Visible-light-harvesting reduction of CO2 to chemical fuels with plasmonic Ag@AgBr/CNT nanocomposites

• Visible-light-active plasmonic Ag@AgBr/CNT performs reduction of CO2 to chemical fuels.
• Ag@AgBr is anchored on carbon nanotubes (CNT).
• The photocatalytic activity of Ag@AgBr/CNT is highly dependent on the length of CNT.
• The longer CNT in Ag@AgBr/CNT is more efficient in charge transfer and separation.

This paper presents the synthesis of visible-light-harvesting photocatalyst, Ag@AgBr/carbon nanotubes (CNT) nanocomposites, by the photoreduction of AgBr/CNT, which was independently prepared by the deposition-precipitation method. Nanocomposites with different carbon tubes lengths were characterized by X-ray diffraction, Brunauer–Emmett–Teller (BET) surface area, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy (EIS) techniques. Ag@AgBr nanopaparticles were found to be anchored onto the surface of CNT. EIS measurements suggested that the longer CNT in Ag@AgBr/CNT were more efficient in transporting charges than that of the shorter length CNT, which agreed with the observed trend of photocatalytic reduction of CO2 under visible light (λ > 420 nm) (Ag@AgBr/CNT-L > Ag@AgBr/CNT-M > Ag@AgBr/CNT-S). The study on the photocatalytic reduction of CO2 to methane, CO, methanol, and ethanol suggested that the reduction process favored under neutral and weak alkaline conditions. Ag@AgBr/CNT can maintain the high stability in five repeated uses.

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