Chang Woo Kim

We present the design, synthesis, and evaluation of novel metal-free photosensitizers based on D-π-A structures featuring tri-arylamine as an electron donor, cyanoacrylic acid as an anchoring group, and substituted derivative π-bridges including 9,9-dimethyl-9H-fluorene, benzo[b]thiophene, or naphtho [1,2-b:4,3-b′]dithiophene. The aim of the current research is to unravel the relationship between chemical structure and photovoltaic performance in solar cell applications by investigating the properties of these organic sensitizers. The newly developed photosensitizers displayed variations in HOMO-LUMO energy gaps and photovoltaic performances due to their distinct π-bridge structures and exhibited diverse spectral responses ranging from 343 to 490 nm. The t-shaped and short linear photosensitizers demonstrated interesting behaviors in dye-sensitized solar cells, such as the effect of the molecular size in electron recombination. The study showed that a t-shaped photosensitizer with a bulky structure reduced electron recombination, while short linear photosensitizers with a smaller molecular size resulted in a higher open-circuit voltage value and enhanced photovoltaic performance. Impedance analysis further supported the findings, highlighting the influence of dye loading and I₃⁻ ion surface passivation on the overall performance of solar cells. The molecular design methodology proposed in this study enables promising photovoltaic performance in solar cells, addressing the demand for highly efficient, metal-free organic photosensitizers.

A NbN catalyst is prepared by the urea-glass route for NRR, with the produced NH₃ originating from the leaching of NbN, rather than from an electrochemical reaction.

Sung Min Heo, Dae Geon Won, Dae Hee Son, Tai Kyung Hwang, and Chang Woo Kim. Applied Science and Convergence Technology 2023;32:77-81. https://doi.org/10.5757/ASCT.2023.32.3.77

Anion vacancies in a ZnO@ZnSe@g-C₃N₄heterojunction for enhanced charge separation.

[This corrects the article DOI: 10.1021/acsomega.2c03897.].

The current work describes room-temperature gas sensing performances using an oligoacenaphthylene (OAN)/p-hydroxyphenylacetic acid (p-HPA) composite. Based on inverse gas chromatography (IGC), the London dispersive surface energy γ_s ^d is calculated by using 14 representative models. Even when the γ_s ^d values of both OAN and the OAN/p-HPA composite are decreased as the temperature increases, the surface of OAN shows a higher value than that of the composite. The Gibbs surface free energy values of both are decreased with an increasing temperature. In our results, higher Lewis basic characters are observed in OAN and the OAN/p-HPA composite and the OAN/p-HPA surface exhibits a higher basicity compared to OAN. Because of the presence of phenolic groups in the OAN/p-HPA composite, the more important basic character drives a significant CO gas sensing ability with a sensitivity of 8.96% and good cycling stability as compared to the pristine counterparts. It is expected that the current study sheds light on a new pathway to exploring polymer composite materials for futuristic diverse and multiple applications, including IGC and gas sensor applications.

Two-dimensional graphitic carbon nitride (g-C₃N₄) has generated tremendous attention in room temperature (RT) gas-sensing applications because of its physicochemical characteristics.

In the current work, the surface thermodynamic properties of Amberlite XAD‐7 acrylic‐ester‐resin have been determined. The inverse gas chromatography (IGC) technique at infinite dilution was applied to estimate the London dispersive surface free energy was estimated by using the well‐known Fowkes equation, Dorris–Gray relation, Hamieh–Dorris–Gray model and six other molecular models based on the values of the surface areas of organic molecules and Hamieh model considering the thermal effect. The London dispersive surface free energy values are reduced by increasing temperature in all used methods and models. The Gibbs surface free energy of the adsorption values also decreased by increasing temperature in all 14 methods such as that of Swayer–Brookman, Saint–Flour Papirer, Donnet, Brendlé and Papirer, Chehimi et al, Hamieh methods (thermal method) and the methods of the enthalpy of vaporization as a function of the temperature and the standard enthalpy of formation and the six molecular models. The Lewis acidity parameter and Lewis basicity parameter, was calculated by the above stated 14 methods. The surface character “S” value was estimated to be greater than one in all the 14 methods. This indicate that the Amberlite XAD‐7 polymer material contains mostly basic sites than the acidic sites, and it can be strongly interactive with an acidic media. In addition, the visual traits such as pore size distribution, surface roughness and intricate surface morphology of the polymer resin in its original form have been explored using computer vision techniques.