Holey Lamellar High‐Entropy Oxide as an Ultra‐High‐Activity Heterogeneous Catalyst for Solvent‐free Aerobic Oxidation of Benzyl Alcohol

Abstract

The development of noble-metal-free heterogeneous catalysts is promising for selective oxidation of aromatic alcohols;h owever,t he relatively lowc onversion of non-noble metal catalysts under solvent-free atmospheric conditions hinders their industrial application. Now,aholey lamellar high entropyoxide (HEO) Co 0.2 Ni 0.2 Cu 0.2 Mg 0.2 Zn 0.2 Omaterial with mesoporous structure is prepared by an anchoring and merging process.The HEO has ultra-high catalytic activity for the solvent-free aerobic oxidation of benzyl alcohol. Up to 98 %conversion can be achieved in only 2h,toour knowledge, the highest conversion of benzyl alcohol by oxidation to date. By regulating the catalytic reaction parameters,benzoicacid or benzaldehyde can be selectively optimizedasthe main product. Analytical characterizations and calculations provide adeeper insight into the catalysis mechanism, revealing abundant oxygen vacancies and holey lamellar framework contribute to the ultra-high catalytic activity.

A Resol‐Assisted Cationic Coordinative Co‐assembly Approach to Mesoporous ABO3 Perovskite Oxides with Rich Oxygen Vacancy for Enhanced Hydrogenation of Furfural to Furfuryl Alcohol

“…The peaks located at about 529.3 eV are assigned to lattice oxygen (O 2− ), while that at about 530.9 eV are usually ascribed to the oxygen atoms in the vicinity of oxygen vacancies deemed as vacancy oxygen species and the peaks at about 531.9 eV corresponded to hydroxy species (OH − ) [40–42] . The amount of vacancy oxygen species characterized by peak area integration of O 1s are 43.7 % of O V ‐rich meso‐LMO and 45.5 % of O V ‐rich bulk LMO higher than 22.9 % of meso‐LMO and 19.3 % of bulk LMO, respectively (detailed data in the Supporting Information, Figure S4 and Table S2), which verifies that the prepared LMO samples can obtained increased concentration of oxygen vacancies after NaBH 4 treatment of meso‐LMO and bulk LMO [10, 43] . The divided Mn 2p 3/2 peaks at 641.7 eV and 642.7 eV were ascribed to Mn 3+ and Mn 4+ , respectively [8] .…”

Nano High‐Entropy Materials: Synthesis Strategies and Catalytic Applications

“…[ 17,89 ] Impressively, a non‐noble metal‐based HEO‐NPs showed higher activity than the most advanced AuPd‐based catalyst in benzyl oxidation reaction. [ 91 ] Moreover, nanostructured HEMs also possess high specific surface areas with more active sites exposed, which would enhance the metal utilization efficiency and catalytic activities in comparison to bulk HEMs. The configurationally disordered and entropy‐stabilized HEM solid solution also showed excellent stability in various reactions, especially in thermal catalysis at high temperature.…”

“…The uncountable elemental combinations of the HEM platform offer us plenty of possibilities to regulate its surface electronic structure and catalytic performances. Therefore, potential applications of HEM‐NPs in heterogeneous catalysts, such as water electrocatalysis, [ 15,39,53,85 ] oxygen reduction, [ 17,32,78,89 ] carbon dioxide reduction, [ 33 ] NH 3 decomposition, [ 90 ] CO oxidation, [ 21 ] and benzyl alcohol oxidation [ 91 ] have been explored. In the following, we will discuss the recent examples of HEA‐NPs heterogeneous catalysts and investigate the origination of their outstanding performance.…”

“…A holey lamellar Co 0.2 Ni 0.2 Cu 0.2 Mg 0.2 Zn 0.2 O HEO‐NPs catalyst prepared by an anchoring–merging process was used in the solvent‐free aerobic oxidation of benzyl alcohol. [ 91 ] Up to 98% conversion of benzyl alcohol was achieved by this HEO‐NPs catalyst after reaction at 120 °C for only 2 h, suppressing that of the most advanced Au/Pd‐TiO 2 catalyst ever reported. [ 158 ] The activity of this holey lamellar HEO‐NPs catalyst was also higher than those of the bulk HEO and the arbitrary quaternary or ternary analogues, indicating that the unique holey lamellar structure and the specific single‐phase HEO structure were both indispensable for the ultrahigh catalytic activity.…”

The Synthesis and Catalytic Applications of Nanosized High‐Entropy Alloys

“…Especially the use of high‐entropy metal oxide in the development of catalysts started almost at the same time as that of HEAs, and there are several reports on enhanced catalytic performance by high‐entropy oxide. All these materials open up a new avenue to design and synthesize heterogeneous catalysts [107–109] …”