A multitude of modifications strategy of ZnFe2O4 nanorod photoanodes for enhanced photoelectrochemical water splitting activity
| Autor: | Sun Hee Choi, Chang-Mo Nam, Jeong Hun Kim, Byeong Jun Lee, Ju Hun Kim, Yoon Bin Park, Jae Sung Lee, Hyun-Gyu Kim, Youn Jeong Jang |
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| Rok vydání: | 2018 |
| Předmět: |
Photocurrent
Materials science Passivation Renewable Energy Sustainability and the Environment Band gap 02 engineering and technology General Chemistry Electrolyte 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Crystallinity Chemical engineering Water splitting General Materials Science Nanorod Surface charge 0210 nano-technology |
| Zdroj: | Journal of Materials Chemistry A. 6:12693-12700 |
| ISSN: | 2050-7496 2050-7488 |
| DOI: | 10.1039/c8ta02161a |
| Popis: | Numerous modifications strategies are applied to spinel ZnFe2O4 nanorods with a band gap energy of ∼2.0 eV to enhance their activity as a photoanode for photoelectrochemical (PEC) water splitting. First, hybrid microwave annealing (HMA) imparts high crystallinity to ZnFe2O4 nanorods, while preserving the formed nanostructure and maintaining high electric conductivity of F:SnO2 (FTO) substrate. This is in contrast to conventional thermal annealing (CTA) at 800 °C that causes aggregation of ZnFe2O4 and degradation of FTO. Second, insertion of a TiO2 underlayer blocks charge recombination at the FTO/electrolyte interface and serves as a source of Ti doping. Third, hydrogen treatment yields oxygen vacancies that increase charge carrier density and cause surface passivation. Last, a NiFeOx co-catalyst promotes hole injection into the electrolyte to improve catalytic water oxidation activity. These synergistic modifications lead to enhanced photocurrent density from 0.025 mA cm−2 at 1.23 VRHE for pristine ZnFe2O4 nanorods prepared by CTA to 0.92 mA cm−2 for a fully modified HMA photoanode: a 37-fold increase in photocurrent density. There is also a cathodic shift of the onset potential down to 0.62 VRHE. The multiple modifications enhance bulk charge separation efficiencies from mere 2% to 30% and surface charge separation efficiency from 40% to 80%. |
| Databáze: | OpenAIRE |
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