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A chloroform-assisted method has been developed to prepare Au–Fe alloy catalysts under mild conditions, and they exhibit an excellent activity in the photothermal hydrogenation of acetylene.

Here, we demonstrate a photochemical strategy to site-specifically deposit Pd atoms on Au nanoparticles. The high-sensitivity low-energy ion scattering spectra combined with the X-ray photoelectron spectra reveal that the surface electronic structure of Pd can be continuously regulated by tailoring the Pd-to-Au molar ratio and the location of Pd atoms in AuPd nanoparticles. It is revealed that electron-rich Pd atoms are considerably more active than the net Pd atoms in aerobic alcohol oxidation. Remarkably, the catalyst with the most electron-rich Pd sites (binding energy downshift: 1.0 eV) exhibits an extremely high turnover frequency (˜500000 h−1 vs 12000 h−1 for that with net Pd atoms) for solvent-free selective oxidation of benzyl alcohol, which is, to the best of our knowledge, the highest value ever reported. Kinetic studies reveal that electron-rich Pd atoms can accelerate the oxidation of benzyl alcohol by facilitating C-H cleavage, as indicated by the significant reduction in the activation energy as compared to net Pd atoms.

The morphology and crystal-plane effects of CeO2 materials (nanorods, octahedra, cubes, and particles) in gas-phase selective oxidation of benzyl alcohol were investigated. HRTEM, XPS and TPR analyses showed that CeO2 nanorods enclosed by {110} and {100} facets are richer in oxygen vacancies than nanocubes, octahedra and nanoparticles. Their catalytic activity towards the gas-phase selective oxidation of benzyl alcohol, however, followed the order nanorods > nanoparticles ≈ nano-octahedra > nanocubes, which was not fully consistent with the content of oxygen vacancies. Further characterization together with density functional theory (DFT) calculations revealed that the exposed crystal planes can not only determine the content of oxygen vacancies, but also influence the ability to abstract H, adsorb O2 and remove water. The combination of all these factors leads to a collective crystal-plane effect of ceria, and these results can help deepen our understanding of ceria surface chemistry.

Nanoporous golds (NPG) exhibit excellent performance on CO oxidation due to unique pore structures with huge surface areas. However, it is a challenge for the prediction-assessing of catalytic performance without any experimental data. Herein, deep-learning methods are used to establish the structure–property relationship on NPGs. By comparing different learning algorithms, the deep recursive neural network (DRNN) can be assessed as the best network up to more than 98% accuracy. With several structural parameters, our trained model can be employed as an accurate descriptor to predict the transformation capability of CO molecules on gold catalysts and further to estimate the optimal zone in this system combined with nonlinear programming map. These meaningful findings greatly expand a way to optimize catalysts combining interdisciplinary research means, exhibiting a great application potential in the design of future catalysts.

The activation of molecular oxygen is a critical step in gold-catalyzed aerobic oxidation of alcohols. In this paper, we demonstrate that the charge of Au-adsorbed oxygen as well as the length of the O–O bond provides a useful descriptor for predicting effective catalysts for glycerol oxidation under base-free conditions. ZnO was theoretically predicted and experimentally confirmed to be the most effective support for Au to activate molecular oxygen and thus to catalyze aerobic oxidation of glycerol. Kinetic studies as well as electron paramagnetic resonance (EPR) spectra indicate that the as-generated O2− species on the surface of Au/ZnO could selectively abstract protons from the central hydroxyl group of glycerol to form dihydroxyacetone (DHA), resulting in a selectivity to DHA of up to 85%.

Though it is widely accepted that both electronic and steric effects are important in ligand-regulated heterogeneous catalysis, no experimental method has visually distinguished these two effects. Herein, by controllably tuning the surface coverage of pyridine on Pt nanoparticles, we successfully achieve bifunctional catalysis in direct methanol fuel cells with simultaneously improved oxygen reduction and methanol oxidation tolerance. More importantly, by combining the experimental results and density functional theory calculations, we reveal that the variation of the activity with the surface coverage of pyridine in these two reactions is due to the competition or cooperation between the electronic and steric effects. Other ligand experiments further confirmed the above conjecture. The stability of the pyridine ligand on Pt was also systematically studied in this paper.

The functionalization of organic ligands on nanoparticles (NPs) to create metal–organic interfaces can tune their activity and selectivity in catalytic reactions. Compared to the well-documented electronic and steric contribution of organic ligands, the coverage of ligands is also a significant factor but has been rarely investigated. Herein, we employ two methods, potential cycling and thermal annealing, to judiciously remove surface ligands from gold nanoparticles (AuNPs) and systematically investigate the influence of surface coverage of ligands on the catalytic performance. Potential cycling enables mild removal of ligands without changing the size of AuNPs and thus provides ideal models to identify the intrinsic influence of the surface coverage of ligands on oxygen reduction reaction (ORR). The ORR activity and selectivity is quantitatively evaluated by plotting the half potential and electron transfer number versus the surface coverage of ligands. Thermal annealing at different temperatures produces differently sized AuNPs with various surface ligand coverages. Compared to the size effect, we found that the surface coverage of ligands played a dominant role in the ORR activity of AuNPs. Most importantly, capping AuNPs with oleylamine and sodium citrate and reverse poisoning clean AuNPs with thiol, butylamine and CTAB further reveal that the difference in the ORR activity/selectivity of the capped AuNPs is directly related to the surface coverage of the ligands regardless of the diverse chemical nature of these ligands. This work highlights that the surface coverage of ligands should be considered as an important factor for catalytic reactions accounting for metal–organic interfaces.

The solvent-free oxidation of benzyl alcohol was studied using supported Pd-Ni bimetallic nanoparticles. Compared with monometallic Pd, the addition of Ni to Pd was found to be effective in suppressing the nondesired product toluene, thereby enhancing the selectivity towards benzaldehyde. This result was attributed to a dual effect of Ni addition: the weakening of dissociative adsorption of benzyl alcohol and the promotion of oxygen species involved in the oxidation pathway.

Metal nanocatalysts hold great promise for a wide range of heterogeneous catalytic reactions, while the optimization strategy of catalytic activity is largely restricted by particle size or shape control. Here, we demonstrate that a reversible microstructural control through the crossover between multiply twinned nanoparticle (MTP) and single crystal (SC) can be readily achieved by solvent post-treatment on gold nanoparticles (AuNPs). Polar solvents (e.g., water, methanol) direct the transformation from MTP to SC accompanied by the disappearance of twinning and stacking faults. A reverse transformation from SC to MTP is achieved in nonpolar solvent (e.g., toluene) mixed with thiol ligands. The transformation between two different microstructures is directly observed by in situ TEM and leads to a drastic modulation of catalytic activity toward the gas-phase selective oxidation of alcohols. On the basis of the combined experimental and theoretical investigations of alcohol chemisorption on these nanocatalysts, we propose that the exposure of {211}-like microfacets associated with twin boundaries and stack faults accounts for the strong chemisorption of alcohol molecules on MTP AuNPs and thus the exceptionally high catalytic activity.

Molecular hydrogen is one of the essential reactants in the chemical industry, and its generation from renewable sources such as biomass materials and water is of great benefit to the future society. Generally, molecular oxygen should be pre-eliminated in the hydrogen evolution reactions (HERs) in order to avoid the reverse hydrogen oxidation reaction (HOR). Here, we report a highly efficient HER from a formaldehyde/water mixture using MgO supported Ag nanoparticles (AgNPs/MgO) as the catalyst and molecular oxygen as a promoter. The HER rate depends almost linearly on the oxygen partial pressure, and the optimal turnover frequency (TOF) of the silver catalyst exceeds 6,600 h–1. Based on the experimental and theoretical results, a surface stabilized MgO/Ag–•OOH complex is suggested to be the main catalytically active species for the HER.

A facile confined solid-state seed-mediated alloying strategy is applied for the rational synthesis of supported Au–Ni bimetallic nanoparticles (BMNPs). The method sequentially deposits nickel salts and AuNP seeds into the ordered array of extra-large mesopores (EP-FDU-12 support) followed by a high-temperature annealing process. The size, structure, and composition of the AuNi BMNPs can be well tuned by varying the AuNP seeds, annealing temperature, and feeding ratio of metal precursors. Kinetic studies and DFT calculations suggest that the introduction of the Ni component can significantly prompt the O2 activation on AuNPs, which is critical for the selective alcohol oxidation using molecular O2 as the oxidant. The optimal Au–Ni BMNP catalyst showed the highest turnover frequency (TOF) (59 000 h–1, 240 °C) and highest space-time yield (STY) of benzyl aldehyde (BAD) productivity (9.23 kg·gAu–1·h–1) in the gas-phase oxidation of benzyl alcohol (BA), which is at least about 5-fold higher than that of other...

Correction for ‘Activating molecular oxygen by Au/ZnO to selectively oxidize glycerol to dihydroxyacetone’ by Ye Meng et al., Catal. Sci. Technol., 2018, 8, 2524–2528.