Tetraphenolphthalein Cobalt(II) Phthalocyanine Polymer Modified with Multiwalled Carbon Nanotubes as an Efficient Catalyst for the Oxygen Reduction Reaction

Abstract

Oxygen reduction reaction (ORR) is the main reaction at the cathode of a fuel cell that utilizes Pt/C as the benchmark catalyst. Due to sluggish activity, high cost, rare abundance, and durability issues, Pt/C must be replaced by nonprecious, stable, and easily synthesizable materials. This work involves the synthesis of novel, simple, low-cost, and environmentally friendly phenolphthalein-bearing cobalt(II) phthalocyanine polymer, poly ( Co II TPpPc ) dyad, as an efficient catalyst for ORR. The results of analytical characterizations reveal the formation of the poly ( Co II TPpPc ) polymer in the pure state. To further enhance the catalytic response of poly ( Co II TPpPc ), a hybrid composite is prepared using poly ( Co II TPpPc ) and multiwalled carbon nanotubes (MWCNTs) that increase the surface area and conductivity. The poly ( Co II TPpPc ) and hybrid composite are separately deposited on the electrode surfaces. The electron microscopy images confirm the uniform distribution of the poly ( Co II TPpPc ) molecules on the electrode surface and MWCNTs. The poly ( Co II TPpPc ) and hybrid composite electrodes are evaluated for ORR, and the hybrid composite exhibits better onset potential at 0.803 V versus reversible hydrogen reference electrode for ORR according to linear sweep voltammograms (LSVs). The obtained data are superior compared to those of other carbon-based redox-active materials reported previously and nearer to those of the benchmark catalyst (Pt/C). The rotating disc electrode measurement of the hybrid composite electrode confirms the total number of electrons involved in ORR to be four. Furthermore, the hybrid composite electrode exhibits an excellent stability for 100 LSV scans. The synergistic effect of poly ( Co II TPpPc ) and MWCNTs leads to the surprisingly high ORR activity due to the improved surface area, conductivity, and interfacial confined surface.

Uranium Phthalocyanine-Anchored Acid-Functionalized Multiwalled Carbon Nanotubes for Water Electrolysis

“…The peaks at 286.4 and 288.8 eV can be assigned to CN (pyrrol) and CO bonds, respectively. The peak noticed at a higher binding energy of 290.5 eV may be credited to the π–π interaction of conjugated rings/delocalized UTBrImPc molecules with the MWCNT backbone, which confirms the π–π electron interaction and parity between these two components . The O 1s spectrum (Figure d) shows two well-superimposable peaks centered at 535 and 533.5 eV as a result of C–O and CO bonds, respectively.…”

“…Metal phthalocyanines (MPc) have structural similarity to the pigment chlorophyll, and the central metal atom is coordinated by four nitrogen atoms of iso-indole groups. They are electrochemically active and hence employed as catalysts for various electrochemical applications. − The transition MPcs are stable, and they have shown efficient activity for either the HER or OER, and only few catalysts have been assessed for bifunctional activity in water electrolyzers, but their performance is poor. ,, In recent years, the coordination chemistry of actinide phthalocyanines has gained interest along with long-studied transition MPcs. Uranium is one of the most prominent actinide elements with a longer half-life period and potential applications in the nuclear industry.…”

Metal Porphyrins as Single Site Catalyst Models Explored by Electrochemical Scanning Tunneling Microscopy: A New Perspective in Electrocatalysis

“…In line with this, a very recent example emerged as a potential further step in finding a suitable model system, which enables access to single sites and at the same time correlates with a more realistic type of material. [ 110 ] it is the case of poly‐cobalt‐phthalocyanine and it has been positively tested versus ORR, reaching similar performances as a standard Pt/C electrode in aqueous solution. However, this has not been well exploited and investigated through EC‐STM, which makes it possible to envisage an important and wide‐ranging research action in the next few years.…”

Recent Advances in the Use of CoPc-MWCNTs Nanocomposites as Electrochemical Sensing Materials

“…Aside from these, CoPcMWCNTs nanocomposite have been utilized in various other processes such as oxidation of styrene to benzaldehyde [ 7 , 75 , 76 ], catalytic oxidation of benzyl alcohol to benzaldehyde [ 6 , 25 ], electrochemical reduction of oxygen [ 77 , 78 , 79 , 80 , 81 ], electrochemical conversion of CO 2 to CO [ 82 ], removal of mercaptan from natural gas [ 83 ], photocatalytic oxidation of butan-2-ol [ 84 ], a catalyst for microbial fuel cell [ 85 ], catalyst in glucose/O 2 fuel cells [ 86 ], and electrochemical reduction of carbon dioxide and carbon monoxide to methanol [ 87 ]. The conversion rate and selectivity recorded in these processes were satisfactory.…”