Hierarchical α-MoC1-x@N-doped carbon nanospheres as counter electrodes for dye-sensitized solar cells

Molybdenum-based carbides , as one of the representatives of transition metal compounds, are a promising alternative to the expensive and resource constrained Pt-based counter electrode (CE) in dye-sensitized solar cells (DSSCs). Herein, a series of hierarchical α-MoC 1- x @N-doped carbon (MDNC) composites are transformed from the step-by-step pyrolysis of uniformly Mo-based compounds and dopamine precursors at the temperatures of 650, 750, 850, and 950 °C under N 2 atmosphere, respectively. The MDNC precursors were synthesized by a simple one-step self-polymerization in a water-in-oil system. And then, the obtained MDNC nanocrystalline composites can accelerate electron conduction and improve the electrocatalytic property of the tri-iodide reduction reaction (IRR) owing to the C carrier obtained through the pyrolysis process and the N-doped of α-MoC 1- x by the carbonization of dopamine and the high temperature nitrogen atmosphere. In addition, the distinct hierarchical structure of MDNC with well-developed porosity and high specific surface area can expose numerous active catalytic sites. The DSSCs using the MDNC series as CEs for I 3 − /I − exhibit power conversion efficiencies (PCE) of 5.99 %, 6.35 %, 6.57 % and 5.57 %, respectively, which were versus 5.83 % of Pt CE.