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Author ORCID ID is 0000000281758555
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  1. Here, we report that ethane (CH 3CH 3), one of the primary components of shale gas, is an attractive candidate for the production of syngas (CO + H 2) and ethylene (CH 2CH 2) via the selective C–C and C–H bond cleavage, respectively. Understanding the origin of the selective conversion is essential to the design of a good catalyst for CH 3CH 3 activation. Herein, we combined density functional theory (DFT) calculations with kinetic Monte Carlo (KMC) simulations to shed light on the mechanism of the oxidative C–H and C–C bond cleavage of CH 3CH 3 on a PtNi(111) modelmore » catalyst using CO 2 as an oxidant, where the estimated selectivity is in good agreement with the experimental results on PtNi nanoparticles supported on CeO 2. Our calculations show that PtNi is selective to CO via direct CO 2 dissociation and the oxidative C–C bond scission of CH 3CH 3 via the oxygenated (*C 2H yO) intermediates. By comparison the CH 2CH 2 selectivity via the selective C–H bond scission of *CH 3CH 3 is much lower. Lastly, the kinetic analysis suggests that the selectivity of PtNi toward syngas can be enhanced by facilitating the formation of key *C 2H yO intermediates, while the selectivity toward CH 2CH 2 is promoted mainly by accelerating the C–H bond scission of *CH 3CH 2 to produce *CH 2CH 2.« less
  2. The hydrodeoxygenation (HDO) reaction is critical to the upgrading of lignocellulosic biomass into valuable fuels and chemicals. Many transition metal carbide (TMC) catalysts have been shown to be highly selective toward the C-O/C=O bond scission, which makes them promising catalysts for the HDO reaction. This review summarizes the reaction pathways of linear and ring-containing biomass-derived oxygenates over TMC model surfaces and powder catalysts, followed by a discussion on the effect of reaction conditions on reaction pathways. The combination of first principle calculations, model surface experiments, and parallel reactor studies demonstrates the feasibility of using model surface science studies to guidemore » the rational design of efficient catalysts for the upgrading of lignocellulosic biomass derivatives. General trends and future research directions of using TMC catalysts for HDO are also discussed.« less
  3. In this paper, supported Cu–Ni bimetallic catalysts were synthesized and evaluated for the in situ hydrogenation and decarboxylation of oleic acid using methanol as a hydrogen donor. The supported Cu–Ni alloy exhibited a significant improvement in both activity and selectivity towards the production of heptadecane in comparison with monometallic Cu and Ni based catalysts. The formation of the Cu–Ni alloy is demonstrated by high-angle annular dark-field scanning transmission electron microscopy (HADDF-STEM), energy dispersive X-ray spectroscopy (EDS-mapping), X-ray diffraction (XRD) and temperature programmed reduction (TPR). A partially oxidized Cu in the Cu–Ni alloy is revealed by diffuse reflectance infrared Fourier transformmore » spectroscopy (DRIFTS) following CO adsorption and X-ray photoelectron spectroscopy (XPS). The temperature programmed desorption of ethylene and propane (ethylene/propane-TPD) suggested that the formation of the Cu–Ni alloy inhibited the cracking of C–C bonds compared to Ni, and remarkably increased the selectivity to heptadecane. The temperature programmed desorption of acetic acid (acetic acid-TPD) indicated that the bimetallic Cu–Ni alloy and Ni catalysts had a stronger adsorption of acetic acid than that of the Cu catalyst. Finally, the formation of the Cu–Ni alloy and a partially oxidized Cu facilitates the decarboxylation reaction and inhibits the cracking reaction of C–C bonds, leading to enhanced catalytic activity and selectivity.« less
  4. Here, we present a new Janus structured catalyst consisting of Pt nanoparticles on Fe–N–C nanoparticles encapsulated by graphene layers for the ORR. The ORR activity of the catalyst increases under potential cycling as the unique Janus nanostructure is further bonded due to a synergetic effect. The present study describes an important advanced approach for the future design of efficient, stable, and low-cost Pt-based electrocatalytic systems.
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  5. The formation of carbides can significantly modify the physical and chemical properties of the parent metals. In the current review, we summarize the general trends in the reactions of water and C1 molecules over transition metal carbide (TMC) and metal-modified TMC surfaces and thin films. Although the primary focus of the current review is on the theoretical and experimental studies of reactions of C1 molecules (CO, CO 2, CH 3OH, etc.), the reactions of water will also be reviewed because water plays an important role in many of the C1 transformation reactions. This review is organized by discussing separately thermalmore » reactions and electrochemical reactions, which provides insights into the application of TMCs in heterogeneous catalysis and electrocatalysis, respectively. In thermal reactions, we discuss the thermal decomposition of water and methanol, as well as the reactions of CO and CO 2 over TMC surfaces. In electrochemical reactions, we summarize recent studies in the hydrogen evolution reaction, electrooxidation of methanol and CO, and electroreduction of CO 2. Lastly, future research opportunities and challenges associated with using TMCs as catalysts and electrocatalysts are also discussed.« less
  6. The selectivity of CO 2 hydrogenation can be significantly tuned by controlling the valence state of nickel using lanthanum-iron-nickel perovskites. Nickel with higher valence states weakens the binding of CO and increases the activation barrier for further CO hydrogenation, leading to a higher CO selectivity than the metallic nickel.

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