The hole-storage layer (HSL) strategy has been demonstrated as an efficient interfacial modification method to overcome the instability of tantalum nitride (Ta₃N₅) photoanodes and further boost high performance in photoelectrochemical (PEC) water oxidation reaction. Herein, we report that the CoO_x/Ni(OH)_x bilayer as a typical HSL could effectively extract and store photogenerated holes from Ta₃N₅, resulting in a decent photocurrent enhancement and stable water oxidation for at least 30 h. Most strikingly, the reversible formation of Co(IV) species inside the ultrathin CoO_x layer during PEC water oxidation is found to regulate the hole-storage process, leading to facilitated photogenerated hole extraction capacity and suppressed charge recombination. Furthermore, upon the insertion of the CoO_x/Ni(OH)_x bilayer for the Ta₃N₅/CoPi photoanode, the photocurrent could be evidently increased, emphasizing the general applicability of the HSL strategy in promoting water oxidation reaction.

中文翻译：

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超薄氧化钴中间层促进复合氮化钽光阳极上持续水氧化的空穴存储

空穴存储层 (HSL) 策略已被证明是一种有效的界面改性方法，可以克服氮化钽 (Ta ₃ N ₅ ) 光阳极的不稳定性，并进一步提高光电化学 (PEC) 水氧化反应的高性能。在此，我们报告作为典型的 HSL的 CoO _x /Ni(OH) _x双层可以有效地从 Ta ₃ N _{5 中}提取和存储光生空穴，从而导致良好的光电流增强和稳定的水氧化至少 30 小时。最引人注目的是，超薄 CoO _x内 Co(IV) 物种的可逆形成发现 PEC 水氧化过程中的层可以调节空穴存储过程，从而促进光生空穴提取能力并抑制电荷复合。此外，在Ta ₃ N ₅ /CoPi 光阳极插入CoO _x /Ni(OH) _x双层后，光电流可以明显增加，强调HSL策略在促进水氧化反应中的普遍适用性。