Journal
CHEMICAL ENGINEERING JOURNAL
Volume 448, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.137602
Keywords
Hematite photoanodes; Gradient Ce doping; Surface polarization; Charge transfer; Solar water splitting
Categories
Funding
- National Natural Science Foundations of China [21965024, 22103042]
- Inner Mongolia funding [21300-5223601, 2020JQ01, 2021BS02009]
- Young Science and Technology Talents Cultivation project of Inner Mongolia University [21221505]
- Inner Mongolia University [10000-21311201/137]
- opening project of Key Laboratory of Materials Processing and Mold from Zhengzhou University
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This study successfully improved the efficiency of photoelectrochemical water splitting by introducing gradient Ce-doped hematite nanorods and conducting a photoactivation process. The gradient Ce doping increased the conductivity of the material and constructed a built-in electric field, enhancing charge separation and transfer. Additionally, surface polarization reduced overpotential and increased photocurrent density.
Photoelectrochemical (PEC) water splitting is one of the most strategies for solar energy storage and utilization. Hematite as one of the promising candidates for PEC research, has a short hole diffusion length and short carrier lifetime, resulting in PEC conversion efficiency far below the theoretical value. In this work, a facile but efficient strategy was introduced for the growth of gradient Ce doped hematite nanorods, following with the sequent photoactivation process. The gradient Ce doping not only increased the conductivity of bulk material, but also importantly, constructed a built-in electric field by the addition of Ce element, which remarkably enhanced the charge separation and transfer from the bulk to the surface. Moreover, the surface polarization under illumi-nation was applied for the reduction of overpotential and the enhancement of photocurrent density, taking a role of cocatalyst decoration. It reduced the oxygen vacancies concentration at the surface, which further reduced the surface recombination owing to the passivation from photoactivation. According to these, the resulting photo-anode exhibited a photocurrent of 1.92 and 2.50 mA cm(-2) at 1.23 and 1.50 VRHE, respectively, with onset po-tential of 0.64 VRHE under AM 1.5G illumination. This work opens a useful strategy of modifying the electronic structure and constructing the interface structure for improving PEC performance on hematite-based photo-electrodes for solar energy storage and utilization.
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