Decoration of ultra-long carbon nanotubes with Cu 2 O nanocrystals: a hybrid platform for enhanced photoelectrochemical CO 2 reduction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2016, Vol.4 (8), p.3139-3147
• Main Authors: Kecsenovity, E., Endrődi, B., Pápa, Zs, Hernádi, K., Rajeshwar, K., Janáky, C.
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C5TA10457B

Photoelectrochemical reduction of CO 2 to form useful chemicals is an increasingly studied avenue for harnessing and storing solar energy. In the quest for efficient and stable photocathode materials, nanostructured hybrid assemblies are eminently attractive candidates, because they exhibit multiple favorable properties that cannot be expected from a single material. One possible direction is to combine p-type inorganic semiconductors with highly conductive large surface area electrodes such as carbon nanotube networks. In this work, the controlled synthesis and photoelectrochemical behavior of CNT/Cu 2 O films was reported for the first time for CO 2 reduction applications. A carefully designed, multiple-step electrodeposition protocol was developed that ensured homogeneous coating of CNTs with Cu 2 O nanocrystals. The hybrid materials were characterized by electron microscopy, X-ray diffraction, Raman spectroscopy, electrochemical impedance spectroscopy, and photoelectrochemical methods. The hybrid films had five-fold higher electrical conductivity compared to their pure Cu 2 O counterparts. This enhanced charge transport property resulted in a drastic increase in the photocurrents measured for CO 2 reduction. In addition to this superior performance, long term photoelectrolysis measurements proved that the CNT/Cu 2 O hybrids were more stable than the oxide alone. These observations, together with the established structure/property relationships, may contribute to the rational design of nanocarbon/inorganic semiconductor hybrid photocathodes for deployment in photoelectrochemical cells.