The oxidative polymerization of p-phenylenediamine with silver nitrate: Toward highly conducting micro/nanostructured silver/conjugated polymer composites

Ultra-sensitive SERS detection of perfluorooctanoic acid based on self-assembled p-phenylenediamine nanoparticle complex

PFOA is a representative perfluorinated compound that is used as a surfactant in various industrial fields. However, because PFOA has severe side effects due to its strong toxicity, such as carcinogenesis, liver damage, and immune system damage, it is crucial to enable PFOA detection with high sensitivity. Herein, we developed a perfluorooctanoic acid (PFOA) surface-enhanced Raman scattering (SERS) sensor using self-assembled p-phenylenediamine (SAp-PD) nanoparticles and an Ag SERS substrate. For the ultra-sensitive detection of PFOA, we synthesized and optimized SAp-PD, which shows a decrease in SERS intensities when reacting with PFOA. Using the Ag nanograss SERS substrate, the change in intensity that resulted from the SAp-PD and PFOA reaction was amplified. Consequently, we detected the 1.28 pM (detection limit) of PFOA in distilled water. Moreover, PFOA molecules were successfully detected in samples of the PFOA-coated frying pan and rice extraction at concentrations up to 1.69 nM and 10.3 μM, respectively.

Self-Activation of Inorganic-Organic Hybrids Derived through Continuous Synthesis of Polyoxomolybdate and para-Phenylenediamine Enables Very High Lithium-Ion Storage Capacity

Inorganic-organic hybrid materials with redox-active components were prepared by an aqueous precipitation reaction of ammonium heptamolybdate (AHM) with para-phenylenediamine (PPD). A scalable and low-energy continuous wet chemical synthesis process, known as the microjet process, was used to prepare particles with large surface area in the submicrometer range with high purity and reproducibility on a large scale. Two different crystalline hybrid products were formed depending on the ratio of molybdate to organic ligand and pH. A ratio of para-phenylenediamine to ammonium heptamolybdate from 1 : 1 to 5 : 1 resulted in the compound [C₆ H₁₀ N₂ ]₂ [Mo₈ O₂₆ ] ⋅ 6 H₂ O, while higher PPD ratios from 9 : 1 to 30 : 1 yielded a composition of [C₆ H₉ N₂ ]₄ [NH₄ ]₂ [Mo₇ O₂₄ ] ⋅ 3 H₂ O. The electrochemical behavior of the two products was tested in a battery cell environment. Only the second of the two hybrid materials showed an exceptionally high capacity of 1084 mAh g^-1 at 100 mA g^-1 after 150 cycles. The maximum capacity was reached after an induction phase, which can be explained by a combination of a conversion reaction with lithium to Li₂ MoO₄ and an additional in situ polymerization of PPD. The final hybrid material is a promising material for lithium-ion battery (LIB) applications.

A colloidal quantum dot spectrometer

Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.

Investigations on the performance of poly(o-anisidine)/graphene nanocomposites for the electrochemical detection of NADH

The electrocatalytic oxidation of dihydronicotinamide adenine dinucleotide (NADH) based on poly(o-anisidine)/graphene (POA/GR) nanocomposites modified glassy carbon electrode (GCE) was explored for the first time. POA/GR nanocomposites were synthesized via chemical oxidative polymerization method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and UV-Vis spectroscopy results demonstrate that nanocomposites are successfully synthesized. An intriguing composite structure was observed using different ratios of o-anisidine monomer and graphene. The electrical properties and electrochemical properties of these nanocomposites are investigated by impedance spectroscopy technique and cyclic voltammetric (CV) method, respectively. The synthesized nanocomposites were used to modify glassy carbon electrode (GCE), and the modified electrodes were found to exhibit electrocatalytic activity for oxidation of NADH at low potential range of +0.045 V in a neutral environment. The fabricated sensor based on POA/GR31-modified GCE exhibited enhanced current response with very high sensitivity of 47.1 μA μM(-1) for the detection of NADH. The developed POA/GR-modified GCE exhibited excellent reproducibility, stability, and selectivity for the determination of NADH. The practical analytical utility of the proposed method was demonstrated by NADH spiked ascorbic acid (AA) and the results confirmed that the proposed method is suitable for the determination of NADH in the presence of AA. This can open up new opportunities for simple and selective detection of NADH and provide a promising platform for biosensor designs.

Sustainable synthesis of hollow Cu-loaded poly(m-phenylenediamine) particles and their application for arsenic removal

A new Cu-catalyzed air oxidation method was successfully developed to prepare Cu-loaded poly(m-phenylenediamine) (PmPD) with monomer conversion rates close to 100%.

A green electrochemical method for the synthesis of new N,N′-diphenylbenzene-1,4-diamine derivatives

A green method for the synthesis of new organosulfur derivatives based on the Michael reaction of electrochemically generated N,N′-diphenyl-p-quinonediimine with some thiols is described.