ABSTRACT
Motivated by a recent study on the air stability of PdSe2, which also reports the metastability of the PdO2 monolayer [Hoffman A. N.. npj 2D Mater. Appl.2019, 3( (1), ), 50.], in this work, we use density functional theory (DFT) to further explore the thermal, dynamic, and mechanical stability of monolayer PdO2 and study its structural and electronic properties. We further studied its vertical heterojunction composed of 1T-PdO2 and graphene monolayers. We show that both the monolayer and the heterojunction are energetically and dynamically stable with no negative frequencies in the phonon spectrum and belong to the vdW-type. 1T-PdO2 is an indirect-band-gap semiconductor with band-gap values of 0.5 eV (GGA) and 1.54 eV (HSE06). The interface properties of the heterojunction show that the n-type Schottky barrier height (SBH) becomes negative at the vertical interface in the PdO2/graphene contact, forming an Ohmic contact and mainly suggesting the potential of graphene for efficient electrical contact with the PdO2 monolayer. However, at the same time, a negative band bending occurs at the lateral interface based on the current-in-plane model. Moreover, the optical absorption of the PdO2/graphene heterojunction under visible-light irradiation is significantly enhanced compared to the situation in their free-standing monolayers.
ABSTRACT
Bisphenol A (BPA) is an endocrine disruptor that leaches into food and is significantly employed in food and beverage storage, and source water cycles. To ensure an outstanding and sustainable biosphere while safeguarding human health and well-being, BPA detection is essential, necessitating an efficient detection methodology. Here, we describe an easy-to-use, inexpensive, and overly sensitive electrochemical detector that uses Fe-MOF nanotextures for identifying BPA in groundwater. This sensing electrode device combines the excellent guest interaction potential of organic ligands with the substantial surface area of metal. Using various analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (XRD), the structural and physicochemical behaviors of the as-synthesized material were evaluated. Electrochemical BPA detection was enabled by a diffusion-controlled oxidation procedure with a comparable number of both protons and electrons. With a 0.1 µM detection limit, the sensor displayed a linear sensitivity of around 0.1 µM and 15 µM. Additionally, the sensors demonstrated an outstanding recovery with actual water samples as well as a repeatable and steady performance over the course of a month exhibiting minimal interference from typical inorganic and organic species. Due to its notable sensitivity, inexpensive cost, robust selectivity, excellent repeatability, and reuse ability, the electroanalytical possibilities of the Fe-MOF-modified GCE suggest that the device can be implemented into real-world applications in its primed condition.
ABSTRACT
The construction of a new electrochemical sensing platform based on a copper metal-organic framework (Cu-MOF) heterostructure is described in this paper. Drop-casting Cu-MOF suspension onto the electrode surface primed the sensor for glutathione detection. The composition and morphology of the Cu-MOF heterostructure were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), and UV-visible spectroscopy. The Cu-MOF heterostructure can identify glutathione (GSH) with an enhanced sensitivity of 0.0437 µA µM-1 at the detection limit (LOD; 0.1 ± 0.005 µM) and a large dynamic range of 0.1-20 µM. Boosting the conductivity and surface area enhances electron transport and promotes redox processes. The constructed sensors were also adequately selective against interference from other contaminants in a similar potential window. Furthermore, the Cu-MOF heterostructure has outstanding selectivity, long-term stability, and repeatability, and the given sensors have demonstrated their capacity to detect GSH with high accuracy (recovery range = 98.2-100.8%) in pharmaceutical samples.