Stepwise synthesis of CoS2-C@CoS2 yolk-shell nanocages with much enhanced electrocatalytic performances both in solar cells and hydrogen evolution reactions

Yolk-shell nanocages possessing complex internal structure and excellent structural tenability are advantageous for the preparation of advanced catalysts. Due to outstanding features such as superior electrical, magnetic, optical and catalytic properties, non-noble metal materials with hollow nanostructures have been considered potential substitutes for highly active and stable abundant noble-metal electrocatalysts. In this study, the as-prepared CoS2-C@CoS2 yolk-shell nanocages were applied in both dye-sensitized solar cells (DSSCs) and hydrogen evolution reactions (HERs). Due to the remarkable structural features and advantageous chemical compositions, CoS2-C@CoS2 yolk-shell nanocages comprising tiny crystals possessed large surface area (161 m(2) g(-1)), well-defined interior voids, excellent conductivity and high catalytic activity. The DSSC with CoS2-C@CoS2 achieved a high power conversion efficiency (PCE) of 9.32% under AM 1.5 G irradiation, and it outperformed the DSSC with Pt (8.24%). Besides, CoS2-C@CoS2 as a kind of HER catalyst also exhibited a low onset overpotential of 19.0 mV, small Tafel slope of 51.9 mV dec(-1) and low overpotential of 79.1 mV at a current density of 10 mA cm(-2) under acidic conditions (0.5 M H2SO4).