Enhanced Photoinduced Electrocatalytic Oxidation of Methanol Using Pt Nanoparticle-Decorated TiO₂–Polyaniline Ternary Nanofibers

Abstract

Herein, perylene-3,4,9,10-tetracarboxylic acid-doped polyaniline (PTP) nanofibers with/without photoreactive anatase TiO 2 (TiO 2 –PTP and PTP, respectively) have been successively synthesized and subsequently decorated by Pt nanoparticles (Pt NPs) to prepare Pt–PTP and Pt–TiO 2 –PTP composites. High-resolution transmission electron microscopy confirms the presence of ∼3 nm spherical-shaped Pt NPs on both the composites along with TiO 2 on Pt–TiO 2 –PTP. Pt loading on the composites is deliberately kept similar to compare the methanol electro-oxidation in the two composites. The Pt nanocomposites along with the precursor polyanilines are characterized by optical characterization, X-ray diffraction study, X-ray fluorescence spectroscopy, and Raman spectroscopy. The ternary composite-modified (Pt–TiO 2 –PTP) electrode demonstrates high electrocatalytic performance for methanol oxidation reaction in acid medium than Pt–PTP and Pt–TiO 2 . The higher electrochemical surface area (1.7 times), high forward/backward current ratio, and the higher CO tolerance ability for Pt–TiO 2 –PTP make it a superior catalyst for methanol oxidation reaction in the electrochemical process than Pt–PTP. Moreover, the catalytic activity of Pt–TiO 2 –PTP is further enhanced significantly with light irradiation. The cooperative effects of photo- and electrocatalysis on methanol oxidation reaction in Pt–TiO 2 –PTP enhance the methanol oxidation catalytic activity approximately 1.3 times higher in light illumination than in dark. Therefore, the present work will be proficient to get a light-assisted sustainable approach for developing the methanol oxidation reaction activity of Pt NP-containing catalysts in direct methanol fuel cells.

Phosphotungstic acid‐Titania loaded polyaniline nanocomposite as efficient methanol electro‐oxidation catalyst in fuel cells

“…Besides, the band at 1620 cm −1 is attributed to the OH bending mode vibration from water molecules absorbed on the surface of TiO 2 nanoparticles shown in Figure 4(iii). However, the characteristic peak of ν(NH) + unsaturated amine in Figure 4(ii and iii) sample slightly changed into a redshift position compared to pure PANI 38,39,41‐46 . This representing the existence of a strong interaction between the composite of PANI, PTA, and TiO 2 components.…”

“…The hydrophilic behavior of TiO 2 providing rich active hydroxyl species, which play a vital role in the MOR. 2,38,43,50 Figure 7(iii) divulges the final PANI/PTA/TiO 2 modified electrode, which has influenced the effect of different methanol concentration was observed. It shows that the anodic oxidation peak current density increased with increasing methanol concentration (1-3 M), which demonstrates that higher electro-catalytic activity of PANI/ PTA/TiO 2 nanohybrid in MOR.…”

“…The CV analysis of Figure 6(i) shows (a) PANI, (b) PANI/ PTA, and (c) PANI/PTA/TiO 2 nanohybrids of modified electrodes which were studied in the 0.5 M H 2 SO 4 solution by the potential range between −0.2 V and 1 V at a scan rate of 100 mV s −1 . 43 The Figure 6(i) (a) PANI exhibits a pair of redox peaks at 0.2/0.06 V and 0.5/0.32 V with the current density 0.82 mA/cm 2 . These peaks are attributed to the conversion of leucoemeraldine state of PANI to the partly oxidized emeraldine state (peak I pa and I pc ) and also the interconversion of emeraldine form of PANI to pernigraniline structure (peak II pa and II pc ), respectively.…”

“…However, the characteristic peak of ν(N H) + unsaturated amine in Figure 4(ii and iii) sample slightly changed into a redshift position compared to pure PANI. 38,39,[41][42][43][44][45][46] This representing the existence of a strong interaction between the composite of PANI, PTA, and TiO 2 components. The above results indicate that the strong interaction of PTA and TiO 2 intercalated with the polyaniline matrix is confirmed.…”

Recent Progress on Photo‐Promoted Alcohol Electrooxidation for Fuel Cells

“…as the support. TiO 2 is coupled with polymers [ 47 ] and other semiconductors such as WO 3 , CuI, multicomponent RuO 2 –MnO 2 –Co 3 O 4 , and so on. [ 48–50 ] A p–n heterojunction, including p‐type CuI and n‐type TiO 2 , is constructed to be the support for the deposition of Pt.…”