α-Fe_2O_3光电催化分解水制备氢气研究进展

Hematite photoanodes for solar water splitting

光电化学池可以将太阳能以氢气的形式储存起来,其中稳定、廉价的催化剂是关键。α-Fe_2O_3具有合适的禁带宽度,较高的理论光-电转化效率,光稳定性好,在地壳中的储量丰富,被认为是最具有发展前景的光电催化材料之一;但是它的导电性差、光生电荷寿命短、氧化反应过电位高,严重阻碍了其发展。本文首先介绍了光电催化理论,然后重点综述了近些年α-Fe_2O_3纳米结构的制备技术,以及针对其不足所采用的改性方法,包括通过元素掺杂来增强α-Fe_2O_3的导电性,表面处理来降低氧化反应过电势或陷阱浓度,与其他材料复合来增加光生电压或催化剂表面积,最后对α-Fe_2O_3作为光阳极催化剂分解水制氢未来的发展前景作出展望,指出多种手段的有效结合是提高其光电流密度的重要途径。

Photoelectrochemical cell is able to turn sunlight into stored energy conveniently in the form of hydrogen,and the stable and low-cost photoanode catalyst is crucial in this device. Hematite is considered as one of the most promising photoanode catalysts due to its suitable band gap,high theoretical solar to hydrogen efficiency,chemical stability under illumination and rich storage in earth. However,the poor conductivity,short photo-generated charge carrier lifetime and high turn-on voltage have limited the performance improvement of hematite severely. This review introduces the basic mechanism of photoelectrocatalysis and energy band excitation,then it summarizes the synthesis of nanostructure α-Fe2O3 and the improvements on the photoelectrocatalysis property of hematite in recent years,including conductivity enhancement by element doping,oxygen evolution overpotential or trap concentration reduction by surface treatment,and photo-induced voltage or specific area increase by coupling with other materials. The future developing perspectives of hematite are also presented, and multi-modified technologies are considered as important ways to improve the photocurrent density.