Dual Role of Polyaniline for Achieving Ag Dendrites and Enhancing Its Oxygen Reduction Reaction Catalytic Activity

In situ synthesis of hierarchical platinum nanosheets-polyaniline array on carbon cloth for electrochemical detection of ammonia

In this work, a self-supported electrode has been designed and fabricated based on carbon cloth-supported polyaniline array and Pt nanosheets (Pt-PANI-CC). PANI array was firstly loaded on the surface of CC via chronoamperometry technique, and then, Pt nanosheets were deposited on the per-grown PANI array through amperometric measurement. The hierarchical structure of Pt-PANI-CC electrode and unique sheet-like Pt nanoparticles offered large specific surface and response centers. The electrochemical sensor based on Pt-PANI-CC electrode has been successfully constructed for detection of ammonia. The experiment results demonstrated that Pt-PANI-CC displayed great catalytic activity for electro-oxidation of ammonia and exhibited acceptable performances for sensing ammonia with low detection limit of 77.2 nM and wide linear range from 0.5 μM to 550 μM. Moreover, the anti-interference ability, reusability, reproducibility and stability of sensor have been investigated and showed great performances. This work provides a promising way for designing self-supported sensing electrode toward a wide electrochemical detection.

Supramolecular Iron Complex Formed Between Nitrogen Riched Phenanthroline Derivative and Iron With Improved Oxygen Reduction Activity in Alkaline Electrolyte

In this work, the synthesis and evaluation of a new type non-noble metal oxygen reduction reaction (ORR) catalyst is reported. The catalyst is a complex containing iron ions and multiple N active sites, which displayed excellent oxygen reduction activity in alkaline medium. 2-(2-(4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)pyridin-2-yl)pyridin-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (PIPhen) was synthesized and used as a ligand to form a rich nitrogen iron coordination complex (Fe-PIPhen), and the complex was then loaded onto the carbon powder to form the target catalyst of Fe-PIPhen/C. The physical characterization of the catalyst was conducted by using Scanning Electron Microscopy (SEM), nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis etc. Electrochemical characterizations were realized by taking cyclic voltammetry (CV), linear sweep voltammetry (LSV) and rotating ring disk electrode (RRDE). The results show that Fe-PIPhen/C possesses the good performance; it exhibits a high electrocatalytic activity, which is mainly via a four electron ORR pathway, with a low hydrogen peroxide yield of 2.58%. And, the average electron transfer number of 3.93 was obtained in alkaline electrolyte. In summary, Fe-PIPhen/C will likely become a promising alternative to Pt catalyst in fuel cell.

In Situ Construction of Ag/Ni(OH)2 Composite Electrode by Combining Electroless Deposition Technology with Electrodeposition

The Ag/Ni(OH)2 composite electrode has been designed and in situ constructed on a copper substrate by combining electroless deposition technology with electrodeposition. The products can be directly used as a high performance binder free electrode. The synergistic effect between the Ag nanocubes (AgNCs) as backbones and the deposited Ni(OH)2 as the shell can significantly improve the electrochemical properties of the composite electrode. Moreover, this in situ growth strategy forms a strong bonding force of active materials to the substrate, which can improve the cycling performance and lower the equivalent series resistance. The Ag/Ni(OH)2 composite electrode exhibits enhanced electrochemical properties with a high specific capacitance of 3.704 F cm−2, coulombic efficiency of 88.3% and long-term cyclic stability.

Recent Advance on Polyaniline or Polypyrrole-Derived Electrocatalysts for Oxygen Reduction Reaction

The fuel cell, as one of the most promising electrochemical devices, is sustainable, clean, and environmentally benign. The sluggish oxygen reduction reaction (ORR) is an important fuel cell cathodic reaction that decides the efficiency of the overall energy conversion. In order to improve ORR efficiency, many efficient catalysts have been developed, in which the N-doped material is most popular. Polyaniline and polypyrrole as common aromatic polymers containing nitrogen were widely applied in the N-doped material. The shape-controlled N-doped carbon material can be prepared from the pyrolysis of the polyaniline or polypyrrole, which is effective to catalyze the ORR. This review is focused on the recent advance of polyaniline or polypyrrole-based ORR electrocatalysts.