One‐Step Hydrothermal Tailoring of NiCo₂S₄ Nanostructures on Conducting Oxide Substrates as an Efficient Counter Electrode in Dye‐Sensitized Solar Cells

A one‐step in situ tailoring of NiCo 2 S 4 nanostructures is demonstrated on fluorine‐doped tin oxide (FTO) as Pt‐free counter electrodes (CEs) for dye‐sensitized solar cells (DSSCs) with performance surpassing that of a conventional Pt‐sputtered CE. An interconnected NiCo 2 S 4 nanosheet network is successfully constructed on the FTO glass via a hydrothermal method, attributed to the synergistic effect of structure‐directing hexamethylenetetramine and L‐cysteine. A growth mechanism is proposed, and the effects of nanostructures and sulfur atomic percentages on the electrocatalytic performance are discussed in depth. A DSSC with the optimized interconnected NiCo 2 S 4 nanosheet CE exhibits higher power conversion efficiency (7.22%) compared to that with a conventional Pt‐sputtered CE (6.87%) due to excellent charge transport properties and enhanced electrocatalytic activity of the NiCo 2 S 4 nanostructures. This work showcases the strong potential of nanostructured ternary chalcogenides, which are composed of earth‐abundant elements and prepared through a single‐step hydrothermal process without tedious posttreatments, to reduce the dependence of platinum in DSSCs and other electrochemical devices.