Abstract:

Water spitting is one of the most import methods to harvest solar energy. Hematite is a promising photoanode material. However, the diffusion length (20 nm) of the photogenerated hole in the hematite is much shorter than the photon penetration depth (120 nm at 550 nm wavelength) which causes significant recombination losses and thus, low solar to hydrogen conversion efficiency. A hematite/Ag nanohole array ultrathin film absorber is presented. The hemate layer is only 20 nm thick and has strong visible light absorption which contributes to a 238% enhancement in the photocurrent density compared with a bare hematite layer water splitting cell. The strong absorption properties are due to ultrathin film interference resonances and localized surface plasmon resonances. These absorption resonances can also be applied for solar photovoltaic cells employing semiconductors with poor photogenerated carrier transport properties.

Key words: solar energy, photochemistry, electrochemistry, ultrathin film, hematite, water splitting

摘要：

太阳能光解水制氢是太阳能利用的重要途径之一。a-氧化铁是极具潜力的阳极材料, 但是a-氧化铁光生空穴的扩散长度(20 nm)远小于其光子穿透距离(波长550 nm时为120 nm), 导致电子空穴对在参与光催化反应之前发生严重的复合, 从而极大地降低太阳能利用效率。提出一种a-氧化铁/银纳米孔阵列的超薄膜双层结构, a-氧化铁的厚度仅为20 nm, 且具有很强的可见光吸收特性, 因此光生电流比相同厚度的a-氧化铁光解水电池高238%。超薄膜光学吸收的机理包括亚波长干涉共振效应和局部表面等离子激元效应, 这两种强化光学吸收的机理也可以应用于光生电荷输运能力差的半导体太阳能光伏器件。

关键词: 太阳能, 光化学, 电化学, 超薄膜, a-氧化铁, 光解水