Enhancing Water Splitting Activity and Chemical Stability of Zinc Oxide Nanowire Photoanodes with Ultrathin Titania Shells
Enhancing Water Splitting Activity and Chemical Stability of Zinc Oxide Nanowire Photoanodes with Ultrathin Titania Shells
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DOI：
10.1021/jp404032p
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发表时间：
2013-07-04
影响因子：
3.7
通讯作者：
Zhang, Lihua
中科院分区：
文献类型：
--
作者：
Liu, Mingzhao;Nam, Chang-Yong;Zhang, Lihua
氧化锌纳米线光阳极通过原子层沉积的二氧化钛的壳层的共形生长而化学稳定，允许它们在强碱性溶液中稳定地操作用于水裂解。由于二氧化钛涂层对氧化锌表面电荷陷阱的钝化，核/壳纳米线阵列在模拟AM 1.5G太阳光下在热力学析氧电位下提供0.5mA/cm（2）的光电流密度，表明与生长的氧化锌线相比高25%的光电化学水裂解活性。通过在表面钝化之前对氧化锌线阵列进行热退火，我们进一步将光电流密度增加到0.7 mA/cm（2）-在类似的模拟阳光下研究的掺杂或未掺杂的氧化锌光阳极的最高报告值。在高于氧化锌带隙的能量下的光激发以大于80%的效率转换。表现最好的纳米线阵列的光致发光测量是一致的，从去除深陷阱状态的改进的水分解活性。
Zinc oxide nanowire photoanodes are chemically stabilized by conformal growth of an ultrathin shell of titania through atomic layer deposition, permitting their stable operation for water splitting in a strongly alkaline solution. Because of the passivation of zinc oxide surface charge traps by titania coating, core/shell nanowire arrays supply a photocurrent density of 0.5 mA/cm(2) under simulated AM1.5G sunlight at the thermodynamic oxygen evolving potential, demonstrating 25% higher photoelectrochemical water splitting activity compared to as-grown zinc oxide wires. By thermally annealing the zinc oxide wire arrays prior to surface passivation, we further increase the photocurrent density to 0.7 mA/cm(2)-the highest reported value for doped or undoped zinc oxide photoanodes studied under similar simulated sunlight. Photoexcitations at energies above the zinc oxide band gap are converted with efficiency greater than 80%. Photoluminescence measurements of the best-performing nanowire arrays are consistent with improved water splitting activity from removal of deep trap states.