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[交流] 一个关于光电化学产氢论文中的问题

请大家看看这段文字，摘自（J. Phys. Chem. 1996, 100, 13061-13078），在该论文（见附件）的第13067页的第三段。该段话说由于对电极金属电极费米能级低于H+/H2的标准电极电位，因此不可能还原氢离子，这段文字提出的一种解决方法是给工作电极施加一个阳极偏压，这样做就可以抬高金属电极的费米能级从而可以还原氢离子了。我对他提出的这种方法不理解，有哪位大侠可以给解释一下，谢谢！
Under illumination (Figure 9), the Fermi level in the semiconductor bulk rises toward Ufb. With the two electrodes shorted together, the maximum Fermi level possible in the cell is the flat-band potential. In Figure 9, Ufb is below the H+/H2 redox potential. Hence, even with illumination intensity sufficient to completely flatten the semiconductor bands, H2 cannot be evolved at the counter electrode because the Fermi level is below the H+/H2 potential. To raise the Fermi level in the metal counter electrode above the H+/H2 potential, an external anodic bias, Eb, must be applied, as shown in Figure 9. This bias also provides the overvoltage at the metal cathode, èe, required to sustain the current flow, and it increases the band bending in the semiconductor to maintain the required charge-separation rate.

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附件 1 : Physical_Chemistry_of_Semiconductor_Liquid_Interfaces.pdf

2013-11-08 18:54:06, 1.18 M