A nanocomposite photoelectrode made of 2.2 eV band gap copper tungstate (CuWO4 and multi-wall carbon nanotubes for solar-assisted water splitting

作者：Gaillard Nicolas^*; Chang Yuancheng; DeAngelis Alexander; Higgins Scott; Braun Artur

来源：International Journal of Hydrogen Energy, 2013, 38(8): 3166-3176.

DOI：10.1016/j.ijhydene.2012.12.104

• Photoelectrochemical cell (PEC)
• Spray-pyrolysis
• Multi-wall carbon nanotubes
• CuWO4
• Bulk resistance
• Electronic transport

We report on the photoelectrochemical performances of a nanocomposite photoactive material made of copper tungstate (CuWO4) and multi-wall carbon nanotubes (MWCNT). The purpose of this work was to create a light absorber/charge collector composite material with tunable electronic transport properties to minimize the bulk resistance of CuWO4 material class. Nanocomposite thin films (typically 2.0 +/- 0.1 gm) were fabricated by means of spray pyrolysis using solutions containing copper acetate, ammonium metatungstate and MWCNT. Spray-deposited polycrystalline CuWO4 films were found to be porous, though crack-free, and made of CuWO4 nanoparticles with dimensions in the 10-50 nm range. Tauc plots derived from UV-visible and photocurrent spectroscopy techniques led to a consistent band gap value of 2.20 (+/- 0.05) eV. Electrochemical impedance spectroscopy performed in pH10 buffer solution under Air Mass 1.5 global (AM1.50(G)) at 0.8 V vs. saturated calomel electrode (1.63V vs. reversible hydrogen electrode) pointed out a bulk resistance reduction by 30% on nanocomposites photoanodes when compared to un-modified CuWO4 control samples. It is worth mentioning that the reduction in bulk resistance was achieved with an extremely low MWCNT:CuWO4 weight ratio (1:10,000), in which MWCNT absorbed less than 2% of incoming light. Subsequent linear scan voltammetry (LSV) performed in the same conditions revealed a photocurrent density increase of 26% at 0.8 V-SCE (1.63 V-RHE) compared to control samples. Additional LSV and incident photon-to-current efficiency measurements demonstrated that MWCNT served as effective electron collectors distributed throughout the entire CuWO4 bulk.

• 出版日期2013-3-19