Hierarchical NiSe microspheres as high-efficiency counter electrode catalysts for triiodide reduction reaction

Abstract The monodispersed NiSe hierarchical microspheres (NiSe-112) were controllably synthesized by the facile solvothermal method and employed as the high-efficiency counter electrode (CE) electrocatalysts for the triiodide (I3−) reduction reaction (IRR). The obtained NiSe-112 combines the advantages of the well monodispersity, the inimitable 3D micro/nanostructure and loosened rough surface structure, which not only facilitated the permeation of the electrolyte containing I3−/I− redox couple, but also provided the substantial active sites for the IRR. As a result, NiSe-112 exhibited excellent catalytic activity for IRR accompanying with an impressive photoelectric conversion efficiency of 7.67 %, which is compared to that of the conventional Pt-based DSSCs (7.85 %). The relevant electrochemical measurements demonstrated that the obtained NiSe-112 possessed Pt-like catalytic activity, rapid electron transport capability and excellent electrochemical stability. Therefore, three-dimensional hierarchical structural NiSe microspheres have a great potential to replace the noble metal Pt, which is beneficial to promote the development of the low-cost CE catalysts for DSSCs.