Carbon-Rich Nanofibers for Photocathodes

Carbon-Rich Nanofibers for Photocathodes


Photoelectrochemical water splitting using solar energy is a useful strategy to produce hydrogen for use as a fuel. The process requires a suitable semiconductor, most often inorganic materials. However, synthetic organic/polymer semiconductors are promising due to their abundance, tunable band structures, low production cost, and environmental sustainability.

Graphitic carbon nitride (g-C3N4) and conjugated carbon-rich polymers have been successfully used for direct solar water reduction, suggesting that carbon-rich materials can be suitable for this reaction. In particular, sp-hybridized (acetylenic) carbon-rich materials have potential as photocatalysts.

Xinliang Feng, Dresden University of Technology, Germany, and colleagues have developed a simple way of preparing acetylenic carbon-rich nanofibers. The team used a metallic copper wafer as a catalyst to induce a Glaser polycondensation of 1,3,5-triethynylbenzene in solution. The resulting poly(1,3,5-triethynylbenzene) (PTEB) nanofibers can be transferred to a variety of substrates, e.g., graphite foils, silicon dioxide, glass, or titanium plates.

The PTEB nanofibers on conductive substrates can be used as high-performance metal-free photocathodes for photoelectrochemical (PEC) devices that generate hydrogen from water. The diversity of terminal alkynes allows the rational design of a broad set of acetylenic carbon-rich materials with controlled optical and electronic properties. The researchers demonstrated this possibility by the introduction of thieno[3,2-b]thiophene segments into the PTEB nanofibers, which resulted in a 100 nm red-shift in light absorption and two-fold enhancement in photocurrent. The resulting performance is comparable with state-of-the-art metal-free photocathodes.


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