Crystal Facet Induced Single‐Atom Pd/Co_xO_y on a Tunable Metal–Support Interface for Low Temperature Catalytic Oxidation

Abstract

Atomic dispersed metal sites in single‐atom catalysts are highly mobile and easily sintered to form large particles, which deteriorates the catalytic performance severely. Moreover, lack of criterion concerning the role of the metal–support interface prevents more efficient and wide application. Here, a general strategy is reported to synthesize stable single atom catalysts by crafting on a variety of cobalt‐based nanoarrays with precisely controlled architectures and compositions. The highly uniform, well‐aligned, and densely packed nanoarrays provide abundant oxygen vacancies (17.48%) for trapping Pd single atoms and lead to the creation of 3D configured catalysts, which exhibit very competitive activity toward low temperature CO oxidation (100% conversion at 90 °C) and prominent long‐term stability (continuous conversion at 60 °C for 118 h). Theoretical calculations show that O vacancies at high‐index {112} facet of CoxOy nanocrystallite are preferential sites for trapping single atoms, which guarantee strong interface adhesion of Pd species to cobalt‐based support and play a pivotal role in preventing the decrement of activity, even under moisture‐rich conditions (≈2% water vapor). The progress presents a promising opportunity for tailoring catalytic properties consistent with the specific demand on target process, beyond a facile design with a tunable metal–support interface.

Oxygen vacancies in a catalyst for VOCs oxidation: synthesis, characterization, and catalytic effects

“…Aer decades of continuous development and innovation of materials, many catalyst synthesis and modication strategies have been reported, such as interface engineering, crystal surface control engineering, and defect engineering. 12,[22][23][24] Among them, defect engineering is an essential and effective strategy to improve catalytic performance by adjusting the geometric and electronic structure of catalysts. [25][26][27] Therefore, more and more attention has been paid to regulate the defects of materials in constructing highperformance catalysts.…”

Single atoms supported on metal oxides for energy catalysis

“…This SAC shows very competitive activity, with 100% conversion of CO oxidation at a low temperature of 90 °C and significant 118 h stability at 60 °C. 206 Isolated Pt atoms supported on TiO 2 nanowires can even catalyze CO oxidation at room temperature. 66 The stability at high temperatures can also be improved by depositing single Au atoms on Co 3 O 4 , which maintains the activity after a 10-cycle temperature-programmed reaction from −100 to 300 °C or one year of storage in air.…”

“…At present, there are 3 types of mechanisms for CO oxidation: Langmuir-Hinshelhood (L-H), Eley-Rideal (E-R), and Mars-van Krevelen (M-vK) mechanisms. 66,197,206,207 In realistic catalytic systems, more than one mechanism coexists. As shown in Fig.…”

Heterogeneous Single Atom Environmental Catalysis: Fundamentals, Applications, and Opportunities

“…The strong interfacial interaction between Pd SAs and Co 3 O 4 guarantees a superior activity (TOF value of 0.22 s -1 ) and sustainability for CO oxidation. [85] Since the low metal loading (usually <1 wt%) is a typical characteristic for supported SACs, questions on the upper limit of the metal loading and the optimal metal content for the catalytic application are to be answered. [77] Therefore, in addition to the efforts to maximize the catalytic efficiency per atom, another important emerging direction is pointed to maximize the single atom density, while this topic is still in the early stage.…”