A hierarchical strategy for fabricating synergistic 3D network bio-based porous carbon and 0D niobium-based bimetallic oxides as counter electrodes for I- and Cu-mediated dye-sensitized solar cells with N719 and Y123 dyes

Designing cost-effective counter electrode (CE) catalysts with advanced nanostructures and exploring their application in different dye-electrolyte systems is crucial for the development of dye-sensitized solar cells (DSSCs). In this work, two types of 3D network bio-based porous carbon (3D-BPC) loaded 0D niobium-based bimetallic oxide nanohybrids (CoNb 2 O 6 /3D-BPC and NiNb 2 O 6 /3D-BPC) were synthesized using a hierarchical strategy. Benefiting from the optimization of the electron transport pathways and enrichment of catalytically active sites via the hierarchical 0D/3D structure, formed by 3D-BPC and MNb 2 O 6 (M = Co, Ni), the catalytic reduction ability of MNb 2 O 6 /3D-BPC was significantly enhanced. To explore the photovoltaic performance of the MNb 2 O 6 /3D-BPC based DSSC, the I 3 − /I − electrolyte and N719 dye system and the Cu 2+ /Cu +  electrolyte and Y123 dye system were simultaneously employed. The solar cells assembled with the CoNb 2 O 6 /3D-BPC and NiNb 2 O 6 /3D-BPC CE exhibited device efficiencies of 7.03% and 7.14% in the N719-I 3 − /I − system, respectively, and 1.84% and 2.42% in the Y123-Cu 2+ /Cu + system, respectively, which were almost equal to those of Pt under the same system. Additionally, MNb 2 O 6 /3D-BPC catalysts exhibited promising stability in I 3 − /I − electrolyte. This work provides guidance for the construction of low-cost and high-efficiency nanohybrid catalysts for new energy conversion devices.