Platinum-free (Pt-free) counter electrodes (CEs) can reduce the cost of dye-sensitized solar cells (DSCs). In this study, a general strategy is proposed to construct Pt-free CEs, namely direct growth of electrocatalytic active nanostructures (metal sulfide, etc.) on conductive substrates via low temperature solution routes. As an implementation, nickel sulfide (NiS) nanoarray film composed of interconnected nanoplatelets is successfully fabricated by a two-step solution route. The as-grown NiS nanoarray film follows the sulfurization process in a thiourea aqueous solution from the precursor of hydrothermally deposited Ni(OH)(2) nanoplatelet arrays on FTO substrates. When applied as a Pt-free CE in DSCs, a maximum power conversion efficiency of 7.10% is achieved, comparable to that of Pt CE (7.35%). (C) 2013 Published by Elsevier B.V.