Abstract
Development of cost-effective counter electrode (CE) materials is a key issue for practical applications of photoelectrochemical solar energy conversion. Kesterite Cu2ZnSnS4 (CZTS) has been recognized as a potential CE material, but its electrocatalytic activity is still insufficient for the recovery of I−/I3− electrolyte in dye-sensitized solar cells (DSSCs). Herein, we attempt to enhance the electrocatalytic activity of kesterite CZTS through element substitution of Zn2+ by Co2+ and Ni2+ cations, considering their high catalytic activity, as well as their similar atomic radius and electron configuration with Zn2+. The Cu2CoSnS4 (CCTS) and Cu2NiSnS4 (CNTS) CEs exhibit smaller charge-transfer resistance and reasonable power conversion efficiency (PCE) (CCTS, 8.3%; CNTS, 8.2%), comparable to that of Pt (8.3%). In contrast, the CZTS-based DSSCs only generate a PCE of 7.9%. Density functional theory calculation indicate that the enhanced catalytic performance is associated to the adsorption and desorption energy of iodine atom on the Co2+ and Ni2+. In addition, the stability of CCTS and CNTS CEs toward electrolyte is also significantly improved as evidenced by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy characterizations. These results thus suggest the effectiveness of the element substitution strategy for developing high-performance CE from the developed materials, particularly for multicomponent compounds.
Highlights
High-efficiency, good-stability and low-cost counter electrodes (CEs) are essential for photoelectrochemical solar energy conversion
To avoid the signals interference of FTO (SnO2: F) to CXTS films, we recorded X-ray diffraction (XRD) patterns and Raman spectra through CXTS films on quartz prepared by the same method
The diffraction peaks at 28.53°, 47.33°, and 56.18° were indexed to (112), (220), and (312) planes respectively, which were in good agreement with those of previously reported kesterite CZTS48–50 (Fig. 1(a))
Summary
The stability of CCTS and CNTS CEs toward electrolyte is significantly improved as evidenced by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy characterizations. These results suggest the effectiveness of the element substitution strategy for developing high-performance CE from the developed materials, for multicomponent compounds. Series of highly efficient CE materials based on Co2+ and Ni2+ have been exploited, including carbides[39], nitrides[40], chalcogenides[41,42] and oxides[43] These two divalent metal ions present similar atomic radius and electron configuration with Zn2+, substituting Zn2+ by Co2+ or Ni2+ may improve the catalytic activity of CZTS. The highly-effective catalytic activity is related to the adsorption and desorption energy of iodine (I) atom calculated by the density functional theory[44,45,46,47]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
