Multiwalled carbon nanotubes confined Mo2C nanoparticles as counter electrodes for boosting triiodide reduction reaction in dye-sensitized solar cells

Multicomponent synergistic regulation has been an effective strategy to enhance the electrochemical properties of Mo2C-based counter electrode (CE) catalysts in dye-sensitized solar cells (DSSCs). Herein, Mo2C/CNTs composites (termed MCNTx, x = 2, 4, 6, 8, means the phosphomolybdic acid (PMo12) concentration) have been prepared using well-crystallized Mo2C nanograins anchored on the wall of multi-walled carbon nanotubes (CNTs) by a facial two-step approach. Through simple ultrasound assistance, PMo12 was spontaneously connected with CNTs, and the obtained precursors can be converted to the target product MCNTx by a simple thermal decomposition at N2 atmosphere. The modified CNTs guarantees the fast transfer of electrons and serves as framework for the support of Mo2C nanoparticles and mass diffusion, moreover the well-defined Mo2C nanoparticles ensures more accessible active sites to promote the triiodide reduction reaction (IRR). As a result of the synergistic effect between modified CNTs and Mo2C nanoparticles, MCNTx show excellent power conversion efficiency (PCE) when fabricated as CEs of DSSCs. The MCNT6-based DSSC exhibits a superior PCE up to 8.06 %, which is significantly higher than DSSC assembled with Pt CE (7.19 %).