CuxS nanoparticle@carbon nanorod composites prepared from metal–organic frameworks as efficient electrode catalysts for quantum dot sensitized solar cells

Abstract

The development of polysulfide reduction electrocatalysts with abundant active sites, high conductivity and good stability is vital to the fabrication of quantum dot sensitized solar cells (QDSCs) but is challenging. Herein, we report a convenient approach for the synthesis of Cu nanoparticle@carbon nanorod (Cu@CNR) composites by the direct pyrolysis of HKUST-1 precursors at temperatures above 1000 °C. The Cu@CNR composite whose carbon nanorods (CNRs) are encased with Cu nanoparticles (Cu NPs) exhibits superior catalytic activity towards polysulfide reduction in QDSCs, which might be ascribed to the abundant Cu_xS active sites derived from Cu NPs and the excellent charge transfer capability of graphitized CNRs. Benefiting from the encasement in CNRs, the dissociation of Cu_xS from counter electrodes (CEs) is effectively suppressed. When Cu@CNR composites deposited on F-doped tin oxide glass were used as CEs, a champion power conversion efficiency of 9.50% (J_sc = 26.50 mA cm⁻², V_oc = 0.628 V, and FF = 0.573) under one sun illumination was observed with Zn–Cu–In–Se QD sensitizers and polysulfide electrolyte.