g-C3N4/conductive carbon black composite as Pt-free counter electrode in dye-sensitized solar cells

•g-C3N4/CCB composite shows a comparable electrocatalytic activity to Pt.•DSC with g-C3N4/CCB counter electrode achieves a conversion efficiency of 5.09%.•The synergistic effect of g-C3N4 and CCB results in the enhanced performance.

The composites of g-C3N4 and conductive carbon black (CCB) were prepared by a simple ball-milling process and explored as the counter electrode for dye-sensitized solar cells (DSCs). The enhanced electrocatalytic activity for I3− reduction can be demonstrated when CCB was incorporated into g-C3N4. The charge-transfer resistance of g-C3N4/CCB (1:1, mass ratio) composite electrode was 2.4 Ω cm2, which is much lower than those of the individual g-C3N4 and CCB electrodes, indicating predominant synergistic effect of g-C3N4 and CCB in electrocatalytic activity. Under illumination of 100 mW cm−2, the DSC with g-C3N4/CCB (1:1) composite counter electrode achieved a conversion efficiency of 5.09%, which is comparable to that of the cell with Pt counter electrode.

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