LAUSR

Abstract Yolk-shell structures based on transition metal chalcogenides (TMCs) have broad application prospects in energy conversion/storage fields. In this work, a facile step-wise synthetic strategy was used to synthesize the yolk-shell structured polyhedrons. The intermediate named as ZIF-67@Co–Fe PBA nanocrystal was formed by the reaction between Co2+ released from ZIF-67 polyhedrons and [Fe(CN)6]3− hydrolyzed from K3 [Fe(CN)6]. N-doped carbon/CoSe2@Co–FeSe2 (CoSe2-NC@Co–FeSe2) and N-doped carbon/CoS2@Co–FeS2 (CoS2-NC@Co–FeS2) polyhedrons with yolk-shell structures were prepared by modifying the ZIF-67@ Co–Fe PBA nanocrystals in the annealing process and they have been applied in dye-sensitized solar cells (DSSCs). Noteworthily, CoSe2-NC@Co–FeSe2 and CoS2-NC@Co–FeS2 yolk-shell polyhedrons showed high catalytic activity in accelerating the reduction of triiodide in DSSCs because of the distinctive structural characteristics and favorable chemical compositions. The power conversion efficiency (PCE) of 9.61% and 9.18% were obtained by CoSe2-NC@Co–FeSe2 and CoS2-NC@Co–FeS2 based DSSCs, respectively, which were both superior to that of Pt (8.15%). This as-designed approach implies the new perspective to prepare more types of TMCs with yolk-shell structures in multitudinous areas of energy conversion.