Chemical bath deposition of NiCo2S4 nanostructures supported on a conductive substrate for efficient quantum-dot-sensitized solar cells and methanol oxidation

Abstract

Hierarchical nanostructures have recently attracted massive attention due to their remarkable performances in energy conversion, storage systems, catalysis, and electronic devices. Considering the advantage of hierarchical nanostructures, we have formulated a facile and cost-effective chemical bath deposition method to synthesize novel NiCo₂S₄ on a conductive substrate for quantum dot sensitized solar cells & methanol electro-oxidation. Owing to the unique nanoarchitecture, the NiCo₂S₄ electrodes were used to grow high quality thin films containing nanoflowers, nanoplatelets, or nanosheets. The nanoplate-structured NiCo₂S₄ CE in QDSSCs under one-sun illumination (AM 1.5, 100 mW cm⁻²) yielded a high short circuit current density (J_sc) of 11.91 mA cm⁻², open circuit voltage (V_oc) of 0.602 V, fill factor (FF) of 0.50, and power conversion efficiency (η) of 3.53%. These values are much higher than those of the Pt CE (J_sc = 6.98 mA cm⁻², V_oc = 0.579, FF = 0.36, and η = 1.10%). The electrocatalytic performance was investigated by cyclic voltammetry and chronoamperometry for NiCo₂S₄ electrodes via methanol electro-oxidation. Electrochemical studies reveal that the as-prepared NiCo₂S₄–NCS6h electrode displayed a significant enhancement in the electrocatalytic activity and stability for methanol oxidation in the presence of 2 M KOH with 0.5 M methanol. The results indicate that the hierarchical structure of NiCo₂S₄ offers a promising electrode material for QDSSCs and methanol electro-oxidation.