We report the use of polyterthiophenes (PTTh) as a rare, combined light-harvester and catalyst for the hydrogen evolution reaction at high pH. Illuminated PTTh in combination with a MnO_x anode in a two-electrode setup exhibited stable water-splitting at a bias-potential of only 0.3 V at pH 12. This confirms that PTTh used as photocathode can produce photovoltages of at least 900 mV for the hydrogen evolution reaction at high pH and is therefore a suitable match for traditional water-oxidation catalysts such as MnO_x, CoO_x, and RuO_x. Films of PTTh were fabricated using a novel, metal-free method where iodine vapor is used as oxidant; thus, previously observed interference from metal residuals was omitted and thereby a gravimetric photo electrocatalytic conversion rate of 330 mmol(H₂) h⁻¹ g⁻¹ was achieved in phosphate buffer (pH 7) at 0 V vs. RHE. A striking property of this new strand of polythiophene was an “inverse” correlation (compared to that predicted using the Nernstian relationship) between the onset potential for the light-assisted water reduction reaction and pH: the potential (vs. RHE) required for a given current was more positive at higher pH, which is not observed for other (photo-) electrocatalytic materials, and indicates that the charge neutralization of PTTh (rather than the pH) guides the onset potential.

中文翻译：

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全电池设置中，在高pH下使用无金属的聚噻吩作为光阴极，在非常低的偏压下进行光辅助电化学水分解†

我们报道了使用聚对噻吩（PTTh）作为稀有的，结合的捕光剂和催化剂，用于在高pH下析氢反应。在两电极设置中，与MnO _x阳极结合使用的发光PTTh在pH值为12的偏压下仅在0.3 V的偏压下表现出稳定的水分解。这证实了用作光电阴极的PTTh可以产生至少900 mV的光电压。高pH下的氢释放反应，因此非常适合传统的水氧化催化剂，如MnO _x，CoO _x和RuO _x。PTTh薄膜是使用一种新颖的，不含金属的方法制造的，其中碘蒸气用作氧化剂；因此，省略了先前观察到的来自金属残余物的干扰，从而在磷酸盐缓冲液（pH 7）中，相对于RHE，在重量计的光电催化转化率达到了330 mmol（H ₂）h ^-1 g ^-1。这条新的聚噻吩链的显着特性是光辅助减水反应的起始电势与pH值之间的“逆”相关性（与使用Nernstian关系预测的相关性）：电势（vs. 给定电流所需的RHE）在较高的pH值下更正，而在其他（光-）电催化材料中则未观察到，表明PTTh的电荷中和（而不是pH值）指导了起始电势。