Fabrication of CoM (M= Ni, Cu) alloys modified carbon electrocatalysts by pyrolysis of dual-metal-site metal-organic frameworks for efficient dye-sensitized solar cells

Abstract

The regulation of interface properties of multi-component transition metals in carbon-based catalyst has been an effective method to boost the electrochemical performance of counter electrode (CE) catalysts for dye-sensitized solar cells (DSSCs). Herein, CoNi-metal-organic framework (MOF) and CoCu-MOF are fabricated through introducing Ni and Cu into the stable Co-MOF, and used as sacrificial precursor in the followed pyrolysis-alloying process. And then, the target product CoM (M=Ni, Cu)/N-doped polyhedron-like carbon (NC) are successfully obtained, in which CoNi and CoCu alloy nanoparticles are uniformly dispersed on the N-doped carbon skeleton. Such MOFs-derived carbon matrix can not only supply as conductive network, but also isolate the alloy nanoparticles to avoid agglomeration, ensuring more effective active sites. Meanwhile, the built-in electric field generated by the Mott-Schottky interface effect of CoM/NCs could regulate the electronic structure inside the catalysts, resulting in faster electron transfer ability. Significantly, the reduced work function due to the introduction of Cu atoms leads to stronger self-driven electron transfer at the heterogeneous interface of CoCu/NC, which helps to improve reaction activity and electrocatalytic efficiency. Among the tested catalysts, CoCu/NC displays a more satisfying power conversion efficiency (PCE) of 7.60 % when assembled into CE of DSSC, also superior to 7.19 % of Pt.