Bimetallic iron complex constructed clusters and single atoms neighboring structure to enhance oxygen reduction reaction performance.

Electrocatalysts are useful in lowering the energy barrier in oxygen reduction reaction (ORR). In this study, a catalyst with neighboring Fe single-atom and cluster is created by adsorbing a bimetallic Fe complex onto N-doped carbon and then pyrolyzing it. The resulting catalyst has good performance and a half-wave potential of 0.89 V. When used in Zn-air batteries, the voltage drops by only 8.13 % after 145 h of cycling. Theoretical studies show that electrons transfer from neighboring clusters to single atoms and the catalyst has a lower d-band center. These reduce intermediate desorption energy, hence improving ORR performance. This work demonstrates the capacity to adjust the catalytic properties through the interaction of diverse metal structures, which helps to design more efficient catalysts.

Molecularly imprinted voltammetric sensor sensibilized by nitrogen-vacancy graphitized carbon nitride and Ag-MWCNTs towards the detection of acetaminophen.

The overdose of acetaminophen (AP) can cause serious acute liver injury even the irreversible liver necrosis. The quantitative detection of AP is of great significance not only for clinical applications but also for the quantity control of its pharmaceutical formulations. In this paper, a sensitive molecularly imprinted voltammetric sensor towards AP was constructed based on synergistic enhancement of nitrogen-vacancy graphitized carbon nitride (NV-g-C3 N4 ) and carboxylated MWCNTs loaded with silver nanoparticles (Ag-MWCNTs). The powder X-Ray diffraction spectrum, field emission scanning and transmission electron microscopes, cyclic voltammetry (CV), and electrochemical impedance spectrum were used to characterize the composites. The results show that NV-g-C3 N4 and Ag-MWCNTs closely embedded each other, forming loose porous hybrid structure by hydrogen bond. The prepared sensor molecular imprinting polymer (MIP)/C3 N4 /Ag-CNTs/GCE shows a strong synergistic enhancement of electroanalytical response by CV and differential pulse voltammetry (DPV) tests when compared with NV-g-C3 N4 /GCE, Ag-CNTs/GCE, and MIP/GCE. Through the optimization of the ratio of monomer and template, electropolymerization cycle, elution cycle, incubation time, and pH, linear ranges of 0.007-5 and 5-100 µM were found with the limit of detection of 2.33 nM by DPV. Moreover, its selectivity towards AP was satisfied when compared with detection towards ascorbic acid, dopamine, and glucose. The recovery range of 96.3%-100.5% was obtained in the spiked human serum and urine samples with the SD below 3.0%. In addition, the prepared sensor shows great detecting robustness with good anti-interference, reproducibility, and stability.

Iron ion irradiated Bi2Te3 nanosheets with defects and regulated hydrophilicity to enhance the hydrogen evolution reaction.

The introduction of defects can enhance the active sites on transition metal dichalcogenides, which can cause changes in crystal structures, and then lead to a change in the original catalytic performance. Herein, an efficient method of introducing defects was reported. In this method, high-energy iron ions were irradiated on the surface of Bi2Te3 nanosheets by ion irradiation technology, which resulted in the generation of a variety of defects. Compared to the original Bi2Te3 nanosheets, the Bi2Te3 nanosheets irradiated by iron ions showed significant improvement in the hydrogen evolution reaction performance in acidic solution. After the iron ion irradiation, the electric double layer capacitance of the Bi2Te3 nanosheets increased significantly, which indicated an increase in the number of active sites on the surface of Bi2Te3. Analysis of high-resolution transmission electron microscopy images reveals the occurrence of various defects on the surface of Bi2Te3 after the iron ion irradiation, which increased the active sites. Moreover, the conductivity of the iron ion-irradiated Bi2Te3 nanosheets was also significantly improved. It is noteworthy that iron ion irradiation changed the characteristic of the Bi2Te3 surface from hydrophobic to hydrophilic, which facilitated the release of hydrogen bubbles from the catalyst surface and exposed the active sites in time. At the same time, the damage caused by the large bubbles to the electrode material could be avoided, and the stability of the material was improved. This efficient iron ion irradiation method provides an innovative idea for the design of other high-efficient catalysts.

Phosphorus-doped CoTe2/C nanoparticles create new Co-P active sites to promote the hydrogen evolution reaction.

Doping has been widely recognized as an effective method for adjusting the performance of electrocatalysts. It can cause changes in the electronic structure of substances. Thereby, it can affect the intrinsic catalytic performance. Herein, we report a facile doping method in which phosphorus can be simultaneously doped into both CoTe2 and C. In the acidic solution, the hydrogen evolution reaction (HER) performance of the obtained P-CoTe2/C nanoparticles was significantly improved compared with that of undoped nanoparticles. At a current density of 10 mA cm-2, the overpotential decreased from 430 mV to 159 mV. Density functional theory (DFT) calculations show that phosphorus doping can produce new high activity Co-P catalytic sites. In addition, phosphorus can be doped into the carbon in the composite at the same time, which enhances the electrical conductivity of the composite. Moreover, in the process of calcination and doping, the electric double layer capacitance (Cdl) of the composite is significantly increased, which helps in exposing more active sites. This work has developed a multi-effect doping method that simultaneously increases the intrinsic activity, conductivity and active sites of the material. This method provides a new strategy for the performance regulation of other electrocatalysts.