To achieve a satisfactory photovoltaic performance in dye-sensitized solar cells (DSSCs), counter electrode (CE) catalysts with low cost, superior catalytic activity, and excellent conductivity should be developed. In this work, the unique rhombic dodecahedron morphology of CoSe2/N-doped carbon (CoSe2/NC) and CoS2/N-doped carbon (CoS2/NC) hybrids with small-size pores were successfully prepared through direct selenization and sulfurization of ZIF-67, respectively. DSSCs fabricated with CoSe2/NC (CoS2/NC) electrode achieved a photoelectric conversion efficiency of 9.06% (8.74%), superior to that of Pt-based DSSCs (8.03%). The satisfactory performance was mainly attributed to the synergic effect between CoSe2 (CoS2) and N-doped carbon. As for this hybrid, CoSe2 (CoS2) and the N-doped species (graphitic-N and pyridinic-N) of carbon framework as catalytic active centers supplied abundant active sites toward I3 – reduction, while NC as fast conductivity platforms facilitated the charge transfer. Meanwhile, the unique rhombic dodecahedron morphology with small-size pores of the hybrids could also accelerate the permeation of redox electrolyte, thus promoting the catalytic reaction between redox species (I–/I3 –) and inner active sites of CoSe2 (CoS2). Therefore, low-cost CoSe2/NC hybrid has great potential for replacing noble Pt for the reduction of I3 – in DSSCs.

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The work presented a practical and low-cost strategy for the preparation of Mo 2 C/graphitic carbon nanocomposite (Mo 2 C/GC). This synthesis has been conducted by a single-step heat treatment of resin-MoO 4 22 -[Fe(CN) 6 ] 42 precursor in N 2 atmosphere. The final material consists of well-dispersed Mo 2 C nanoparticles (typically 10-15 nm) on graphitic carbon. The formation process of Mo 2 C/GC has been investigated. The resultant material exhibits good supporting effect on Pt and Pd catalysts toward electrooxidation of methanol, ethanol and formyl acid. This method is very simple and enables a systematic design of new, predictable catalysts.

An active-site-enriched NiS/CNT composite with a unique interface was synthesized and exhibited a surprising photoelectric conversion efficiency of 10.82%.