Computational Design of Spinel Oxides through Coverage-Dependent Screening on the Reaction Phase Diagram

Abstract

Binary spinel-type metal oxides provide additional opportunities to achieve various catalytic reactions. However, the complexity of the catalytic reaction network, particularly the one containing lattice O involved steps on oxide surfaces, makes it difficult to parse reliable reaction mechanisms. It further challenges the accurate description of catalytic activity in the computational design of catalysts. Therefore, in this work, the rational design of spinel oxides was set out with all elementary steps considered on either perfect or defect sites with also lattice O involved steps. As a result, 2108 possible reaction pathways were enumerated within a complete reaction network for HCl oxidation as a model reaction. The strategy of energy global optimization was performed to obtain favored mechanisms within all possible pathways, building an “energy level” activity trend, namely, the “reaction phase” diagram (RPD). The activity screening for 18 spinel oxides was conducted by descriptors on the RPD. Taking care of the poisoning effect by chloride on the surface, the coverage-dependent screening was performed to search more reliable candidates on the “energy level” trend. Six spinel oxides were finally selected from the coverage-dependent screening on the RPD, where the theoretical activity trend was validated by experiments. At the end, a rigorous rate calculation was performed by the coverage self-consistent microkinetic modeling on the most active surface (CuCo2O4). The reliability of models and approximations used in the scheme of coverage-dependent screening on the RPD, together with the importance of coverage effect, were discussed.

Cyanide-Isolated Cobalt Catalyst for Ultraefficient Advanced Oxidation Treatment

“…The self-consistent calculations applies a convergence energy threshold of 10 –5 eV, and the force convergency was set to 0.05 eV/Å. The Gibbs free energy (G, eV) corrections were considered at the temperature of 298 K, following Δ G = Δ E + Δ G ZPE + Δ G U – TΔ S , where Δ E , Δ G ZPE , Δ G U , and Δ S refer to the DFT-calculated energy change, the correction from zero-point energy, the correction from inner energy, and the correction from entropy. , …”

“…The Gibbs free energy (G, eV) corrections were considered at the temperature of 298 K, following ΔG = ΔE + ΔG ZPE + ΔG U − TΔS, where ΔE, ΔG ZPE , ΔG U , and ΔS refer to the DFTcalculated energy change, the correction from zero-point energy, the correction from inner energy, and the correction from entropy. 24,25 ■ RESULTS AND DISCUSSION Catalyst Synthesis and Characterization. Our hydrothermal synthesis yielded a black powder, characterized by a face-centered-cubic crystal structure matching that of cobalt hexacyanocobaltate (Figure 1a).…”

Deep Oxidation of Chlorinated VOCs by Efficient Catalytic Peroxide Activation over Nanoconfined Co@NCNT Catalysts

“…The electron transfer quantities were consistent with the adsorption energy of PMS in the catalyst configurations, conforming to "Sabatier's principle" (also known as the "Volcano curve") in theoretical calculation. 42,43 When the molecular adsorption energy was neither the strongest nor the weakest, it was the most favorable to proceed with the catalytic reaction. Although Co@NCNS had slightly higher electron transfer to PMS than Co@NCNT, it required more energy to dissociate PMS, explaining its poor catalytic activity for chlorobenzene removal.…”

Bioinspired porous three-coordinated single-atom Fe nanozyme with oxidase-like activity for tumor visual identification via glutathione

“…The self-consistent calculations apply a convergence energy threshold of 10 -5 eV, and the force convergency was set to 0.05 The reaction free energy was calculated following the computational hydrogen electrode (CHE) model. The free energy corrections were considered at the temperature of 298 K, following: ΔG = ΔE + ΔGZPE + ΔGU -TΔS where ΔE, ΔGZPE, ΔGU, and ΔS refer to the DFT calculated energy change, the correction from zero-point energy, the correction from inner energy and the correction from entropy 56 .…”