@article {48036, title = {From molecular adsorption to decomposition of methanol on various ZnO facets: a periodic DFT study}, journal = {Applied Surface Science}, volume = {602}, year = {2022}, month = {NOV}, pages = {154150}, type = {Article}, abstract = {

Methanol is an interesting and important molecule to study because of its potential to replace existing fuels. It is also a prominent hydrogen source which can be used to generate hydrogen in-situ. ZnO is widely used as catalyst in synthesis of methanol from CO2 at industrial scale. In this work, we demonstrate that the same catalyst could be used for MeOH decomposition. We have investigated interaction of methanol with various flat and stepped facets of ZnO by employing Density Functional Theory (DFT). Two flat [(10(1)overbar 0) and (11(2)overbar 0)] and two stepped [(10(1)overbar 3) and (11(2)overbar 2)] facets are studied in detail for methanol adsorption. Chemisorption of MeOH with varying strength is common to all four facets. Most importantly spontaneous dissociation of O-H bond of methanol is observed on all facets except (11(2)overbar 0). Our DFT calculations reveal that molecular adsorption is favored on flat facets, while dissociation is favored on step facets. Also, (10(1)overbar 0) facet undergoes substantial reconstruction upon MeOH adsorption. Activation of C-H bond along with strengthening of C-O bond on ZnO facets suggest partial oxidation of methanol. With our DFT investigations, we dig deeper into the underlying electronic structure of various facets of ZnO and provide rationale for the observed facet dependent interaction of ZnO with MeOH.

}, keywords = {DFT, MeOH, Surface interactions, ZnO}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2022.154150}, author = {Mehta, Shweta and Joshi, Kavita} } @article {48695, title = {Electronic fingerprints for diverse interactions of methanol with various Zn-based systems}, journal = {Surface Science}, volume = {736}, year = {2023}, month = {OCT}, pages = {122350}, type = {Article}, abstract = {

We have investigated various Zn-based catalysts for their interaction with methanol (MeOH). MeOH is one of the most critical molecules being studied extensively, and Zn-based catalysts are widely used in many industrially relevant reactions involving MeOH. We note that the same element (Zn and O, in the present study) exhibits different catalytic activity in different environments. The changing environment is captured in the underlying electronic structure of the catalysts. In the present work, we compared the electronic structure of Zn-based systems, i.e., ZnAl2O4 and ZnO along with oxygen preadsorbed Zn (O-Zn) and metallic Zn. We demonstrate the one-to-one correlation between the pDOS of the bare facet and the outcome of that facet{\textquoteright}s interaction (i.e. either adsorption or dissociation of MeOH) with MeOH. These findings would pave the way towards the in-silico design of catalysts.

}, keywords = {DFT, Electronic properties, Methanol, Zn-based systems, ZnO}, issn = {0039-6028}, doi = {10.1016/j.susc.2023.122350}, author = {Mehta, Shweta and Joshi, Kavita} } @article {49310, title = {From digital blueprint to chemical reality: methanol to formaldehyde at ambient conditions}, journal = {Applied Surface Science}, volume = {669}, year = {2024}, month = {OCT }, pages = {160527}, type = {Article}, abstract = {

Partial oxidation of methanol to value added product presents an intriguing yet challenging process. Among these products, formaldehyde is the simplest and one of the most vital aliphatic aldehydes, which has extensive application across various domains. Industrially, silver and iron-molybdenum oxides are used as catalysts for the conversion of methanol to formaldehyde at elevated temperatures (600 degrees C and 250-400 degrees C, respectively). However, in this computational and experimental study, we have demonstrated the efficacy of ZnO as a catalyst. Notably, in the presence of ZnO, methanol readily converts to formaldehyde even under ambient conditions. We employed periodic density functional theory (DFT) to explore (10 1 1) facet of ZnO to elucidate its interaction with methanol. Our comprehensive analysis identified the most active facet (10 1 1) involved in the spontaneous conversion of methanol to formaldehyde. Subsequently, experimental validation supported our theoretical findings, demonstrating the conversion of methanol to formaldehyde with 100\% selectivity at room temperature and atmospheric pressure in the presence of ZnO. This study exemplifies the pivotal role of theory in catalyst design.

}, keywords = {DFT, Formaldehyde, MeOH, ZnO}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2024.160527}, author = {Mehta, Shweta and Kasabe, Mirabai and Umbarkar, Shubhangi B. and Joshi, Kavita} } @article {50019, title = {When facets meet impurities: Trace gas dominance over CO2 adsorption on ZnO}, journal = {Applied Surface Science}, volume = {729}, year = {2026}, month = {MAY}, pages = {166151}, type = {Article}, abstract = {

The catalytic hydrogenation of CO2 to methanol using Cu-ZnO/Al2O3 (CZA) is a key route for sustainable chemical production, when coupled with CO2-rich industrial off-gases. However, trace secondary gases, though present only at ppm levels, can poison active sites and suppress catalytic performance. In this work, we employ periodic density functional theory (DFT) to investigate interactions of H2S, SO2, NO2, NO, CO and CH4 with ZnO surfaces:(10(-)10), (10(-)11), (11(-)20), (10(-)13), and (11(-)22), and compared their adsorption pattern with CO2, the principle component of methanol synthesis. H2S dissociates on all the surfaces, SO2, and NO2 are chemisorbed, CH4 remains physisorbed, and NO, CO, and CO2 exhibit facet-dependent adsorption. Electronic structure analysis reveal that chemisorption occurs when surface energy states near the Fermi level overlap with HOMO of adsorbate, enabling charge transfer, whereas physisorption lacks such overlap. The adsorption strength follows the order: H2S SO2 NO2 NO CO CO2 CH4, suggesting that sulfur and nitrogen containing species exhibit strong chemisorption and compete with CO2 for active sites, potentially impacting the efficiency of methanol synthesis. These insights provide an atomic scale understanding of impurity-surface interactions and highlight potential role of ZnO as an efficient feed stock purifier for CO2-rich gas streams.

}, keywords = {CZA catalyst, flue gases, Valorization of CO2, ZnO}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2026.166151}, author = {Bhati, Meema and Joshi, Kavita} }