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

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 CoS nanoparticles endowed with excellent intrinsic catalytic activity were hydrothermally incorporated to form a CNA-supported CoS (CNA-CoS) CE, which was due to the large number of catalytically active sites and sufficient connections between CoS 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-CoS hybrid CE exhibited a remarkably higher electrocatalytic activity toward I reduction, and faster ion diffusion and electron transfer than the pure CNA CE. Such cost-effective DSSCs assembled with an optimized CNA-CoS 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-CoS CE can be considered as a promising candidate for Pt-free CEs used in low-cost and high-performance DSSCs.