Cuicui Du

High visible light sensitive MoS2 ultrathin nanosheets for photoelectrochemical biosensing.

For the purpose of effectively utilizing the visible light, photoelectrochemical (PEC) detection represents a unique detection signal and different energy form of the excitation source. In this work, ultrathin MoS2 nanosheets with narrow band gap were successfully fabricated by a facile C3N4 sacrificial template assisted thermolytical approach. Upon immobilizing glucose oxidase, excellent photocatalytic activity towards glucose is achieved in neutral buffer solution. As a novel visible light sensitive photocatalytic material, ultrathin MoS2 nanosheets present a detection limit of ~0.61nM, which is much lower than those with the similar configurations reported previously. Based on the excellent anti-interference property, the feasibility of applying the proposed sensor to determine glucose in human serum is further demonstrated. This work provides new insight into the fabrication of promising visible light sensitive two-dimensional layered transition-metal chalcogenides nanostructures for construction of photoelectrochemical biosensors.

Confining MoS2 nanodots in 3D porous nitrogen-doped graphene with amendable ORR performance

MoS2 nanodots (NDs) were successfully embedded in the three-dimensional (3D) porous frameworks of N-doped graphene (NGr) via in situ pyrolysis of glucose, a layered C3N4 sacrificial template and monolayered MoS2 NDs. The monolayered MoS2 NDs were hydrothermally pre-synthesized and acted as size-controlled precursors. By varying the content of the MoS2 NDs, a series of MoS2 NDs/NGr was obtained, which displayed amendable activity towards oxygen reduction reaction (ORR) in basic solution, due to the balance between the exposed edge sites of the MoS2 NDs and the internal conductive channels of the 3D porous NGr. The optimal composition generated an efficient Pt-free ORR catalyst with good four-electron selectivity, and was shown to have a more positive shift in both the onset and peak potentials than its counterparts. The novel catalyst also demonstrated superior tolerance against methanol and better durability than commercial Pt/C.

Incorporated oxygen in MoS2 ultrathin nanosheets for efficient ORR catalysis

Controllable engineering of high-electronegativity oxygen (O)-heteroatoms into MoS2 ultrathin nanosheets is realized via a facile post-modification process. The incorporated oxygen atoms impart a dramatically enhanced ORR activity to the pristine nanosheets, with a 7.8-fold current increase as well as 180 mV and 160 mV positive shifts in both onset and half-wave potentials that are almost comparable with the commercial Pt/C catalyst. Furthermore, oxygen incorporation also triggers a transformation of the process from two-electron to a four-electron process. The improved topical conductivity, as well as the preferential adsorption of oxygen molecules originating from the heteroatoms engineering is supposed to be responsible for the efficient ORR. The prospect of controllably engineering heteroatoms into MoS2 ultrathin nanosheets with versatile applications is also highlighted in this work.

One-step pyrolytic synthesis of small iron carbide nanoparticles/3D porous nitrogen-rich graphene for efficient electrocatalysis

Uniform iron carbide nanoparticles (Fe3C, ∼10 nm), size evolved from nano-scaled Fe-MIL-88b, were one-pot pyrolytically embedded in 3D porous N-rich graphene. Extra ORR catalytic activity with four-electron selectivity was achieved in an alkaline electrolyte. The onset and peak potential were 10 mV and 40 mV more positive, respectively, than commercial Pt/C.

VS 2 quantum dot label-free fluorescent probe for sensitive and selective detection of ALP

AbstractAs an essential enzyme highly associated with various human diseases, alkaline phosphatase (ALP) plays an important role in human tissues. Developing new materials and strategies for monitoring ALP is thus important. We have developed a novel label-free fluorescent sensing system for ALP activity that is based on the “turn-on” fluorescence of VS2 quantum dots. The fluorescence of VS2 quantum dots quenched by Fe3+ can be restored by ascorbic acid, which is generated by hydrolysis of l-ascorbic acid 2-phosphate catalyzed by ALP. Rapid, convenient, and sensitive detection of ALP is achieved in the range from 3 to 1000 U/L (R2 =0.9985), with a detection limit of 0.27 U/L. The proposed sensor exhibits excellent selectivity for ALP compared with other enzymes and proteins, such as glucose oxidase, lysozyme, trypsin, human serum albumin, and bovine serum albumin. The reliability for ALP determination in human serum plasma has been demonstrated with satisfactory recovery, revealing promising application in clinical diagnosis and biomedical research. Graphical abstractHydrothermally synthesized VS2 quantum dots serving as a novel turn-on fluorescent probe for detection of alkaline phosphatase (ALP) activity. AA l-ascorbic acid, AAP l-ascorbic acid 2-phosphate, NAC N-acetyl-l-cysteine

Direct electrochemical growth of amorphous molybdenum sulfide nanosheets on Ni foam for high-performance supercapacitors

Crystalline molybdenum sulfides (MoSx) have gained much attention as electrode materials for supercapacitors due to their specific atomic structure and high theoretical specific capacitance. However, poor electric conductivity and few accessible active sites as well as strictly controlled synthetic processes limit their capacitive performances. In this work, amorphous MoSx (a-MoSx) nanosheets with porous structure was directly grown on Ni foam by a simple and low-cost electrodeposition technique. By using a-MoSx/Ni foam directly as the electrode material for supercapacitor, a high specific capacitance of 463 F/g was achieved at 1 A/g with good cycling stability at high rate. The isotropic and porous natures as well as ion reservoir function of the amorphous phase offers abundant active sites, transportation channels for ions and large electrode/electrolyte contact area, ensuring facile electrolyte diffusion within the active material. The strong adhesive of electrodeposited material to the underlying Ni foam substrate constructs an effective electron transport channel during the charging and discharging process. This work highlights the importance of electrodeposited amorphous MoSx for potential application in supercapacitors.