Science. 1984 Mar 16;223(4641):1141-8. doi: 10.1126/science.223.4641.1141.
Sunlight is directly converted to chemical energy in hydrogen-evolving photoelectrochemical cells with semiconductor electrodes. Their Gibbs free energy efficiency of solar-to-hydrogen conversion, 13.3 percent, exceeds the solar-to-fuel conversion efficiency of green plants and approaches the solar-to-electrical conversion efficiency of the best p-n junction cells. In hydrogen-evolving photoelectrodes, electron-hole pairs photogenerated in the semiconductor are separated at electrical microcontacts between the semiconductor and group VIII metal catalyst islands. Conversion is efficient when the island diameters are small relative to the wave-lengths of sunlight exciting the semiconductor; when the island spacings are smaller than the diffusion length of electrons at the semiconductor surface; when the height of the potential energy barriers that separate the photogenerated electrons from holes at the semiconductor surface is raised by hydrogen alloying of the islands; when radiationless recombination of electron-hole pairs at the semiconductor-solution interface between the islands is suppressed by controlling the semiconductor surface chemistry; and when the semiconductor has an appropriate band gap (1.0 to 1.8 electron volts) for efficient solar conversion.
在具有半导体电极的析氢光电化学电池中，阳光被直接转化为化学能。它们的太阳能到氢能转化的吉布斯自由能效率为 13.3%，超过了绿色植物的太阳能到燃料的转化效率，接近最佳 p-n 结电池的太阳能到电能的转化效率。在析氢光电电极中，半导体中光生的电子-空穴对在半导体和 VIII 族金属催化剂岛之间的电微接触处分离。当岛的直径相对于激发半导体的太阳光的波长较小时；当岛的间距小于半导体表面电子的扩散长度时；当通过岛的氢合金化提高将光生电子与半导体表面孔分离的势能垒的高度时；当通过控制半导体表面化学抑制岛之间的半导体-溶液界面处的电子-空穴对无辐射复合时；并且当半导体具有用于有效太阳能转化的适当能带隙（1.0 至 1.8 电子伏特）时，转化是有效的。
