The oxidation of carbon monoxide (CO) to carbon dioxide (CO₂) is critical due to the harmful effects of CO emissions on human health and the environment. As a colorless and odorless gas, CO poses serious health risks, including headaches, fatigue, dizziness, and, in severe cases, death, primarily due to its interference with oxygen delivery to the brain. CO emissions from sources such as automobiles, power generators, and industrial processes continue to significantly contribute to air pollution, especially in developing nations. This study employs a computational approach to compare the catalytic effectiveness of noble and non-noble metals in the oxidation of CO to CO₂. The investigation explores various adsorption modes of surface oxygen, CO, and CO₂ across selected metal surfaces. The results highlight the comparative catalytic potential of noble versus non-noble metals in facilitating CO oxidation. Insights from this study could play a critical role in optimizing CO oxidation strategies to reduce harmful emissions, thereby contributing to improved air quality and environmental sustainability, particularly in communities most affected by CO pollution. The findings have important implications for the development of more efficient and sustainable catalytic converters and exhaust treatment systems. By enhancing the understanding of CO oxidation on different metal surfaces, this research can inform the design of better emission control technologies, promoting both environmental sustainability and improved air quality. Ultimately, this study emphasizes the need to continue refining catalytic processes to tackle the global challenge of air pollution and its associated health risks.

Amidst the widespread enthusiasm for machine learning, one often-overlooked domain is predictive catalysis. In the realm of computational chemistry for sustainability, this research group advocates for the maximum utilization of predictive catalysis, employing machine learning principles. Their endeavors extend beyond identifying reaction mechanisms; once the rate-determining state (rds) is established, the focus shifts to exploring alternative catalysts, aiming for more benign reaction conditions. The computational research spans various domains, encompassing processes such as olefin metathesis using Ru-based catalysts, gold chemistry for organometallic reactions, and green chemistry strategies for CO₂ avoidance or reduction, including water oxidation catalysis and alcohol transformation to aldehydes with H₂ generation as an energy source ^[1].

DFT calculations have unveiled the mechanisms underlying the formation of N-substituted hydrazones through the coupling of alcohols and hydrazine, achieved via sequential processes of acceptorless dehydrogenation and borrowing hydrogen ^[2,3]. This process, facilitated by a Mn-PNN pincer-based catalyst, aligns with green chemistry principles, releasing water and H₂ as environmentally friendly byproducts ^[3].

This research also delves into the reductive amination of aliphatic carbonyl compounds catalyzed by a Knölker-type iron catalyst. Utilizing DFT calculations and a detailed chemical structure analysis, the team investigates the reaction mechanism ^[4]. Armed with insights into the mechanism, various catalyst modifications are explored with the goal of steering catalytic reactions towards milder conditions.

The simulations of electrochemical performances of perovskite materials for hydrogen oxidation reactions (HOR) in H₂ gas environments were investigated using planewave-based Density Functional Theory (DFT) modeling, and the simulation results unveiled significant findings. The impacts of the oxygen chemical potential and surface hydrogen bonding interactions, when the steam content in the H₂ gas and nonstoichiometry of the perovskite (001) slabs varied, were found to significantly alter the HOR energy landscapes. In the realm of the CO₂ capture reaction with NH₃ as a model amine solvent, the variational quantum eigensolver (VQE)-based algorithms have shown remarkable predictive quality, enhancing calculations of vibrational ground-state energies, addressing molecular anharmonicity [2], and providing results for the reacting and producing molecules in the CO₂ capture reaction with accuracy that rivals the direct diagonalization method for CO₂ and NH₃. The performances and computing cost of the VQE algorithms implemented on current quantum simulators and hardware will be further discussed.

References:

1. Positive Effects of H₂O on the Hydrogen Oxidation Reaction on Sr2Fe_1.5Mo_0.5O_6−δ-Based Perovskite Anodes for Solid Oxide Fuel Cells, ACS Catalysis, 2020. 10(10): p. 5567-5578, doi:10.1021/acscatal.9b05458.
2. Description of reaction and vibrational energetics of CO₂–NH₃ interaction using quantum computing algorithms, AVS Quantum Science, 2023. 5(1): p. 013801, doi: 10.1116/5.0137750.

Strontium oxide (SrO) is a promising material for CO₂ capture through a reversible cycle of carbonation and calcination, where SrO reacts with CO₂ to form strontium carbonate (SrCO₃) and can be regenerated by calcination. In the presence of moisture, SrO forms strontium hydroxide and its hydrates (Sr(OH)₂×nH₂O). This study employs density functional theory (DFT) to investigate the underlying mechanism of these processes on various crystal surfaces of SrO, Sr(OH)₂, Sr(OH)₂·H₂O, and Sr(OH)₂·8H₂O. The interaction of CO₂ with these surfaces leads to carbonate formation via electron transfer, with notable differences in CO₂ orientation and bond characteristics between SrO and the hydroxylated surfaces. The hydration of SrO increases the CO₂ surface adsorption energy with the exception of the monohydrate. CO₂ adsorption reaction on the Sr(OH)₂·H₂O surface is more thermodynamically favorable than on the anhydrate and octahydrate surfaces. Reaction pathway analysis reveals that bicarbonate formation is preferred on the anhydrate and octahydrate surfaces, while carbonate formation is favored on the SrO and monohydrate surfaces. The CO₂ removal reaction from the SrCO₃ surface is also investigated. This study provides valuable insights into the fundamental mechanism for CO₂ capture using SrO and its hydrated forms.

Introduction: The activation of dinitrogen is essential for sustainable ammonia synthesis, a critical process for agricultural and energy applications. Transition metal catalysts, including iron, ruthenium, and cobalt, along with bi-, tri-, and multimetallic alloys, are pivotal in enhancing this activation within the Haber--Bosch process.

Methods: This study summarizes theoretical modeling techniques within the density functional theory utilizing functionals such as PBE and RPBE, as well as database investigations, to demonstrate the performance of various transition metal catalysts in activating dinitrogen. Key physical property changes, such as bond length elongation, vibrational red-shifts, and charge transfer dynamics, will be presented.

Results: Our findings reveal that specific transition metal catalysts that contain iron/cobalt/ruthenium can enhance nitrogen activation upon adsorption, leading to measurable alterations in the nitrogen molecule's physical properties, as discussed in some recent studies. Notably, we delineate a marked decrease in activation energy for the dissociative adsorption of nitrogen, indicating improved reaction kinetics. Furthermore, detailed analysis of the hydrogenation reaction mechanism provides insights into the underlying processes that govern surface reactivity.

Conclusions: Advancements in transition metal catalysis for dinitrogen activation not only enhance ammonia synthesis efficiency, but have also contributed to the development of more sustainable chemical processes in recent years. These insights pave the way for innovative approaches in catalysis, with the potential to significantly impact future energy solutions and agricultural practices. Continued research in this area is essential for realizing the full potential of sustainable ammonia production.

Charged species are often found in various chemical processes such as catalysis, electrochemistry and acid–base reactions. DFT studies are always used to gain an in-depth understanding of these reactions. However, in periodic metallic systems, the presence of charge in supercells faces serious convergence problems, and a new method is needed to calculate charged slabs to study the reactions involving charged species.

To study the heterogeneous catalysis reactions, a simple method is proposed for the calculations of charged adsorbents. The DFT calculations are performed using the VASP package. The VASPsol solvation model and Grimmie dispersion corrections are considered in all calculations. The transition state for each reaction is located using the climb-NEB method. The zero point vibrations (ZPE) are obtained using the harmonic oscillator approximation to confirm the ground state and transition state geometries.

In the proposed new approach, a counter ion is placed at a non-interactive distance in the supercell, in an aqueous medium, to maintain the neutral behaviour of the systems while the adsorbents are charged. The charged species are confirmed using the Bader charged analysis. The method is used to study the adsorption of monovalent anions such as halides, hydroxides and H^- and bivalent anions such as Se^2- and SO₄^2-. The method is later used to study the detailed mechanism of BH₄^- hydrolysis on Ag⁰ and Au⁰ surfaces, and the obtained conclusions are validated with experiments. This approach offers a valuable method for studying the charged species in the catalytic process.

The current energy scenario is changing and challenging, with a current trend focused on the search for alternative energy sources to reduce energy dependence due to different factors such as geopolitical aspects, among others. In this sense, apart from the obvious environmental advantages compared to refineries based on oil, biorefineries based on different wastes (with a difficult management approach) could be an interesting starting point to foster sustainable economic growth of different areas around the world. For instance, biogas is a promising energy source with endless opportunities, depending on its final use. In this sense, a gas with a relatively homogeneous gas composition can be obtained from variable wastes (agro-industrial, wastewater, manure, etc.), with a wide range of technologies related to energy production (upgrading, steam reforming, Fischer--Tropsch synthesis, etc.). However, high efficiency for these biorefineries is required in order to compete with traditional refineries. In this context, the role of catalysts is essential, which can have an influence on biorefinery processes (and, equally, these processes can influence their catalytic performance). Considering the above, the aim of this work was to assess, according to our own experience and resorting to the literature, different aspects related to catalytic conversion of biogas through different technologies (mainly steam reforming and Fischer--Tropsch synthesis). As a result, several recommendations like the use of high-quality biogas and purification technologies are offered in order to improve the efficiency of these processes.

Lignin is one of the most abundant renewable materials on Earth. Despite representing a significant carbon and energy resource with great potential as a source of aromatic compounds, lignin is often treated as waste in the context of lignocellulosic biomass biorefineries. The electrochemical oxidation of biomass waste (e.g., lignin) from biorefineries and pulping mills represents a potentially renewable development for hydrogen production with the co-generation of valuable marketable chemicals. By using a low-voltage anodic oxidation process, this method might significantly lower the cost of producing hydrogen and industrial, value-added compounds. Biomass compounds such as lignin have primarily been studied electrochemically on costly metal electrodes up to this point. Therefore, non-precious metal-based electrocatalysts, such as Iron (Fe), Nickel (Ni), Copper (Cu), Manganese (Mn), etc., were synthesized with a simple innovative method, thoroughly characterized, and tested for the electro-oxidation of Phenol, 4-phenoxy phenol, and lignin. The surface area available for electrochemical reactions is increased by nanoparticle electrocatalysts, which may result in better mass transport of reactants and products across the electrocatalyst layer. Non-precious metal electrocatalysts also enable special alloying and the synergistic interaction of several metals. Our research explores the utilization of non-precious metal nanoparticle electrocatalysts for the electrochemical lignin oxidation approach to promote hydrogen production.