Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, P. R. China.
Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China.
Small. 2016 Jul;12(25):3415-22. doi: 10.1002/smll.201600940. Epub 2016 May 19.
Hematite suffers from poor charge transport and separation properties for solar water splitting. This paper describes the design and fabrication of a 3D Fe2 O3 /Fe2 TiO5 heterojunction photoanode with improved charge separation, via a facile hydrothermal method followed by atomic layer deposition and air annealing. A highly crystallized Fe2 TiO5 phase forms with a distinct interface with the underlying Fe2 O3 core, where a 4 nm Fe2 TiO5 overlayer leads to the best photoelectrochemical performance. The favorable band offset between Fe2 O3 and Fe2 TiO5 establishes a type-II heterojunction at the Fe2 O3 /Fe2 TiO5 interface, which drives electron-hole separation effectively. The Fe2 O3 /Fe2 TiO5 composite electrode exhibits a dramatically improved photocurrent of 1.63 mA cm(-2) at 1.23 V versus reversible hydrogen electrode (RHE) under simulated 1 sun illumination (100 mW cm(-2) ), which is 3.5 times that of the bare Fe2 O3 electrode. Decorating the Fe2 O3 /Fe2 TiO5 heterojunction photoanode with earth-abundant FeNiOx cocatalyst further expedites surface reaction kinetics, leading to an onset potential of 0.8 V versus RHE with a photocurrent of 2.7 mA cm(-2) at 1.23 V and 4.6 mA cm(-2) at 1.6 V versus RHE. This sandwich photoanode shows an excellent stability for 5 h and achieves an overall Faradaic efficiency of 95% for O2 generation. This is the best performance ever reported for Fe2 O3 /Fe2 TiO5 photoanodes.
赤铁矿在太阳能水分解中存在电荷输运和分离性能差的问题。本文通过简便的水热法结合原子层沉积和空气退火，设计并制备了一种具有改进电荷分离的 3D Fe2 O3 /Fe2 TiO5 异质结光阳极。高度结晶的 Fe2 TiO5 相形成，与底层 Fe2 O3 核具有明显的界面，其中 4nm 的 Fe2 TiO5 覆盖层导致最佳的光电化学性能。Fe2 O3 和 Fe2 TiO5 之间有利的能带偏移在 Fe2 O3 /Fe2 TiO5 界面建立了 II 型异质结，有效地驱动电子-空穴分离。Fe2 O3 /Fe2 TiO5 复合电极在模拟 1 太阳光照（100mW cm(-2)）下，在 1.23V 相对于可逆氢电极（RHE）时表现出显著提高的光电流为 1.63mA cm(-2)，是裸 Fe2 O3 电极的 3.5 倍。在 Fe2 O3 /Fe2 TiO5 异质结光阳极上修饰丰富的 FeNiOx 共催化剂进一步加速了表面反应动力学，导致起始电位为 0.8V 相对于 RHE，在 1.23V 时光电流为 2.7mA cm(-2)，在 1.6V 相对于 RHE 时光电流为 4.6mA cm(-2)。这种三明治光阳极在 5 小时内表现出优异的稳定性，对于 O2 的生成，整体法拉第效率达到 95%。这是迄今为止报道的 Fe2 O3 /Fe2 TiO5 光阳极的最佳性能。
