Metal-Organic Framework Derived CoNi@CNTs Embedded Carbon Nanocages for Efficient Dye-Sensitized Solar Cells

The commercialization of dye-sensitized solar cells (DSSCs) has been severely hindered by high cost and scarcity of Pt as counter electrode (CE). Up to date, the design of low-cost Pt-free CE materials with an ideal combination of high electrical conductivity, excellent catalytic activity and satisfactory long-term electrochemical stability still poses challenges to researchers. In this work, we have developed novel CoNi alloy@carbon nanotubes embedded carbon nanocages (CoNi@CNTs-C) as the CE of DSSCs for the first time, by applying Co/Ni bimetallic metal organic framework (MOF) as the template. The power conversion efficiency (PCE) of DSSCs can be maximized by simply optimizing the ratio of Ni2+/Co2+ precursor ratio during the synthesis. As a result, the DSSC based on CoNi@CNTs-C-200 CE with a Co/Ni atomic ratio of 9:1 exhibits a remarkable PCE of 9.04%, showing a, similar to 15% enhancement compared to that of Pt CE (7.88%). Notably, the CoNi@CNTs-C-200 CE also demonstrates excellent long-term electrochemical stability over 300 cyclic voltammetry cycles, which is much superior to that of Conventional Pt CE. Thus, the CoNi@CNTs-C demonstrates a great potential as a low-cost, stable and efficient CE material for next-generation DSSCs. (C) 2017 Elsevier Ltd. All rights reserved.