W–N/C@Co9S8@WS2-hollow carbon nanocage as multifunctional electrocatalysts for DSSCS,ORR and OER

Due to the unique characteristics like large specific surface area of Transition Metal Dichalcogenides (TMDs) and its well-defined hollow Metal-Organic Framework (MOF), it is widely used in dye-sensitized solar cells (DSSCs), oxygen reduction (ORR) and oxygen evolution reaction(OER). Herein, we prepare N-doped C hollow metal organic frame structure materials , which are used as a template, WS 2 nanocrystals are grown and encapsulated in MOF with interfacial W–N coupling centers. During the pyrolysis, after carbonizing, ZIF-67 becomes Co, N-doped C materials, and the growth of WS 2 is effectively suppressed, creating multi-functional groups W–N/C@Co 9 S 8 @WS 2 materials. The synthesized material is employed as a counter electrode (CE) for dye-sensitized solar cells, its high power conversion efficiency (PCE) (7.38%) based DSSC under AM 1.5G irradiation was much more than that of Pt (7.06%). Such excellent electrocatalytic performance was resulted from the unique frame pore structure , the synergistic effect of WS 2 , Co 9 S 8 and W–N multi-functional groups. Besides, W–N/C-4@Co 9 S 8 @WS 2 shows E 1/2 ≈0.84 V and a little Tafel slope of 44 mVdec −1 when employed as electrocatalysts for ORR and potential ≈ 1.79 V to achieve the current density of 10 mA cm −2 , which are lower than that of Pt/C ≈ 1.91 V catalysts in 0.1 M KOH.