Energy Materials Laboratory, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Chemistry. 2012 Sep 10;18(37):11798-803. doi: 10.1002/chem.201200739. Epub 2012 Aug 2.
We show that a robust molybdenum hydride system can sustain photoelectrocatalysis of a hydrogen evolution reaction at boron-doped, hydrogen-terminated, p-type silicon. The photovoltage for the system is about 600-650 mV and the current densities, which can be sustained at the photocathode in non-catalytic and catalytic regimes, are similar to those at a photoinert vitreous carbon electrode. The kinetics of electrocatalysed hydrogen evolution at the photocathode are also very similar to those measured at vitreous carbon-evidently visible light does not significantly perturb the catalytic mechanism. Importantly, we show that the doped (1-10 Ω cm) p-type Si can function perfectly well in the dark as an ohmic conductor and this has allowed direct comparison of the cyclic voltammetric behaviour of the response of the system under dark and illuminated conditions at the same electrode. The p-type Si we have employed optimally harvests light energy in the 600-700 nm region and with 37 mW cm(-2) illumination in this range; the light to electrochemical energy conversion is estimated to be 2.8 %. The current yield of hydrogen under broad tungsten halide lamp illumination at 90 mW cm(-2) is (91±5) % with a corresponding chemical yield of (98±5) %.
我们证明，在掺硼、氢终止的 p 型硅上，稳定的钼氢化物体系可以持续进行光电催化析氢反应。该体系的光电压约为 600-650 mV，在非催化和催化条件下可以在光电阴极维持的电流密度与在光电惰性玻璃碳电极上的电流密度相似。光电阴极上电催化析氢的动力学也与在玻璃碳上测量的非常相似——显然可见光不会显著干扰催化机制。重要的是，我们证明了掺杂（1-10 Ω cm）的 p 型 Si 可以在黑暗中作为欧姆导体完美地工作，这使得我们可以在同一电极上直接比较该体系在黑暗和光照条件下的循环伏安行为。我们所采用的 p 型 Si 可以在 600-700nm 范围内最佳地收集光能，在 37mW cm(-2) 的该范围内的光能量转换为电化学能量的效率估计为 2.8%。在 90mW cm(-2)的宽钨卤灯照射下，氢气的电流产率为（91±5）%，相应的化学产率为（98±5）%。
