Hierarchical & alpha;-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 & alpha;-MoC1-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 degrees C under N2 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 & alpha;-MoC1-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 I3 � /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.

Automated summary

Researchers have successfully synthesized a series of hierarchical MoC1-x@N-doped carbon composites through a simple one-step self-polymerization method. These composites exhibit excellent electron conduction and electrocatalytic performance, and have numerous active catalytic sites. As counter electrodes in dye-sensitized solar cells, these composites achieve comparable power conversion efficiencies to Pt counter electrodes.