20]	H.J. Li, C.Y. Pu, C.Y. Ma, S. Li, W.J. Dong, S.Y. Bao, Q.Y. Zhang, Thin Solid Films 520 (2011) 212-216.
[21]	H. Wu, W. Chen, J. Am. Chem. Soc. 133 (2011) 15236-15239.
[22]	C. Zhu, A. Osherov, M.J. Panzer, Electrochim. Acta 111 (2013) 771-778.
[23]	J.Y. Park, Y.S. Jung, J. Cho, W.-K. Choi, Appl.Surf. Sci. 252 (2006) 5877-5891.
[24]	R. Garuthara, W. Siripala, J. Lumin. 121 (2006) 173-178.
[25]	A. Mittiga, F. Biccari, C. Malerba, Thin Solid Films 517 (2009) 2469-2472.
[26]	W.C. Wang, D.X. Wu, Q.M. Zhang, L.C. Wang, M. Tao, J. Appl. Phys. 107 (2010), 123717.
[27]	Y. Yang, J. Han, X. Ning, J. Su, J. Shi, W. Cao, W. Xu, Int. J. Energy. Res. 40 (2016) 112-123.
[28]	H.B. Michaelson, J. Appl. Phys. 48 (1977) 4729-4733.
[29]	M. Pourbaix, Houston, 1974, pp. 384.
[30]	D.O. Scanlon, B.J. Morgan, G.W. Watson, A. Walsh, Phys. Rev. Lett. 103 (2009), 096405.
[31]	G.P. Pollack, D. Trivich, J. Appl. Phys. 46 (1975) 163-172.
[32]	L. Wang, M. Tao, Electrochem. Solid-State Lett. 10 (2007) 248-250.
[33]	C.M. McShane, K.S. Choi, Phys. Chem. Chem. Phys. 14 (2012) 6112-6118.
[34]	T. Jiang, T. Xie, W. Yang, L. Chen, H. Fan, D. Wang, J. Phys. Chem. C. 117 (2013) 4619-4624.
[35]	L.C.K. Liau, Y.C. Lin, Y.J. Peng, J. Phys. Chem. C 117 (2013) 26426-26431.

Modulating conductivity type of cuprous oxide (Cu₂O) films on copper foil in aqueous solution by comproportionation

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