Copper tungstates directly derived from polyoxotungstate-MOF as counter electrodes for dye-sensitized solar cells

The strategically selection of different selection of reaction temperature directly affects the performance of the target catalyst. Herein, copper tungstate species catalysts were directly derived from polyoxotungstate-based metal-organic frameworks ([Cu2(BTC)4/3(H2O)2]6[H3PW12O40], PW12-MOF) as sacrificial template by in-situ pyrolysis at temperatures of 600, 700, 800, 900, 1000 degrees C under the protec-tion of N2, and further served as counter electrodes (CEs) to assemble dye-sensitized solar cells (DSSCs). The corresponding characterization of XRD, XPS, SEM and N2 adsorption/desorption revealed that PW12- MOF can be converted into copper tungstate, and the ligand groups can be carbonized into graphitic C to embedded in CuWO4, thus forming CuWO4@C composite at 800 degrees C. The significant effect of different pyrolysis temperatures on the electrocatalytic performance of the prepared CuWO4-based catalysts were identified with cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization. Furthermore, five different CuWO4-based catalysts were applied to regenerate I3-/I- shuttles in DSSCs, and then achieved power conversion efficiencies (PCE) of 5.79, 6.39, 7.01, 6.15 and 5.40% by photocurrent-voltage measurement, respectively, which was caused by the enhancement of electrical conductivity and the increase of catalytic active sites by the synergistic effect between CuWO4 and C, illustrating an excellent alternative to Pt CEs in the encapsulated DSSCs.(c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.