Chaoqun Ma,Da Liu,Yanli Zhang,Jin Yong Lee,Jian Tian,Bingping Liu,Shihai Yan
Electrochemical ammonia synthesis (EAS) is considered to be an ecofriendly and sustainable method for artificial N 2 fixation. It is urgent to develop cost-effective and efficient electrocatalysts for EAS because present catalysts have low activity and poor selectivity. Herein, Fe 2 O 3 nanoparticles anchored on MoS 2 nanoflowers (Fe 2 O 3 @MoS 2 ) were developed as a highly efficient EAS electrocatalyst under ambient conditions. Electrochemical measurements indicate that Fe 2 O 3 @MoS 2 achieves a remarkable NH 3 yield of 112.15 μg h −1 mg cat −1 at − 0.6 V vs. reversible hydrogen electrode (RHE) and a high faradaic efficiency (FE) of 8.62% at − 0.4 V vs. RHE in 0.1 M Na 2 SO 4 , much better than the EAS performance of separate MoS 2 and Fe 2 O 3 . The superior electrochemical stability is confirmed by long-term (at least 24 h) continuous tests. Density functional theory (DFT) calculations show that Fe 2 O 3 @MoS 2 , compared to MoS 2 , is better able to activate inert N 2 molecules, as reflected by its greater adsorption energy (−0.32 eV vs. − 0.10 eV), greater N≡N bond distance (1.223 Å vs. 1.159 Å), lower energy barrier (0.40 eV vs. 0.78 eV), and greater charge transfer from active sites to N 2 molecules (1.16 e − vs. 0.62 e − ). Thus, this work provides new perspectives on the development of efficient EAS catalysts using MoS 2 -based materials as the substrate.
Core–shell structures and interfacial polarization are of great significance to meet the diversified requirements of microwave attenuation. Herein, α-Fe2O3@MoS2 nanocomposites are fabricated via a simple two-step hydrothermal process, in which MoS2 nanosheets as the shell are self-assembled and α-Fe2O3 microdrums are used as the core to constitute a special flower-like morphology with core–shell structure. This structure can provide more interface contact to achieve strong interfacial polarization and possibly offer more multiple reflection and scattering of electromagnetic waves. Furthermore, the microwave dissipation performances of α-Fe2O3@MoS2 nanocomposites can be significantly improved through construction of core–shell structure and flower-like morphology, controlling the content of α-Fe2O3 microdrums and adjusting the filler loading ratios. This work proves that the as-synthesized nanocomposites achieve excellent effective absorption bandwidth and outstanding electromagnetic wave absorption capabilities due to their special interfaces, core–shell structures and good impedance matching conditions. Therefore, α-Fe2O3@MoS2 nanocomposites are expected to be a novel and desirable candidate for high-performance electromagnetic wave absorbers.
A novel photoelectrochemical (PEC) aptasensor based on a dual Z-scheme α-Fe2O3/MoS2/Bi2S3 ternary heterojunction for the ultrasensitive detection of circulating tumor cells (CTCs) was developed. The α-Fe2O3/MoS2/Bi2S3 nanocomposite was prepared via a step-by-step route, and the photoproduced electron/hole transfer path was speculated by conducting trapping experiments of reactive species. α-Fe2O3/MoS2/Bi2S3-modified electrodes exhibited greatly enhanced photocurrent under visible light due to the double Z-scheme charge transfer process, which met the requirement of the PEC sensor for detecting larger targets. After the aptamer was conjugated on the photoelectrode through chitosan (CS) and glutaraldehyde (GA), when MCF-7 cells were presented and captured, the photocurrent of the PEC biosensing system decreased due to steric hindrance. The current intensity had a linear relationship with the logarithm of MCF-7 cell concentration ranging from 10 to 1×105 cells mL−1, with a low detection limit of 3 cell mL−1 (S/N = 3). The dual Z-scheme α-Fe2O3/MoS2/Bi2S3 ternary heterojunction-modified PEC aptasensor exhibited high sensitivity and excellent specificity and stability. Additionally, MCF-7 cells in human serum were determined by this PEC aptasensor, exhibiting great potential as a promising tool for clinical detection.
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