沿[111]方向择优生长Pt/Ti电极制备及析氯电催化活性

针对目前低浓度氯化钠电解过程中存在的氧化物尺寸稳定阳极(DSA)使用寿命短以及Pt电极使用量高的问题, 本研究通过磁控溅射法制备了具有沿[111]方向择优生长的Pt/Ti电极。SEM结果显示, 磁控Pt表面平整, 分散均匀, 粒度大小为10 nm; 通过XPS表征, 未见到基体Ti的特征峰, 说明其表面覆盖度好。电化学循环伏安曲线(CV)显示, 磁控Pt的电化学面积最小, 仅为1.08 cm², 接近电极表观面积; 磁控Pt氧区吸附电量和氢区吸附电量的比仅为0.83, 说明其对氧吸附能力较差, 不利于发生析氧反应。在单位电化学面积上, 当电极电势为1.6 V时, 磁控Pt的析氯电流达到0.085 A/cm², 分别是电沉积Pt和热分解Pt的3.27和49.0倍, 说明磁控Pt单位活性位点上具有很高的析氯反应活性。在此基础上, 进一步研究表明磁控Pt电极析氯反应的Tafel斜率为44.3 mV/dec, 其析氯反应机理符合Volmer-Heyrovsky机理, 速控步骤为电化学复合脱附步骤。

Preparation of Pt/Ti Electrodes Preferred Growth along the [111] Direction and Its Electrocatalytic Activity for Chlorine Evolution

To solve the short service life of dimensionally stable anode (DSA) and the high dosage of Pt electrode in the process of low concentration sodium chloride electrolysis, the Pt/Ti electrode preferred growth along the [111] direction was prepared by magnetron sputtering. The electrode surface of the magnetron sputtering Pt was uniform with particle size of 10 nm. The characteristic peaks of Ti were not found in the XPS spectrum, which showed that the Ti matrix was completely covered by Pt. Electrochemical cyclic voltammetry (CV) results showed that the electrochemical area of the magnetron sputtering Pt was the smallest (1.08 cm²), which was close to the apparent surface area of the electrode. In addition, the electrical amperage ratio of the oxygen adsorption area to the hydrogen adsorption area was only 0.83 calculated from the CV diagram. So it can be predicted that the oxygen adsorption capacity on the magnetron sputtering Pt is very poor and not prone to the oxygen evolution reaction. When the electrode potential was 1.6 V, the chlorine evolution reaction current of the magnetron sputtering Pt was 0.085 A/cm² in the unit electrochemical area, which was 3.27 and 49.0 times that of the electro-deposition Pt and thermal decomposition Pt, respectively. It showed that the magnetron sputtering Pt had a high activity of chlorine evolution in the unite active site. It may be related to the special morphology of its surface (111) crystal surface. On the basis of the above, the Tafel slope of the magnetron sputtering Pt was 44.3 mV/dec. The mechanism of chlorine evolution reaction was in accordance with the mechanism of Volmer-Heyrovsky, and the rate controlling step was the electrochemical desorption step.