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Considerable attention has been drawn to tune the geometric and electronic structure of interfacial catalysts via modulating strong metal-support interactions (SMSI). Herein, we report the construction of a series of TiO2−x/Ni catalysts, where disordered TiO2−x overlayers immobilized onto the surface of Ni nanoparticles (~20 nm) are successfully engineered with SMSI effect. The optimal TiO2−x/Ni catalyst shows a CO conversion of ~19.8% in Fischer–Tropsch synthesis (FTS) process under atmospheric pressure at 220 °C. More importantly, ~64.6% of the product is C2+ paraffins, which is in sharp contrast to the result of the conventional Ni catalyst with the main product being methane. A combination study of advanced electron microscopy, multiple in-situ spectroscopic characterizations, and density functional theory calculations indicates the presence of Niδ−/TiO2−x interfacial sites, which could bind carbon atom strongly, inhibit methane formation and facilitate the C-C chain propagation, lead to the production of C2+ hydrocarbon on Ni surface. Considerable attention has been drawn to tune the geometric and electronic structure of interfacial catalysts via modulating strong metal-support interactions (SMSI). Here the authors report the remarkable catalytic performance of CO hydrogenation over an interfacial TiO2−x/Ni catalyst by means of SMSI. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) has been established as a powerful research tool for heterogeneous catalysis research in obtaining key thermodynamic and/or kinetic parameters like adsorption energies, enthalpies of reaction, activation barriers, and rate constants. Understanding of density functional exchange-correlation approximations is essential to reveal the mechanism and performance of a catalyst. In the present work, we reported the influence of six exchange-correlation density functionals, including PBE, RPBE, BEEF+vdW, optB86b+vdW, SCAN, and SCAN+rVV10, on the adsorption energies, reaction energies and activation barriers of carbon hydrogenation and carbon-carbon couplings during the formation of methane and ethane over Ru(0001) and Ru(10 1 ¯ 1) surfaces. We found the calculated reaction energies are strongly dependent on exchange-correlation density functionals due to the difference in coordination number between reactants and products on surfaces. The deviation of the calculated elementary reaction energies can be accumulated to a large value for chemical reaction involving multiple steps and vary considerably with different exchange-correlation density functionals calculations. The different exchange-correlation density functionals are found to influence considerably the selectivity of Ru(0001) surface for methane, ethylene, and ethane formation determined by the adsorption energies of intermediates involved. However, the influence on the barriers of the elementary surface reactions and the structural sensitivity of Ru(0001) and Ru(10 1 ¯ 1) are modest. Our work highlights the limitation of exchange-correlation density functionals on computational catalysis and the importance of choosing a proper exchange-correlation density functional in correctly evaluating the activity and selectivity of a catalyst. [ABSTRACT FROM AUTHOR]

Synthesis of atomically dispersed catalysts with high metal loading and thermal stability is challenging but particularly valuable for industrial application in heterogeneous catalysis. Here, we report a facile synthesis of a thermally stable atomically dispersed Ir/α-MoC catalyst with metal loading as high as 4 wt%, an unusually high value for carbide supported metal catalysts. The strong interaction between Ir and the α-MoC substrate enables high dispersion of Ir on the α-MoC surface, and modulates the electronic structure of the supported Ir species. Using quinoline hydrogenation as a model reaction, we demonstrate that this atomically dispersed Ir/α-MoC catalyst exhibits remarkable reactivity, selectivity and stability, for which the presence of high-density isolated Ir atoms is the key to achieving high metal-normalized activity and mass-specific activity. We also show that the water-promoted quinoline hydrogenation mechanism is preferred over the Ir/α-MoC, and contributes to high selectivity towards 1,2,3,4-tetrahydroquinoline. The present work demonstrates a new strategy in constructing a high-loading atomically dispersed catalyst for the hydrogenation reaction. [ABSTRACT FROM AUTHOR]

An active and stable bi-functional catalyst for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is highly desirable for clean energy conversion devices, such as anion exchange membrane fuel cells (AEMFCs) and magnesium (Mg)–seawater batteries. Herein, DFT analysis predicates that the amine-ligand modulation manipulates the d-band center of ruthenium (Ru) downshift from the Fermi level, resulting in optimized hydrogen and hydroxide bonding energies (HBE and OHBE), and thus lowering the limiting energy of the HOR/HER. We elaborately fabricate NH2-ligand modulated Ru nanoclusters (Ru/PEI-XC), taking advantage of the abundant –NH2 groups of polyethylene imine (PEI). The optimal Ru/PEI-XC catalyst exhibits a superior HOR activity of 423.3 A gmetal−1 at an overpotential (η) of 50 mV and a specific exchange current density of 687.1 μA cmmetal−2, which are about 1.7 and 3.6 fold those of the commercial Pt/C catalyst. Ru/PEI-XC presents an overwhelming advantage for the HER in a wide pH range, especially in alkaline electrolyte, with η = 13 mV at −10 mA cm−2, which is 20 mV lower than that of Pt/C. Both the potentiostatic and accelerated degradation tests manifest the excellent long-term stability of Ru/PEI-XC in catalyzing the HOR and HER. Furthermore, Ru/PEI-XC as the anode of an AEMFC delivers a peak power density of 1.4 W mgPGM−1, comparable with that of its Pt/C-based counterpart. A proof-of-concept rechargeable Mg–seawater battery could also be driven by the Ru/PEI-XC cathode, delivering a maximum discharging power density of 18.9 mW cm−2, with low charging voltage and good cycling properties. This study reveals that ligand modulation is an effective strategy to manipulate the d-band center of metals and tune the reactivity, which paves an avenue for designing advanced hydrogen electrocatalysts. [ABSTRACT FROM AUTHOR]

Precise regulation of the active site structure is an important means to enhance the activity and selectivity of catalysts in CO 2 electroreduction. Here, we creatively introduce anionic groups, which can not only stabilize metal sites with strong coordination ability but also have rich interactions with protons at active sites to modify the electronic structure and proton transfer process of catalysts. This strategy helps to convert CO 2 into fuel chemicals at low overpotentials. As a typical example, a composite catalyst, CuO/Cu-NSO 4 /CN, with highly dispersed Cu(II)-SO 4 sites has been reported, in which CO 2 electroreduction to formate occurs at a low overpotential with a high Faradaic efficiency (-0.5 V vs. RHE, FE formate =87.4 %). Pure HCOOH is produced with an energy conversion efficiency of 44.3 % at a cell voltage of 2.8 V. Theoretical modeling demonstrates that sulfate promotes CO 2 transformation into a carboxyl intermediate followed by HCOOH generation, whose mechanism is significantly different from that of the traditional process via a formate intermediate for HCOOH production., (© 2024 Wiley-VCH GmbH.)