Puerres Jhon, Díaz Mauro, Hurtado John, Ortiz Pablo, Cortés María T
Chemistry Department, Universidad de los Andes, Bogotá D.C. 111711, Colombia.
Chemical Engineering Department, Universidad de los Andes, Bogotá D.C. 111711, Colombia.
Polymers (Basel). 2021 Feb 23;13(4):657. doi: 10.3390/polym13040657.
Cobalt porphyrins have emerged as promising catalysts for electrochemical and photoelectrochemical applications because of their good performance, low cost and the abundance of cobalt in the earth. Herein, a negatively charged porphyrin meso-tetra-(4-sulfonatophenyl)-porphin (TPPS) was immobilized in polypyrrole (PPy) during the electro-polymerization, and then it was metallized with cobalt to obtain meso-tetra-(4-sulfonatophenyl)-porphyrinato cobalt (II) (CoTPPS) as a dopant in PPy. The coatings were evaluated as photoelectrodes towards thiosulfate oxidation and oxygen reduction. For comparison purposes, the photoelectrochemical behavior of ClO-doped polypyrrole films was also evaluated. Characterizations by chronoamperometry, UV-Vis spectroscopy and Raman spectroscopy showed that polypyrrole is stable under anodic and cathodic conditions, but CoTPPS and TPPS immobilized in PPy are degraded during the anodic process. Thus, decreases in photocurrent of up to 87% and 97% for CoTPPS-doped PPy and TPPS-doped PPy were observed after a 30-min chronoamperometry test. On the other hand, good stability of CoTPPS and TPPS immobilized in PPy was observed during photoelectrochemical oxygen reduction, which was reflected in almost constant photocurrents obtained by chronoamperometry. These findings are relevant to understanding the role of CoTPPS as a catalyst or pre-catalyst in photoelectrochemical applications such as water splitting. In addition, these results could pave the way for further research to include CoTPPS-doped PPy in the design of novel photocathodes.
钴卟啉因其良好的性能、低成本以及地球上钴的丰富储量，已成为电化学和光电化学应用中颇具前景的催化剂。在此，带负电荷的卟啉中-四-(4-磺酸苯基)-卟吩（TPPS）在电聚合过程中被固定在聚吡咯（PPy）中，然后用钴进行金属化，以获得中-四-(4-磺酸苯基)-卟啉钴（II）（CoTPPS）作为PPy中的掺杂剂。对这些涂层作为硫代硫酸盐氧化和氧还原光电极进行了评估。为作比较，还评估了ClO掺杂的聚吡咯薄膜的光电化学行为。计时电流法、紫外-可见光谱和拉曼光谱表征表明，聚吡咯在阳极和阴极条件下是稳定的，但固定在PPy中的CoTPPS和TPPS在阳极过程中会降解。因此，在30分钟的计时电流法测试后，观察到CoTPPS掺杂的PPy和TPPS掺杂的PPy的光电流分别下降高达87%和97%。另一方面，在光电化学氧还原过程中，观察到固定在PPy中的CoTPPS和TPPS具有良好的稳定性，这反映在计时电流法获得的光电流几乎恒定。这些发现对于理解CoTPPS作为光催化应用（如水分解）中的催化剂或预催化剂的作用具有重要意义。此外，这些结果可为进一步研究将CoTPPS掺杂的PPy纳入新型光电阴极的设计铺平道路。
