Generalised two-dimensional correlation analysis of the Co, Ce, and Pd mixed oxide catalytic systems for methane combustion using in situ infrared spectroscopy

Application of a multi-channel in-situ infrared spectroscopy: The case of LLM-105

The thermal decomposition process of 2,6-diamino-3,5-dinitropyrazine-1-oxide(LLM-105)under several constant temperatures (100 °C, 115 °C, 130 °C, and 145 °C) have been studied by a multi-channel in-situ reaction system. Almost 1000 spectra were obtained within 24 days by Fourier-transform infrared spectroscopy (FT-IR). The thermal decomposition activation energies (E_α) of C-NH₂ and C-NO₂ in LLM-105 were calculated by the Arrhenius equation to be 89.65 and 145.09 kJ mol^-1, respectively. The thermal decomposition process of LLM-105 under long-term constant temperature is divided into two paths: intramolecular H-transfer and C-NO₂ partition. It is feasible to study the aging process of materials using a combination of a multi-channel in-situ reaction system and FT-IR, which can effectively monitor the evolution of structure.

Spectroscopic properties and activated mechanism of NO on isolated cationic tantalum clusters: A first-principles study

The adsorption and dissociation of NO on the cationic Ta₁₅⁺ cluster were investigated using the density-functional theory (DFT) calculations, and the Ta-centered bicapped hexagonal antiprism (BHA) structure of cationic Ta₁₅⁺ cluster can be identified as the global minimum, which reproduces well the infrared multiple photo dissociation (IR-MPD) spectrum. Our results show that the cationic BHATa₁₅⁺ cluster provides the hollow region for NO to interact effectively, and possess larger adsorption strength on the region than other sites. The density of states, charge density differences and frontier molecular orbitals were analyzed to understand the electronic properties of the stable NO-adsorbed isomers. The characteristic IR peaks of the firstly two low-lying isomers are properly assigned, in which the strongest IR peak originates from the N - O stretching vibration. For the dissociation of NO on the BHATa₁₅⁺ cluster, it is found that the reaction path II easily occurs rather than path I due to small reaction barrier, and the cluster may possess the great catalytic behavior to dissociate NO molecule. The present results will inevitably stimulate future theoretical and experimental studies for the design of novel Ta-based catalytic materials for the NO dissociation.

Application of modulation excitation-phase sensitive detection-DRIFTS for in situ/operando characterization of heterogeneous catalysts

A new more general method and guidelines for the implementation of modulation excitation-phase sensitive detection-diffuse reflectance Fourier transform spectroscopy (ME-PSD-DRIFTS).