Ni3S2 entrenched MWCNT composite as a low-cost Pt-free counter electrode for dye-sensitized solar cell: Conversion efficiency reached to 9.28%

Abstract

• A simple and cost effective hydrothermal method was adopted to synthesize ultrafine Ni 3 S 2 /MWCNT hybrid CEs. • Ni 3 S 2 /CNT50 composite counter electrode has the maximum Power Conversion Efficiency (PCE) of 10.2 %. • This could be due to the Enhancing the light absorption property in the visible light region and diminish the recombination process. Engineering the surface structure and constructing a suitable internal conductive network is essential for the electron transfer rate and the active materials utilization efficiency of an electrode A novel porous micro-nanostructure based on nickel disulfide (Ni 3 S 2 ) nanoparticles interconnected with carbon nanotubes (CNTs) has been synthesized through a facile hydrothermal method. Shape, quantum states, optical behavior and phase purity have been elucidated using SEM, TEM, XPS, UV-DRD, PL and XRD spectra, respectively. Among all, Ni 3 S 2 /CNT50 composite counter electrode delivers the highest Power Conversion Efficiency (PCE) of 9.28 ± 0.03% with a short circuit current (J SC ) of 18.46 ± 0.01 mAcm −2 and open-circuit voltage (V OC ) of 0.73 ± 0.01 V. The improvement observed is due to the lower peak-to-peak separation (E pp ), higher exchange current density (J 0 ) and lower charge transfer resistance (R CT ). External quantum efficiency and electrochemical impedance analysis for the boost in efficiency and improved electrocatalytic activity with low charge-transfer resistance at (CE)/electrolyte interface are well in support for the synergistic effect of Ni 3 S 2 and MWCNTs.