Fundamental aspects of photoelectrochemical water splitting at semiconductor electrodes

Fundamental aspects of light-driven water splitting are reviewed with emphasis on the kinetics and mechanism of the oxygen and hydrogen evolution reactions at semiconductor photoelectrodes. Information provided by in operando techniques is discussed and related to the mechanisms of light-driven reactions and catalysis.</p

Recent advances in homogeneous borrowing hydrogen catalysis using earth-abundant first row transition metals

The review highlights the recent advances (2013-present) in the use of earth-abundant first row transition metals in homogeneous borrowing hydrogen catalysis. The utility of catalysts based on Mn, Fe, Co, Ni and Cu to promote a diverse array of important C–C and C–N bond forming reactions is described, including discussion on reaction mechanisms, scope and limitations, and future challenges in this burgeoning area of sustainable catalysis

Catalytic Bond‐Forming Reactions Using Aluminium(III)

AbstractStatic catalysis using neutral and cationic Al(III) complexes, in which the oxidation state of the metal does not change, can be applied to a range of catalytic bond‐forming reactions which have similar characteristics to transition metal analogues. This short review (although not intended to be comprehensive) highlights the current state of development in the areas of dehydrocoupling, alkene polymerisation, and other bond forming reactions involving single‐site Al(III) catalysts, focusing in particular on the key factors involved in molecular activation and the mechanisms of catalysis.</jats:p

A microscopic description of acid-base equilibrium

Acid-base reactions are ubiquitous in nature. Understanding their mechanisms is crucial in many fields, from biochemistry to industrial catalysis. Unfortunately, experiments only give limited information without much insight into the molecular behaviour. Atomistic simulations could complement experiments and shed precious light on microscopic mechanisms. The large free energy barriers connected to proton dissociation however make the use of enhanced sampling methods mandatory. Here we perform an ab initio molecular dynamics (MD) simulation and enhance sampling with the help of methadynamics. This has been made possible by the introduction of novel descriptors or collective variables (CVs) that are based on a conceptually new outlook on acid-base equilibria. We test successfully our approach on three different aqueous solutions of acetic acid, ammonia, and bicarbonate. These are representative of acid, basic, and amphoteric behaviour

On the role of water in heterogeneous catalysis: a tribute to Professor M. Wyn Roberts

From the earliest studies of heterogeneous catalysis, it was apparent that water plays a more important role in many systems than simply acting as a solvent. Its wide ranging effects have attracted increasing attention in recent years and was the topic of Prof. M.W. Roberts’ final paper. The present review explores some of the latest work on water in reactions ranging from CO oxidation to Fischer Tropsch catalysis, the different mechanisms proposed for its role are discussed and compared

Hydrothermal Organic Reduction and Deoxygenation

abstract: Organic reactions in natural hydrothermal settings have relevance toward the deep carbon cycle, petroleum formation, the ecology of deep microbial communities, and potentially the origin of life. Many reaction pathways involving organic compounds under geochemically relevant hydrothermal conditions have now been characterized, but their mechanisms, in particular those involving mineral surface catalysis, are largely unknown. The overall goal of this work is to describe these mechanisms so that predictive models of reactivity can be developed and so that applications of these reactions beyond geochemistry can be explored. The focus of this dissertation is the mechanisms of hydrothermal dehydration and catalytic hydrogenation reactions. Kinetic and structure/activity relationships show that elimination occurs mainly by the E1 mechanism for simple alcohols via homogeneous catalysis. Stereochemical probes show that hydrogenation on nickel occurs on the metal surface. By combining dehydration with and catalytic reduction, effective deoxygenation of organic structures with various functional groups such as alkenes, polyols, ketones, and carboxylic acids can be accomplished under hydrothermal conditions, using either nickel or copper-zinc alloy. These geomimetic reactions can potentially be used in biomass reduction to generate useful fuels and other high value chemicals. Through the use of earth-abundant metal catalysts, and water as the solvent, the reactions presented in this dissertation are a green alternative to current biomass deoxygenation/reduction methods, which often use exotic, rare-metal catalysts, and organic solvents.Dissertation/ThesisDoctoral Dissertation Chemistry 201

Concluding remarks: Reaction mechanisms in catalysis: perspectives and prospects

We consider the current status of our understanding of reaction mechanisms in catalysis in the light of the papers presented in this Discussion. We identify some of the challenges in both theoretical and experimental studies, which we illustrate by considering three key reactions

Propagating Surface Plasmon Polaritons: Towards Applications for Remote-Excitation Surface Catalytic Reactions

Plasmonics is a well-established field, exploiting the interaction of light and metals at the nanoscale; with the help of surface plasmon polaritons, remote-excitation can also be observed by using silver or gold plasmonic waveguides. Recently, plasmonic catalysis was established as a new exciting platform for heterogeneous catalytic reactions. Recent reports present remote-excitation surface catalytic reactions as a route to enhance the rate of chemical reactions, and offer a pathway to control surface catalytic reactions. In this review, we focus on recent advanced reports on silver plasmonic waveguide for remote-excitation surface catalytic reactions. First, the synthesis methods and characterization techniques of sivelr nanowire plasmonic waveguides are summarized, and the properties and physical mechanisms of plasmonic waveguides are presented in detail. Then, the applications of plasmonic waveguides including remote excitation fluorescence and SERS are introduced, and we focus on the field of remote-excitation surface catalytic reactions. Finally, forecasts are made for possible future applications for the remote-excitation surface catalysis by plasmonic waveguides in living cells

Thermodynamics of accuracy in kinetic proofreading: Dissipation and efficiency trade-offs

The high accuracy exhibited by biological information transcription processes is due to kinetic proofreading, i.e., by a mechanism which reduces the error rate of the information-handling process by driving it out of equilibrium. We provide a consistent thermodynamic description of enzyme-assisted assembly processes involving competing substrates, in a Master Equation framework. We introduce and evaluate a measure of the efficiency based on rigorous non-equilibrium inequalities. The performance of several proofreading models are thus analyzed and the related time, dissipation and efficiency vs. error trade-offs exhibited for different discrimination regimes. We finally introduce and analyze in the same framework a simple model which takes into account correlations between consecutive enzyme-assisted assembly steps. This work highlights the relevance of the distinction between energetic and kinetic discrimination regimes in enzyme-substrate interactions.Comment: IOP Class, 20 pages, 9 figure