Carbon nanotube aerogel–CoS2 hybrid catalytic counter electrodes for enhanced photovoltaic performance dye-sensitized solar cells

Abstract

The carbon nanotube aerogel (CNA) with an ultra-low density, three-dimensional network nanostructure, superior electronic conductivity and large surface area is being widely employed as a catalytic electrode and catalytic support. Impressively, dye-sensitized solar cells (DSSCs) assembled with a CNA counter electrode (CE) achieved a maximum power conversion efficiency (PCE) of 8.28%, which exceeded that of the conventional platinum (Pt)-based DSSC (7.20%) under the same conditions. Furthermore, highly dispersed CoS₂ nanoparticles endowed with excellent intrinsic catalytic activity were hydrothermally incorporated to form a CNA-supported CoS₂ (CNA–CoS₂) CE, which was due to the large number of catalytically active sites and sufficient connections between CoS₂ and the CNA. The electrocatalytic ability and stability were systematically evaluated by cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and Tafel polarization, which confirmed that the resultant CNA–CoS₂ hybrid CE exhibited a remarkably higher electrocatalytic activity toward I₃⁻ reduction, and faster ion diffusion and electron transfer than the pure CNA CE. Such cost-effective DSSCs assembled with an optimized CNA–CoS₂ CE yielded an enhanced PCE of 8.92%, comparable to that of the cell fabricated with the CNA–Pt hybrid CE reported in our published literature (9.04%). These results indicate that the CNA–CoS₂ CE can be considered as a promising candidate for Pt-free CEs used in low-cost and high-performance DSSCs.