Co-Fe-MoSx hollow nanoboxes as high-performance counter electrode catalysts for Pt-free dye-sensitized solar cells

Abstract

Box-structured nanomaterials with complicated surface texture, whose morphologies can be adjusted through changing mass ratios of reactants, are attractive in the field of electrochemical energy conversion. Herein, we report the shape-controllable synthesis of MoS2 doped cobalt iron sulfide (Co-Fe-MoSx) hollow nanoboxes with three different mass ratios of cobalt iron Prussian-blue-analog (Co-Fe PBA) nanocubes to (NH4)2MoS4 and their applications in dye-sensitized solar cells (DSSCs). As the increment of MoS42− in system, the surface of Co-Fe-MoSx became rough with bushy embedded nanosheets. Benefiting from the three-dimensional nanostructure with more exposed edge sites and appropriate doped ratio, the Co-Fe-MoSx-2 hollow nanoboxes performed rough shells, well-defined interior voids, large specific surface areas and outstanding catalytic actives. By contrast, the sulfide of Co-Fe PBA (Co-Fe-S) and bare MoS2 showed bad morphology and poor catalytic performance. It is notable that the DSSC with Co-Fe-MoSx-2 showed a much higher power conversion efficiency (PCE) of 9.63% than that of Pt based cell (8.23%) under AM 1.5G irradiation.