No abstract

In this study, cadmium sulfide (CdS) quantum dots (QDs) and barium (Ba) (3 and 6 wt %)-doped CdS QDs were synthesized via a hydrothermal technique. The basic purpose of this work is to degrade methylene blue (MB) dye and evaluate density functional theory (DFT). The synthesized samples were characterized through X-ray powder diffraction (XRD), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HR-TEM), UV–vis spectrophotometer, PL, and density functional theory (DFT). The XRD (structural analysis) confirmed that the hexagonal crystal structure and crystallinity increased upon doping. Selected area electron diffraction (SAED) analysis confirmed the polycrystalline nature of the prepared QDs. The functional groups have been investigated using FTIR analysis. The surface and structural morphologies of the synthesized specimen have been investigated by applying TEM and FE-SEM, and it was found to exhibit the topology of QDs. In addition, optical characteristics have been investigated via UV–vis absorption spectroscopy, which exhibited a bathochromic shift (red shift) as a consequence of the reduction of the band-gap energy upon doping from 2.56 to 2.38 eV. PL analysis was used to observe the electron–hole recombination rate. Moreover, the electronic and optical properties of Ba-doped CdS were further explored using density functional theory. Pristine and Ba-doped QDs exhibit sufficient catalytic activity (CA) against the MB dye in all media as 62.59, 70.15, and 72.74% in neutral, basic, and acidic solutions, respectively.

Developing high-performance biocathodes remain one of the most challenging aspects of the microbial electrosynthesis (MES) system and the primary factor limiting its output. Herein, a hollow porous carbon (PC) fabricated with MXenes coated over an electrode was developed for MES systems to facilitate the direct delivery of CO 2 to microorganisms colonized. The result highlighted that MXene@PC (Ti 3 C 2 T x @PC) has a surface area of 434 m 2 /g. The Ti 3 C 2 T x @PC MES cycle shows that in cycle 4 and cycle 5, the values are −309.2 and −352.3. Cyclic voltammetry showed that the coated electrode current response (mA) increased from −4.5 to −20.2. The substantial redox peaks of Ti 3 C 2 T x @PC biofilms are displayed at −741, −516, and −427 mV vs Ag/AgCl, suggesting an enhanced electron transfer owing to the Ti 3 C 2 T x @PC complex coating. Additionally, more active sites enhanced mass transfer and microbial development, resulting in a 46% rise in butyrate compared to the uncoated control. These findings demonstrate the value of PC modification as a method for MES-based product selection.