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In this paper, the pyrrolic nitrogen functional group’s presence is investigated in the selective adsorption of CO2. The grand canonical Monte Carlo (GCMC), molecular dynamics (MD), and density functional theory (DFT) were used for this study’s goal. GCMC was used to calculate adsorption isotherms, selectivity, and isosteric heats. MD was used to calculate the radial distribution function (RDF) and diffusion. Reactivity parameters, electrostatic potential (ESP), reduced density gradient (RDG), and independent gradient model (IGM) were calculated using DFT. Adsorption isotherms, selectivity, and isosteric heats demonstrated that the NH group caused the selective adsorption of CO2 among CH4, CO, and N2 gases. The adsorption quantities for CO2, CH4, CO, and N2 are 4.77, 2.65, 2.38, and 2.09 average loading (per cell), respectively, at 10 MPa and 298 K. Furthermore, the thermodynamic parameters and Henry’s constant were calculated, indicating that CO2 adsorption is more dependent on temperature than that of other gases. RDF results showed an effective interaction between oxygen and carbon of CO2 and hydrogen and nitrogen of NH, respectively. Additionally, ESP results revealed that the NH group changed the electron’s density in the molecule surface, causing a more vital interaction between CO2 and NH, confirming the RDG and IGM results.

The oxygen evolution reaction (OER) with its sluggish kinetics has imposed a significant barrier to the sustainable and green generation of hydrogen fuel (via electrolysis of water) and the development of metal-air batteries. In this study, we report an efficient and novel OER electrocatalyst based on NiSe 2 nanoparticles (NPs) and the naturally abundant halloysite clay mineral. The NiSe 2 /halloysite nanocomposite (NiSe 2 /H) was prepared by a simple one-step hydrothermal route. The electrocatalytic performance of the as-synthesized nanocomposite and its components (pristine NiSe 2 and halloysite) toward OER in 1.0 KOH solution was examined. The NiSe 2 /H nanocomposite exhibited a significantly enhanced catalytic activity in OER, with a low overpotential of 235 mV (measured at the current density of 60 mA cm −2 ), a Tafel slope of 146 mV dec −1 , and an outstanding long-term electrochemical durability for 16 h. Moreover, this nanocomposite required only 340 mV of overpotential to deliver the high current density of 250 mA cm −2 . Further investigations revealed that the improved catalytic performance of NiSe 2 /H can be attributed to the increased number of active sites and the optimized adsorption energy of OH − . These results indicate that NiSe 2 /H is a promising non-precious metal-based catalyst for alkaline OER.

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The oxygen evolution reaction (OER) as the anodic half-reaction of water electrolysis has received growing attention due to its paramount role in the green and sustainable production of hydrogen fuel...