Christopher Heard

Christopher Heard
Charles University in Prague | CUNI

MA, MSci, PhD

About

44
Publications
5,540
Reads
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915
Citations
Citations since 2016
34 Research Items
821 Citations
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
Introduction
My current work involves the application of electronic structure methods to the reactive and catalytic properties of metal and metal oxide surfaces. Additionally, a major focus is the understanding of ultra-small metal nanoparticle (cluster) structure-property relationships, both through global optimisation/structure prediction techniques, and by simulation of appropriate spectra. More exotic cluster species, including binary and ligand-passivated clusters are a particular interest of mine.
Additional affiliations
July 2014 - present
Chalmers University of Technology
Position
  • PostDoc Position
October 2010 - June 2014
University of Birmingham
Position
  • PhD Student
May 2010 - May 2012
Max Planck Institute for Solid State Research
Position
  • visiting PhD student
Education
October 2006 - July 2010
University of Cambridge
Field of study
  • Natural Sciences

Publications

Publications (44)
Article
Supported metal nanoparticles are used as heterogeneous catalysts but often deactivated due to sintering at high temperatures. Confining metal species into a porous matrix reduces sintering, yet supports rarely provide additional stabilization. Here, we used the silanol‐rich layered zeolite IPC‐1P to stabilize ultra‐small Rh nanoparticles. By adjus...
Preprint
Full-text available
Supported metal nanoparticles are widely used as heterogeneous catalysts but often deactivated due to sintering under harsh conditions, especially at high temperatures. Sintering can be prevented by confining metal species into a porous matrix, although supports rarely provide additional stabilization effects. Herein, we used silanol-rich layered z...
Preprint
Full-text available
Acidic zeolites are one of the most important catalysts. In many of their catalytic applications, the mode of interaction with water heavily influences their activity, efficiency, and durability as a catalyst. Despite the recent (first principles) computational efforts to understand the mechanistic underpinning of the water-zeolite interactions, it...
Article
The encapsulation of noble metal atoms into zeolites is a promising route to generate controlled size distributions of stable metal catalysts. Pinning of single metal atoms to particular binding sites...
Article
The controlled desilication of zeolites, leading to hierarchical micro-/mesoporous materials, is one of the most promising approaches to increase the application potential of zeolites. It can lift the restrictions connected to diffusion limitations in many industrially important processes and it can also modify the Si/Al ratio of the final material...
Preprint
Full-text available
Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ sig...
Preprint
Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ sig...
Preprint
New zeolitic frameworks can be prepared through the Assembly-Disassembly-Organisation-Reassembly (ADOR) process by exploiting the lability of Ge-O bonds in germanosilicate zeolites to control their hydrolysis. In the disassembly step, two key factors are water and germanium content, but their exact roles remain unknown. Nevertheless, we combined ex...
Preprint
Unbiased density functional global optimisation calculations, followed by kinetic Monte Carlo simulations are used to enumerate the potential energy surfaces for migration of noble metals Pt and Au inside the pore system of siliceous zeolite LTA. The effects of reducing adsorbates CO and H2 are determined. It is found that the two metals differ sig...
Article
Full-text available
Ultrathin layers of oxides, e.g. MgO or SiO 2 , deposited on atomically flat metal surfaces have been shown to significantly influence the electronic structure of the underlying metal, which in turn alters the catalytic performance. Although these model catalysts delivered a most valuable and fundamental understanding of catalytic processes, upscal...
Article
Full-text available
Palladium‐Nanopartikel wurden teilweise von subnanometerdicken Schichten aus Hectorit bedeckt. Aufgrund elektronischer Wechselwirkungen zwischen den Nanopartikeln und den ultradünnen Schichten waren die Nanopartikel positiv geladen. Dies wiederum erhöhte die Aktivität in der Oxidation von Kohlenmonoxid. Abstract Durch die Abscheidung von ultradünn...
Article
Full-text available
Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor. However, at extreme conditions as high temper...
Article
Full-text available
The mechanism by which single metal atoms and small, zeolite-encapsulated metal particles are stabilized against migration and growth is not currently well understood. In this work, we employ an unbiased density functional global optimization strategy to identify the locations and energetic barriers for migration pathways between sites, for platinu...
Article
Full-text available
Aluminosilicate zeolites are traditionally used in high-temperature applications at low water vapour pressures where the zeolite framework is generally considered to be stable and static. Increasingly, zeolites are being considered for applications under milder aqueous conditions. However, it has not yet been established how neutral liquid water at...
Article
Layered double hydroxides (LDH) of various compositions have been shown to be potent photo- and electrocatalysts. Recently, mössbauerite, obtained by chemical oxidation of an all-iron, mixed valence green rust LDH was introduced as an efficient oxygen evolution (OER) electrocatalyst. An accurate characterization of the structure of mössbauerite is...
Article
Full-text available
The introduction of dopant atoms into metal nanoparticles is an effective way to control the interaction with adsorbate molecules and is important in many catalytic processes. In this work, experimental and theoretical evidence of the influence of Pd doping on the bonding between small cationic AuN+ clusters and CO is presented. The CO adsorption i...
Article
Full-text available
The common understanding of zeolite acidity is based on Löwenstein’s rule, which states that Al-O-Al aluminium pairs are forbidden in zeolites. This rule is generally accepted to be inviolate in zeolites. However, recent computational research using a 0 K DFT model has suggested that the rule is violated for the acid form of several zeolites under...
Article
Full-text available
2D oxide nanomaterials constitute a broad range of materials, with a wide array of current and potential applications, particularly in the fields of energy storage and catalysis for sustainable energy production. Despite the many similarities in structure, composition, and synthetic methods and uses, the current literature on layered oxides is dive...
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An increased synergy between experimental and theoretical investigations in heterogeneous catalysis has become apparent during the last decade. Experimental work has extended from ultra-high vacuum and low temperature towards operando conditions. These developments have motivated the computational community to move from standard descriptive computa...
Article
We analyze in detail how the interplay between electronic structure and cluster geometry determines the stability and the fragmentation channels of single Pd-doped cationic Au clusters, PdAuN−1+ (N=2−20). For this purpose, a combination of photofragmentation experiments and density functional theory calculations was employed. A remarkable agreement...
Article
Single crystal adsorption calorimetry on Pt(111) surfaces allows us to study the influence of different functional groups on heats of ad- sorption. At zero coverage we find 103 kJ/mol, 194 kJ/mol and 325 kJ/mol for acetonitrile, benzene and benzonitrile, respectively. This leads to the idea of summing up the heats of adsorption of acetonitrile and...
Article
Full-text available
One layer thick iron oxide films are attractive from both applied and fundamental science perspectives. The structural and chemical properties of these systems can be tuned by changing the substrate, making them promising materials for heterogeneous catalysis. In the present work, we investigate the structure of FeO(111) monolayer films grown on Ag...
Chapter
The computational prediction of thermodynamically stable metal cluster structures has developed into a sophisticated and successful field of research. To this end, research groups have developed, combined and improved algorithms for the location of energetically low-lying structures of unitary and alloy clusters containing several metallic species....
Article
The effect of Pd doping on the structure and optical absorption of small cationic gold clusters is investigated by a combined photodissociation spectroscopy and time-dependent density functional theory study of Aun+Arp and PdAun-1+Arp (n = 4,5; p = 0,1). While pure Au clusters are planar, the Pd-doped clusters are 3D. UV-visible absorption is studi...
Article
On page 364, E. Janssens and co-workers report on the effect of a single Pd dopant atom on the laser light absorption of small gas phase gold and palladium-doped gold clusters. Laser-induced dissociation reveals quenching of absorption bands for the doped species, which is attributed by density functional theory calculations to charge transfers and...
Article
Ultrathin metal oxides exhibit unique chemical properties and show promise for applications in heterogeneous catalysis. Monolayer FeO films supported on metal surfaces show large differences in reactivity depending on the metal substrate, potentially enabling tuning of the catalytic properties of these materials. Nitric oxide (NO) adsorption is fac...
Article
Ultrathin metal oxides exhibit unique chemical properties and show promise for applications in heterogeneous catalysis. Monolayer FeO films supported on metal surfaces show large differences in reactivity depending on the metal substrate, potentially enabling tuning of the catalytic properties of these materials. Nitric oxide (NO) adsorption is fac...
Article
A first-principles microkinetic model has been developed and applied to ethylene hydrogenation over close-packed transition-metal surfaces of Ru, Rh, Pd, Os, Ir, and Pt. The model is based on density functional theory calculations, which have been used to determine the activation energies of the elementary steps of the reaction according to the Hor...
Article
Full-text available
The unbiased density functional-based Birmingham Cluster Genetic Algorithm is employed to locate the global minima of all neutral and mono-ionic silver-gold octamer clusters. Structural, energetic and electronic trends are determined across the series, in order to clarify the role of composition and charge on the position of the 2D–3D transition in...
Article
Density functional theory calculations are used to investigate the catalytic hydrogenation of ethylene to ethane over a wide range of transition metal (TM) surfaces. Assuming the Horuiti-Polanyi mechanism, the enthalpies of adsorption, surface diffusion, and hydrogenation barriers are examined over close-packed surfaces of Co, Ni, Cu, Ru, Rh, Pd, A...
Article
The energy landscapes of sub-nanometre bimetallic coinage metal clusters are explored with the Threshold Algorithm coupled with the Birmingham Cluster Genetic Algorithm. Global and energetically low-lying minima along with their permutational isomers are located for the Cu${_4 }$Ag${_4 }$ cluster with the Gupta potential and density functional theo...
Article
Full-text available
The novel surface mode of the Birmingham Cluster Genetic Algorithm (S-BCGA) is employed for the global optimisation of noble metal tetramers upon an MgO (100) substrate at the GGA-DFT level of theory. The effect of element identity and alloying in surface-bound neutral subnanometre clusters is determined by energetic comparison between all composit...
Article
Full-text available
AuAg nanoclusters are promising supported co-catalysts for photocatalytic hydrogen reduction. However, beyond the quantum regime (N > 100) little is known about how the electronic properties of these nanoparticles are affected by chemical ordering. We investigate the effects of chemical ordering on the properties of 147-atom cuboctahedral AuAg nano...
Article
The structures and optical response of helical clusters ("Bernal spirals") with compositions Ag12Cu1(+) and Ag1Cu12(+) are calculated within Kohn-Sham density functional theory and the configuration interaction singles variant of time dependent density functional theory. The effects of dopant position within the cluster on the vertical excitation s...
Article
Full-text available
We present experimental and theoretical studies of the optical response of mixed AunAg(4-n)+ (n=1–3) clusters in the photon energy range ℏω = 1.9–3.5 eV. Absorption spectra are recorded by a newly built longitudinal molecular beam depletion spectroscopy apparatus providing lower limits to absolute photodissociation cross sections. The experimental...
Article
The effect of cluster size, oxidation state, and the support upon the structures and energetics of subnanometer palladium nanoparticles is investigated within a density functional framework. Gas phase global minima of Pd4 and Pd10 along with their suboxide counterparts are determined using a genetic algorithm and deposited upon MgO (001) and a high...
Article
Water oxidation is a key catalytic step for electrical fuels generation. Recently, significant progress has been made in synthesizing electro-catalytic materials with reduced overpotentials and increased turnover rates, both key parameters enabling commercial use in electrolysis or solar to fuels applications. The complexity of both the catalytic m...
Article
Full-text available
The effect of doping on the energetics and dimensionality of eight atom coinage metal subnanometre particles is fully resolved using a genetic algorithm in tandem with on the fly density functional theory calculations to determine the global minima (GM) for CunAg(8−n) and CunAu(8−n) clusters. Comparisons are made to previous ab initio work on mono-...
Article
Full-text available
When a cluster or nanodroplet bears charge, its structure and thermodynamics are altered and, if the charge exceeds a certain limit, the system becomes unstable with respect to fragmentation. Some of the key results in this area were derived by Rayleigh in the nineteenth century using a continuum model of liquid droplets. Here we revisit the topic...

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