Selective Electrochemical Hydrogenation of Phenol with Earth‐abundant Ni−MoO₂ Heterostructured Catalysts: Effect of Oxygen Vacancy on Product Selectivity

Abstract

Herein, we report highly efficient carbon supported NiÀ MoO 2 heterostructured catalysts for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 °C. Highest yields for cyclohexanol and cyclohexanone of 95 % and 86 % with faradaic efficiencies of ~50 % are obtained with catalysts bearing high and low densities of oxygen vacancy (O v ) sites, respectively. In situ diffuse reflectance infrared spectroscopy and density functional theory calculations reveal that the enhanced phenol adsorption strength is responsible for the superior catalytic efficiency. Furthermore, 1-cyclohexene-1-ol is an important intermediate. Its hydrogenation route and hence the final product are affected by the O v density. This work opens a promising avenue to the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.

MOF‐Derived Mn2O3 Nanocage with Oxygen Vacancies as Efficient Cathode Catalysts for Li–O2 Batteries

“…All samples have shown an accurate signal of g = 2.004, which further reveals the existence of oxygen vacancies. [41] The defect signal of Mn 2 O 3 @350 is significantly stronger than that of Mn 2 O 3 @450 and Mn 2 O 3 @550, indicating that Mn 2 O 3 @350 has the most oxygen vacancies, which is consistent with the XPS results. In the metal oxides obtained by pyrolysis of MOF, the lower the crystallinity of the sample is, the more oxygen vacancies there will be in it.…”

Hydrophilic amorphous Cr2O3 supported Co species toward efficient hydrogen production from ammonia borane under visible light irradiation

“…40,41 Notably, compared with pristine KIT-6-F, the band at 1 635 960 and 464 cm −1 in compound are red-shied, indicating the strong interaction between pristine KIT-6-F and Cr 2 O 3 , which is facilitated to regulate electron density of catalyst and obtain high performance. 42 Combined with the above characterization result, Cr 2 O 3 -F-0.5 strong interaction between amorphous Cr 2 O 3 and KIT-6-F had been successfully synthesized. Additionally, The IR spectra of KIT-6-F were collected aer ve months (Fig.…”

Developing electrochemical hydrogenation towards industrial application

“…Expectedly, small particle sizes are usually preferred due to the increased surface area and as for other electrocatalytic reactions and nanostructuring as well as the incorporation of defects can severely improve the observed catalyst activity. 52,134,136,150,199,236,237 In a similar fashion, single atom catalysts 238 are well known for their high (electro)catalytic activity and have been reported for several electrochemical reductions, e.g. , of protons, 239–241 carbon dioxide, 239–241 nitrogen, 240,241 and nitrate.…”

“…[182][183][184][185][186][187][188] Even for the hydrogenation of phenol derivatives to cyclohexanols nickel based catalysts are known although operating at low current densities (o10 mA cm À2 ) and at elevated temperatures (60-75 1C). 108,208,237 On the other hand, one relevant substrate class discussed in literature that still requires PGMs for efficient catalysis are aromatic compounds like toluene. This fact is especially interesting since the hydrogenation of toluene and similar compounds is one of the only types of EChH, that is well known to efficiently operate at current densities of 4400 mA cm À2 in polymer electrolyte membrane reactors.…”