Electrosynthesis and photoelectrochemical properties of polyaniline/SiC nanohybrid electrodes

- Polyaniline/SiC nanocomposite photoelectrodes were synthesized by electrochemical polymerization.
- Higher photocurrents were detected for the nanocomposites compared to the individual components.
- H2, CO, methanol, and ethanol were detected as CO2 reduction products.

The growing amount of carbon dioxide (CO2) emission in parallel with the increasing greenhouse effect put the utilization of carbon dioxide in the focus of scientific interest in the past decade. Photoelectrochemical (PEC) conversion of CO2 to useful products is one of the promising possibilities towards reaching this goal. In this paper, we report on the PEC behavior of polyaniline (PANI)/SiC photoelectrodes with various PANI/SiC ratios, obtained by electrochemical polymerization. Electrochemical polymerization allowed for the precise control over the composition and morphology; and ensured that PANI was only deposited on the surface of the SiC nanoparticles. The nanocomposite samples were characterized by scanning and transmission electron microscopy and Raman spectroscopy. Linear sweep photovoltammetry measurements showed improved PEC properties of the nanocomposites compared to their pristine counterparts (i.e., SiC and PANI). The enhancement was rooted in the (i) higher electrochemically available surface area, (ii) decreased bandgap (2.9 eV vs. 3.1 eV), and the (iii) mediating effect of PANI in both H2 evolution and CO2 reduction. Long-term CO2 photoelectrolysis measurements coupled with analytical techniques (1H NMR and GC-BID) confirmed the formation of hydrogen, carbon monoxide, methanol, and ethanol proving the capability of the nanocomposite material to reduce CO2 to useful products. We think that lessons learned from this study may contribute to the rational design of nanocomposite photoelectrodes with enhanced performance for solar fuel generation.

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