Selective Oxidation Of Benzyl Alcohol Research Articles

Icosahedral AuPd/carbonized poly-dopamine sphere@TiO2 yolk-shell nano-photoreactor for plasmon-enhanced catalytic activity and stability

Icosahedral AuPd bimetallic nanoparticles exhibit the localized surface plasmon resonance effect with their excellent thermocatalytic activity. However, the nanoparticle aggregation and recovery difficulty challenge the widespread adoption. In this work, we designed and fabricated a yolk-shell structured icosahedral AuPd/carbonized poly-dopamine sphere@titanium dioxide (I-AuPd/C-PDA@TiO2), which exhibited excellent catalytic performance towards photocatalytic selective oxidation of benzyl alcohol (BA). Specifically, the introduction of C-PDA not only improved the chemical stability of AuPd nanoparticles but also promoted electron transfer. Meanwhile, the controlled growth of monodisperse icosahedral AuPd benefited the selective oxidation of BA due to the LSPR effect. Compared to yolk-shell Pd/C-PDA@TiO2, Au/C-PDA@TiO2 and spherical AuPd/C-PDA@TiO2 (S-AuPd/C-PDA@TiO2) photocatalysts, I-AuPd/C-PDA@TiO2 showed the highest catalytic performance with 96.0% conversion rate and 99% selectivity in 6 h under an O2-saturated reaction environment. Moreover, no obvious performance decay was observed with I-AuPd/C-PDA@TiO2 after five successive cycles, confirming the outstanding stability of I-AuPd/C-PDA@TiO2. The current strategy would be a significant contribution of AuPd bimetallic nanocrystals for plasmon-enhanced catalysis.

Synergistic reduction of U(VI) and selective oxidation of benzyl alcohol to prepare benzaldehyde via WOx/g-C3N4

In the photoreduction of U(VI), protective gases and additional sacrificial agents are still the major obstacles. Herein, we developed an oxygen-deficient WOx/g-C3N4 catalyst for the simultaneous reduction of U(VI) and preparation of benzaldehyde by selective oxidation of benzyl alcohol without protective gases and sacrificial agents. The removal of U(VI) by WOx/g-C3N4 could reach 98.5% and the conversion of benzyl alcohol was nearly 32% with a selectivity close to 100%. Compared with single g-C3N4 and defect-free WO3, the photoreduction activity of WOx/g-C3N4 was 10.4 and 7 times higher, respectively. Besides, the role of oxygen and oxygen defects was explored. Owing to oxygen defects in the catalyst, oxygen was adsorbed on the oxidation end (WOx) of the catalyst and activated without entering the reduction end to interfere with the photoreduction of U(VI), while favoring the generation of •O2- to improve the selectivity of benzaldehyde. Finally, a new mechanism was proposed.

Improved Catalytic Performance toward Selective Oxidation of Benzyl Alcohols Originated from New Open-Framework Copper Molybdovanadate with a Unique V/Mo Ratio.

A new organic-inorganic hybrid open-framework molybdovanadate with mixed-valences of vanadium (V4+ /V5+ =4/3) and molybdenum (Mo5+ /Mo6+ =8/2) cations has been synthesized. The complex possesses the unique V/Mo ratio (7/10), fascinating 8-C topological network and 1D 4-MR channels (7.793 Å×6.699 Å). Importantly, its catalytic activities for the selective oxidation of benzyl alcohol to benzaldehyde (oxidant: H2 O2 , 30 wt %) have been well evaluated. The results indicated that it exhibited improved catalytic activities (conv.: 96.8 %) compared with the catalyst (Cpyr)5 PV2 Mo5 W5 O40 [conv.: 88.51 %, Cpyr=(C16 H32 C5 H4 N)+ )], high recyclability and structural stability. Moreover, the conversions and selectivities (conv.: 82.4-92.5 %; sele.: 91.5-95.7 %) of the substrates containing electron donating groups (-OH, -CH3 , -OCH3 and -Cl) were significantly higher than those of the substrate containing electron withdrawing group (-NO2 ) (conv. 67.4 %; sele.: 80.8 %). This is due to the fact that the -NO2 with a large Hammett substituent constant is not conducive to the generation of transition state products. The studies revealed the complex could act as a highly efficient heterogeneous catalyst in selective oxidation of benzyl alcohols.

Semi-closed synthesis of mesoporous carbon supported metal oxide nanoparticles

Common methods for preparing mesoporous carbon (MC)-supported metal oxide nanoparticles include chemical vapor deposition, sol-gel, hydrothermal, and microemulsion methods. It is necessary to first prepare carbon materials and thereafter load the metal oxide nanoparticles. In recent years, simple one-pot methods to prepare mesoporous carbon-supported metal and metal oxide nanoparticles has received a lot of attention. Inspired by the semi-closed method for preparing MC materials, in this study, we report a method for preparing MC-supported metal oxide nanoparticles in a single-step process in a muffle furnace after adding a one-step in situ synthesized precursor in a semi-closed system. The porous carbon-supported metal oxide nanoparticles prepared using this method have the advantages of a small particle size, uniform distribution, stable structure, and applicability to various metal oxides. The MoO3/MC catalysts prepared using this method exhibited excellent catalytic performance for the selective oxidation of benzyl alcohol. Only 5 mg of MoO3/MC-2 was used to convert 0.5 mmol benzyl alcohol to benzaldehyde in 2 mL DMSO with a conversion of 99% under air. The catalytic reaction is carried out at a high TON and TOF of 181 and 30.2 h−1, respectively. Furthermore, the MoO3/MC catalysts exhibited high selectivity, wide substrate universality, and excellent stability.

Solvent‐Free Selective Oxidation of Benzyl Alcohol at Atmospheric Pressure Catalyzed by Pd Nanoparticles Supported on g‐C3N4 Materials with Tunable Nitrogen Distributions

AbstractSolvent‐free atmospheric selective oxidation of benzyl alcohol (BZA) by molecular oxygen is a promising and green process for the synthesis of benzaldehyde (BZL). Supported Pd nanoparticles have been widely reported in the catalytic selective oxidation of BZA where the activity depends on the chemical valence and dispersion of the Pd nanoparticles. Herein, a series of thermally exfoliated g‐C3N4 (eg‐C3N4) have been synthesized under various gas conditions (air/N2) and then applied as catalyst supports to load Pd nanoparticles. The physicochemical properties of the prepared Pd/eg‐C3N4 materials have been characterized by N2 adsorption–desorption, XRD, FT‐IR, UV‐vis, XPS, and TEM. Pd nanoparticles dispersed well on the supports, and the distributions of Pd and nitrogen species of the catalysts were related to the gas conditions of the supports. In the selective oxidation of BZA, 2.5Pd/eg‐C3N4‐AN catalyst afforded conversion of BZA and the selectivity to BZL of 88 % and 92 %, respectively. The metallic Pd0 species are considered the catalytic sites of Pd/eg‐C3N4 in the catalytic reaction and meanwhile, the basic Nb species of eg‐C3N4 were beneficial to the overall activity of the catalyst.

Gold nanoparticles supported on modified dumbbell shaped nanorod cluster CuBi2O4 for the selective oxidation of benzyl alcohol under visible light

Dumbbell-shaped nanorod cluster CuBi2O4 was fabricated by a hydrothermal method, and a variety of × wt% Au/CuBi2O4 (x = 1, 2, 3, 4, 5, 6) were prepared by NaBH4 reduction method. By using XRD, XPS, SEM, TEM, UV–vis DRS and BET, it was demonstrated that the catalysts were successfully synthesized. Density functional theory (DFT) was used to study the band structure, density of states (DOS) and differential charge density of catalysts. DFT results showed that the energy gap of CBO and Au/CBO was 1.74 eV and 1.59 eV, respectively. Because of Au loading, the recombination of e- and h+ pairs is significantly inhibited because h+ has a greater effective mass in the VB and its photocatalytic selective oxidation of benzyl alcohol is enhanced. Au was found to have an important effect on the enhancement of the photocatalytic activity of the catalyst. Au/CuBi2O4 composites have dramatically a higher degree of separation of the photogenerated carriers than that of pristine CuBi2O4 according to PL and EIS. By optimizing the reaction conditions and comparing different catalysts, GC and GC–MS revealed that 4 wt% Au/CuBi2O4 was the optimum catalyst. Under green mild conditions, the conversion of benzyl alcohol to benzaldehyde can achieve 88.9% with a selectivity of 99%. Moreover, the catalyst was stable by the reuse experiment. A plausible mechanism for the selective oxidation of benzyl alcohol was proposed based on the DFT and experimental results.

Highly Efficient and Selective Oxidation of Benzyl Alcohol by WO42− Catalyst Immobilized by a Phosphonium-Containing Porous Aromatic Framework

Benzoic acid has found a wide range of applications in the chemical industry. The selective oxidation of benzyl alcohol is one of the main routes to produce benzoic acid. In this work, tris(4-bromobiphenyl)phosphine was chosen as a building block to synthesize PAF-181 with a high specific surface area and high yield via a Yamamoto–Ullmann reductive coupling reaction. Subsequently, the WO4@PAF-181 catalyst was successfully prepared via methylation and ion exchange, in which PAF-181 acts as a carrier while WO42− serves as the active catalytic site. The synergistic effect between functional carriers and active sites endows WO4@PAF-181 with distinctive catalytic property for efficient selective oxidation of benzyl alcohol to benzoic acid. Importantly, the catalyst can be conveniently recovered and reused by simple filtration, still maintaining its high catalytic activity.

Photocatalytic activity of CuBi2O4/WO3 p-n heterojunction photocatalysts in benzyl alcohol oxidation to benzaldehyde

CuBi2O4/WO3 (CBO/WO3) p-n heterojunction composite was synthesized by mechanical stirring and sonication for the selective oxidation of benzyl alcohol to benzaldehyde under visible light. Multiple characterization methods, including XRD, XPS, SEM, TEM, UV–vis DRS, BET, EIS and ESR, were used to investigate the origin of the excellent photocatalytic activity. The results of XRD, XPS, SEM, and TEM revealed that CBO/WO3 catalyst was successfully synthesized. Benzaldehyde selectivity of over 99 % and benzyl alcohol conversion of 54.8 % were obtained under an optimized condition using 50 mg of 40-CBO/WO3 (40 stood for the mass percentage of CBO in CBO and WO3.). DFT results showed that ∆Eads values of benzyl alcohol were − 0.51, − 0.66 and − 0.88 eV on CBO, WO3 and CBO/WO3. The oxidation of benzyl alcohol occurred more easily on the surface of CBO/WO3. Meanwhile, the stability of 40-CBO/WO3 was investigated. After 5 repeated experiments, a high conversion was still maintained, indicating its potential in practical application. A possible mechanism of benzyl alcohol to benzaldehyde was proposed through the capturing experiment of active species. This work successfully designed an efficient p-n heterojunction composite catalyst for selective oxidation of benzyl alcohol. Replacing traditional thermal synthesis with selective photocatalysis can promote more environmentally friendly processes.

Selective oxidation of benzyl alcohol to benzaldehyde over CoFe2O4 nanocatalyst

Co/Fe bimetallic spherical nanomaterials were synthesized by hydrothermal method as an efficient heterogeneous catalyst, which can catalyze the selective oxidation of benzyl alcohol to benzaldehyde by O2, thereby replacing stoichiometric oxidation reagents such as chromate and manganese oxide. CoFe2O4 has good oxidation activity and selectivity for benzyl alcohol. The catalyst catalyzes the preparation of formaldehyde from benzyl alcohol oxide by O2 at 150 °C, with a conversion rate of 95.3% and a yield of 96.7%. Furthermore, the catalyst is recycled for 5 consecutive uses without significant degradation of its catalytic performance.

Efficient photocatalytic dehydrogenation and synergistic selective oxidation of benzyl alcohol to benzaldehyde for Zn0.5Cd0.5S co-modified with MoS2 nanoflowers and g-C3N4 nanosheets

Zn0.5Cd0.5S solid solution co-modified by MoS2 nanoflowers and g-C3N4 nanosheets (C3N4/MoS2/Zn0.5Cd0.5S) was synthesized with highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). The photocatalytic dehydrogenation rate and BAD yield are 1.7 mmol·g−1·h−1 and 35.8% for C3N4/MoS2/Zn0.5Cd0.5S, and selective oxidation to BAD is almost 100%. Reaction selectivity was explored by detecting all the substances of the solution after reaction for Zn0.5Cd0.5S and C3N4/Zn0.5Cd0.5S using gas chromatography-mass spectrometry (GCMS), and analysis results indicated that BA was converted to other substances because of the insufficient hole oxidation capacity of the samples. The mechanism for highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD was systematically investigated by electron paramagnetic resonance (EPR) and first-principle density-functional theory calculations. The EPR spectra of the phenyl-N-tert-butyl-nitrone (PBN)-carbon centered radical indicated that ·C induced by photo-generated holes are the key intermediate of the photocatalytic dehydrogenation of BA. The loading of flower-like MoS2 accelerates charge transport and enhances the hole oxidation ability of Zn0.5Cd0.5S, and the introduction of g-C3N4 has a negative valence band potential that can collect photogenerated holes of Zn0.5Cd0.5S, thereby inhibiting photocorrosion. Therefore, the photocatalytic dehydrogenation and synergistic selection of BA to BAD for the C3N4/MoS2/Zn0.5Cd0.5S ternary heterostructure were greatly improved. The research work would provide a feasible, sustainable, economical, and potential technique for the highly efficient dehydrogenation and synergistic selective oxidation of BA based on photocatalysis that excludes the usage of noble metals and sacrificial reagents.

A DFT investigation of the catalytic oxidation of benzyl alcohol using graphene oxide.

Metal-free heterogeneous materials have attracted great interest due to their potential to facilitate various organic transformations in line with circular economy and green chemistry principles. Among various 2D materials, graphene oxide (GO) is considered an attractive material for numerous applications in physics, chemistry, biology, material sciences, and catalysis. Furthermore, graphene-based catalysts exhibit good catalytic activity toward the selective oxidation of benzyl alcohol to benzaldehyde or benzoic acid under eco-friendly conditions. In this regard, a theoretical investigation was carried out to study both catalytic oxidation reaction pathways (i.e., benzyl alcohols to aldehyde and to benzoic acid) using GO as an eco-friendly and metal-free catalyst. In this study, we report a theoretical investigation at the B3LYP/6-31G level to better understand the oxidation of benzyl alcohol using GO as a metal-free catalyst. The possible bond formation was investigated using the global and local reactivity indexes derived from Fukui functions. Furthermore, we performed a non-covalent interaction (NCI) analysis to unveil the stability and the interaction nature between both reagents and GO surface. The effect of the solvent on the oxidation efficiency was also performed and the results indicate that the solvent significantly affects the decrease of reactivity by increasing the activation barriers through oxidation reactions of benzyl alcohol. Additionally, the electron localization function (ELF) analysis was performed for all intermediates showing the ionic nature of the studied epoxide structure of GO and rules out any type of covalent interaction during the oxidation reaction of benzyl alcohol. All these obtained results are in good agreement with experimental observations and reveal that the epoxide functions on the graphene surface promote an excellent catalyst turnover.

Solvent-free and efficiently selective oxidation of benzyl alcohol catalyzed by Pd/CeO2 materials under atmospheric oxygen

Selective oxidation alcohol under solvent-free and atmosphere-pressure oxygen is a green and promising strategy for the synthesis of aldehydes and other carboxylic compounds. The design and preparation of efficient heterogeneous catalysts is a hot topic for the process. In this work, CeO2 materials were prepared through a convenient decomposition of Ce(NO3)3·6 H2O precursor, and then employed as supports to load Pd nanoparticles. The decomposition temperature had an important effect on the distributions of Pd0/Pd2+ and Ce3+/Ce4+ species, as well as the oxygen vacancy of Pd/CeO2 materials. In solvent-free and atmosphere-pressure conditions, Pd/CeO2 could smoothly convert benzyl alcohol (BZA) to benzaldehyde (BZL) with oxygen, and the catalytic activity was correlated with the percentage of Pd2+ and oxygen vacancy fractions. Under the reaction time of 4 h, temperature of 90 °C and 4 mL of benzyl alcohol, the conversion of BZA and selectivity to BZL were 72.6% and 96.3%, respectively. The catalyst could be reused at least five times without any significant loss in activity and had no leaching problem of catalytic sites.

A Rhombus-Like Tetrameric Vanadoniobate Containing Pseudo-Sandwich-Type {Li ⊂ V2O8(Nb5O14)2} and Its Electrocatalytic Activity for the Selective Oxidation of Benzyl Alcohol.

Ongoing research on V-containing polyoxoniobates (PONbs) is driven by their diverse structures and potential applications. Although Lindqvist-type {Nb6O19} is a widely used building block in PONbs, vanadoniobates based on {Nb6O19} and/or its derivatives are still very limited. Herein, a discrete vanadoniobate, LiNa14K11[Li2 ⊂ VIV8Nb32O110]·45H2O (1), has been synthesized by a hydrothermal method, which shows a rhombus-like tetrameric structure composed of two {V2O6(Nb6O19)} and two {Li ⊂ V2O8(Nb5O14)2} subunits derived from {Nb6O19}. Notably, the {Li ⊂ V2O8(Nb5O14)2} subunit has an interesting pseudo-sandwich-type structure, where a {LiV2O8} belt is coordinated by two monolacunary {Nb5O14} molecules and the central site of the cluster is occupied by Li+. Considering that 1 has both basic hexaniobates and redox active V centers, 1 was used as a noble metal-free electrocatalyst for the selective oxidation of benzyl alcohol to benzaldehyde, achieving complete conversion of benzyl alcohol with 94% selectivity for benzaldehyde in 3 h under ambient conditions without using any alkaline additives. Moreover, the catalytic performance of 1 remained largely unchanged after four cycles.

Enhanced photocatalytic hydrogen production and simultaneous benzyl alcohol oxidation by modulating the Schottky barrier with nano high-entropy alloys

Catalysts play a vital role in photocatalytic water-splitting by converting solar energy into storable chemical energy. In this study, we successfully synthesized an HCN/HEA heterostructure by rationally combining the Pt18Ni26Fe15Co14Cu27 nano-high-entropy alloy (HEA) as an effective cocatalyst with protonated g-C3N4 (HCN) nanosheets, via an electrostatic self-assembly method. The resulting HCN/HEA exhibited remarkable performance in both photocatalytic H2 production and selective oxidation of benzyl alcohol to benzaldehyde. The integration of HEA into HCN leads to the formation of Schottky junctions, which can significantly accelerate charge migration and reduce the recombination of charge carriers. Further investigations using in situ surface photovoltage imaging demonstrated that the reducing cocatalyst HEA can act as a photogenerated electron trap. The best HCN/HEA heterojunction exhibited excellent photocatalytic hydrogen production activity, reaching 2.4 mmol g−1 h−1 and an impressive benzaldehyde production rate of 5.44 mmol g−1 h−1. These values were 958 and 6.6 times higher than those achieved with pristine HCN, respectively. This study offers promise for the rational design of high-performance cocatalysts to improve the transport, separation, and utilization of light-release charge carriers.

Simultaneous benzyl alcohol oxidation and H2 generation over MOF/CdS S-scheme photocatalysts and mechanism study

The conversion from solar energy into storable chemical energy can be achieved through synergistic coupling of photocatalytic H2 production and organic synthesis, during which photogenerated electrons and holes can be simultaneously utilized. Herein, we combined a zirconium-based metal-organic framework, UiO-66-NH2, and CdS nanoparticles (NPs) to form a core-shell structure by a chemical bath method. The step-scheme (S-scheme) heterojunction exhibits both substantially enhanced selective oxidation of benzyl alcohol and efficient H2 generation under light irradiation simultaneously. The electron transfer paths at the S-scheme heterostructure interface were investigated in depth by in situ irradiated X-ray photoelectron spectroscopy. The dynamics of carrier migration at the heterojunction were obtained through femtosecond transient absorption (fs-TA) spectroscopy. Furthermore, the evolution mechanism of benzaldehyde was revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy and electron paramagnetic resonance. This work illustrates the electron transfer mechanism of S-scheme heterojunction by fs-TA spectroscopy and provides new insights into the design of MOF/inorganic composite photocatalysts.

Mononuclear Cu-complex embedded ordered nano-porous silica based hybrid catalyst for oxidation of benzyl alcohol

A novel mixed ligand copper (׀׀) complex having 2,9-dimethyl-1,10-phenanthroline and nitrate has been successfully synthesized and characterized by single crystal XRD. Following synthesis, this complex was anchored on acid functionalized nano-porous materials such as MCM-41-SO3H and SBA-15-SO3H, and these hybrid materials were characterized using a variety of techniques such as FT-IR, PXRD, BET, SEM, TG, and so on. These modified mesoporous materials (MCM-41-SO3HCu and SBA-15-SO3HCu) were subjected to solvent-free selective benzyl alcohol oxidation with TBHP (Tert-Butyl Hydroperoxide) as an oxidant. Various reaction parameters were investigated to optimize the reaction conditions. MCM-41-SO3HCu was discovered to be an excellent catalyst in terms of benzyl alcohol conversion and benzaldehyde selectivity.

Iron-palladium supported graphene as an efficient bimetallic catalyst for the selective oxidation of benzyl alcohol to benzaldehyde

The catalytic oxidation of benzyl alcohol (OBA) is one of the significant methods to produce benzaldehyde, an essential reagent in the chemical and pharmaceutical industries. However, developing an active and efficient catalyst for OBA is a tremendous challenge in commercialization. This research describes a simple, eco-friendly method for producing Fe, Pd, and Fe: Pd bimetallic nanoparticles fabricated by sol immobilization over graphene to conduct OBA. The resulting composite nano-alloys were then characterized using X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The oxidation state and elemental composition of as-fabricated nanoparticles were analyzed using XPS. The point of zero charges (pHPZC) was analyzed and the PZC value indicated that the proposed adsorbent material tends to have a positive charge. The OBA reaction efficiency (87%) of bimetallic nanocatalysts stabilized in graphene support was increased through surface modification of the ratio of both metals. The experimental error was based on three parallel tests and the carbon balance (99.6%) was analyzed during the experiments A proposed reaction mechanism of OBA validated the β-hydride step's elimination by molecular oxygen converting the metal hydride into a water molecule, forming a peroxide intermediate to form water and oxygen molecules. The Fe on the nanocatalyst’s surface is preferentially responsible for the adsorption of the substrate molecule, resulting in the formation of metal-alkoxide. Since it lacks electrons, Fe is more likely to be oxidized, allowing it to perform better than monometallic catalysts in terms of catalytic activity. The present study has great potential to be applied on an industrial scale and studied for industrialists, researchers, and academicians.

Preparation of CuFe2O4 composite metal oxides and selective oxidation of benzyl alcohol

Using iron nitrate and copper nitrate as raw materials, mesoporous material SBA-15 as template agent and n-hexane as solvent, CuFe2O4 samples of mesoporous loaded composite metal oxide catalysts were successfully prepared by calcination at 600 °C. The samples were characterized by X-ray diffraction (XRD), thermogravimetric-differential scanning analysis (TG-DSC), and scanning electron microscopy (SEM). The selective oxidation of benzyl alcohol by CuFe2O4 under different catalytic conditions was investigated using benzyl alcohol as a model compound, and the oxidation products were analyzed by high performance liquid chromatography (HPLC). The results showed that the CuFe2O4 catalyst prepared by calcination at 600°Cwas the best. The best selective oxidation conditions were achieved at a reaction system temperature of 90 °C, a catalyst dosage of 4 g/L, a molar ratio 1:1 of H2O2 dosage to benzyl alcohol, and a reaction time of 4 h. The conversion of benzyl alcohol under this condition was 66.95%, and the selective conversion of benzaldehyde was 96.07%. This indicates that CuFe2O4 is a composite metal oxide with high selective oxidation of benzyl alcohol and has wide application prospects.

The role of AgNPs in selective oxidation of benzyl alcohol in vapor phase using morphologically tailored MnO2 nanorods in the presence of air

Vapor phase benzyl alcohol (BnOH) oxidation reaction is investigated over a pre–synthesised morphologically designed shape controlled spherical silver nanoparticles (AgNPs) decorated on manganese oxide nanorods (α–MnO2NRs) in the presence of air. The combination of silver nanoparticles and the α–MnO2NRs interface enabled the increased oxygen vacancies (Ov) and exhibited the strong metal–support interactions (SMSI) in surface oxygen activation. The effect of Ag loadings is significant and the optimal 1 wt% Ag loaded catalyst (1Ag/MnO2NRs) showed excellent performance in benzyl alcohol oxidation due to high adsorption capacity, enhanced oxygen vacancies and red–ox properties. The DFT calculations confirmed that the high BnOH surface adsorption was exhibited over Ag modified MnO2NRs than the bare α–MnO2NRs. The optimized 1Ag/α–MnO2NRs catalytic system achieved 2.6 fold higher activity compared to bare α–MnO2NRs. These results provided novel insights on the rational design of shape dependent metal/metal oxide based heterogeneous catalysts.

Boosting photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol to benzaldehyde over flower-like MoS2 modified Zn0.5Cd0.5S solid solution

A series of MoS2/Zn0.5Cd0.5S with varying concentrations of flower-like MoS2 is prepared based on a simple and practical method with highly efficient photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). A comparative study between the composites and their two components (pristine MoS2 and Zn0.5Cd0.5S) is carried out for various structural, optical, electrical, and photocatalytic characterization. The studies reveal that the size of Zn0.5Cd0.5S nanoparticles is in the order of 3∼5 nm and is distributed uniformly over the surface of the flower-like 350 nm sized MoS2. The optical research conducted using UV–vis diffuse reflectance spectroscopy reflecting an excellent photoresponse by the MoS2/Zn0.5Cd0.5S. The photoelectrochemical tests showed that the adding of proper ratio of flower-like MoS2 (6%) results in an efficient separation and migration of photogenerated carriers for pristine Zn0.5Cd0.5S nanoparticles. The photocatalytic dehydrogenation rate of BA for the 6%-MoS2/Zn0.5Cd0.5S is the highest at 3.03 mmol g−1 h−1, meanwhile the yield of BAD and the selective conversion of BA to BAD are 49.3% and 100%, respectively. The essential stages of the photocatalytic dehydrogenation of BA are ·C caused by the photo-generated holes, according to the EPR spectra of the PBN-carbon centered radical (PBN–C). Besides, the mechanism for improved photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD with flower-like MoS2 modified Zn0.5Cd0.5S nanoparticles was systematically studied through gas chromatography-mass spectrometry analysis and first principle density functional theory calculations. The highly efficient dehydrogenation and synergistic selective oxidation of BA to BAD for MoS2/Zn0.5Cd0.5S are mainly attributed to the introduction of MoS2 nanoflowers that can provide abundant active sites, and formed MoS2/Zn0.5Cd0.5S heterostructures could further promote the separation of photogenerated electron-hole pairs. Moreover, the valance band position of the 6%-MoS2/Zn0.5Cd0.5S is more positive, so the hole at the VB position has the stronger ability to oxidize BA. This study provides a feasible method for efficiently photocatalytic dehydrogenation synergism selective oxidation of organic substrates into valuable products.