Palladium Content Effect on the Electrocatalytic Activity of Palladium–Polypyrrole Nanocomposite for Cathodic Reduction of Oxygen

Carbon dots derived from metformin by electrochemical synthesis with broad-spectrum antibacterial properties

Due to the advantages of good aqueous dispersion and biocompatibility, carbon dots (CDs) are promising candidates for a wide range of applications in the biological field. Notably, CDs derived from biosafe organic precursors will contribute both new types of CDs and new bioactivities. Herein, metformin (MET), a first-line drug for the treatment of type II diabetes, was selected as an organic precursor to fabricate a new type of CDs, namely, semi-carbonized MET (MCDs). These MCDs derived from MET possess a completely new antibacterial activity against Staphylococcus aureus (SA) and Escherichia coli (E. coli) compared with that of MET and achieve complete antibacterial activity at 200 μg mL-1. The broad-spectrum antibacterial mechanism of MCDs involves two aspects. For the Gram-positive bacteria SA, MCDs mainly affect the transport of nutrients by adsorbing onto the surface of bacteria, thereby inhibiting bacterial growth. For the Gram-negative bacteria E. coli, MCDs can easily pass through their thin cell walls and stimulate the bacteria to produce excess ROS, eventually leading to the death of the bacteria. This work may open a new way for the future design and development of CDs prepared from biosafe organic precursors with specific functions.

Electrochemistry at Krakowian research institutions

The electrochemistry research team activity from Poland is marked by significant increase in the last 20 years. The joining of European Community in 2004 gives an impulse for the development of Polish science. The development of electrochemistry has been stimulated by cooperation with industry and the establishment of technology transfer centers, technology parks, business incubators, etc. and the mostly by simplified international collaborations. Five research institutions from Krakow reports work in the field of electrochemistry. The achievements of all teams are briefly described.

Conducting Polymer-Based Nanohybrids for Fuel Cell Application

Carbon materials such as carbon graphitic structures, carbon nanotubes, and graphene nanosheets are extensively used as supports for electrocatalysts in fuel cells. Alternatively, conducting polymers displayed ultrahigh electrical conductivity and high chemical stability havegenerated an intense research interest as catalysts support for polymer electrolyte membrane fuel cells (PEMFCs) as well as microbial fuel cells (MFCs). Moreover, metal or metal oxides catalysts can be immobilized on the pure polymer or the functionalized polymer surface to generate conducting polymer-based nanohybrids (CPNHs) with improved catalytic performance and stability. Metal oxides generally have large surface area and/or porous structures and showed unique synergistic effects with CPs. Therefore, a stable, environmentally friendly bio/electro-catalyst can be obtained with CPNHs along with better catalytic activity and enhanced electron-transfer rate. The mass activity of Pd/polypyrrole (PPy) CPNHs as an anode material for ethanol oxidation is 7.5 and 78 times higher than that of commercial Pd/C and bulk Pd/PPy. The Pd rich multimetallic alloys incorporated on PPy nanofibers exhibited an excellent electrocatalytic activity which is approximately 5.5 times higher than monometallic counter parts. Similarly, binary and ternary Pt-rich electrocatalysts demonstrated superior catalytic activity for the methanol oxidation, and the catalytic activity of Pt24Pd26Au50/PPy significantly improved up to 12.5 A per mg Pt, which is approximately15 times higher than commercial Pt/C (0.85 A per mg Pt). The recent progress on CPNH materials as anode/cathode and membranes for fuel cell has been systematically reviewed, with detailed understandings into the characteristics, modifications, and performances of the electrode materials.

Pulse electrochemical synthesis of polypyrrole/graphene oxide@graphene aerogel for high-performance supercapacitor

A novel electroactive polypyrrole/graphene oxide@graphene aerogel (PGO@GA) was synthesized for the first time by pulse electropolymerization. The off-time in this technique allows polypyrrole (PPy) to go through a more stable structural arrangement, meanwhile its electronic transmission performance is enhanced by immobilizing graphene oxide between PPy chains. Moreover, graphene aerogel provides a three-dimensional structure with high conductivity to protect PPy from swelling and shrinking during the capacitive testing. Under these synergistic effects, PGO@GA presents exceptional capacitive performances including high specific capacitance (625 F g⁻¹ at 1 A g⁻¹), excellent rate capability (keeping 478 F g⁻¹ at 15 A g⁻¹ with retention rate of 76.5%), and excellent cycling life (retaining 85.7% of its initial value when cycling 5000 times at 10 A g⁻¹). Therefore, the strategy adopted by this research provides a good reference for preparing other PPy-based electrode materials applied in the fields of catalysis, sensing, adsorption and energy storage.

The as-prepared polypyrrole/graphene oxide@graphene aerogel by pulse electropolymerization technique presents excellent capacitive performance.

Porous palladium coated conducting polymer nanoparticles for ultrasensitive hydrogen sensors

Hydrogen, a clean-burning fuel, is of key importance to various industrial applications, including fuel cells and in the aerospace and automotive industries. However, hydrogen gas is odorless, colorless, and highly flammable; thus appropriate safety protocol implementation and monitoring are essential. Highly sensitive hydrogen leak detection and surveillance sensor systems are needed; additionally, the ability to maintain uniformity through repetitive hydrogen sensing is becoming increasingly important. In this report, we detail the fabrication of porous palladium coated conducting polymer (3-carboxylate polypyrrole) nanoparticles (Pd@CPPys) to detect hydrogen gas. The Pd@CPPys are produced by means of facile alkyl functionalization and chemical reduction of a pristine 3-carboxylate polypyrrole nanoparticle-contained palladium precursor (PdCl(2)) solution. The resulting Pd@CPPy-based sensor electrode exhibits ultrahigh sensitivity (0.1 ppm) and stability toward hydrogen gas at room temperature due to the palladium sensing layer.

Controllable synthesis of core–satellite Fe3O4@polypyrrole/Pd nanoarchitectures with aggregation-free Pd nanocrystals confined into polypyrrole satellites as magnetically recoverable and highly efficient heterogeneous catalysts

A soft template-assisted redox strategy has been developed to fabricate core–satellite Fe₃O₄@PPy/Pd nanocomposites as efficient nanocatalysts for reduction of nitroaromatics.