2026-10-14T05:33:37Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34036774 2026-09-30T20:03:34Z category_146 category_7 category_873 category_734 category_69 portal_63 item_type_6 month_year_09_2026

In Situ DRIFTS and Modulation–Excitation Studies for CO₂ Hydrogenation on Nanostructures of CeO₂: Unraveling the Dynamic Nature of CO₂↔Hydroxylated-Ceria Interfaces Yuxi Wang (450170) Kaixi Deng (9114707) Jorge Moncada (5697965) Xiaobo Chen (825719) Hongda Zhu (2205952) Juan J. Bravo-Suárez (2049517) Arturo Martínez-Arias (1795576) José A. Rodriguez (1446364) Space Science Medicine Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified Inorganic Chemistry phase sensitive detection kinetically controlled reduction highly morphology dependent five different types direct carbonate decomposition 250 ° c regular carbonates formed surface tridentate carbonates vacancy </ sub gas </ sub adsorbed </ sub ads </ sub influenced reaction paths associated reaction mechanisms additional reaction pathway 2 </ sub oh groups produced surface adsorbates oh groups hydroxyl groups hydrogen carbonates tremendous impact successfully optimize strongly emphasize rich set results illustrate oxide surfaces oxide substrates modulation excitation limited contribution hydroxycarbonate species dynamic species dynamic nature desorption processes ceria nanocubes A combination of DRIFTS and transient studies with Modulation Excitation and Phase Sensitive Detection (ME-PSD) was used to study the hydrogenation of CO₂ on ceria nanocubes and nanospheres. Up to five different types of OH groups were produced after the reaction of molecular H₂ with the ceria nanostructures at a temperature of 250 °C typically used in catalytic processes. The formation of these OH groups induced morphological changes in the ceria nanostructures that affected the adsorption of CO₂ and influenced reaction paths for the reverse water–gas shift (RWGS) reaction (CO₂ + H₂ → CO + H₂O). The behavior of surface adsorbates and hence the associated reaction mechanisms were found to be highly morphology dependent, reflecting the dynamic nature of these CO₂↔hydroxylated-ceria interfaces. In general, the reaction of CO₂ with OH groups produced a rich set of formate and hydroxycarbonate species, and the existence of surface OH groups affected the stability of regular carbonates formed by the reaction of CO₂ with O centers of the oxide substrates. In transient or ME-PSD studies, performed with the exposure of the ceria nanostructures to CO₂/H₂ mixtures at 250 °C, hydrogen carbonates and formates were identified as dynamic species in adsorption/desorption processes that have a limited contribution to the RWGS reaction. On both catalytic surfaces, hydroxyl groups and carbonate adsorbates initially experienced a rapid, kinetically controlled reduction (OH_adsorbed + 0.5H_2,gas → O_vacancy + H₂O_gas) and oxidation (CO_3,ads + O_vacancy→ CO_gas + 2O_oxide) process that was part of the RWGS reaction. The ceria nanocubes had an additional reaction pathway, where direct carbonate decomposition, involving the transformation of transient and surface tridentate carbonates, enhanced the RWGS rate. Overall, these results illustrate the tremendous impact that hydrogen can have on the adsorption and reaction of CO₂ with oxide surfaces and strongly emphasize the need to consider different oxide nanostructures to successfully optimize the performance of CeO₂-based catalysts for CO₂ hydrogenation. 2026-09-30T00:00:00Z Text Journal contribution 10.1021/acs.jpcc.6c04833.s001 https://figshare.com/articles/journal_contribution/In_Situ_DRIFTS_and_Modulation_Excitation_Studies_for_CO_sub_2_sub_Hydrogenation_on_Nanostructures_of_CeO_sub_2_sub_Unraveling_the_Dynamic_Nature_of_CO_sub_2_sub_Hydroxylated-Ceria_Interfaces/34036774 CC BY-NC 4.0