The Influence of Pt Surface Area on the Photo‐Enhancement of the Methanol Oxidation Reaction

Abstract

The methanol oxidation reaction (MOR) on both Pt/TiO2/C and Pt/C‐based electrodes can be photo‐enhanced by illuminating the electrodes with UV light. This fact has called into question the role of TiO2 in the photo‐enhancement of MOR when Pt is present. To examine this further, we have studied the change in the photo‐enhancement of methanol electro‐oxidation with Pt surface area. For each catalyst, there was greater MOR activity in the presence of UV‐irradiation. However, upon potential cycling, there was a faster decline in MOR activity in the presence of UV‐irradiation compared to the MOR activity in the dark. A linear relation between the decay in methanol oxidation current with the decay in Pt surface area for both catalysts was observed. This strongly suggests that irradiation enhances the methanol oxidation process on the Pt surface. When TiO2 is present, it has a synergetic electronic effect that further enhances the oxidation process on the Pt surface.

Synergistic photo-enhanced electrocatalysis of Pt–ZnO–Bi2O3 heterojunction for methanol oxidation under visible light illumination

“…The photo-electrocatalytic activity of MOR can be guided by the electrochemically active specific surface area (ECSA) of Pt in the catalysts, particle dispersion in the surface, the interaction of Pt with metal oxide, and bandgap of the heterojunctions. 13,24,26,46 For all the PZB heterojunctions, the smaller the size of Pt (from TEM), the larger the surface area of catalysts. The ECSA (m 2 g −1 ) calculated from the reduction of PtO monolayer 22 from cyclic voltammogram using 1 M NaOH solution (supporting document S1, Fig.…”

“…This dispersion in the surface, the interaction of Pt with metal oxide and bandgap of heterojunctions. 13,24,26,46 For all the PZB heterojunctions, smaller the size of Pt (from TEM) larger is the surface area of catalysts. The ECSA (m 2 g -1 ) calculated from the reduction of PtO S5) decreases in the order: PZ5B1 (40.5) > PZ20B1 (32.5) > PZ25B1 (30.9) > PZ30B1 (24.6) > PZ1B1 (20.9) > PZ (18.5) > PZ1B5 (17.9) > PB (14).…”

“…It can be understood that there is a linear relationship between ECSA and photo-enhanced methanol oxidation activity. 46,84 The lower photo-electrooxidation (MOR) activity of PZ1B5 is due to the large Pt size (ca. 4.35 AE 0.7 nm), nonuniform particle distribution, and high bandgap energy.…”

“…Moreover, the corrosive nature of the anode material is less in a mild alkaline atmosphere; thereby, increasing the cycle life and durability of the system. 46,47 The photo-electrocatalytic activity of the ternary heterojunction was optimized with the proper amount of ZnO loading. We found that the construction of the p-n heterojunction is helpful in decreasing the bandgap of ZnO and Pt acts as an electron mediator between Bi 2 O 3 and ZnO, thus decreasing the recombination of photogenerated electronhole pairs, enhancing the catalytic performance and stability of the ternary heterojunction-catalyst toward methanol oxidation reaction.…”

Co Ion‐, NiS2‐ and CNT‐Co‐Doped Nanoflower/Hollow Spherical NiO Nanocomposites for Efficient Electrocatalytic Oxidation of Methanol

“…Pt, Pd and other precious metals have good catalytic performance for methanol, [9–11] However, during the MOR process, Pt may experience CO poisoning, which is a reaction intermediate blocking the active site of Pt for further reaction and leading to decreased activity [12,13] . Their high costs also make it difficult to industrialize [14–18] . Therefore, nickel containing materials are widely studied in fuel cells as electrocatalysts [19–22] .…”