Issue 3, 2020

In situ preparation of Ru–N-doped template-free mesoporous carbons as a transparent counter electrode for bifacial dye-sensitized solar cells

Abstract

The development of a highly active, long-lasting, and cost-effective electrocatalyst as an alternative to platinum (Pt) is a vital issue for the commercialization of dye-sensitized solar cells. In this study, Ru–N-doped template-free mesoporous carbon (Ru–N-TMC) was prepared by the direct stabilization and carbonization of the poly(butyl acrylate)-b-polyacrylonitrile (PBA-b-PAN) block copolymer and ruthenium(III) acetylacetonate [Ru(acac)3]. During the stabilization process, microphase separation occurred in the PBA-b-PAN block copolymer due to the incompatibility between the two blocks, and the PAN block transformed to N-doped semi-graphitic carbon. In the carbonization step, the PBA block was eliminated as a porous template, creating hierarchal mesopores/micropores. Meanwhile, Ru(acac)3 was decomposed to Ru, which was homogeneously distributed over the carbon substrate and anchored through N and O heteroatoms. The resulting Ru–N-TMC showed ultra-low charge transfer resistance (Rct = 0.034 Ω cm2) in the Co(bipyridine)33+/2+ reduction reaction, indicating very high electrocatalytic ability. Even though it is a transparent counter electrode (CE, average visible transmittance of 42.25%), covering a small fraction of the fluorine doped tin oxide (FTO)/glass substrate with Ru–N-TMC, it led to lower charge transfer resistance (Rct = 0.55 Ω cm2) compared to Pt (Rct = 1.00 Ω cm2). The Ru–N-TMC counter electrode exhibited a superior power conversion efficiency (PCE) of 11.42% compared to Pt (11.16%) when employed in SGT-021/Co(bpy)33+/2+ based dye-sensitized solar cells (DSSCs). Furthermore, a remarkable PCE of 10.13% and 8.64% from front and rear illumination, respectively, was obtained when the Ru–N-TMC counter electrode was employed in a bifacial DSSC. The outstanding catalytic activity and PCE of Ru–N-TMC were due to the high surface area of Ru–N-TMC, which contained numerous active species (Ru and N), easily facilitated to redox ions through the hierarchical microporous/mesoporous structure.

Graphical abstract: In situ preparation of Ru–N-doped template-free mesoporous carbons as a transparent counter electrode for bifacial dye-sensitized solar cells

Supplementary files

Article information

Article type
Paper
Submitted
22 Oct 2019
Accepted
13 Dec 2019
First published
13 Dec 2019

Nanoscale, 2020,12, 1602-1616

In situ preparation of Ru–N-doped template-free mesoporous carbons as a transparent counter electrode for bifacial dye-sensitized solar cells

M. Aftabuzzaman, C. K. Kim, H. Zhou and H. K. Kim, Nanoscale, 2020, 12, 1602 DOI: 10.1039/C9NR09019C

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