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The prevailing view about molecular catalysts is that the central metal ion is responsible for the reaction mechanism and selectivity, whereas the ligands mainly affect the reaction kinetics. Here, we question this paradigm and show that ligands have a dramatic influence on the selectivity of the product. We show how even a seemingly small change in ligand isomerization sharply alters the selectivity of the well‐researched oxygen reduction reaction (ORR) Co phthalocyanine catalyst from an indirect 2e− to a direct 4e− pathway. Detailed analysis reveals that intramolecular hydrogen‐bond interactions in the ligand activate the catalytic Co, directing the oxygen binding and thus deciding the final product. The resulting catalyst is the first example of a Co‐based molecular catalyst catalyzing a direct 4e− ORR via ligand isomerization, for which it shows an activity close to the benchmark Pt in an actual H2−O2 fuel cell. The effect of the ligand isomerism is demonstrated with different central metal ions, thus highlighting the generalizability of the findings and their potential to open new possibilities in the design of molecular catalysts. [ABSTRACT FROM AUTHOR]

A new electrochemical sensing platform based on tetra‐amino cobalt (II) phthalocyanine (TACoPc) ingrained polyaniline (PANI) nanofiber composite (TACoPc/PANI hybrid) has been developed for the selective detection of dopamine. The uniform fibrous network of PANI/TACoPc hybrid was synthesized by a one‐step oxidative polymerization at room temperature. The synthesized nanocomposite was characterized using field emission scanning electron microscopy (FESEM), energy dispersive X‐ray (EDX), fourier transmission infrared spectroscopy (FTIR), raman spectroscopy, X‐ray diffraction (XRD) and UV‐Visible spectroscopy. The electrochemical behavior of the TACoPc/PANI hybrid material was studied by using different electrochemical techniques, including cyclic voltammetry (CV) and chronoamperometry in 0.1 M phosphate buffer solution (PBS) of pH 7 by modifying the glassy carbon electrode (GCE). Due to the synergistic impact of PANI and TACoPc, the suggested altered electrode provided superior catalytic performance for dopamine even in the presence of ascorbic acid. It exhibited a linear reaction with a high sensitivity of 1.212 μA/μM cm−2 and a low detection limit of 0.064 μM over the 20–200 μM concentration range in 0.1 M PBS. One of the commonly faced problems of interference of ascorbic acid and uric acid in the electrochemical detection of dopamine was completely excluded from this modified electrode which led to an increase in the catalytic activity of the material for the detection of dopamine in the presence of ascorbic acid. [ABSTRACT FROM AUTHOR]

Abstract: We illustrate an all solid‐state Zn−air battery by utilizing the ability of a titanium‐nitride‐functionalized molecular catalyst to mediate the oxygen reduction reaction by avoiding the parasitic corrosion chemistry and the hydroxide‐holding capacity of the Zirfon membrane. The efficient ionic communication between the half‐cell electrodes provided by the Zirfon membrane in combination with the chemical/electrochemical stability of the TiN‐based air electrode ultimately led to an all solid‐state and air‐breathing battery possessing high durability and stability. [ABSTRACT FROM AUTHOR]

In a fuel cell, almost 80% efficiency loss arises due to the cathode; consequently, the cathode requires the largest amount of precious metal catalyst. Here, we show a precious-metal-free cathode for a proton exchange membrane fuel cell (PEMFC) containing only carbon nanoparticles as the catalyst and a freely diffusing molecule as the electron acceptor. Factors controlling the true rate of electrochemical reactions are amplified just by using carbon nanoparticles, leading to a carbon corrosion-free PEMFC delivering 154 mW/cm2 at 358 mA/cm2 without any precious metals. [ABSTRACT FROM AUTHOR]

The prevailing view about molecular catalysts is that the central metal ion is responsible for the reaction mechanism and selectivity, whereas the ligands mainly affect the reaction kinetics. Here, we question this paradigm and show that ligands have a dramatic influence on the selectivity of the product. We show how even a seemingly small change in ligand isomerization sharply alters the selectivity of the well-researched oxygen reduction reaction (ORR) Co phthalocyanine catalyst from an indirect 2e - to a direct 4e - pathway. Detailed analysis reveals that intramolecular hydrogen-bond interactions in the ligand activate the catalytic Co, directing the oxygen binding and thus deciding the final product. The resulting catalyst is the first example of a Co-based molecular catalyst catalyzing a direct 4e - ORR via ligand isomerization, for which it shows an activity close to the benchmark Pt in an actual H 2 -O 2 fuel cell. The effect of the ligand isomerism is demonstrated with different central metal ions, thus highlighting the generalizability of the findings and their potential to open new possibilities in the design of molecular catalysts., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)