Enhancing Methane Combustion Activity by Modulating the Local Environment of Pd Single Atoms in Pd₁/CeO₂ Catalysts

Abstract

Reducing methane emissions is crucial for mitigating global warming. Developing highly efficient catalysts for low-temperature methane combustion is of great importance. Supported single-atom catalysts (SACs) have received significant attention in this regard. However, their long-term stability and activity remain challenging. In this study, we present a method for creating a highly active and thermally stable Pd 1 /CeO 2 catalyst by using thermal-shock synthesis (Pd 1 /CeO 2 -TS). By subjecting isolated Pd 2+ ions to ultrafast shockwaves, we control their local environment, resulting in unique electronic structures and the geometry of the Pd single atoms. Compared with the single-atom Pd 1 /CeO 2 catalyst formed through atom trapping (Pd 1 /CeO 2 -AT), Pd 1 /CeO 2 -TS showed improved activity for methane combustion with a nearly 20-fold increase in turnover frequency and reversible stability against water. This increase in activity is attributed to the presence of coordination-unsaturated Pd−O species and surface hydroxyls on ceria. These factors enhance the oxygen activity and reduce the barrier for C−H bond activation, resulting in increased catalytic performance.

Carbon Vacancies in Graphitic Carbon Nitride-Driven High Catalytic Performance of Pd/CN for Phenol-Selective Hydrogenation to Cyclohexanone

“…To further demonstrate the existence of Pd species in a single atom state on Pd/CN-60, CO adsorption at 303 K over Pd/CN and Pd/CN-60 catalysts is studied using the in situ DRIFTS technique, and the results are shown in Figure S8. For Pd/CN catalysts, there are three CO adsorption peaks at 2088, 1980, and 1928 cm –1 , which are assigned to linearly bound, bidentate bridged adsorption (Pd 2 –CO), and tridentate bridged adsorption (Pd 3 –CO) of CO molecules on the palladium species, respectively. , However, there are no Pd 2 –CO and Pd 3 –CO adsorption peaks in the range of 1900–2000 cm –1 ,and only a Pd 1 –CO adsorption peak is observed at 2090 cm –1 . The CO adsorption result further indicated that the Pd species on Pd/CN-60 mainly existed in a single atom state, which is consistent with the results of aberration-corrected HAADF–STEM.…”

Ultrafast micro/nano-manufacturing of metastable materials for energy

“…PtPdRhRuCe, CoMoFeNiCu, AuAgPtPdCu and PtPdCoNiFeCuAuSn) [ 26 , 38 ], single atoms (e.g. Ru, Pt, Pd and Co) [ 23 , 39 ] and metallic compounds (e.g. SiC, CoS, FeS 2 , Co 3 O 4 , MoS 2 , CoFeP x , LiMn 2 O 4 , LiCoO 2 , LiFePO 4 and Li-rich layered oxide/NiO heterostructures) [ 40–45 ].…”