Formation of PdO on Au–Pd bimetallic catalysts and the effect on benzyl alcohol oxidation

Engineering of Pore Design and Oxygen Vacancy on High-Entropy Oxides by a Microenvironment Tailoring Strategy

High-entropy oxides (HEOs) exhibit abundant structural diversity due to cationic and anionic sublattices with independence, rendering them superior in catalytic applications compared to monometallic oxides. Nevertheless, the conventional high-temperature calcination approach undermines the porosity and reduces the exposure of active sites (such as oxygen vacancies, OVs) in HEOs, leading to diminished catalytic efficiency. Herein, we fabricate a series of HEOs with a large surface area utilizing a microenvironment modulation strategy (m-NiMgCuZnCo: 86 m2/g, m-MnCuCoNiFe: 67 m2/g, and m-FeCrCoNiMn: 54 m2/g). The enhanced porosity in m-NiMgCuZnCo facilitates the presentation of numerous OVs, exhibiting an exceptional catalytic performance. This tactic creates inspiration for designing HEOs with rich porosity and active species with vast potential applications.

An S-scheme NH2-MIL-101(Fe)@MCN/Bi2O3 heterojunction photocatalyst for the degradation of tetracycline and production of H2O2

Effective and durable photocatalysts are essential for the decomposition of persistent contaminants and the generation of hydrogen peroxide. In this study, we successfully constructed an S-type heterojunction by in situ growing Bi2O3 nanocrystals and NH2-MIL-101(Fe) onto surface-modified g-C3N4. The process of charge transfer in the S-type heterojunction was confirmed using ISI-XPS, DFT calculations, capture experiments, and EPR signals. The combined influence of the heterojunction and MOF demonstrated remarkable photocatalytic performance in the breakdown of tetracycline (TC) and the generation of hydrogen peroxide (H2O2). In the enhanced setup (10%-NH2-MIL-101(Fe)@MCN/Bi2O3), full degradation of TC was accomplished within 50 min under visible light exposure. Additionally, a notable H2O2 yield of 655.63 μmol/g was attained, all achieved without the necessity of sacrificial agents or supplementary oxygen. Based on the outcomes of the dual functionality, the exceptional performance of the ternary composite material can be ascribed to the collaborative influence of the heterojunction and MOF. This collaborative effect expands the light absorption range in the visible region, suppresses the recombination of electron-hole pairs, and enhances the photocatalytic redox ability. The system demonstrates significant potential in the efficient in situ production of H2O2 and removal of recalcitrant organic pollutants in pure water.

Enhanced Fatty Acid Photodecarboxylation over Bimetallic Au-Pd Core-Shell Nanoparticles Deposited on TiO2

Photodecarboxylation of biomass-derived fatty acids to alkanes offers significant potential to obtain hydrocarbons and economic benefits due to the mild conditions and high activity. Herein, the photodecarboxylation of hexanoic acid into alkanes using TiO2-supported monometallic Au or Pd and bimetallic Au-Pd catalysts is reported. It was found that bimetallic Au-Pd catalysts, featuring a core-shell structure evidenced by EDX-mapping and element line profile, show better photocatalytic performance, achieving 94.7% conversion of hexanoic acid and nearly 100% selectivity to pentane under UV-vis irradiation in the absence of H2 than the monometallic Au analogue. This remarkable enhancement in activity compared to its TiO2 supported monometallic Au or Pd analogues can be attributed to the synergistic effect between Au and Pd within the nanostructured Au(core)-Pd(shell) alloy for achieving more efficient charge-separation efficiency upon visible light excitation. This photocatalyst exhibits a wide scope converting multiple fatty acids into hydrocarbons. Moreover, it can even photocatalyze the conversion of raw bio-oils into alkanes directly. No obvious activity loss was observed during the reusability tests, demonstrating the good stability of the present catalyst. Density functional theory (DFT) calculations indicate that oxidation of carboxylates on TiO2 leads to alkyl radicals that become bound to metal nanoparticles. The superior catalytic performance of Au(core)-Pd(shell)/TiO2 is derived from the weaker adsorption for H on the alloy and the lower hydrogen evolution reaction overpotential. Our research can result in an efficient bio-oil upgrading, resulting in the synthesis of biofuels from biomass under mild conditions.

Enhanced Hot Electron Flow and Catalytic Synergy by Engineering Core-Shell Structures on Au-Pd Nanocatalysts

The synergistic catalytic performances of bimetallic catalysts are often attributed to the reaction mechanism associated with the alloying process of the catalytic metals. Chemically induced hot electron flux is strongly correlated with catalytic activity, and the interference between two metals at the atomic level can have a huge impact on the hot electron generation on the bimetallic catalysts. In this study, we investigate the correlation between catalytic synergy and hot electron chemistry driven by the electron coupling effect using a model system of Au-Pd bimetallic nanoparticles. We show that the bimetallic nanocatalysts exhibit enhanced catalytic activity under the hydrogen oxidation reaction compared with that of monometallic Pd nanocatalysts. Analysis of the hot electron flux generated in each system revealed the formation of Au/PdOx interfaces, resulting in high reactivity on the bimetallic catalyst. In further experiments with engineering the Au@Pd core-shell structures, we reveal that the hot electron flux, when the topmost surface Pd atoms were less affected by inner Au, due to the concrete shell, was smaller than the alloyed one. The alloyed bimetallic catalyst forming the metal-oxide interfaces has a more direct effect on the hot electron chemistry, as well as on the catalytic reactivity. The great significance of this study is in the confirmation that the change in the hot electron formation rate with the metal-oxide interfaces can be observed by shell engineering of nanocatalysts.

Efficient oxidation of benzyl alcohol into benzaldehyde catalyzed by graphene oxide and reduced graphene oxide supported bimetallic Au-Sn catalysts

A series of bimetallic and monometallic catalysts comprising Au and Sn nanoparticles loaded on graphene oxide (GO) and reduced graphene oxide (rGO) were prepared using three distinct techniques: two-step immobilization, co-immobilization, and immobilization. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), and Inductively-coupled plasma optical emission spectroscopy (ICP-OES) were used to characterize the chemical and physical properties of prepared Au-Sn bimetallic and Au or Sn monometallic nanocatalysts. The catalytic performance of the prepared nanocatalysts was evaluated in the selective oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using O2 as an oxidizing agent under moderate conditions. To obtain the optimal BzH yield, the experimental conditions and parameters, including the effects of the reaction time, temperature, pressure, and solvent type on BzOH oxidation, were optimized. Under optimal reaction conditions, bimetallic Au-Sn nanoparticles supported on GO (AuSn/GO-TS, 49.3%) produced a greater yield of BzH than the AuSn/rGO-TS catalysts (35.5%). The Au-Sn bimetallic catalysts were more active than the monometallic catalysts. AuSn/GO-TS and AuSn/rGO-TS prepared by the two-step immobilization method were more active than AuSn/GO-CoIM and AuSn/rGO-CoIM prepared by co-immobilization. In addition, the AuSn/GO-TS and AuSn/rGO-TS catalysts were easily separated from the mixture by centrifugation and reused at least four times without reducing the yield of BzH. These properties make Au-Sn bimetallic nanoparticles supported on GO and rGO particularly attractive for the environmentally friendly synthesis of benzaldehyde.

Rational Design of Highly Efficient PdIn-In2O3 Interfaces by a Capture-Alloying Strategy for Benzyl Alcohol Partial Oxidation

Well-dispersed PdIn bimetallic alloy nanoparticles (1-4 nm) were immobilized on mesostructured silica by an in situ capture-alloying strategy, and PdIn-In₂O₃ interfaces were rationally constructed by changing the In₂O₃ loading and reduction temperature. The catalytic performance for benzyl alcohol partial oxidation was evaluated, and a catalytic synergy was observed. The Pd-rich PdIn-In₂O₃ interface is prone to be formed on the catalyst with a low In₂O₃ loading after being reduced at 300 °C. It was demonstrated that the Pd-rich PdIn-In₂O₃ interface was more active for benzyl alcohol partial oxidation than In-rich Pd₂In₃ species, which was likely to be formed at a high reduction temperature (400 °C). The high catalytic activity on the Pd-rich PdIn-In₂O₃ interface was attributed to the exposure of more Pd-enriched active sites, and an optimized PdIn-In₂O₃/Pd assemble ratio enhanced the oxygen transfer during partial oxidation. The density functional theory (DFT) calculation confirmed that the Pd-rich Pd₃In₁(111)-In₂O₃ interface facilitated the activation of oxygen molecules, resulting in high catalytic activity.

Synthesis of a Novel Spherical-Shell-Structure Polymerized Ionic Liquid Microsphere PILM/Au/Al(OH)3 Catalyst for Benzyl Alcohol Oxidation

In order to selectively oxidize benzyl alcohol, a novel noble metal catalyst based on polymer ionic liquids with a core-shell structure was created. First, polymer ionic liquid microspheres (PILMs) were prepared by free radical polymerization. Second, the in situ adsorption of Au nanoparticles on the surface of PILMs was accomplished, thanks to the strong electrostatic interaction between N atoms and metal ions on the diazole ring of PILMs. Additionally, the introduction of Al(OH)₃ prevented the aggregation of Au nanoparticles and promoted the catalytic reaction. Finally, the PILM/Au/Al(OH)₃ catalyst with a core-shell structure was formed. The effectiveness of the PILM/Au/Al(OH)₃ catalyst was assessed by varying the catalyst's type, quantity, amount of Au, amount of H₂O₂, temperature, and reaction time. After five cycles of experiments, the catalyst was effective and reusable. In addition, the potential catalytic mechanism of the catalyst in the oxidation of benzyl alcohol was proposed.

Constructing a Photocatalyst for Selective Oxidation of Benzyl Alcohol to Benzaldehyde by Photo-Fenton-like Catalysis

A photoactive metal-organic framework (MOF), [K(H₂O)][Cu(DPNDI)][Cu(DPNDI)(CH₃CN)(H₂O)] [Cu_1.5(DPNDI)_1.5H_1.5P₂W₁₈O₆₂]·2H₂O (Cu(Ι)W-DPNDI), was prepared by combining a functional photosensitizer N, N'-bis(4-pyridylmethyl)naphthalene diimide (DPNDI), copper(I) ions, and an oxidation catalyst [P₂W₁₈O₆₂]^6- into a single framework via a hydrothermal process. Cu(Ι)W-DPNDI exhibited a stable structure, strong light absorption capacity, a suitable band gap, and photoelectric properties, which provided favorable conditions for photocatalysis. In the confined space, the well-aligned Cu(I) ions and POM polyanions played a synergetic effect in the electron-transfer process and reactive oxygen species generation. By coupling photocatalysis and heterogeneous Fenton-like catalysis, Cu(Ι)W-DPNDI displayed high efficiency for the selective oxidation of aromatic alcohols, with up to >99% selectivity and 75% yield.

Recent Advances in the Applications of Mesoporous Silica in Heterogenous Catalysis

Mesoporous silica is a class of silica material with a large specific surface area, high specific pore volume and meso-sized pores. These properties make mesoporous silica a good choice of...

The solvent-free and aerobic oxidation of benzyl alcohol catalyzed by Pd supported on carbon nitride/CeO2 composites

Palladium catalysts supported on carbon nitride/ceria composites showed superior activity during the solvent-free and aerobic oxidation of benzyl alcohol to benzaldehyde.

Photocatalytic cascade reactions and dye degradation over CdS-metal-organic framework hybrids

Two bifunctional CdS–MOF composites have been designed and fabricated. The hybrids exhibited synergistic photocatalytic performance toward two cascade reactions under visible light integrating photooxidation activity of CdS and Lewis acids/bases of the MOF. The composite further promoted the photodegradation of dyes benefiting from effective electron transfer between the MOF and CdS.

Two bifunctional CdS–MOF composites have been successfully fabricated and exhibited synergistic photocatalytic performance toward two-step cascade reactions and dye photodegradation.

Compatibility between Activity and Selectivity in Catalytic Oxidation of Benzyl Alcohol with Au-Pd Nanoparticles through Redox Switching of SnOx

A balance between catalytic activity and product selectivity remains a dilemma for the partial oxidation processes because the products are prone to be overoxidized. In this work, we report on the partial oxidation of benzyl alcohol using a modified catalyst consisting of nanosized Au-Pd particles (NPs) with tin oxide (SnO_x) deposited on a mesoporous silica support. We found that the SnO_x promotes the autogenous reduction of PdO to active Pd⁰ species on the Au-Pd NP catalyst (SnO_x@AP-ox) before H₂ reduction, which is due to the high oxophilicity of Sn. The presence of active Pd⁰ species and the enhancement of oxygen transfer by SnO_x led to high catalytic activity. The benzaldehyde selectivity was enhanced with the increase of SnO_x content on catalyst SnO_x@AP-ox, which is ascribed to the modulated affinity of reactants and products on the catalyst surface through the redox switching of Sn species. After H₂ reduction, SnO_x was partially reduced and Au-Pd-Sn alloy was formed. The formation of Au-Pd-Sn alloy weakened both the catalytic synergy of Au-Pd alloy NPs and the adsorption of benzyl alcohol on the reduced catalyst, thus leading to low catalytic activity.

Prompting the FDH/Hases-based electron transfers during Pt(IV) reduction mediated by bio-Pd(0)

Due to the excellent hydrogen affinity and high conductivity, palladium nanoparticles (Pd NPs) were considered as a potential strategy to regulate bacterial electron transfer and energy metabolism. Herein, Citrobacter freundii JH, capable of in-situ biosynthesizing Pd(0) NPs, was employed to promote Pt(IV) reduction. The results showed that the Pt(IV) reduction to Pt(II) was accomplished mainly via the flavins-mediated extracellular electron transfer (EET) process, while Pt(II) reduction to Pt(0) was limit step, and proceeded via two intracellular respiratory chains, including FDH/Hases-based short chain (S-chain) and typical CoQ-involved long respiratory chain (L-chain). Noteworthily, the incorporation of Pd(0) NPs mainly diverted the electrons to S-chain (as high as 71.7%-73.4%) by improving the hydrogenases (Hases) activity. Furthermore, Pd(0) NPs could stimulate the secreting of flavins and the combination between flavins and cytochrome c (c-Cyt), which converted electron transfer manner of L-chain. Additionally, Pd(0) NPs might also act as alternative proton channels to improve the energy metabolism. These findings provided significant insights into the promotion by Pd(0) NPs in terms of electron generation, electron consumption and proton translocation.

Versatile precursor-dependent copper sulfide nanoparticles as a multifunctional catalyst for the photocatalytic removal of water pollutants and the synthesis of aromatic aldehydes and NH-triazoles

A series of copper sulfide (CS) nanoparticles (NPs) were synthesized just by varying the amount of the sulfur precursor and have been explored for the first time as a three-way heterogeneous catalyst in the photocatalytic oxidation of a number of aromatic alcohols, photocatalytic degradation and the reduction of water pollutants, and the facile synthesis of pharmaceutically important moiety 4-aryl-NH-1,2,3-triazoles. The green and novel protocol was successfully developed for the synthesis of covellite (CuS, Cu2+) and the covellite-villamaninite (CuS-CuS2) (copper in Cu2+, Cu1+) phases of copper sulfide, employing EDTA both as the chelating and capping agent via a simple precipitation method at room temperature using water as the solvent. A blue shift in the absorption spectra and band gap in the range of 2.02-2.07 eV prompted the investigation of the as-synthesized CS nanoparticles as the photocatalyst under visible light irradiation. In the absence of any oxidizing or reducing agent, covellite CuS nanoparticles showed the highest photocatalytic efficiency for the degradation of methylene blue (MB) and the reduction of carcinogenic and mutagenic Cr(vi) to non-toxic Cr(iii). Interestingly, the mixed phase of CS (CuS-CuS2), where Cu is present in both +1 and +2 oxidation states, was found to be the most efficient catalyst compared to CuS toward the visible light-mediated selective oxidation of various benzyl alcohols to their corresponding aldehydes. However, in the synthesis of substituted NH-1,2,3-triazoles, single-phase CS nanoparticles (i.e., CuS) provided the best catalytic result. This significant outcome certainly opens up the scope for realizing the present demand of low-cost multifunctional semiconductor nano-materials, which will have a huge impact on the economy and environment when they show more than two potential applications.

Recognition of Water-Induced Effects toward Enhanced Interaction between Catalyst and Reactant in Alcohol Oxidation

Pickering emulsion stabilized by solid nanoparticles provides a diverse solvent microenvironment and enables to promote the phase transfer of reaction substrates/products in catalytic reactions, but the intrinsic role of solvent is still not clear. Herein, using benzyl alcohol (BA) as a model reactant, we demonstrate the nature of the water-promoted activity for alcohol oxidation over the Pd/MgAl-LDO catalyst. Depending on the water in the solvent, we observe different reactivities regarding the proportion of the water in the system. Kinetic isotope effects confirm the participation and positive effects of water for oxidation of BA. The water promotion effects are recognized and identified by the water vapor pulse adsorption coupled with temperature program desorption. Moreover, the adsorption behavior of BA or benzaldehyde at the interface of water and Pd/MgAl-LDO is also investigated by quasi-in-situ Raman spectroscopy. In addition, the mechanism of water-promoted alcohol oxidation is rationally proposed based on the Langmuir-Hinshelwood mechanism. The general applicability of the water promotion effects is further demonstrated over different supports and substrates, which well achieves excellent catalytic activity and selectivity in Pickering emulsion compared to that in the pure toluene system.

Steric Effects of Mesoporous Silica Supported Bimetallic Au-Pt Catalysts on the Selective Aerobic Oxidation of Aromatic Alcohols

Three series of catalysts consisting of gold (Au), platinum (Pt), or gold-platinum bimetallic nanoparticles (NPs) with controlled sizes (Au NPs 10 ± 2 nm, Pt NPs 6 ± 2 nm) anchored on hierarchical micro-/meso-/macroporous silica were successfully developed and systematically evaluated for the selective oxidation of aromatic alcohols to their corresponding aldehydes. The catalysts were prepared by the sol-immobilization method using as-made Au NPs and/or Pt NPs colloids; the silica supports were prepared with controlled pore structures and the hierarchical porous structures of catalysts were created by controllable desilication via the alkaline solution of the metal colloids. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), and these results showed no synergistic effect between Au and Pt on boosting the catalytic performance, whereas they demonstrated a clear dependence of catalytic conversions and reaction rates on the structural porosity of Au-Pt bimetallic catalysts. Our findings could potentially inspire peer researchers and scientists to develop designer porous catalysts and processes in the selective organic conversions.

Eco-Friendly and Solvent-Less Mechanochemical Synthesis of ZrO2–MnCO3/N-Doped Graphene Nanocomposites: A Highly Efficacious Catalyst for Base-Free Aerobic Oxidation of Various Types of Alcohols

In recent years, the development of green mechanochemical processes for the synthesis of new catalysts with higher catalytic efficacy and selectivity has received manifest interest. In continuation of our previous study, in which graphene oxide (GRO) and highly reduced graphene oxide (HRG) based nanocomposites were prepared and assessed, herein, we have explored a facile and solvent-less mechanochemical approach for the synthesis of N-doped graphene (NDG)/mixed metal oxide (MnCO3–ZrO2) ((X%)NDG/MnCO3–ZrO2), as the (X%)NDG/MnCO3–ZrO2 nano-composite was synthesized using physical grinding of separately synthesized NDG and pre-calcined (300 °C) MnCO3–ZrO2 via green milling method. The structures of the prepared materials were characterized in detail using X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), Raman, Thermogravimetric analysis (TGA), and N2 adsorption-desorption isotherm analysis. Besides, the obtained nanocomposites were employed as heterogeneous oxidation catalyst for the alcohol oxidation using green oxidant O2 without involving any surfactants or bases. The reaction factors were systematically studied during the oxidation of benzyl alcohol (PhCH2OH) as the model reactant to benzaldehyde (PhCHO). The NDG/MnCO3–ZrO2 exhibits premium specific activity (66.7 mmol·g−1·h−1) with 100% conversion of PhCH2OH and > 99.9% selectivity to PhCHO after only 6 min. The mechanochemically prepared NDG based nanocomposite exhibited notable improvement in the catalytic efficacy as well as the surface area compared to the pristine MnCO3–ZrO2. Under the optimal circumstances, the NDG/MnCO3–ZrO2 catalyst could selectively catalyze the aerobic oxidation of a broad array of alcohols to carbonyls with full convertibility without over-oxidized side products like acids. The NDG/MnCO3–ZrO2 catalyst were efficiently reused for six subsequent recycling reactions with a marginal decline in performance and selectivity.

In Situ Hydrogen Peroxide Production for Selective Oxidation of Benzyl Alcohol over a Pd@Hierarchical Titanium Silicalite Catalyst

Using in situ generated H2O2 is potentially an effective approach for benzyl alcohol selective oxidation. While the microporous titanium silicate (TS-1) supported with Pd is promising for selective oxidation, the Pd particles are preferentially anchored on the external surface, which leads to the problems such as non-uniform dispersion and low thermal stability. Here, we prepared a Pd@HTS-1 catalyst in which the Pd subnanoparticles were encapsulated in the channels of the hierarchical TS-1 (HTS-1), for benzyl alcohol selective oxidation with in situ produced H2O2. We find that the oxidation rate of benzyl alcohol by in situ H2O2 over the Pd@HTS-1 is up to 4268.8 mmol h-1 kgcat -1, and the selectivity of benzaldehyde approaches 100%. In contrast to the conventional Pd/HTS-1, the present Pd@HTS-1 benefits the benzyl alcohol selective oxidation due to the increased dispersion of Pd particles (forming uniformly dispersed subnano-sized particles), as well as the confinement effect and hierarchical porosity of the HTS-1 host. We further suggested that hydrogen peroxide produced in situ from the molecular hydrogen and oxygen over the Pd sites can be spilled over to the framework Ti4+ sites, forming the Ti-OOH active species, which selectively oxidizes the chemisorbed benzyl alcohol to benzaldehyde on the Pd sites.

The Influence of Reaction Conditions on the Oxidation of Cyclohexane via the In-Situ Production of H2O2

Abstract

The oxidation of cyclohexane via the in-situ production of H2O2 from molecular H2 and O2 offers an attractive route to the current industrial means of producing cyclohexanone and cyclohexanol (KA oil), both key materials in the production of Nylon. Herein we demonstrate that through the in-situ production of H2O2 supported AuPd nanoparticles catalyse the formation of KA oil under conditions where activity is limited when using molecular O2, with no loss in catalytic activity observed upon re-use. The effect of key reaction parameters, including reaction temperature, catalyst mass and H2:O2 ratio are evaluated.

Graphic Abstract

Flexible nanofiber sensor for low-concentration hydrogen detection

A palladium nanoparticle-decorated three-dimensional polyacrylonitrile nanofiber network (Pd-PAN) is prepared as a hydrogen sensor by a chemical bath method. A simple low-temperature annealing treatment is adopted to stabilize the active materials and eliminate the zero-drift of the sensor. The prepared Pd-PAN device exhibits stable performance for hydrogen detection with high sensitivity, especially in a low-concentration hydrogen environment. A minimum detectable limitation of 2 ppm is achieved. In addition, an excellent repeatability is confirmed by continuous measurement under 1% hydrogen. Although the response amplitude decreases with the increased temperature from 30 °C to 70 °C, the fast and stable sensitivity demonstrate the excellent environmental adaptivity and device stability. Notably, due to the accelerated diffusion speed under higher testing temperature, the response time and recovery time are shortened. Moreover, the difference of response as low as 0.01% under bending states at 70 °C strongly confirms the robust mechanical flexibility and superior device performance. The systematic measurements demonstrate the promising application of Pd-PAN sensors for low-concentration hydrogen detection.

Ag–CoO nanocomposites for gas-phase oxidation of alcohols to aldehydes and ketones: intensified O2 activation at Ag–CoO interfacial sites

The fabrication of qualified catalysts is a key issue to implement gas-phase aerobic alcohol oxidation, but necessarily requires understanding the structures of catalytic active sites and the supply of active oxygen species.

Reaction induced robust PdxBiy/SiC catalyst for the gas phase oxidation of monopolistic alcohols

Reaction induced Pd_xBi_y/SiC catalysts exhibit excellent catalytic activity (92% conversion of benzyl alcohol and 98% selectivity of benzyl aldehyde) and stability (time on stream of 200 h) in the gas phase oxidation of alcohols at a low temperature of 240 °C due to the formation of Pd⁰–Bi₂O₃ species. TEM indicates that the agglomeration of the 5.8 nm nanoparticles is inhibited under the reaction conditions. The transformation from inactive PdO–Bi₂O₃ to active Pd⁰–Bi₂O₃ under the reaction conditions is confirmed elaborately by XRD and XPS.

Reaction induced Pd_xBi_y/SiC catalysts exhibit excellent catalytic activity and stability in the gas phase oxidation of monopolistic alcohols at a low temperature of 240 °C due to the formation of Pd⁰–Bi₂O₃ species.