A sensitive sandwich-type electrochemical immunosensor for the detection of hepatitis B e antigen (HBeAg) was successfully developed based on the gold@palladium nanoparticles (Au@Pd NPs) loaded by molybdenum disulfide functionalized multiwalled carbon nanotubes (Au@Pd/MoS 2 @MWCNTs). The resultant nanocomposites not only possessed high specific surface area and good biocompatibility , but also exhibited excellent electro-catalytical property. Au NPs functionalized porous graphene oxide (p-GO@Au) were used as sensing platforms and primary antibodies carriers, which can accelerate the electron transfer and improve the load capacity of primary antibodies (Ab 1 ), improving the sensitivity of the immunosensor. Under optimal conditions, the designed immunosensor could detect target HBeAg concentration in the range from 0.1pg/mL to 500 pg/mL, with a low detection limit of 26 fg/mL (S/N = 3) for HBeAg. Additionally, the designed immunosensor showed excellent specificity, good reproducibility and acceptable stability. The satisfactory results in analysis of human serum samples indicated that it had potential application in clinical monitoring of tumor markers.
Fabricating solution-processable composite materials of transition metal dichalcogenides (TMDs) with ultrasmall noble metal structures employing an easy preparation method poses a significant challenge. In this study, we utilized a green, one-step synthetic method by directly employing electrochemical lithium intercalation-based exfoliated metallic TMD nanosheets (MoS2, WS2, and TiS2) to reduce palladium ions (Pd2+) to metallic Pd0, leading to the deposition on their surfaces. The resulting Pd nanoparticles (Pd NPs) in composites (Pd-MoS2, Pd-WS2, and Pd-TiS2) were found to be amorphous, with a size ranging from 0.81 to 1.37 nm. The impact of Pd NP size on hydrogen evolution reaction (HER) activity was elucidated. Among the fabricated composites, Pd-MoS2 exhibits the best HER performance, attributed to its smallest Pd NP size (0.81 nm). It shows an overpotential of 70 mV at a current density of 10 mA cm−2, along with a Tafel slope of 43 mV dec−1. These HER performance metrics surpass those of most Pd-decorated 2D catalysts.
A general and facile method for water-dispersed noble metal (Au, Ag, Pd, Pt) nanocrystal modified MoS2 nanosheets (NM–MoS2 NSs) has been developed. By using sodium carboxymethyl cellulose as a stabilizer, well-dispersed NM–MoS2 NSs with homogeneously deposited noble metal nanocrystals (NM NCs) can be synthesized in aqueous solutions. Due to the transition from the semiconducting 2H phase to the metallic 1T phase, the chemically exfoliated MoS2 (ce-MoS2) NSs have improved electrochemical activity. The partially metallic nature of the ce-MoS2 NSs and the catalytic activity of the NM NCs synergistically make NM–MoS2 NSs a potential electrochemical catalyst. For the first time, Pd–MoS2 NSs were used as an electrocatalyst for methanol oxidation in alkaline media. The results showed that Pd–MoS2 NSs have enhanced catalytic activity with 2.8-fold anodic peak current mass density compared to a commercial Pd/C catalyst, suggesting potential for application in direct methanol fuel cells (DMFCs).
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