Highly-dispersed CoS2/N-doped carbon nanoparticles anchored on RGO skeleton as a hierarchical composite counter electrode for quantum dot sensitized solar cells

Hierarchical nanostructures with tailored components and architectures have attracted widespread interest in improving the performance of electrocatalysts, but the construction of exquisite structures with remarkable electrocatalytic performance is still challenging. Herein, the hierarchical CoS 2 /NC-RGO composite is designed via a delicate yet facile three-step process, including in-situ growth of ZIF-67, carbonization, and vulcanization. The key preparation step is that GO sheets and the O-20 surfactant are introduced simultaneously into the process of ZIF-67 preparation to obtain the precursor of the hierarchical structure. The composite employed as the counter electrode in the polysulfide electrolyte exhibits a low charge transfer resistance of 1.07 Ω, and the CdS/CdSe co-sensitized quantum dot sensitized solar cell obtains a PCE up to 5.14%. The successive cyclic voltammetry test results prove that it exhibits ultrastrong durability in the polysulfide electrolyte. The excellent performance is mainly due to the well-design of the RGO conductive skeleton and the CS/NC nanoparticles that are uniformly and tightly anchored on the RGO surface. This work provides a new perspective for the preparation of novel and high-efficient hierarchical carbonaceous composite CEs for QDSSCs.