CoSe₂/N-Doped Carbon Hybrid Derived from ZIF-67 as High-Efficiency Counter Electrode for Dye-Sensitized Solar Cells

Abstract

To achieve a satisfactory photovoltaic performance in dye-sensitized solar cells (DSSCs), counter electrode (CE) catalysts with low cost, superior catalytic activity, and excellent conductivity should be developed. In this work, the unique rhombic dodecahedron morphology of CoSe2/N-doped carbon (CoSe2/NC) and CoS2/N-doped carbon (CoS2/NC) hybrids with small-size pores were successfully prepared through direct selenization and sulfurization of ZIF-67, respectively. DSSCs fabricated with CoSe2/NC (CoS2/NC) electrode achieved a photoelectric conversion efficiency of 9.06% (8.74%), superior to that of Pt-based DSSCs (8.03%). The satisfactory performance was mainly attributed to the synergic effect between CoSe2 (CoS2) and N-doped carbon. As for this hybrid, CoSe2 (CoS2) and the N-doped species (graphitic-N and pyridinic-N) of carbon framework as catalytic active centers supplied abundant active sites toward I3 – reduction, while NC as fast conductivity platforms facilitated the charge transfer. Meanwhile, the unique rhombic dodecahedron morphology with small-size pores of the hybrids could also accelerate the permeation of redox electrolyte, thus promoting the catalytic reaction between redox species (I–/I3 –) and inner active sites of CoSe2 (CoS2). Therefore, low-cost CoSe2/NC hybrid has great potential for replacing noble Pt for the reduction of I3 – in DSSCs.

A Novel Metal–Organic Framework Intermediated Synthesis of Heterogeneous CoS2/CoS Porous Nanosheets for Enhanced Oxygen Evolution Reaction

“…Finally, with the molar ratio of Co 2+ /2‐MIM further reduced to 1/4, typical rhombic dodecahedron ZIF‐67 particles with a smooth surface were synthesized (Figure S2c, Supporting Information), which possessed the same XRD pattern (Figure S3, Supporting Information) as that in the published literature. [ 42 ] As shown in Figure S3, Supporting Information, the XRD peaks of the products become sharper with the decrease of Co 2+ content. This result demonstrates that extra Co 2+ plays an important role in the formation of the structure of the MOF.…”

Application of Metal-Organic Frameworks and Covalent Organic Frameworks as (Photo)Active Material in Hybrid Photovoltaic Technologies

“…Selenization or sulfurization process of ZIF-67 could be a feasible approach to produce Co-based selenide (sulphide)/N-doped carbonaceous hybrid material. Wang and co-workers synthesized CoSe 2 /NC and CoS 2 /NC (NC; N-doped carbon) electrocatalytic film as counter-electrode in DSSCs [166]. These composites were proved to assure huge catalytic activity and high conductivity and a PCE of 9% was achieved.…”

“…Illustration of synthesis and structure for preparing CoSe2/NC and CoS2/NC. Reproduced with permission from[166].…”

In Situ Growth of CoSe2 Coated in Porous Carbon Layers as Anode for Efficient Sodium‐Ion Batteries

“…[ 18 ] Although the sodium storage performance of TMCs has been greatly improved, long‐term cycle stability, especially at high current densities, still needs to be improved further. [ 19,20 ]…”