Herein, we have designed and synthesized highly electocatalytically active 2D MoS2 nanosheets (NS), by a facile hydrothermal method, for hydrogen evolution reaction (HER).

How to improve the accuracy of target detection substance in low-content and complex of real sample, which is still a major challenge in the analysis field. There is no doubt that the internal standard method is the best choice in the analysis methods. The internal standard method of ECL strategy can furnish more accurate detection results in the changeable complex environment, and it can dispel the primary vaguest interference in the system through the self-calibration of two emission spectra. Herein, we effectually explored a strong and stable bimodal ECL system based on graphitic carbon nitride quantum dots (g-CNQDs) as single luminophore in the presence of double coreactants potassium persulfate (KSO) and tetrabutylammonium bromide (TBAB) under the optimized conditions. ECL-1 at 2.82 V and ECL-2 at 1.73 V were observed when the potential was scanned between -3 and 3 V at the scan rate of 0.2 V·s. The ECL-1 was responding to the analyte, that is, ascorbic acid (AA) and the ECL-2 was not for a certain concentration of AA; hence, the developed bimodal ECL system was used as internal standard method for quantitative AA in human serum due to the different sensitivity of the double-peak ECL signals to the target analytes. The linear relationships were obtained based on the ln I (ECL-1/ECL-2) against the concentration of AA in the concentration range of 3.5 to 330 nM, with a detection limit of 110 pM (S/N = 3).

Recombination of photogenerated electron-hole pairs is extremely limited in the practical application of photocatalysis toward solving the energy crisis and environmental pollution. A rational design of the cascade system (i.e., rGO/Bi WO /Au, and ternary composites) with highly efficient charge carrier separation is successfully constructed. As expected, the integrated system (rGO/Bi WO /Au) shows enhanced photocatalytic activity compared to bare Bi WO and other binary composites, and it is proved in multiple electron transfer (MET) behavior, namely a cooperative electron transfer (ET) cascade effect. Simultaneously, UV-vis/scanning electrochemical microscopy is used to directly identify MET kinetic information through an in situ probe scanning technique, where the "fast" and "slow" heterogeneous ET rate constants (K ) of corresponding photocatalysts on the different interfaces are found, which further reveals that the MET behavior is the prime source for enhanced photocatalytic activity. This work not only offers a new insight to study catalytic performance during photocatalysis and electrocatalysis systems, but also opens up a new avenue to design highly efficient catalysts in photocatalytic CO conversion to useful chemicals and photovoltaic devices.

J- and H-aggregates of zinc tetraphenylporphyrin (ZnTPP) on carbon nanotube films (CNTFs) were prepared using the mixed solvent method. This resulted in completely different structures, such as the four-leaf clover and flower, on the CNTF, which were observed by recording SEM images. Characteristic changes in the electronic spectra of the ZnTPP monomer appeared when it underwent J- and H-aggregation. The measured photocurrent significantly varied for the same molecule when it was aggregated in two different ways on ITO and ITO/CNTF. The electron recombination resistance of the two aggregates, which was investigated using electrochemical impedance spectroscopy, was also different. The photocatalytic efficiency of the J- and H-aggregates was examined by performing methylene blue dye decoloration studies. In addition, a scanning electrochemical microscope was used to investigate the photoinduced charge transfer kinetics of the J- and H-aggregates at the electrode/electrolyte interface as a fresh attempt. The heterogeneous charge transfer constants for the J- and H-aggregates in the presence of light at varied intensities were calculated. Thereby, striking differences in the photophysical, photocatalytic, and photoelectrochemical properties of the J- and H-aggregates were visualized throughout our studies.

a b s t r a c tA new protocol toward the synthesis of cobalt nitroprusside (CoNP) coordination nanoparticles has been described based on drop-by-drop (DbD) method without using any additives. It was also prepared by sonication as well as bulk mixing methods for comparison purpose. The prepared complex was characterized by Infrared spectroscopy (FTIR), XRD and cyclicvoltammetry (CV) techniques. The CoNP complexes prepared by different synthetic approaches were used as modifier molecules to fabricate carbon paste electrodes (CPE's) toward electrochemical oxidation of sulfite. The experimental results revealed that the cobalt nitroprusside nanoparticles (n-CoNP) prepared by drop-by-drop method showed a considerable enhancement in the electrocatalytic activity when compared to its counterparts prepared by other approaches. Electrochemical behavior of the n-CoNP CPE was studied and used as an electrochemical sensor for the quantification of sulfite at trace level. It showed a linear response over the concentration range 1-5.9 × 10 −5 M and 2-8 × 10 −3 M of sulfite. The limit of detection and limit of quantification were found to be 0.4 × 10 −5 M and 2.29 × 10 −5 M respectively. The interference of various organic acids and inorganic ions commonly present in different food and water sample matrices were studied. The n-CoNP modified electrode was used for the quantification of sulfite in different food samples and the results were in good agreement with those obtained by the standard iodometric protocol.

The cathodic electrochemiluminescence (ECL) behavior of meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) with potassium peroxydisulfate (K2S2O8) as the coreactant in aqueous solution with strong and stable emission was exploited to determine Cu(2+) down to nanomolar concentration. Two possible reaction mechanisms have been proposed to understand the generation of ECL by the TSPP/K2S2O8 system. The effects of the concentration of TSPP and K2S2O8, pH of the medium, and scan rate on the ECL intensity were studied in detail. The ECL intensity was efficiently quenched by trace amounts of Cu(2+). This phenomenon was used to develop a new method, which can offer rapid, reliable, and selective detection of Cu(2+). Under the optimum conditions, plots of the ECL of the TSPP/K2S2O8 system versus the concentration of Cu(2+) are linear in the range of 5 to 160 nM with a detection limit of 1.56 nM (S/N = 3). The proposed ECL sensor was successfully applied for analysis of tap and river water samples. It is anticipated that TSPP could be a new class of promising luminescent agent for ECL sensors. Graphical Abstract A two-step cathodic elelctrochemiluminescence (ECL) behavior of TSPP/K2S2O8 system in the aqueous solution and Cu(2+) determination using the same.

Nanoparticles of ultra-porous MoO3 were synthesized in a single step by a solution combustion reaction using molybdenum metal powder for the first time as a precursor.

In this study, we reported rectangular CoP nanosheet (NS) arrays on carbon cloth (CoP NS/CC) prepared via a concise two-step synthetic method.