Research Article Just accepted
Theoretical and experimental investigations on single-atom catalysis: Pt1/FeOx for water-gas shift reaction
Nano Research
Available online: 25 March 2024

Oxide-supported metal single-atom catalysts have exhibited excellent catalytic performance for water gas shift (WGS) reaction.  Here, we report the single-atom catalyst (SAC) Pt1/FeOx exhibits excellent medium temperature catalytic performance for WGS reactions by the density functional theory (DFT) calculations and experimental results. The calculations indicate that H2O molecules are easily dissociated at oxygen vacancies, and the formed OH* and O* are adsorbed on Pt1 single atoms and the adjacent O atoms, respectively. After studying four possible reaction mechanisms, the optimal WGS reaction pathway is proceeded along the carboxyl mechanism (Pathway III), in which the formation of *COOH intermediates can promote the stability of Pt1/FeOx SAC and the occurrence of WGS reaction more easily. The energy barrier of the rate-determining step during the entire reaction cycle is only 1.16 eV, showing the high activity for the medium temperature WGS reaction on Pt1/FeOx SAC, which was verified by experimental results. Moreover, the calculated turn-over frequencies (TOF) of CO2 and H2 formation on Pt1/FeOx at 610 K (337 ℃) can reach up to 1.14´10-3 s−1 site−1 through carboxyl mechanism. In this work, we further expand the application potential of Pt1/FeOx SAC in water gas shift (WGS) reaction.

Research Article Issue
Ultrastable nickel single-atom catalysts with high activity and selectivity for electrocatalytic CO2 methanation
Nano Research 2023, 16 (7): 8987-8995
Published: 25 April 2023

Electrochemical conversion of CO2 into valuable hydrocarbon fuel is one of the key steps in solving carbon emission and energy issue. Herein, we report a non-noble metal catalyst, nickel single-atom catalyst (SAC) of Ni1/UiO-66-NH2, with high stability and selectivity for electrochemical reduction of CO2 to CH4. Based on ab initio molecular dynamics (AIMD) simulations, the CO2 molecule is at first reduced into CO2 when stably adsorbed on a Ni single atom with the bidentate coordination mode. To evaluate its activity and selectivity for electrocatalytic reduction of CO2 to different products (HCOOH, CO, CH3OH, and CH4) on Ni1/UiO-66-NH2, we have used density functional theory (DFT) to study different reaction pathways. The results show that CH4 is generated preferentially on Ni1/UiO-66-NH2 and the calculated limiting potential is as low as −0.24 V. Moreover, the competitive hydrogen evolution reaction is unfavorable at the activation site of Ni1/UiO-66-NH2 owing to the higher limiting potential of −0.56 V. Furthermore, the change of Ni single atom valence state plays an important role in promoting CO2 reduction to CH4. This work provides a theoretical foundation for further experimental studies and practical applications of metal–organic framework (UiO-66)-based SAC electrocatalysts with high activity and selectivity for the CO2 reduction reaction.

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