Zeng Min, Peng Xiange, Liao Jianjun, Wang Guizhen, Li Yanfang, Li Jianbao, Qin Yong, Wilson Joshua, Song Aimin, Lin Shiwei
Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228, China.
Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou 570228, China.
Phys Chem Chem Phys. 2016 Jun 29;18(26):17404-13. doi: 10.1039/c6cp01299j.
While TiO2 nanotube arrays cosensitized with CdS and PbS quantum dots can achieve water splitting under visible light excitation, the use of quantum dots is limited by the relatively slow interfacial hole transfer rate and low internal quantum efficiencies in the visible region. Al2O3 overcoating by atomic layer deposition (ALD) can drastically enhance the photoelectrochemical performance of the quantum dot-sensitized TiO2 nanotube arrays. 30 ALD cycles of the Al2O3 overlayer can achieve a good balance between surface coverage and charge transfer resistance. The resulting maximum photocurrent density of 5.19 mA cm(-2) under simulated solar illumination shows a 52 times improvement over the pure TiO2 nanotube arrays, and more significantly, a 60% enhancement over bare quantum dot-sensitized TiO2 nanotube arrays. The incident photon-to-current conversion efficiency can reach the record value of 83% at 350 nm and remain above 30% up to 450 nm. A systematic examination of the role of the ALD Al2O3 overlayer indicates that surface recombination passivation, catalytic improvement in interfacial charge transfer kinetics, and chemical stabilization might synergistically enhance the photoelectrochemical performance in the visible region. These results provide a physical insight into the facile surface treatment, which could be applied to develop and optimize high-performance photoelectrodes for artificial photosynthesis.
虽然硫化镉（CdS）和硫化铅（PbS）量子点共敏化的二氧化钛（TiO₂）纳米管阵列在可见光激发下可实现水分解，但量子点的使用受到可见光区域相对较慢的界面空穴转移速率和较低的内量子效率的限制。通过原子层沉积（ALD）进行氧化铝（Al₂O₃）包覆可大幅提高量子点敏化TiO₂纳米管阵列的光电化学性能。Al₂O₃覆盖层进行30次ALD循环可在表面覆盖率和电荷转移电阻之间实现良好平衡。在模拟太阳光照下，所得的最大光电流密度为5.19 mA cm⁻²，比纯TiO₂纳米管阵列提高了52倍，更显著的是，比裸量子点敏化TiO₂纳米管阵列提高了60%。在350 nm处，入射光子到电流的转换效率可达到创纪录的83%，在450 nm以下时仍保持在30%以上。对ALD Al₂O₃覆盖层作用的系统研究表明，表面复合钝化、界面电荷转移动力学的催化改善以及化学稳定性可能协同提高可见光区域的光电化学性能。这些结果为简便的表面处理提供了物理见解，可应用于开发和优化用于人工光合作用的高性能光电极。
