Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA. Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125, USA.
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Science. 2014 May 30;344(6187):1005-9. doi: 10.1126/science.1251428.
Although semiconductors such as silicon (Si), gallium arsenide (GaAs), and gallium phosphide (GaP) have band gaps that make them efficient photoanodes for solar fuel production, these materials are unstable in aqueous media. We show that TiO2 coatings (4 to 143 nanometers thick) grown by atomic layer deposition prevent corrosion, have electronic defects that promote hole conduction, and are sufficiently transparent to reach the light-limited performance of protected semiconductors. In conjunction with a thin layer or islands of Ni oxide electrocatalysts, Si photoanodes exhibited continuous oxidation of 1.0 molar aqueous KOH to O2 for more than 100 hours at photocurrent densities of >30 milliamperes per square centimeter and ~100% Faradaic efficiency. TiO2-coated GaAs and GaP photoelectrodes exhibited photovoltages of 0.81 and 0.59 V and light-limiting photocurrent densities of 14.3 and 3.4 milliamperes per square centimeter, respectively, for water oxidation.
尽管硅（Si）、砷化镓（GaAs）和磷化镓（GaP）等半导体具有使其成为太阳能燃料生产高效光阳极的带隙，但这些材料在水介质中不稳定。我们表明，通过原子层沉积生长的 TiO2 涂层（4 至 143 纳米厚）可防止腐蚀，具有促进空穴传导的电子缺陷，并且足够透明，可达到受保护半导体的光限制性能。与薄的 Ni 氧化物电催化剂层或岛结合，Si 光阳极在大于 30 毫安/平方厘米的光电流密度和~100%的法拉第效率下，将 1.0 摩尔的水性 KOH 连续氧化为 O2 超过 100 小时。TiO2 涂层的 GaAs 和 GaP 光电管分别表现出 0.81 和 0.59 V 的光电压和 14.3 和 3.4 毫安/平方厘米的光限制光电流密度，用于水氧化。
