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An FeMgOy-modified Cu interfacial structure is constructed as a photocatalyst for CO2 conversion with H2O via the structural topological transformation of layered double hydroxides.

Aiming at the comprehensive utilization of waste and renewable carbon resources, we achieved a photocatalytic coupling process of CO2 reduction and 5-hydroxymethylfurfural oxidation mediated by the anionic compound of layered double hydroxides.

The ZnO/BiVO4/NiFePB photoanode was fabricated successfully and showed the excellent performance of PEC water oxidation compared with the ZnO photoanode, which is attributed to the formation of a heterojunction and decoration of NiFePB cocatalyst.

Qualitatively identifying the dominant catalytic site for each step of a semi-continuous reaction and semi-quantitatively correlating such different sites to the catalytic performance is of great significance toward the integration of multiple well-optimized sites on a heterogeneous catalyst. Herein, a series of structurally defined TiOx-based catalysts were synthesized to provide a feasible approach to investigate the aforementioned issues using the semi-continuous oxidation of glycerol as a model reaction. Detailed investigations have verified the simultaneous presence of two kinds of Pt active sites: 1) Negatively charged Pt bound to the oxygen vacancies of modified TiOx in the form of Ptδ−-Ov-Ti3+ sites and 2) metallic Pt (Pt0 site) located away from the interface. Meanwhile, the proportion of surficial and interfacial sites varies over this series of catalysts. Combined in situ FTIR experiments revealed that the reaction network was well-tuned via a site cooperation mechanism: The surficial Pt0 sites dissociatively adsorb the OH group of glycerol with a monodentate bonding geometry and the Ptδ−-Ov-Ti3+ sites dissociate the C=O bond of the aldehyde group in a bidentate form. Furthermore, CO-FTIR spectroscopy confirmed a correlation between the reaction rate/product selectivity and the fraction of surficial/interfacial sites. A rational proportion of surficial and interfacial sites is key to enabling a high yield of glyceric acid. The most active catalyst with 32% surface sites and 68% interfacial sites exhibited 90.0% glycerol conversion and 68.5% GLYA selectivity. These findings provide a deeper understanding of the structure-activity relationships using qualitative identification and semi-quantitative analysis.

We reported a strategy of carbon-negative H2 production in which CO2 capture was coupled with H2 evolution at ambient temperature and pressure. For this purpose, carbonate-type CuxMgyFez layered double hydroxide (LDH) was preciously constructed, and then a photocatalysis reaction of interlayer CO32- reduction with glycerol oxidation was performed as driving force to induce the electron storage on LDH layers. With the participation of pre-stored electrons, CO2 was captured to recover interlayer CO32- in presence of H2O, accompanied with equivalent H2 production. During photocatalysis reaction, Cu0.6Mg1.4Fe1 exhibited a decent CO evolution amount of 1.63 mmol/g and dihydroxyacetone yield of 3.81 mmol/g. In carbon-negative H2 production process, it showed an exciting CO2 capture quantity of 1.61 mmol/g and H2 yield of 1.44 mmol/g. Besides, this system possessed stable operation capability under simulated flu gas condition with negligible performance loss, exhibiting application prospect.

A novel 9ZBFO/rGO(1 wt%) composite exhibits excellent gas sensor performance, which is attributed to heterojunction interface modulation and rGO modification.

The catalytic upgrading of phenolic derivatives is vital for the efficient utilization of biomass resources. Herein, we construct a reductive layered double oxide material (CoAlCe-LDO) with the Ce–...

In this work, two Pt catalysts using anatase and rutile as supports were prepared, and then the support effect on catalytic performance in glycerol oxidation was investigated. Different Pt/TiO2 catalysts exhibited not so negligible distinction on the product distribution. On one side, the C=O bonds of intermediate glyceraldehyde (GLYAD) highly dissociated in the form of bidentate species through C atom bonding to O atom and O atom bonding to Ti atom of rutile support, which largely promoted the transformation from GLYAD to glyceric acid (GLYA). While, in the case of anatase support, the adsorption form of C=O was monodentate. On another side, the formed GLYA was weakly adsorbed through two O atoms bridging/bonding to two Ti atoms. Due to the longer Ti–Ti distance in anatase, C–C cleavage of GLYA was obviously inhibited. The rutile support with shorter Ti–Ti distance inevitably led to obvious C–C cleavage. The discovery of the support effect could offer an alternative method to controllably regulate product distribution and offers specific perspective on designing efficient catalysts in semicontinuous oxidation reactions.

In this work, we synthesized a series of Cu/ZrO2 catalysts with tunable Vo-Cu0 (oxygen vacancy adjacent to Cu metal) and VZr-Cuδ+ (zirconium vacancy adjacent to electron-deficient Cu species) dual-interface sites and investigated the role of the dual-interface sites in the 5-hydroxymethylfurfural (5-HMF) hydrogenolysis reaction with isopropanol as the hydrogen source. By combining a series of in situ infrared characterization and catalytic performance analysis, it is identified that Vo-Cu0 interface sites were responsible for activating isopropanol dehydrogenation and C═O dissociation of 5-HMF, while the VZr-Cuδ+ interface sites were responsible for the dehydroxylation of an intermediate product 5-methyl-2-furfuryl alcohol (5-MFA). Specifically, C-OH was first deprotonated on the VZr at the VZr-Cuδ+ interface site to reduce the activation energy of 5-MFA dehydroxylation and then adjacent Cuδ+ promoted the dissociation of the C-O bond by enhancing the adsorption energy while elongating the C-O bond, as confirmed by the density functional theory calculations. Because the dual-interface sites provided separate sites for activating intermediate products and reactants, the coupling reaction caused by competitive adsorption is thus well avoided. Therefore, the optimized Cu/ZrO2 catalyst with the most VZr-Cuδ+ and moderate Vo-Cu0 sites exhibited 98.4% of 2,5-dimethylfuran yield under the conditions of 180 °C and self-vapor pressure.

Choosing an appropriate metal precursor is a basic step in the preparation of catalysts. In this paper, PdCl42−, PdSO4 and Pd(acac)2 were selected as the metal precursor, which was supported on α-Al2O3 commonly used in industry to explore the impact of palladium precursor on the structure and catalytic behavior for selective acetylene hydrogenation. The activity for the three catalysts is similar, while the ethylene selectivity of Pd(acac)2 can outclass the other two catalysts at the fixed conversion. The different catalytic performance is mainly ascribed to the influence of non-metal residua distribution on valence state structure and size effect determined by HRTEM, CO chemisorption, XPS and in situ CO-IR. More importantly, the catalyst prepared by Pd(acac)2 perform better stability due to the formation of the Pd carbide species after 24 h reaction. The catalytic deactivation with time-on-stream for other two catalysts was attributed to the sintering of Pd particles and carbon deposition under reaction conditions.

The interaction between the metal and the support of supported metal catalysts, which are widely used in industry, is the primary focus of the study of such catalysts. With the developing understanding of the metal–support interaction, the intrinsic factor that influences the catalytic performance has been determined to be the structure of interfacial sites. Layered double hydroxides (LDHs, a class of two-dimensional layered anion clay) possess several unique characteristics, such as the following: (1) tunable elemental component, homogeneous distribution of metal cations. (2) anchoring effect. (3) multiple layered structure for exfoliation or intercalation and special memory effect; and (4) internal/external confinement effects during topological transformation. Taking LDHs and their derivatives as precursors or supports shows superior advantages in designing interfacial active catalysts with tunable properties. Therefore, this review is mainly focused on constructing interfacial active catalysts by LDHs and revealing the interfacial effects (including electronic, geometric, and bifunctional effects) on the catalytic performance that will provide new perspectives and approaches for the development of heterogeneous catalysis.

In this work, layered double hydroxides (LDHs) including the variable valence Co2+ ions (CoAl-LDHs) is discovered to be capable of serving as the support and the reducing agent for the fabrication of well-distributed PdAu nanoparticles because of the low potential for reduction. Specifically, the active metal precursors undergo the redox process, in which Co2+ is oxidized to Co3+, while active metal ions are successfully reduced to bimetallic PdAu nanoparticles with the dispersion of 73%. Furthermore, the obtained catalysts are evaluated in the selective oxidation of benzyl alcohol as the probing reaction to explore the catalytic behavior. As for intrinsic activity, PdAu/CoAl-LDHs derived by the above in situ spontaneous reduction exhibits activation energy of 62.4 kJ mol−1, much lower than that of PdAu/CoAl-LDHs prepared by sol-immobilization. When the reaction time reaches to 4 h, the benzaldehyde selectivity over the former catalyst is up to 94%, originating from the surface electron starvation of active metals that promots the hydroxyl groups reacting with O2 to produce benzaldehyde.

A series of TiO2 anatase materials were synthesized with varying proportions of exposed (101) and (001) facets. Pt was subsequently impregnated onto these materials, which were then exposed to either an aerobic or reductive thermal treatment. The final catalysts were assessed for their performance in the aerobic, solvent free oxidation of octanol. Many kinds of characterization methods were employed to gain insight on how the exposed support facets influenced the catalysis. Thermal reduction of the catalysts led to a loss in the support surface structure, but in the contrary, after calcination, the defined facets remained, which was revealed by Raman and XRD. We further provide evidence that the coordinately unsaturated O2c–Ti5c–O2c sites present in the support promoted the dispersion of Pt after calcination in Air, leading to the formation of low-coordinated and electron-deficient Pt clusters, based on high resolution- and spherical- aberration corrected transmission electron microscopy and X-ray absorption fine structure analysis. The calcined catalysts were far more active for both the oxidation of octanol and intermediate octanal, thus resulting in a higher selectivity of octanoic acid. Catalyst performance closely correlated with the proportion of low-coordinated Pt species and the specific surface coordination structure of the support in the catalyst. Subsequent in-situ Fourier transfer infrared experiments, conducted using alcohol and aldehydic probe molecules, confirmed that substrate adsorption was strongly influenced by the low-coordinated sites of both the Pt cluster and the exposed surface facets on the support.

Five boehmite adsorbents with high percentage of exposed (020) facets and large specific surface area were prepared by the separate nucleation and aging steps (SNAS) method at different rotating speeds, namely B-n (n = rotating speeds) from 500 to 1500 rpm of the rotating liquid film reactor (RLFR). From 500 rpm to 1500 rpm, both specific surface area and percentage of exposed (020) facets increased by ca. 10.8% and 16.9%, respectively. For all the samples, the adsorption behavior followed the pseudo-second-order model and Langmuir isotherm model towards Congo red (CR). The B-1500 sample exhibited the best adsorption performance for CR with the maximum adsorption quantity of 1298.3 mg g−1 in neutral pH solution because of the smallest average particle size (d = 55.6 nm), highest specific surface area (BET = 224.42 m2 g−1), and highest percentage of exposed (020) facets (55.18%). In particular, the boehmite pellets shaped with the alginate-assisted moulding method showed promising practical applications for the removal of CR in water through a fixed-bed adsorption column; for example, ca. 600 mL of boehmite pellets including ca. 15.0 g of boehmite powder has the removal efficiency of 75% in 3500 mL of aqueous solution with 100 mg L−1 CR.