Thanawit Kuamit

The influence of diaromatic π-linkers on the optoelectronic properties and photovoltaic performance of bis-N,N-dimethylaniline–cyanoacrylic acid (bis-DMA-CAA)-based dye-sensitized solar cells (DSSCs) was systematically investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT). A series of donor–π–acceptor (D–π–A) dyes incorporating monoaromatic and diaromatic π-linkers with non-fused, fused, and inverted fused-ring configurations was designed and evaluated. The calculated optical and photovoltaic descriptors included the maximum absorption wavelength (λmax), oscillator strength, light-harvesting efficiency (LHE), electron-injection free energy (ΔGinject), dye-regeneration free energy (ΔGregen), charge-recombination free energy (ΔGCR), and vertical dipole moment (μnormal).Extending the π-conjugated system generally produced a pronounced bathochromic shift and enhanced light-harvesting capability, with non-fused diaromatic linkers exhibiting the longest absorption wavelengths, reaching 716 nm. Although fused diaromatic systems displayed distinct electronic behavior associated with linker aromaticity, no universal correlation between aromaticity and optical properties was observed. Evaluation of the photovoltaic descriptors showed that all designed dyes possessed thermodynamically favorable electron-injection properties; however, their overall DSSC performance depended on a balance among charge injection, regeneration, recombination, and dipole moment. A comprehensive scoring analysis identified AO-O, AS-S, ACC, and ANiN as the most promising sensitizers, with the non-fused dithiophene-linked AS-S dye offering the best overall balance among light harvesting, open-circuit voltage, and charge-transfer characteristics. These results demonstrate that replacing monoaromatic π-linkers with appropriately designed diaromatic linkers is an effective strategy for improving the predicted performance of bis-DMA-based DSSC sensitizers and provides valuable guidelines for the rational design of next-generation metal-free organic dyes.

Metal–organic framework (MOF) catalysts are promising platforms for hydrogen energy systems, enabling CO ₂ conversion to formic acid (HCOOH), a liquid organic hydrogen carrier (LOHC) for hydrogen storage and release. Density functional theory (DFT) calculations (M06‐2X/6‐31G(d)/LANL2DZ) are performed to investigate CO ₂ hydrogenation on PCN‐250(Fe) clusters featuring frustrated Lewis pair (FLP) sites formed by linker removal. The full hydrogenation pathway, including H ₂ adsorption, activation, and HCOOH formation, is explored, with HCOOH formation identified as the rate‐determining step. Activation barriers from large and small cluster models are consistent (10.0 and 9.4 kcal mol ⁻¹ ). Secondary metal substitution at the Fe ₂ MO node is screened using first‐ and second‐row transition metals (Mn–Zn and Tc–Cd). Results show electronic effects dominate first‐row metals, whereas steric effects govern second‐row systems. Kinetic volcano analysis identifies Cu(II) and Ru(III) as optimal catalysts for efficient CO ₂ hydrogenation, supporting rational design of MOF‐based hydrogen storage and conversion systems for sustainable energy applications.

Metal-organic framework (MOF) catalysts are highly adjustable platforms for converting CO2 into valuable chemicals, especially formic acid (HCOOH), which is a promising liquid organic hydrogen carrier (LOHC) for safe and efficient energy storage. In this work, density functional theory (DFT) calculations at the M06-2X/6-31G(d)/LANL2DZ level were used to study CO2 hydrogenation to HCOOH over PCN-250(Fe) clusters with Frustrated Lewis pair (FLP) sites created by linker removal. The entire reaction pathway, including H2 absorption, H2 dissociation, and HCOOH formation, was mapped out, with HCOOH formation identified as the rate-determining step. To improve catalytic performance, auxiliary secondary metal substitution (M) at the Fe2MO node was systematically investigated using first-row (Mn, Co, Ni, Cu, Zn) and second-row (Tc, Ru, Rh, Pd, Ag, Cd) transition metals. Mechanistic analysis shows electronic effects primarily govern activation barriers for first-row metals, while steric effects are more impactful for second-row metals within the MOF structure. Finally, kinetic volcano plots based on the Gibbs free energy of key intermediates highlight Cu(II), Ru(III), and Tc(II) as the most promising secondary metals for efficient CO2 utilization. These insights offer a rational, bottom-up approach for designing defect-engineered Fe-based MOFs for sustainable fuel production.

We conducted a study to examine the impact of an external electric field on the curvature of metal and divalent metal ion doped 4N divacancy-defected graphene quantum dots (4N-GQDs), utilizing Density Functional Theory (DFT). We considered six common metal species, namely Ca, Ca²⁺, Cr, Cr²⁺, Fe, and Fe²⁺. Our findings reveal that the curvature of metal and divalent metal ion-doped-4N-GQDs increases as the external electric field strength rises in both positive and negative directions. However, the direction of curvature is contingent upon the orientation of the electric field, which is perpendicular to the 4N-GQD plane. The curvature directions of metal and divalent metal ion-doped-4N-GQDs under positive and negative electric fields are opposite. It is interesting to note that the HOMO–LUMO gap of metal and divalent metal ion doped 4N-GQDs can be altered by applying an external electric field exceeding ±0.020 a.u. Within this context, the gap for 4N-GQDs doped with these ions typically spans from 1.64 to 2.98 eV, which is lower than that of GQDs and undoped 4N-GQDs. As a result, we advocate a technique to deliberately induce curvature for metal and divalent metal ion-doped 4N-GQDs, thereby altering their electronic properties through the application of an external electric field. These materials show substantial promise as anchoring materials for electronic devices.

Investigating the mechanism of CO₂ electrochemical reduction to CO using Ni complex catalysts via DFT calculations.