Significance of Surface Formate Coverage on the Reaction Kinetics of Methanol Synthesis from CO₂ Hydrogenation over Cu

The hydrogenation of CO₂ to methanol over copper-based catalysts has attracted considerable attention recently. Among all the proposed reaction mechanisms, a large number of experimental and theoretical studies have focused on the one that includes a HCOO intermediate due to the fact that high coverages of formate over catalyst surfaces were observed experimentally. To systematically understand the influence of formate species coverage on the reaction kinetics of methanol synthesis, the energetics of the CO₂ hydrogenation pathway over clean and one- or two-formate preadsorbed Cu(211) are obtained using density functional theory calculations, and these energetics are further employed for microkinetic modeling. We find that the adsorption energies of the intermediates and transition states involved in the reaction pathway are changed in the presence of spectating formate species, and consequently, the potential energy diagrams are varied. Microkinetic analysis shows that the turnover frequencies (TOFs) over different formate preadsorbed surfaces vary under the same reaction condition. In particular, the reaction rates obtained over clean Cu(211) are generally the lowest, while those over one- or two-formate preadsorbed surfaces depend on the reaction temperatures and pressures. Meanwhile, we find that only when the formate coverage effect is considered, some of the TOFs obtained from microkinetic modeling are in fair agreement with previous experimental results under similar conditions. After the degree of rate control analysis, it is found that the combination of HCOO and HCOOH hydrogenation steps can be treated as the “effective rate-determining step”, which can be written as HCOO* + 2H* → H₂COOH* + 2*. Therefore, the formation of methanol is mainly controlled by the surface coverage of formate and hydrogen at the steady state, as well as the free energy barriers of the effective rate-determining step, i.e., effective free energy barriers

One of the 134 parsimonious trees derived from <i>TrnL/F</i> sequence data was conducted using heuristic search with TBR branch swapping.

<p>Numbers above branches are MP bootstrap values and Bayesian posterior probability (PP) values, respectively. <i>Bromus tectorum</i> was used as an outgroup. Consistency index (CI) = 0.903, retention index (RI) = 0.941.</p

One of the 570 parsimonious trees derived from <i>pepc</i> sequence data was conducted using heuristic search with TBR branch swapping.

<p>Numbers above and below branches are bootstrap values from MP and Bayesian posterior probability (PP) values, respectively. <i>Bromus tectorum</i> was used as an outgroup. Consistency index (CI) = 0.735, retention index (RI) = 0.906.</p

Effects of iNO on lung eNOS expression at day 7.

<p>(A) eNOS mRNA expression (normalized to GAPDH) increased in the iNO group compared to the Con group. (B) Representative immunohistochemical images show enhanced eNOS expression in iNO relative to ARDS. (* P<0.05 vs. Con group. n = 5–6 in each group).</p

Vessel density of animals in different groups at day 7.

<p>(A) Representative photomicrographs (×400) illustrating Factor VIII staining to identify blood vessels in the lung. (B) The number of vessels per high-powered field is significantly higher in the iNO group relative to the ARDS group. (* <i>P</i><0.05 vs. ARDS group, n = 5–6 in each group).</p

Table_1_Unraveling the spatial–temporal distribution patterns of soil abundant and rare bacterial communities in China’s subtropical mountain forest.XLS

IntroductionThe pivotal roles of both abundant and rare bacteria in ecosystem function are widely acknowledged. Despite this, the diversity elevational patterns of these two bacterial taxa in different seasons and influencing factors remains underexplored, especially in the case of rare bacteria.MethodsHere, a metabarcoding approach was employed to investigate elevational patterns of these two bacterial communities in different seasons and tested the roles of soil physico-chemical properties in structuring these abundant and rare bacterial community.Results and discussionOur findings revealed that variation in elevation and season exerted notably effects on the rare bacterial diversity. Despite the reactions of abundant and rare communities to the elevational gradient exhibited similarities during both summer and winter, distinct elevational patterns were observed in their respective diversity. Specifically, abundant bacterial diversity exhibited a roughly U-shaped pattern along the elevation gradient, while rare bacterial diversity increased with the elevational gradient. Soil moisture and N:P were the dominant factor leading to the pronounced divergence in elevational distributions in summer. Soil temperature and pH were the key factors in winter. The network analysis revealed the bacteria are better able to adapt to environmental fluctuations during the summer season. Additionally, compared to abundant bacteria, the taxonomy of rare bacteria displayed a higher degree of complexity. Our discovery contributes to advancing our comprehension of intricate dynamic diversity patterns in abundant and rare bacteria in the context of environmental gradients and seasonal fluctuations.</p

Data_Sheet_1_Unraveling the spatial–temporal distribution patterns of soil abundant and rare bacterial communities in China’s subtropical mountain forest.docx

IntroductionThe pivotal roles of both abundant and rare bacteria in ecosystem function are widely acknowledged. Despite this, the diversity elevational patterns of these two bacterial taxa in different seasons and influencing factors remains underexplored, especially in the case of rare bacteria.MethodsHere, a metabarcoding approach was employed to investigate elevational patterns of these two bacterial communities in different seasons and tested the roles of soil physico-chemical properties in structuring these abundant and rare bacterial community.Results and discussionOur findings revealed that variation in elevation and season exerted notably effects on the rare bacterial diversity. Despite the reactions of abundant and rare communities to the elevational gradient exhibited similarities during both summer and winter, distinct elevational patterns were observed in their respective diversity. Specifically, abundant bacterial diversity exhibited a roughly U-shaped pattern along the elevation gradient, while rare bacterial diversity increased with the elevational gradient. Soil moisture and N:P were the dominant factor leading to the pronounced divergence in elevational distributions in summer. Soil temperature and pH were the key factors in winter. The network analysis revealed the bacteria are better able to adapt to environmental fluctuations during the summer season. Additionally, compared to abundant bacteria, the taxonomy of rare bacteria displayed a higher degree of complexity. Our discovery contributes to advancing our comprehension of intricate dynamic diversity patterns in abundant and rare bacteria in the context of environmental gradients and seasonal fluctuations.</p

General conditions and oxygenation values at 0 h.

<p>Values are means ± SD. Cdyn, dynamic compliance.</p

Lung CD34 and CD133 mRNA expression at day 7.

<p>In the iNO group, lung CD34 (A) and CD133 (B) mRNA levels were increased compared to the Con and ARDS groups. (* <i>P</i><0.05 vs. ARDS group; † <i>P</i><0.05 vs. Con group; n = 5–6 in each group).</p

Effects of iNO on NO₂⁻/NO₃⁻ and MMP-9 in bone marrow.

<p>(A) In the iNO group, the NO₂⁻/NO₃⁻ concentration was increased at 72 h compared to the ARDS group. In the ARDS group, the NO₂⁻/NO₃⁻ level decreased at 24 and 72 h compared to baseline. (B) MMP-9 expression measured by Zymography in bone marrow, A–D represent ARDS, G-CSF, iNO and Con, respectively. (C) Inhaled NO enhanced the MMP-9 expression at day 1 and 3. (* <i>P</i><0.05 vs. B; † <i>P</i><0.05 vs. ARDS group. n = 5–6 in each group).</p