Ta3N5 Nanowire Bundles as Visible-Light-Responsive Photoanodes
Ta3N5 Nanowire Bundles as Visible-Light-Responsive Photoanodes
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DOI：
10.1002/asia.201300717
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发表时间：
2013-10-01
影响因子：
4.1
通讯作者：
Yang, Peidong
中科院分区：
文献类型：
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作者：
Wu, Cheng Hao;Hahn, Christopher;Yang, Peidong
太阳能是最有希望取代化石燃料的可再生能源之一。利用阳光来分解水，可以将太阳能储存在氢的化学键中。[1,2]自Fujishima和Honda首次报道了利用TiO2电极进行水分解以来，[3]金属氧化物作为水氧化的光阳极得到了广泛的研究然而，氧化物的价带具有很强的氧2p特征。因此，价带最大值（VBM）通常大大低于水的氧化电位，这导致析氧反应效率的显著损失。为了减少这种能量损失，研究人员提出了一种策略，用其他阴离子（如氮）部分或完全取代氧，以提高VBM。利用这种策略，几种氮氧化物/氮化物半导体，如InxGa (1Àx) N,[5,6] TaON,[7-9] Ta3N5,[10,11] CaTaO2N和SrNbO2N，[12,13]最近被确定为有前途的光阳极材料。在这些半导体中，Ta3N5因其2.1 eV的带隙而具有吸引力，这与Fe2O3 （2.2 eV）相似。这个带隙可以实现太阳能制氢（STH）的最高效率约为15%此外，Ta3N5的VBM比Fe2O3的VBM高约0.8 eV,[1,15]这可以减少光阳极的效率损失。虽然Ta3N5具有良好的能带结构，但其在水溶液中的化学和功能不稳定。这种不稳定性的一个可能原因是N3 À物质在光产生的空穴积累过程中的自氧化
Solar energy is one of the most promising renewable energy sources to replace fossil fuels. Using sunlight to split water enables the storage of solar energy in the chemical bonds of hydrogen.[1, 2] Since Fujishima and Honda first reported water splitting using a TiO2 electrode,[3] metal oxides have been extensively studied as photoanodes for water oxidation.[4] However, valence bands of oxides have strong oxygen 2p character. As a result, the valence band maximum (VBM) is usually substantially lower than the water oxidation potential, which leads to a significant loss in the efficiency of the oxygen evolution reaction. To reduce this energy loss, researchers have proposed a strategy of partially or completely replacing oxygen with other anions, such as nitrogen, to raise the VBM. Using this strategy, several oxynitride/nitride semiconductors, such as InxGa (1Àx) N,[5, 6] TaON,[7–9] Ta3N5,[10, 11] CaTaO2N, and SrNbO2N,[12, 13] have recently been identified as promising photoanode materials. Among these semiconductors, Ta3N5 is attractive because of its band gap of 2.1 eV, which is similar to Fe2O3 (2.2 eV). This band gap can achieve a maximum solar-to-hydrogen (STH) efficiency of about 15%.[14] Also, the VBM of Ta3N5 is about 0.8 eV higher than the VBM of Fe2O3,[1, 15] which could reduce efficiency losses at the photoanode. Although Ta3N5 has an advantageous band structure, it suffers from its chemical and functional instability in aqueous solution. One possible reason for this instability is the self-oxidation of N3 À species from the accumulation of photo-generated holes.[9]