Computational chemistry provides powerful research tools for catalysis. It potentially allows us to study the structures of the catalytic sites and reaction mechanisms, which are difficult to observe only by experiment. This is particularly true for supported heterogeneous catalysts, of which reactivity and catalytic behavior are directly related to the presence of various functional groups and reactive ensembles on their surfaces. Such surface heterogeneities give rise to the formation of multifunctional reactive ensembles ready to convert substrate molecules to the desired products efficiently. At the same time, the presence of various reactive centers on the surface may contribute to undesirable conversion paths. Understanding the role of the multifunctional reaction environments established on the complex surfaces of supported heterogeneous catalysts is key to formulating design rules for achieving control over their activity and selectivity....@en

Supported metal catalysts have shown to be efficient for CO ₂ conversion due to their multifunctionality and high stability. Herein, we have combined density functional theory calculations with microkinetic modeling to investigate the catalytic reaction mechanisms of CO ₂ hydrogenation to CH ₃OH over a recently reported catalyst of Cd ₄/TiO ₂. Calculations reveal that the metal-oxide interface is the active center for CO ₂ hydrogenation and methanol formation via the formate pathway dominates over the reverse water-gas shift (RWGS) pathway. Microkinetic modeling demonstrated that formate species on the surface of Cd ₄/TiO ₂ is the relevant intermediate for the production of CH ₃OH, and CH ₂O ^# formation is the rate-determining step. These findings demonstrate the crucial role of the Cd-TiO ₂ interface for controlling the CO ₂ reduction reactivity and CH ₃OH selectivity.

@en

The conversion of CO2 with high activity and high selectivity to methanol remains challenging because of both the kinetics and thermodynamics difficulties associated with the chemical reactivity of CO2. Herein, we report a new catalyst of Cd/TiO2 enabling 81% methanol selectivity at 15.8% CO2 conversion with the CH4 selectivity below 0.7%. The combination of experimental and computational studies show that the unique electronic properties of Cd cluster supported on TiO2 are responsible for the high selectivity for CO2 hydrogenation to methanol via a HCOO* pathway realized at the interface catalytic sites.@en

Finding alternative ways to tailor the electronic properties of a catalyst to actively and selectively drive reactions of interest has been a growing research topic in the field of electrochemistry. In this Letter, we investigate the tuning of the surface electronic properties of electrocatalysts via polymer modification. We show that when a nickel oxide water oxidation catalyst is coated with polytetrafluoroethylene, stable Ni-CFx bonds are introduced at the nickel oxide/polymer interface, resulting in shifting of the reaction selectivity away from the oxygen evolution reaction and toward hydrogen peroxide formation. It is shown that the electron-withdrawing character of the surface fluorocarbon molecule leaves a slight positive charge on the water oxidation intermediates at the adjacent active nickel sites, making their bonds weaker. The concept of modifying the surface electronic properties of an electrocatalyst via stable polymer modification offers an additional route to tune multipathway reactions in polymer/electrocatalyst environments, like with ionomer-modified catalysts or with membrane electrode assemblies.

@en

Potassium carbonate dispersed over a defective TiO₂support (K₂CO₃/TiO₂) is an efficient catalyst for benzene esterification with CO₂and CH₃OH. Density functional theory calculations reveal that this unique catalytic reactivity originates from the cooperation of the Ti³⁺/K⁺surface sites. The K₂CO₃promotor steers the stabilization of surface intermediates thus preventing catalyst deactivation.

@en

Heterogeneous derivatives of catalysts discovered by Ziegler and Natta are important for the industrial production of polyolefin plastics. However, the interaction between precatalysts, alkylaluminum activators, and oxide supports to form catalytically active materials is poorly understood. This is in contrast to homogeneous or model heterogeneous catalysts that contain resolved molecular structures that relate to activity and selectivity in polymerization reactions. This study describes the reactivity of triisobutylaluminum with high surface area aluminum oxide and a zirconocene precatalyst. Triisobutylaluminum reacts with the zirconocene precatalyst to form hydrides and passivates -OH sites on the alumina surface. The combination of passivated alumina and zirconium hydrides formed in this mixture generates ion pairs that polymerize ethylene.

@en

The reductive amination of benzoic acid and its derivatives would be an effective addition to current synthesis methods for benzylamine. However, with current technology it is very difficult to keep the aromaticity intact when starting from benzoic acid, and salt wastes are often generated in the process. Here, we report a heterogeneous catalytic system for such a reductive amination, requiring solely H2 and NH3 as the reactants. The Ag/TiO2 or Au/TiO2 catalysts can be used multiple times and very little noble metal is required; only 0.025 mol% Au. The catalysts are bifunctional: the support catalyzes the dehydration of both the ammonium carboxylate to the amide and of the amide to the nitrile, while the sites at the metal-support interface promote the hydrogenation of the in situ generated nitrile. Yields of up to 92% benzylamine were obtained.@en

Plasmon-induced photocatalysts hold great promise for solar energy conversion owing to their strong light-harvesting ability and tunable optical properties. However, the complex process of interfacial extraction of hot carriers and the roles of metal/semiconductor interfaces in plasmonic photocatalysts are still not clearly understood. Herein, the manipulation of the interface between a plasmon metal (Au) and a semiconductor (rutile TiO₂) by introducing an interfacial metal oxide (Al₂O₃) is reported. The resulting Au/Al₂O₃/TiO₂ exhibits remarkable enhancement in photocatalytic water oxidation activity compared with Au/TiO₂, giving an apparent quantum efficiency exceeding 1.3% at 520 nm for photocatalytic water oxidation. Such an interfacial modulation approach significantly prolongs the lifetime of hot carriers in the Au/TiO₂ system, which conclusively improves the utilization of hot carriers for plasmon-induced water oxidation reaction upon irradiation. This work emphasizes the essential role of the interfacial structure in plasmonic devices and provides an alternative method for designing efficient plasmonic photocatalysts for solar energy conversion.

@en

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 computational models, based on inspection of the potential energy surface at 0 K and low reactant concentrations (0 K/UHV model), to more realistic conditions. The transition from 0 K/UHV to operando models has been backed by significant developments in computer hardware and software over the past few decades. New methodological developments, designed to overcome part of the gap between 0 K/UHV and operando conditions, include (i) global optimization techniques, (ii) ab initio constrained thermodynamics, (iii) biased molecular dynamics, (iv) microkinetic models of reaction networks and (v) machine learning approaches. The importance of the transition is highlighted by discussing how the molecular level picture of catalytic sites and the associated reaction mechanisms changes when the chemical environment, pressure and temperature effects are correctly accounted for in molecular simulations. It is the purpose of this review to discuss each method on an equal footing, and to draw connections between methods, particularly where they may be applied in combination.

@en