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Instruments / Technical Area	Publication Details	Published
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Methanol synthesis at a wide range of H2/CO2 ratios over Rh‐In bimetallic catalyst Molly Meng-jung Li , Hanbo Zou , Jianwei Zheng , Tai-sing Wu , Ting-shan Chan , Yun-liang Soo , Xin-ping Wu , Xueqing Gong , Tianyi Chen , Kanak Roy , Georg Held , Edman Shik Chi Tsang Angewandte Chemie International Edition DOI: 10.1002/anie.202000841 Show Abstract ▼ Abstract: Recent years have seen an increasing interest in capturing hydrogen generated from renewables with CO 2 to produce methanol. However, renewable hydrogen production is currently expensive and in limited quantity as compared to CO 2 . Excess CO 2 and limited H 2 in the feedstock gas mixture is not favourable for the CO 2 hydrogenation to methanol reaction, which causes low activity and poor methanol selectivity. Here we report a new class of Rh‐In catalysts with optimal adsorption property to the intermediates of methanol production. The Rh‐In catalyst can effectively catalyse methanol synthesis but inhibit reverse water‐gas shift reaction under H 2 ‐deficient gas flow and shows the best competitive methanol productivity under industrially applicable conditions in comparison with the literature reported values. This work demonstrates a strong potential of Rh‐In bimetallic composition, from which a convenient methanol synthesis based on flexible feedstock compositions (e.g. H 2 /CO 2 from biomass derivatives) with lower energy cost can be established.	May 2020
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS E01-JEM ARM 200CF	Elucidating the mechanism of the methanation reaction over Ni-hydrotalcite-derived catalysts via surface-sensitive in situ XPS and NEXAFS Gianfranco Giorgianni , Chalachew Mebrahtu , Manfred E. Schuster , Alexander I. Large , Georg Held , Pilar Ferrer , Federica Venturini , David Grinter , Regina Palkovits , Siglinda Perathoner , Gabriele Centi , Salvatore Abate , Rosa Arrigo Physical Chemistry Chemical Physics DOI: 10.1039/D0CP00622J Diamond Proposal Number(s): [19472] Show Abstract ▼ Abstract: Hydrotalcite-derived Ni and Fe-promoted hydrotalcite-derived Ni catalysts were found to outperform industrial catalysts in the CO2 methanation reaction, however the origin of the improved activity and selectivity of these catalysts is not clear. Here, we report a study of these systems by means of in situ X-ray photoelectron spectroscopy and near-edge X-ray absorption spectroscopy elucidating the chemical nature of the catalysts` surface under reaction conditions and revealing the mechanism by which Fe promotes activity and selectivity towards methane. We show that the increase of the conversion leads to hydroxylation of the Ni surface following the formation of water during the reaction. This excessive Ni surface hydroxylation has however a detrimental effect as shown by a controlled study. A dominant metallic Ni surface exists in conditions of higher selectivity towards methane whereas if an increase of the Ni surface hydroxylation occurs, a higher selectivity towards carbon monoxide is observed. The electronic structure analysis of the Fe species under reaction conditions reveals the existence of predominantly Fe(III) species at the surface, whereas a mixture of Fe(II)/Fe(III) species is present underneath the surface. Our results highlight that Fe(II) exerts a beneficial effect on maintaining Ni in a metallic state, whereas the extension of the Fe oxidation front from the surface towards the bulk is accompanied by a more extended Ni surface hydroxylation with a negative impact on the selectivity towards methane.	Apr 2020
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Removal of hydrogen poisoning by electrostatically polar MgO support for low pressure NH3 synthesis at high rate over Ru catalyst Simson Wu , Yung-kang Peng , Tianyi Chen , Jiaying Mo , Alex Large , Ian Mcpherson , Hung-lung Chou , Ian Wilkinson , Federica Venturini , David Grinter , Pilar Ferrer Escorihuela , Georg Held , Shik Chi Edman Tsang Acs Catalysis DOI: 10.1021/acscatal.0c00954 Show Abstract ▼ Abstract: The increasing availability of low-cost and low pressure, renewable H2 from wind and solar means has triggered tremendous interest in developing low pressure ammonia synthesis with N2 as energy carrier as well as green fertilizer. As such Cs-promoted Ru/MgO catalysts used in Kellogg process show superiority to Fe-based catalysts at milder conditions, however, as known, the surface poisoning of Ru sites by competitive strong H2 dissociative adsorption limits the overall rate. It is demonstrated for the first time that the use of simple polar MgO(111) to replace non-polar MgO as support can significantly alleviate the hydrogen poisoning and facilitate an unprecedented ammonia production rate by its high intrinsic proton capture ability.	Apr 2020
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies Baran Eren , Christopher G. Sole , Jesús Sánchez Lacasa , David Grinter , Federica Venturini , Georg Held , Santiago Esconjauregui , Robert S. Weatherup Physical Chemistry Chemical Physics DOI: 10.1039/D0CP00347F Diamond Proposal Number(s): [19299] Show Abstract ▼ Abstract: Methanol is a promising chemical for the safe and efficient storage of hydrogen, where methanol conversion reactions can generate a hydrogen-containing gas mixture. Understanding the chemical state of the catalyst over which these reactions occur and the interplay with the adsorbed species present is key to the design of improved catalysts and process conditions. Here we study polycrystalline Cu foils using ambient pressure X-ray spectroscopies to reveal the Cu oxidation state and identify the adsorbed species during partial oxidation (CH3OH + O2), steam reforming (CH3OH + H2O), and autothermal reforming (CH3OH + O2 + H2O) of methanol at 200 °C surface temperature and in the mbar pressure range. We find that the Cu surface remains highly metallic throughout partial oxidation and steam reforming reactions, even for oxygen-rich conditions. However, for autothermal reforming the Cu surface shows significant oxidation towards Cu2O. We rationalise this behaviour on the basis of the shift in equilibrium of the CH3OH* + O* ⇌ CH3O* + OH* caused by the addition of H2O.	Mar 2020
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS B18-Core EXAFS E01-JEM ARM 200CF	Influence of synthesis conditions on the structure of nickel nanoparticles and their reactivity in selective asymmetric hydrogenation Rosa Arrigo , Simone Gallarati , Manfred E. Schuster , Jake Seymour , Diego Gianolio , Ivan Da Silva , June Callison , Haosheng Feng , John E. Proctor , Pilar Ferrer , Federica Venturini , Dave Grinter , Georg Held Chemcatchem DOI: 10.1002/cctc.201901955 Open Access Show Abstract ▼ Abstract: Unsupported and SiO 2 ‐supported Ni nanoparticles (NPs), were synthesised via hot‐injection colloidal route using oleylamine (OAm) and trioctylphosphine (TOP) as reducing and protective agents, respectively. By adopting a multi‐length scale structural characterization, it was found that by changing equivalents of OAM and TOP not only the size of the nanoparticles is affected but also the Ni electronic structure. The synthetized NPs were modified with ( R , R )‐tartaric acid (TA) and investigated in the asymmetric hydrogenation of methyl acetoacetate to chiral methyl‐3‐hydroxy butyrate. The comparative analysis of structure and catalytic performance for the synthetized catalysts has enabled us to identify a Ni metallic active surface, whereby the activity increases with the size of the metallic domains. Conversely, at the high conversion obtained for the unsupported NPs there was no impact of particle size on the selectivity. ( R )‐selectivity was very high only on catalysts containing positively charged Ni species such as over the SiO 2 ‐supported NiO NPs. This work shows that the chiral modification of metallic Ni NPs with TA is insufficient to maintain high selectivity towards the ( R )‐enantiomer at long reaction time and provide guidance for the engineering of long‐term stable enantioselective catalysts.	Dec 2019
I09-Surface and Interface Structural Analysis	Adsorption behavior of organic molecules: a study of benzotriazole on Cu(111) with spectroscopic and theoretical methods Chiara Gattinoni , Panayiotis Tsaousis , Chanan Euaruksakul , Rachel Price , David A. Duncan , Tod Pascal , David Prendergast , Georg Held , Angelos Michaelides Langmuir DOI: 10.1021/acs.langmuir.8b03528 Diamond Proposal Number(s): [12800] Show Abstract ▼ Abstract: The adsorption of organic molecules on solid substrates is important to applications in fields such as catalysis, photovoltaics, corrosion inhibition, adhesion, and sensors. The molecular level description of the surface-molecule interaction and of the adsorption structures in these complex systems is crucial to understand their properties and function. Here we present the investigation of one such system, benzotriazole (BTAH) on single crystal Cu(111) in vacuum conditions. BTAH is the most widely used corrosion inhibitor for copper and thus a molecule of great industrial relevance. We show that the co-application of a wide range of spectroscopic techniques with theoretical methods provides unique insight in the description of the atomistic details of the adsorbed structures. Specifically, spectroscopic photoemission, absorption and standing wave experiments combined with ab initio computational modeling allowed us to identify that benzotriazole forms overlayers of intact BTAH when deposited at low temperature and it dissociates into BTA and H at room temperature and above. The dissociated molecule then forms complex structures of mixed chains and dimers of BTA bound to copper adatoms. Our work also reveals that copper adatoms at low concentrations, such as the theoretically predicted superstructures cannot be be resolved by means of current X-ray photoelectron spectroscopy (XPS) as the modelled Cu 2p spectra are practically indistinguishable from those for a Cu surface without adatoms. Overall this study significantly deepens understanding of BTAH on Cu – a system studied for more than 50 years – and it highlights the benefits of combining spectroscopic and computational methods in order to obtain a complete picture of a complex adsorption system.	Jan 2019
Optics	Compensation of x-ray mirror distortion by cooling temperature control Matthew Hand , Hongchang Wang , Maria Harkiolaki , Federica Venturini , Rosa Arrigo , Pilar Ferrer Escorihuela , Simon Alcock , Ioana Nistea , Andy Marshall , Stewart Scott , Liz Duke , Georg Held , Kawal Sawhney Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation – SRI2018 DOI: 10.1063/1.5084675 Open Access Show Abstract ▼ Abstract: Synchrotron radiation is emitted from a bending magnet source in a wide ray fan which is collected by the first optical element in a beamline. In order to maximize angular acceptance, and hence flux, it is beneficial to increase the length of this mirror and optical design requirements may necessitate that the optical surface be over 1 m in length. Such mirrors also require cooling as they may be subject to high heat loads from the incident radiation. Two beamlines, B07 and B24, at Diamond Light Source, UK, use 1.4 m long toroidal mirrors which utilize a similar side-clamped cooling manifold design. While this scheme has been successful in providing effective cooling of the mirror, it has also been discovered that it introduces deformation of the radius of curvature which is sufficient to alter the focusing characteristics of the mirror. At both beamlines, the horizontal focus of the beam was found to differ by up to several meter from the design position at the exit slit which resulted in poor flux throughput, reduced energy resolution and other side effects. A pencil beam scan method has been used to diagnose this issue and infer the position of the focus and mirror shape. Through the use of a standalone chiller to alter the temperature of the water within the cooling loop, it has been possible to correct the distortion of the radius and restore the focus to its nominal position.	Jan 2019
B18-Core EXAFS E01-JEM ARM 200CF	Operando spectroscopy study of the carbon dioxide electro-reduction by iron species on nitrogen-doped carbon Chiara Genovese , Manfred E. Schuster , Emma K. Gibson , Diego Gianolio , Victor Posligua , Ricardo Grau-crespo , Giannantonio Cibin , Peter Wells , Debi Garai , Vladyslav Solokha , Sandra Krick Calderon , Juan J. Velasco-velez , Claudio Ampelli , Siglinda Perathoner , Georg Held , Gabriele Centi , Rosa Arrigo Nature Communications 9 DOI: 10.1038/s41467-018-03138-7 Diamond Proposal Number(s): [17031, 10306] Open Access Show Abstract ▼ Abstract: The carbon–carbon coupling via electrochemical reduction of carbon dioxide represents the biggest challenge for using this route as platform for chemicals synthesis. Here we show that nanostructured iron (III) oxyhydroxide on nitrogen-doped carbon enables high Faraday efficiency (97.4%) and selectivity to acetic acid (61%) at very-low potential (−0.5 V vs silver/silver chloride). Using a combination of electron microscopy, operando X-ray spectroscopy techniques and density functional theory simulations, we correlate the activity to acetic acid at this potential to the formation of nitrogen-coordinated iron (II) sites as single atoms or polyatomic species at the interface between iron oxyhydroxide and the nitrogen-doped carbon. The evolution of hydrogen is correlated to the formation of metallic iron and observed as dominant reaction path over iron oxyhydroxide on oxygen-doped carbon in the overall range of negative potential investigated, whereas over iron oxyhydroxide on nitrogen-doped carbon it becomes important only at more negative potentials.	Mar 2018
	Combined Experimental and Theoretical Study of Methyl Acetoacetate Adsorption on Ni{100} Panayiotis Tsaousis , Jorge Ontaneda , Luca Bignardi , Roger A. Bennett , Ricardo Grau-crespo , Georg Held The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.8b00204 Show Abstract ▼ Abstract: The enantioselective hydrogenation of methyl acetoacetate (MAA) over modified Ni-based catalysts is a key reaction in the understanding of enantioselective heterogeneous catalysis as it represents the only example of this class of reactions catalyzed by base metals. Yet, there is very little molecular-level information available about the adsorption complex formed by the reactants on Ni surfaces. Here, we report a combined experimental and theoretical study of the adsorption of MAA on the Ni{100} surface. X-ray photoelectron spectroscopy shows that MAA forms stable multilayers at low temperatures, which desorb between 200 and 220 K. At higher temperatures a single chemisorbed layer is formed, which decomposes between 300 and 350 K. Density functional theory modeling predicts an enolate species with bidentate coordination as the most stable chemisorbed species. Comparison of photoelectron spectroscopy and X-ray absorption data with simulations using this adsorption model show good qualitative and quantitative agreement. The molecular plane is tilted with respect to the surface plane by about 50°. This breaking of symmetry provides a mechanism for the enantioselective hydrogenation.	Mar 2018
	"Pop-On and Pop-Off" Surface Chemistry of Alanine on Ni{111} Under Elevated Hydrogen Pressures Richard E. J. Nicklin , Andrey Shavorskiy , Funda Aksoy Akgul , Zhi Liu , Roger A. Bennett , Marco Sacchi , Georg Held The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.8b00186 Show Abstract ▼ Abstract: The co-adsorption of hydrogen with a simple chiral modifier, alanine, on Ni{111} was studied using Density Functional Theory in combination with ambient-pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy at temperatures of 300~K and above, which are representative of chiral hydrogenation reactions. Depending on the hydrogen pressure, the surface enables protons to "pop on and off" the modifier molecules, thus significantly altering the adsorption geometry and chemical nature of alanine from anionic tridentate in ultra-high vacuum to predominantly zwitterionic bidentate at hydrogen pressures above 0.1 Torr. This hydrogen-stabilised modifier geometry allows alternative mechanisms for proton transfer and the creation of enatioselective reaction environments.	Mar 2018

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