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Stoichiometry-Controlled Mo<i><sub>x</sub></i>W<sub>1–<i>x</i></sub>Te<sub>2</sub> Nanowhiskers: A Novel Electrocatalyst for Pt-Free Dye-Sensitized Solar Cells

DOI

22

Citations

54

References

2020

Year

Roshan Jesus Mathew, Chuan‐Pei Lee, Chi‐Ang Tseng, Pradyumna Kumar Chand, Yi‐June Huang, Han‐Ting Chen, Kuo–Chuan Ho, Aswin kumar Anbalagan, Chih‐Hao Lee, Yit‐Tsong Chen
ACS Applied Materials & Interfaces

Abstract

Novel polymorphic Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub>-based counter electrodes possess high carrier mobility, phase-dependent lattice distortion, and surface charge density wave to boost the charge-transfer kinetics and electrocatalytic activity in dye-sensitized solar cells (DSSCs). Here, we report the syntheses of stoichiometry-controlled binary and ternary Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub> nanowhiskers directly on carbon cloth (CC), denoted by Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub>/CC, with an atmospheric chemical vapor deposition technique. The synthesized Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub>/CC samples, including <i>1T'</i>-MoTe<sub>2</sub>/CC, <i>T<sub>d</sub>-</i>WTe<sub>2</sub>/CC, <i>T<sub>d</sub>-</i>Mo<sub>0.26</sub>W<sub>0.73</sub>Te<sub>2.01</sub>/CC, and <i>1T'-</i> & <i>T<sub>d</sub></i>-Mo<sub>0.66</sub>W<sub>0.32</sub>Te<sub>2.02</sub>/CC, were then employed as different counter electrodes to study their electrochemical activities and efficiencies in DSSCs. The photovoltaic parameter analysis manifests that Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub>/CCs are more stable than a standard Pt/CC in the <i>I</i><sup>-</sup>/<i>I</i><sub>3</sub><sup>-</sup> electrolyte examined by cyclic voltammetry over 100 cycles. A <i>1T'-</i> & <i>T<sub>d</sub></i>-Mo<sub>0.66</sub>W<sub>0.32</sub>Te<sub>2.02</sub>/CC-based DSSC can achieve a photocurrent density of 16.29 mA cm<sup>-2</sup>, a maximum incident photon-to-electron conversion efficiency of 90% at 550 nm excitation, and an efficiency of 9.40%, as compared with 8.93% of the Pt/CC counterpart. Moreover, the <i>1T'-</i> & <i>T<sub>d</sub></i>-Mo<sub>0.66</sub>W<sub>0.32</sub>Te<sub>2.02</sub>/CC shows lower charge-transfer resistance (0.62 Ω cm<sup>2</sup>) than a standard Pt/CC (1.19 Ω cm<sup>2</sup>) in electrocatalytic reactions. Notably, Mo<i><sub>x</sub></i>W<sub>1-<i>x</i></sub>Te<sub>2</sub> nanowhiskers act as an electron expressway by shortening the path of carrier transportation in the axial direction from a counter electrode to electrolytic ions to enhance the reaction kinetics in DSSCs. This work demonstrates that the nanowhisker-structured <i>1T'-</i> & <i>T<sub>d</sub></i>-Mo<sub>0.66</sub>W<sub>0.32</sub>Te<sub>2.02</sub>/CC with high carrier mobility and robust surface states can serve as a highly efficient counter electrode in DSSCs to replace the conventional Pt counter electrode for electrocatalytic applications.

References

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