Novel CoS₂embedded carbon nanocages by direct sulfurizing metal–organic frameworks for dye-sensitized solar cells

Abstract

Owing to its excellent electrocatalytic properties, cobalt disulfide (CoS2) is regarded as a promising counter electrode (CE) material for dye-sensitized solar cells (DSSCs). However, hindered by its relatively poor electrical conductivity and chemical instability, it remains a challenge to apply it into high-performance DSSCs. In this work, we have developed novel CoS2 embedded carbon nanocages as a CE in DSSCs, using ZIF-67 (zeolitic imidazolate framework 67, Co(mim)2, mim = 2-methylimidolate) as a template. The CoS2 samples sulfurized for different time lengths are prepared through a facile solution process. It is found that the sulfurization time can be optimized to maximize the DSSC efficiency and the DSSC based on the CoS2 embedded carbon nanocages sulfurized for 4 hours exhibits the highest photovoltaic conversion efficiency (PCE) of 8.20%, higher than those of DSSCs consisting of other CoS2 CEs and Pt-based DSSC (7.88%). The significantly improved DSSC PCE is contributed by the synergic effect of inner CoS2 nanoparticles and an amorphous carbon matrix, leading to a CE with high catalytic activity, good electrical conductivity and excellent durability. This study demonstrates that the CE based on inexpensive CoS2 embedded carbon nanocages is a prospective substitute to expensive platinum and provides a new approach for commercializing high-efficiency DSSCs.

Metal organic framework-mediated synthesis of potassium-promoted cobalt-based catalysts for higher oxygenates synthesis

“…Therefore, the organic ligands are removed and the catalyst consists of only cobalt oxide after calcination. This agrees with previous reported decomposition of ZIF-67 using Thermo-gravimetric analysis and XRD [40][41][42]. The XPS spectra of the calcined samples at Co (2p 3/2 ) are shown in Fig.…”

“…The uncalcined sample is composed of polyhedral-shaped particles with < 500 nm in size. ZIF-67 is reported to form a stable suspension in methanol, and the average size of the particle ranges from 228 nm to 500 nm [37,40,41]. In this study, ZIF-67 serves as the precursors to the cobaltbased catalysts and the sample is calcined under air flow at 500°C for 2 h. After the calcination in air (Fig.…”

Recent Progress in Metal–Organic Frameworks and Their Derived Nanostructures for Energy and Environmental Applications

“…[120] This robust carbon materiald isplays as urfacea rea of 982.1 m 2 g À1 .T he annealing temperature is very important for controlling the morphology and porosity. [123] To synthesize CoS 2 -embedded carbonn anocages, the as-prepared ZIF-67 crystals were transferred into ab eaker containing 0.1 m thioacetamide( TAA), anhydrous ethanol (150 mL), and distilled water (150 mL). In comparison, nitrogendoped carbon spheres synthesized through am icrowave-assisted approach only deliver aP CE of 6.28 %.…”

“…[122] More recently,C ui et al reported the synthesis of CoS 2 -embedded carbonn anocages through directly sulfurizing ZIF-67 ( Figure 9). [123] To synthesize CoS 2 -embedded carbonn anocages, the as-prepared ZIF-67 crystals were transferred into ab eaker containing 0.1 m thioacetamide( TAA), anhydrous ethanol (150 mL), and distilled water (150 mL). Then the mixturew as heated at 90 8Cf or different times.…”

One‐Step Transformation from Cu2S Nanocrystal to CuS Nanocrystal with Photocatalytic Properties

“…To date various metal sulfides have been synthesized and their applications have been explored. For instance, NiS 2 , Co 9 S 8 , CoS 2 , SnS 2 and MoS 2 have been considered as the prospective counter electrode materials for dye‐sensitized solar cells due to their good electrocatalytic property . CdS QDs, Mn/ZnS QDs, CdSe/CdS/ZnS nanorods, CuS nanoparticles have application in biomedicine field.…”