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Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Correlating orbital composition and activity of LaMnxNi1–xO3 nanostructures toward oxygen electrocatalysis Mohammed A. Alkhalifah , Benjamin Howchen , Joseph Staddon , Veronica Celorrio , Devendra Tiwari , David J. Fermin Journal Of The American Chemical Society DOI: 10.1021/jacs.1c11757 Diamond Proposal Number(s): [10306] Show Abstract ▼ Abstract: The atomistic rationalization of the activity of transition metal oxides toward oxygen electrocatalysis is one of the most complex challenges in the field of electrochemical energy conversion. Transition metal oxides exhibit a wide range of structural and electronic properties, which are acutely dependent on composition and crystal structure. So far, identifying one or several properties of transition metal oxides as descriptors for oxygen electrocatalysis remains elusive. In this work, we performed a detailed experimental and computational study of LaMnxNi1–xO3 perovskite nanostructures, establishing an unprecedented correlation between electrocatalytic activity and orbital composition. The composition and structure of the single-phase rhombohedral oxide nanostructures are characterized by a variety of techniques, including X-ray diffraction, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. Systematic electrochemical analysis of pseudocapacitive responses in the potential region relevant to oxygen electrocatalysis shows the evolution of Mn and Ni d-orbitals as a function of the perovskite composition. We rationalize these observations on the basis of electronic structure calculations employing DFT with HSE06 hybrid functional. Our analysis clearly shows a linear correlation between the OER kinetics and the integrated density of states (DOS) associated with Ni and Mn 3d states in the energy range relevant to operational conditions. In contrast, the ORR kinetics exhibits a second-order reaction with respect to the electron density in Mn and Ni 3d states. For the first time, our study identifies the relevant DOS dominating both reactions and the importance of understanding orbital occupancy under operational conditions.	Mar 2022
B18-Core EXAFS E01-JEM ARM 200CF E02-JEM ARM 300CF	Identification and manipulation of dynamic active site deficiency-induced competing reactions in electrocatalytic oxidation processes Runjia Lin , Liqun Kang , Tianqi Zhao , Jianrui Feng , Veronica Celorrio , Guohui Zhang , Giannantonio Cibin , Anthony Kucernak , Dan Brett , Furio Cora , Ivan P. Parkin , Guanjie He Energy & Environmental Science DOI: 10.1039/D1EE03522C Diamond Proposal Number(s): [25410, 29207] Open Access Show Abstract ▼ Abstract: Electrocatalytic organic compound oxidation reactions (OCORs) have been intensively studied for energy and environmentally benign applications. However, relatively little effort has been devoted to developing a fundamental understanding of OCOR, including the detailed competition with side reactions and activity limitations, thus inhibiting the rational design of high-performance electrocatalysts. Herein, by taking NiWO4-catalysed urea oxidation reaction (UOR) in aqueous media as an example, the competition between the OCOR and the oxygen evolution reaction (OER) within a wide potential range is examined. It is shown that the root of the competition can be ascribed to insufficient surface concentration of dynamic Ni3+, an active site shared by both UOR and OER. Similar phenomenon are observed in other OCOR electrocatalysts and systems. To address the issue, a “controllable reconstruction of pseudo-crystalline bimetal oxides” design strategy is proposed to maximise the dynamic Ni3+ population and manipulate the competition between UOR and OER. The optimised electrocatalyst delivers best-in-class performance and a ~10-fold increase in current density at 1.6 V versus the reversible hydrogen electrode for alkaline urea electrolysis compared to that of the pristine materials.	Mar 2022
B18-Core EXAFS	Insight into the activity and selectivity of nanostructured copper titanates during electrochemical conversion of CO2 at neutral pH via in situ X-ray Absorption Spectroscopy Matthew J. Lawrence , Veronica Celorrio , Elizabeth Sargeant , Haoliang Huang , Joaquín Rodríguez-López , Yuanmin Zhu , Meng Gu , Andrea E. Russell , Paramaconi Rodriguez Acs Applied Materials & Interfaces DOI: 10.1021/acsami.1c19298 Diamond Proposal Number(s): [21533] Open Access Show Abstract ▼ Abstract: The electrochemical conversion of carbon dioxide (CO2) to useful chemical fuels is a promising route toward the achievement of carbon neutral and carbon negative energy technologies. Copper (Cu)- and Cu oxide-derived surfaces are known to electrochemically convert CO2 to high-value and energy-dense products. However, the nature and stability of oxidized Cu species under reaction conditions are the subject of much debate in the literature. Herein, we present the synthesis and characterization of copper-titanate nanocatalysts, with discrete Cu–O coordination environments, for the electrochemical CO2 reduction reaction (CO2RR). We employ real-time in situ X-ray absorption spectroscopy (XAS) to monitor Cu species under neutral-pH CO2RR conditions. Combination of voltammetry and on-line electrochemical mass spectrometry with XAS results demonstrates that the titanate motif promotes the retention of oxidized Cu species under reducing conditions for extended periods, without itself possessing any CO2RR activity. Additionally, we demonstrate that the specific nature of the Cu–O environment and the size of the catalyst dictate the long-term stability of the oxidized Cu species and, subsequently, the product selectivity.	Jan 2022
B18-Core EXAFS E01-JEM ARM 200CF	Structure-activity relationships in highly active platinum-tin MFI-type zeolite catalysts for propane dehydrogenation Andrew Beale , Ines Lezcano-Gonzalez , Peixi Cong , Emma Campbell , Monik Panchal , Miren Agote-Aran , Veronica Celorrio , Qian He , Ramon Oord , Bert M. Weckhuysen Chemcatchem DOI: 10.1002/cctc.202101828 Show Abstract ▼ Abstract: Pt/Sn-containing MFI zeolites prepared by one-pot hydrothermal methods are highly active and selective catalysts for propane dehydrogenation. An alternative preparation method is reported alongside an in-depth characterization of Pt and Sn before and after reaction. Pt species dispersed on highly-defective Silicalite-1 show a significantly long catalytic lifetime with an improved coke resistance, but increased Pt-Sn alloying and the (eventual) build-up of carbon leads to deactivation.	Jan 2022
B18-Core EXAFS	Na2.4Al0.4Mn2.6O7 anionic redox cathode material for sodium ion batteries - a combined experimental and theoretical approach to elucidate its charge storage mechanism Cindy Soares , Begoña Silvan , Yong-Seok Choi , Veronica Celorrio , Giannantonio Cibin , David O. Scanlon , Nuria Tapia-Ruiz Journal Of Materials Chemistry A DOI: 10.1039/D1TA05137G Diamond Proposal Number(s): [21847] Open Access Show Abstract ▼ Abstract: Here we report the synthesis via ceramic methods of the high-performance Mn-rich Na2.4Al0.4Mn2.6O7 oxygen-redox cathode material for Na-ion batteries which we use as a testbed material to study the effects of Al substitution and subsequent Na excess in the high-capacity, anionic redox-based cathode material Na2Mn3O7. The material shows a stable electrochemical performance, with a specific capacity of 200 mAh g-1 in the 1.5 - 4.7 voltage window at C/20 and capacity retention of 90 % after 40 cycles. Using a combination of electrochemical and structural analysis together with hybrid density functional theory calculations we explain the behaviour of this material with changes in Mn/anionic redox reactions and associated O2 release reactions occurring in the material during electrochemical cycling (Na insertion/extraction) and compare these findings to Na2Mn3O7. We expect that these results will advance understanding of the effect of dopants in Mn-rich cathode materials with oxygen redox activity to pave their way towards real applications in high-performing sodium-ion battery applications.	Dec 2021
B18-Core EXAFS	Isolating the contributions of surface Sn atoms in the bifunctional behaviour of PtSn CO oxidation electrocatalysts Haoliang Huang , Oliver F. Blackman , Veronica Celorrio , Andrea E. Russell Electrochimica Acta 52 DOI: 10.1016/j.electacta.2021.138811 Diamond Proposal Number(s): [19850] Show Abstract ▼ Abstract: The bifunctional mechanism is well-acknowledged for the promoted CO oxidation on Pt-based bimetallic electrocatalysts. However, the direct identification of the active oxygenated species and the nature and electrochemistry of the second component are still a matter of debate. Herein, Snad-Pt/C catalysts, where Sn ad-atoms are exclusively on the surface of Pt nanoparticles at low coverages ranging from 0.0033 to 0.2 monolayers to avoid sub-surface Sn and alloy formation, were prepared as a model system to resolve these issues using a surface organometallic chemistry approach. Effects of the Sn ad-atoms on CO oxidation were studied by CO stripping voltammograms as a function of Sn coverage. Using in situ XAS measurements, the Sn average oxidation state is estimated to increase from +0.2 to +3.1 as the potential increases from 0 to 0.8 VRHE, with the number of the oxygen neighbours increasing stepwise. Pt4.5-Sn-(OH)1.5 is revealed as the active species responsible for the bifunctional mechanism at low overpotentials and is generated via a redox couple corresponding to Pt4.5-Sn*/Pt4.5-Sn-(OH)1.5.	Jun 2021
B18-Core EXAFS	A novel method to synthesize BiSI uniformly coated with rGO by chemical bonding and its application as a supercapacitor electrode material Huapeng Sun , Xufeng Xiao , Veronica Celorrio , Zhenfu Guo , Yue Wu , Caroline Kirk , Neil Robertson Journal Of Materials Chemistry A 29 DOI: 10.1039/D1TA02988F Diamond Proposal Number(s): [25651] Open Access Show Abstract ▼ Abstract: In this paper, we demonstrate a novel synthetic route to assemble reduced graphene oxide (rGO) uniformly coated on BiSI composite and investigate its potential as the active electrode material for supercapacitors. In this strategy, graphene oxide (GO) was not a simple physical mixture with the BiSI material but bismuth cations were uniformly anchored on the surface of GO by chemical bonding during material growth and the size of GO can determine the final size of rGO coated BiSI composite. The galvanostatic charge–discharge measurement results show that the BiSI–rGO electrode has a maximum specific capacity of 234 C g−1 at the current density of 1 A g−1 and excellent capacity retention of 92.4% after 2000 cycles. In situ XANES and EXAFS were employed to study the electrochemical oxidation and reduction processes of the bismuth-based material with rGO coating and investigate the origins of the structural stabilities. The results show that our novel rGO coating route can not only significantly increase the capacity but also improve cycling stability.	Jun 2021
	Roadmap on inorganic perovskites for energy applications John Irvine , Jennifer Rupp , Gang Liu , Xiaoxiang Xu , Sossina M Haile , Xin Qian , Alem Snyder , Robert Freer , Dursun Ekren , Stephen Skinner , Ozden Celikbilek , Shigang Chen , Shanwen Tao , Tae Ho Shin , Ryan O'Hayre , Jake Huang , Chuancheng Duan , Meagan Papac , Shuangbin Li , Andrea Russell , Veronica Celorrio , Brian Hayden , Hugo Nolan , Xiubing Huang , Ge Wang , Ian Metcalfe , Dragos Neagu , Susana Garcia Martin Journal Of Physics: Energy DOI: 10.1088/2515-7655/abff18 Open Access Show Abstract ▼ Abstract: Inorganic perovskites exhibit many important physical properties such as ferroelectricity, magnetoresistance and superconductivity as well their importance as Energy Materials. Many of the most important energy materials are inorganic perovskites and find application in batteries, fuel cells, photocatalysts, catalysis, thermoelectrics and solar thermal. In all these applications, perovskite oxides, or their derivatives offer highly competitive performance, often state of the art and so tend to dominate research into energy material. In the following sections, we review these functionalities in turn seeking to facilitate the interchange of ideas between domains. The potential for improvement is explored and we highlight the importance of both detailed modelling and in situ and operando studies in taking these materials forward.	May 2021
I20-Scanning-X-ray spectroscopy (XAS/XES)	Relationship between Mn oxidation state changes and oxygen reduction activity in (La,Ca)MnO3 as probed by in situ XAS and XES Veronica Celorrio , Andrew S. Leach , Haoliang Huang , Shusaku Hayama , Adam Freeman , David W. Inwood , David J. Fermin , Andrea E. Russell Acs Catalysis DOI: 10.1021/acscatal.1c00997 Diamond Proposal Number(s): [16479] Open Access Show Abstract ▼ Abstract: In situ X-ray absorption and emission spectroscopies (XAS and XES) are used to provide details regarding the role of the accessibility and extent of redox activity of the Mn ions in determining the oxygen reduction activity of LaMnO3 and CaMnO3, with X-ray absorption near-edge structure (XANES) providing the average oxidation state, extended X-ray absorption fine structure (EXAFS) providing the local coordination environment, and XES providing the population ratios of the Mn2+, Mn3+, and Mn4+ sites as a function of the applied potential. For LaMnO3, XANES and XES show that Mn3+ is formed, but Mn4+ ions are retained, which leads to the 4e– reduction between 0.85 and 0.6 V. At more negative potentials, down to 0.2 V, EXAFS confirms an increase in oxygen vacancies as evidenced by changes in the Mn–O coordination distance and number, while XES shows that the Mn3+ to Mn4+ ratio increases. For CaMnO3, XANES and XES show the formation of both Mn3+ and Mn2+ as the potential is made more negative, with little retention of Mn4+ at 0.2 V. The EXAFS for CaMnO3 also indicates the formation of oxygen vacancies, but in contrast to LaMnO3, this is accompanied by loss of the perovskite structure leading to structural collapse. The results presented have implications in terms of understanding of both the pseudocapacitive response of Mn oxide electrocatalysts and the processes behind degradation of the activity of the materials.	May 2021
B18-Core EXAFS	Contrasting the EXAFS obtained under air and H2 environments to reveal details of the surface structure of Pt–Sn nanoparticles Haoliang Huang , Abu Bakr Ahmed Amine Nassr , Veronica Celorrio , Diego Gianolio , Christopher Hardacre , Dan J. L. Brett , Andrea E. Russell Physical Chemistry Chemical Physics 30 DOI: 10.1039/D1CP00979F Diamond Proposal Number(s): [10306, 19850] Open Access Show Abstract ▼ Abstract: Understanding the surface structure of bimetallic nanoparticles is crucial for heterogeneous catalysis. Although surface contraction has been established in monometallic systems, less is known for bimetallic systems, especially of nanoparticles. In this work, the bond length contraction on the surface of bimetallic nanoparticles is revealed by XAS in H2 at room temperature on dealloyed Pt–Sn nanoparticles, where most Sn atoms were oxidized and segregated to the surface when measured in air. The average Sn–Pt bond length is found to be ∼0.09 Å shorter than observed in the bulk. To ascertain the effect of the Sn location on the decrease of the average bond length, Pt–Sn samples with lower surface-to-bulk Sn ratios than the dealloyed Pt–Sn were studied. The structural information specifically from the surface was extracted from the averaged XAS results using an improved fitting model combining the data measured in H2 and in air. Two samples prepared so as to ensure the absence of Sn in the bulk were also studied in the same fashion. The bond length of surface Sn–Pt and the corresponding coordination number obtained in this study show a nearly linear correlation, the origin of which is discussed and attributed to the poor overlap between the Sn 5p orbitals and the available orbitals of the Pt surface atoms.	May 2021

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