| 1. |
- Haydous, Fatima, et al.
(författare)
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The effect of downstream laser fragmentation on the specific surface area and photoelectrochemical performance of barium tantalum oxynitride
- 2020
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 510
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Tidskriftsartikel (refereegranskat)abstract
- One approach to improve the photoelectrochemical solar water splitting performance of photoanodes based on oxynitride perovskite particles is through increasing the active surface area which allows the generation of more electron-hole pairs that contribute in the water reduction and oxidation reactions. In this study, we explore the pros and cons of downstream laser fragmentation as a method to increase the specific surface area of oxynitride particles and highlight the important issues that must be considered for effective solar water splitting. The synthesis of particles with a high surface area of up to 32.4 m(2) g(-1) is demonstrated. Furthermore, the fragmented oxynitrides revealed lower absorbance values, a blue shift in the absorption edge and a higher background absorbance. These observations, in addition to the lower crystalline quality of the fragmented oxynitrides, were attributed to the loss of N content during fragmentation and the formation of secondary phases. The photoanodes based on the fragmented particles showed lower photocurrents than those prepared from the unfragmented particles even though the surface area was increased. The decrease in photoactivity was ascribed to the presence of more grain boundaries in the fragmented oxynitride photoanodes which leads to more recombinations of the photogenerated carriers. Interestingly, after seven fragmentation passages, the photocurrent starts to increase again due to the formation of an amorphous layer which improves the transport of the photogenerated carriers.
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| 2. |
- Si, Wenping, et al.
(författare)
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Yttrium Tantalum Oxynitride Multiphases as Photoanodes for Water Oxidation
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:43, s. 26211-26217
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Tidskriftsartikel (refereegranskat)abstract
- The perovskite yttrium tantalum oxynitride is theoretically proposed as a promising semiconductor for solar water splitting because of the predicted band gap and energy positions of band edges. In experiments, however, we show here that depending on the processing parameters, yttrium tantalum oxynitrides exist in multi phases, including the desired perovskite YTaON2, defect fluorite YTa(O,N,square)(4), and N-doped YTaO4. These multiphases have band gaps ranging between 2.13 and 2.31 eV, all responsive to visible light. The N-doped YTaO4, perovskite main phase, and fluorite main phase derived from crystalline fergusonite oxide precursors exhibit interesting photoelectrochemical performances for water oxidation, while the defect fluorite derived from low-crystallized scheelite-type oxide precursors shows negligible activity. Preliminary measurements show that loading an IrOx, cocatalyst on N-doped YTaO4 significantly improves its photoelectrochemical performance, encouraging further studies to optimize this new material for solar fuel production.
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