In this paper, the first photoelectrocatalytic (PEC) 3-pyridinemethanol oxidation to 3-pyridinemethanal and vitamin B₃ was investigated. To meet this aim, efficient nanotube structured TiO₂ on a Ti plate as a photoanode was prepared by an anodic oxidation method in ethylene glycol and characterized by XRD, SEM, and photocurrent techniques. The effect of nanotube morphology, applied potential, Na₂SO₄ concentration, stirring speed of solution, and pH on the reaction activity and product selectivities were investigated. The TiO₂ phase of all of the anodes was mainly the anatase one. The PEC activity, the intensity of the XRD peak and the photocurrent increased by increasing the nanotube length. The activity decreased by decreasing both the Na₂SO₄ concentration and the applied potential, whereas 3-pyridinemethanal selectivity increased. By increasing the stirring speed of the solution, both the activity and the 3-pyridinemethanal selectivity increased. A lower or no activity was observed for photocatalytic (PC) and electrocatalytic runs, respectively, which were carried out for the sake of comparison. No PC activity was obtained in the presence of N₂, but PEC reactions in the presence of N₂ were faster than those in the presence of O₂. The produced 3-pyridinemethanal in both N₂ and O₂ atmosphere was reduced at the cathode in the PEC reaction, but its oxidation appeared to be much more favourable. The PC reactions could not be carried out under acidic conditions, whilst the PEC ones could be performed in the pH range of 2–12. Moreover, the results indicate that the PEC method allows higher conversions and selectivities to vitamin B₃ to be obtained at pH 7 with respect to those reported in the literature.

中文翻译：

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TiO2纳米管将3-吡啶甲醇光催化氧化为3-吡啶甲醛和维生素B3

本文研究了第一个光电催化（PEC）3-吡啶甲醇氧化为3-吡啶甲烷甲醛和维生素B _3的方法。为了达到该目的，通过在乙二醇中通过阳极氧化法制备了在Ti板上作为光阳极的高效纳米管结构的TiO ₂，并通过XRD，SEM和光电流技术对其进行了表征。研究了纳米管的形貌，施加的电势，Na ₂ SO _4的浓度，溶液的搅拌速度和pH对反应活性和产物选择性的影响。TiO ₂所有阳极的相主要是锐钛矿。通过增加纳米管长度，PEC活性，XRD峰强度和光电流增加。活性通过同时降低Na ₂ SO ₄浓度和施加的电位而降低，而3-吡啶甲烷甲基选择性提高。通过提高溶液的搅拌速度，活性和3-吡啶甲醛的选择性均增加。为了进行比较，分别对光催化（PC）和电催化运行观察到较低或没有活性。在N ₂存在下没有获得PC活性，但是在N ₂存在下的PEC反应比在O ₂存在下的PEC反应要快。。在PEC反应中，在N ₂和O ₂气氛中在阴极生成的3-吡啶甲烷甲醛均被还原，但其氧化似乎更为有利。PC反应不能在酸性条件下进行，而PEC反应可以在2-12的pH范围内进行。而且，结果表明，相对于文献报道的那些，PEC方法允许在pH 7下获得更高的转化率和对维生素B _3的选择性。