摘要
Photoelectrochemical（PEC） water splitting is a promising approach to producing H2 and O2. Hematite（α-Fe2O3） is considered one of the most promising photoelectrodes for PEC water splitting, due to its good photochemical stability, non-toxicity, abundance in earth, and suitable bandgap（Eg2.1 eV）. However, the PEC water splitting efficiency of hematite is severely hampered by its short hole diffusion length（2–4 nm）, poor conductivity, and ultrafast recombination of photogenerated carriers（about 10 ps）. Here,we show a novel and effective method for significantly improving the PEC water splitting performance of hematite by Au ion implantation and the following high-temperature annealing process. Based on a series of characterizations and analyses, we have found Fe2＋ species and tightly attached Au particles were produced at Au-implanted hematite. As a result,the charge separation and charge injection efficiency of Auimplanted Fe2O3 are markedly increased. The photocurrent density of optimized Au-implanted Fe2O3 could reach1.16 m A cm-2 at 1.5 V vs. RHE which was nearly 300 times higher than that of the pristine Fe2O3（4 μA cm-2）. Furthermore, the Au-implanted Fe2O3 photoelectrode exhibited great stability for the 8-hour PEC water splitting test without photocurrent decay.
光电化学催化分解水是一种极具发展前景的生产H_2和O_2的方法.α-Fe_2O_3由于其具有优良的光电化学稳定性、无毒害、地球储量大以及合适的能带宽度E_g^2.1 eV等优点,被认为是最有潜力的光电催化分解水的材料之一.然而由于其空穴传输距离短(约2~4 nm)、导电性差、光生载流子复合速度极快等原因,α-Fe_2O_3的光电催化分解水的效率受到了极大限制.在此,我们报道了一种新颖并且高效的离子注入Au元素并且退火的方法显著提高了α-Fe_2O_3光电化学分解水的效率.根据一系列的表征和分析,发现Fe^(2+)和紧密接触的金颗粒在金注入的α-Fe_2O_3样品中产生.因此,金注入的α-Fe_2O_3样品的载流子分离效率和注入效率得到了显著提高.该样品光电流密度在1.5 Vvs.RHE偏压下可以达到1.16 m A cm^(-2),相对原始样品光电流密度提升接近300倍(4μA cm^(-2)).此外,金注入的α-Fe_2O_3样品在8 h的光电催化分解水的测试中没有出现光电流衰减的现象,表现了良好的稳定性.
基金
supported by the National Natural Science Foundation of China (51371131, 11375134, 51571153 and 11722543)
the Fundamental Research Funds for the Central Universities (2042017kf0168)
