An in situ fluorine and ex situ titanium two-step co-doping strategy for efficient solar water splitting by hematite photoanodes.
An in situ fluorine and ex situ titanium two-step co-doping strategy for efficient solar water splitting by hematite photoanodes.
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DOI：
10.1039/d2na00029f
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发表时间：
2022-03-15
影响因子：
4.7
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中科院分区：
文献类型：
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原位氟掺杂接着非原位钛掺杂的独特的两步共掺杂策略比全部原位或全部非原位的单步共掺杂策略更有效地增强了赤铁矿光阳极在光电化学水裂解中的性能。优化的氟、钛共掺杂的Fe 2 O3光阳极在没有任何助催化剂的情况下在100 mW cm-2太阳辐射下在1.23 VRHE下达到1.61 mA cm-2，这分别是钛或氟单掺杂的Fe 2 O3光阳极的1.2倍和3倍。这种促进作用归因于两种掺杂剂的协同作用，其中掺杂的氟阴离子取代Fe 2 O3中的氧以增加铁位的正电荷，而掺杂的钛阳离子取代铁以增加自由电子。此外，表面上过量的钛抑制了高温退火过程中原位掺杂氟的流失和赤铁矿的团聚，并钝化了表面陷阱态，以进一步促进两种掺杂剂的协同效应。一种新的两步共掺杂策略，即原位F−阴离子，然后是非原位Ti4+阳离子，比全部原位或全部非原位的单步共掺杂策略更有效地促进了赤铁矿光阳极的水分解。
A unique two-step co-doping strategy of in situ fluorine doping followed by ex situ titanium doping enhances the performance of the hematite photoanode in photoelectrochemical water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ. The optimized fluorine, titanium co-doped Fe2O3 photoanode without any cocatalyst achieves 1.61 mA cm−2 at 1.23 VRHE under 100 mW cm−2 solar irradiation, which is ∼2 and 3 times those of titanium or fluorine singly-doped Fe2O3 photoanodes, respectively. The promotional effect is attributed to the synergy of the two dopants, in which the doped fluorine anion substitutes oxygen of Fe2O3 to increase the positive charges of iron sites, while the doped titanium cation substitutes iron to increase free electrons. Moreover, excess titanium on the surface suppresses the drain of in situ doped fluorine and agglomeration of hematite during the high-temperature annealing process, and passivates the surface trap states to further promote the synergy effects of the two dopants. A novel two-step co-doping strategy of in situ F− anion, followed by ex situ Ti4+ cation promotes the hematite photoanode for water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ.
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