Hydrogen-Treated TiO2 Nanowire Arrays for Photoelectrochemical Water Splitting
Hydrogen-Treated TiO2 Nanowire Arrays for Photoelectrochemical Water Splitting
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DOI：
10.1021/nl201766h
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发表时间：
2011-07-01
期刊：
影响因子：
10.8
通讯作者：
Li, Yat
中科院分区：
文献类型：
--
作者：
Wang, Gongming;Wang, Hanyu;Li, Yat
我们报告的第一个演示氢处理作为一个简单而有效的策略，从根本上提高光电化学（PEC）水分解的二氧化钛纳米线的性能。通过在氢气气氛中在200-550 ℃范围内的各种温度下退火原始TiO 2纳米线来制备氢处理的金红石TiO 2（H：TiO 2）纳米线。与原始的TiO 2纳米线相比，H：TiO 2样品在整个电势窗口中显示出显著增强的光电流。更重要的是，H：TiO 2样品具有非常低的光电流饱和电势，为-0.6 V vs. Ag/AgCl（0.4 V vs. RHE），表明非常有效的电荷分离和传输。优化的H：TiO 2纳米线样品在模拟太阳光（100 mW/cm（2）来自与AM 1.5G滤光片耦合的150 W氙灯）照射下在1 M NaOH溶液中在相对于Ag/AgCl的-0.6 V下产生类似于1.97 mA/cm（2）的光电流密度。该光电流密度对应于类似于1.63%的太阳能转化氢（STH）效率。在消除氙灯和太阳光的辐照度之间的差异后，通过将H：TiO 2纳米线样品的入射光子-电流转换效率（IPCE）光谱与标准AM 1.5G太阳光谱积分，计算出STH效率类似于1.1%，这是TiO 2光阳极的最佳值。IPCE分析证实光电流增强主要是由于TiO 2在紫外区的光活性提高。氢处理通过产生高密度的氧空位作为电子供体，使TiO 2纳米线的供体密度增加了3个数量级。在TiO 2纳米管中也观察到类似的光电流增强。制造高度光活性的H：TiO 2纳米线和纳米管的能力在各个领域开辟了新的机会，包括PEC水分解，染料敏化太阳能电池和太阳能电池。
We report the first demonstration of hydrogen treatment as a simple and effective strategy to fundamentally improve the performance of TiO2 nanowires for photoelectrochemical (PEC) water splitting. Hydrogen-treated rutile TiO2 (H:TiO2) nanowires were prepared by annealing the pristine TiO2 nanowires in hydrogen atmosphere at various temperatures in a range of 200-550 degrees C. In comparison to pristine TiO2 nanowires, H:TiO2 samples show substantially enhanced photocurrent in the entire potential window. More importantly, H:TiO2 samples have exceptionally low photocurrent saturation potentials of -0.6 V vs Ag/AgCl (0.4 V vs RHE), indicating very efficient charge separation and transportation. The optimized H:TiO2 nanowire sample yields a photocurrent density of similar to 1.97 mA/cm(2) at -0.6 V vs Ag/AgCl, in 1 M NaOH solution under the illumination of simulated solar light (100 mW/cm(2) from 150 W xenon lamp coupled with an AM 1.5G filter). This photocurrent density corresponds to a solar-to-hydrogen (STH) efficiency of similar to 1.63%. After eliminating the discrepancy between the irradiance of the xenon lamp and solar light, by integrating the incident-photon-to-current-conversion efficiency (IPCE) spectrum of the H:TiO2 nanowire sample with a standard AM 1.5G solar spectrum, the STH efficiency is calculated to be similar to 1.1%, which is the best value for a TiO2 photoanode. IPCE analyses confirm the photocurrent enhancement is mainly due to the improved photoactivity of TiO2 in the UV region. Hydrogen treatment increases the donor density of TiO2 nanowires by 3 orders of magnitudes, via creating a high density of oxygen vacancies that serve as electron donors. Similar enhancements in photocurrent were also observed in anatase H:TiO2 nanotubes. The capability of making highly photoactive H:TiO2 nanowires and nanotubes opens up new opportunities in various areas, including PEC water splitting, dye-sensitized solar cells, and photocatalysis.