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Instruments / Technical Area	Publication Details	Published	Actions
B18-Core EXAFS	Interfacial chemistry in the electrocatalytic hydrogenation of CO2 over C-supported Cu-based systems Diego Gianolio , Michael D. Higham , Matthew G. Quesne , Matteo Aramini , Ruoyu Xu , Alex I. Large , Georg Held , Juan-Jesús Velasco-Vélez , Michael Haevecker , Axel Knop-Gericke , Chiara Genovese , Claudio Ampelli , Manfred Erwin Schuster , Siglinda Perathoner , Gabriele Centi , C. Richard A. Catlow , Rosa Arrigo Acs Catalysis DOI: 10.1021/acscatal.3c01288 Diamond Proposal Number(s): [24919] Open Access Show Abstract ▼ Abstract: Operando soft and hard X-ray spectroscopic techniques were used in combination with plane-wave density functional theory (DFT) simulations to rationalize the enhanced activities of Zn-containing Cu nanostructured electrocatalysts in the electrocatalytic CO2 hydrogenation reaction. We show that at a potential for CO2 hydrogenation, Zn is alloyed with Cu in the bulk of the nanoparticles with no metallic Zn segregated; at the interface, low reducible Cu(I)–O species are consumed. Additional spectroscopic features are observed, which are identified as various surface Cu(I) ligated species; these respond to the potential, revealing characteristic interfacial dynamics. Similar behavior was observed for the Fe–Cu system in its active state, confirming the general validity of this mechanism; however, the performance of this system deteriorates after successive applied cathodic potentials, as the hydrogen evolution reaction then becomes the main reaction pathway. In contrast to an active system, Cu(I)–O is now consumed at cathodic potentials and not reversibly reformed when the voltage is allowed to equilibrate at the open-circuit voltage; rather, only the oxidation to Cu(II) is observed. We show that the Cu–Zn system represents the optimal active ensembles with stabilized Cu(I)–O; DFT simulations rationalize this observation by indicating that Cu–Zn–O neighboring atoms are able to activate CO2, whereas Cu–Cu sites provide the supply of H atoms for the hydrogenation reaction. Our results demonstrate an electronic effect exerted by the heterometal, which depends on its intimate distribution within the Cu phase and confirms the general validity of these mechanistic insights for future electrocatalyst design strategies.	Apr 2023
B18-Core EXAFS	Synergistic ultraviolet and visible light photo-activation enables intensified low-temperature methanol synthesis over copper/zinc oxide/alumina Bingqiao Xie , Roong Jien Wong , Tze Hao Tan , Michael Higham , Emma K. Gibson , Donato Decarolis , June Callison , Kondo-Francois Aguey-Zinsou , Michael Bowker , C. Richard A. Catlow , Jason Scott , Rose Amal Nature Communications 11 DOI: 10.1038/s41467-020-15445-z Diamond Proposal Number(s): [19850] Open Access Show Abstract ▼ Abstract: Although photoexcitation has been employed to unlock the low-temperature equilibrium regimes of thermal catalysis, mechanism underlining potential interplay between electron excitations and surface chemical processes remains elusive. Here, we report an associative zinc oxide band-gap excitation and copper plasmonic excitation that can cooperatively promote methanol-production at the copper-zinc oxide interfacial perimeter of copper/zinc oxide/alumina (CZA) catalyst. Conversely, selective excitation of individual components only leads to the promotion of carbon monoxide production. Accompanied by the variation in surface copper oxidation state and local electronic structure of zinc, electrons originating from the zinc oxide excitation and copper plasmonic excitation serve to activate surface adsorbates, catalysing key elementary processes (namely formate conversion and hydrogen molecule activation), thus providing one explanation for the observed photothermal activity. These observations give valuable insights into the key elementary processes occurring on the surface of the CZA catalyst under light-heat dual activation.	Mar 2020

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