Robust sub-monolayers of Co3O4 nano-islands: a highly transparent morphology for efficient water oxidation catalysis

Guanyu Liu, Siva Krishna Karuturi, Alexandr Simonov, Monika Fekete, Hongjun Chen, Noushin Nasiri, Nhien Hon Le, Parvathala Reddy Narangari, Mykhaylo Lysevych, Thomas R Gengenbach, Adrian J Lowe, Hark Hoe Tan, Chennupati Jagadish, Leone Spiccia, Antonio Tricoli

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42 Citations (Scopus)


The scalable synthesis of highly transparent and robust sub-monolayers of Co3O4 nano-islands, which efficiently catalyze water oxidation, is reported. Rapid aerosol deposition of Co3O4 nanoparticles and thermally induced self-organization lead to an ultra-fine nano-island morphology with more than 94% light transmission at a wavelength of 500 nm. These transparent sub-monolayers demonstrate a remarkable mass-weighted water oxidation activity of 2070–2350 A gCo3O4 −1 and per-metal turnover frequency of 0.38–0.62 s−1 at an overpotential of 400 mV in 1 m NaOH aqueous solution. This mixed valent cobalt oxide structure exhibits excellent long-term electrochemical and mechanical stability preserving the initial catalytic activity over more than 12 h of constant current electrolysis and 1000 consecutive voltammetric cycles. The potential of the Co3O4 nano-islands for photoelectrochemical water splitting has been demonstrated by incorporation of co-catalysts in GaN nanowire photoanodes. The Co3O4-GaN photoanodes reveal significantly reduced onset overpotentials, improved photoresponse and photostability compared to the bare GaN ones. These findings provide a highly performing catalyst structure and a scalable synthesis method for the engineering of efficient photoanodes for integrated solar water-splitting cells.

Original languageEnglish
Article number1600697
Number of pages9
JournalAdvanced Energy Materials
Issue number15
Publication statusPublished - 10 Aug 2016


  • cobalt oxide
  • gallium nitride
  • highly transparent
  • photoelectrochemical
  • water oxidation

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