Ni2+ enriched carbon nanotubes nanohybrids based non-platinum counter electrodes for dye sensitized solar cells

Abstract

The development of competent substitutes for Pt counter electrode (CE), possessing excellent electrocatalytic activity, stability, and ready availability, is a key issue to materialize the long-term stability and economical large-scale industrial production of future generation dye sensitized solar cells (DSSCs). In the present work, a cost effective and solution processable hydrothermal technique has been utilized to synthesize Ni2+ enriched nanohybrids of nickel oxide (NiO) and nickel sulfide (Ni3S2) nanoparticles with multi-walled carbon nanotubes (MWCNTs) as CE in DSSCs. NiO/MWCNTs nanohybrids showed superior electrocatalytic behaviour among MWCNTs, NiO, Ni3S2, nanohybrids, and Pt. The nanohybrids containing aligned network MWCNTs exhibited good electrical conductivity, high specific surface area and better stability. These nanohybrids have been further employed as CE in DSSCs and observed higher Power Conversion Efficiency (PCE) for NiO/MWCNTs nanohybrids CE (3.80%) among others and is almost comparable to that of Pt based DSSC (3.90%). It has been explained on the basis of Ni2+content present in the nanohybrids. The higher content of Ni2+species provides a greater number of active sites representing higher electrocatalytic activity that would further productively catalyze the reactions occurring at CE/electrolyte interface in DSSCs.