Quenching-Induced Defect-Rich Platinum/Metal Oxide Catalysts Promote Catalytic Oxidation

Abstract

Enhancing oxygen activation through defect engineering is an effective strategy for boosting catalytic oxidation performance. Herein, we demonstrate that quenching is an effective strategy for preparing defect-rich Pt/metal oxide catalysts with superior catalytic oxidation activity. As a proof of concept, quenching of α-Fe2O3 in aqueous Pt(NO3)2 solution yielded a catalyst containing Pt single atoms and clusters over defect-rich α-Fe2O3 (Pt/Fe2O3-Q), which possessed state-of-the-art activity for toluene oxidation. Structural and spectroscopic analyses established that the quenching process created abundant lattice defects and lattice dislocations in the α-Fe2O3 support, and stronger electronic interactions between Pt species and Fe2O3 promote the generation of higher oxidation Pt species to modulate the adsorption/desorption behavior of reactants. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) characterization studies and density functional theory (DFT) calculations determined that molecular oxygen and Fe2O3 lattice oxygen were both activated on the Pt/Fe2O3-Q catalyst. Pt/CoMn2O4, Pt/MnO2, and Pt/LaFeO3 catalysts synthesized by the quenching method also offered superior catalytic activity for toluene oxidation. Results encourage the wider use of quenching for the preparation of highly active oxidation catalysts.

Pt on Atomic-Layered WO3 Islands: Electronic Tuning of Platinum–Tungsten Heterostructures for Highly Efficient Low-Temperature VOC Combustion

“…Heterogeneous catalytic combustion has shown promise in eliminating VOCs by converting pollutants into harmless CO 2 and H 2 O. − Noble metal catalysts, particularly platinum (Pt), exhibit high VOC oxidation activity at relatively low temperatures. , However, current Pt catalysts still encounter limitations, such as unsatisfactory light-off temperatures and inefficient adsorption/activation of VOC and O 2 molecules . There are opportunities to further enhance the Pt catalyst performance.…”

Multistep Quenching of a Rust-Derived Catalyst for Enhanced Volatile Organic Compound Catalytic Oxidation

“…A quenching method has been shown to be highly effective for modifying the near-surface region of oxide catalysts . The surface and interfacial structures of the Fe 2 O 3 support can be fine-tuned via foreign atom doping or creation of oxygen vacancies. , Besides, oxygen vacancy on catalysts was evidenced to facilitate the adsorption and activation of O 2 . , Moreover, a previous study demonstrated that the Pt species prepared via a quenching method exhibited weakened adsorption strength for toluene, alleviating the poisoning of catalysts . Therefore, the quenching method could be applied to modulate the structure of Pt species, regulating the adsorption strength between the reactants and catalysts.…”

Local Electron Environment Regulation of Spinel CoMn2O4 Induced Effective Reactant Adsorption and Transformation of Lattice Oxygen for Toluene Oxidation

“…Volatile organic compounds (VOCs) from residential activities and industrial processes are extremely harmful to the environment and human health. − Catalytic oxidation is considered the most promising method due to its high efficiency and reliability. , However, the core issue of this technology is the development of efficient catalysts that can mineralize VOCs into nontoxic CO 2 and H 2 O at low temperature. − So far, metal oxides have been extensively studied, and significant progress has been made by tuning their compositions, synthesis conditions, and structures. ,− In the spinel AB 2 O 4 structure, A and B metal ions are located at tetrahedron and octahedron sites, respectively, and both sites can be adjusted by metals to obtain excellent catalytic performance. − Our previous work has found that spinel (CoMn 2 O 4 ) completes the reaction via oxygen cycling between gaseous oxygen, bulk oxygen, and surface oxygen, which is obviously different than supported oxides (Co 3 O 4 /MnO x ) . However, the migration of bulk lattice oxygen to surface lattice oxygen in spinel CoMn 2 O 4 requires a higher temperature and limits further improvement of low-temperature activity.…”