In situ grown hierarchical NiCo2O4@MnMoO4 core-shell nanoarrays on carbon cloth as high-performance counter electrode for dye-sensitized solar cells

Carbon cloth (CC) supported core-shell NiCo2O4@MnMoO4 nanoarrays composite is successfully synthesized by two-step hydrothermal method, and used as binder-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). In comparison with the NiCo2O4/CC, MnMoO4/CC, CC and Pt CEs, the NiCo2O4@MnMoO4/CC CE exhibits the significantly improved electrochemical performance. And the improved electrochemical performance can be attributed to the contribution from CC combination outer-sphere MnMoO4 nanosheet and inner sphere NiCo2O4 nanowires array, which offer a large electrochemical surface area, good electrochemical activity to iodide/triiodide couple, and lower charge-transfer and series resistances. The DSSCs device assembled with core-shell composite NiCo2O4@MnMoO4/CC CE achieved excellent power conversion efficiency of 11.87%, which is higher than that of counter parts of NiCo2O4/CC (10.97%), MnMoO4/CC (11.08%), CC (4.84%) and Pt (8.55%) CEs. Also, the NiCo2O4@MnMoO4/CC based device remains 90.9% efficiency up to 10 days under ambient conditions. Therefore, the NiCo2O4@MnMoO4/CC composite with unique structure can be further developed as an efficient and cost-effective metal oxides electrocatalysts in DSSCs and other related fields.