Multiscale simulations of photocatalytic water splitting

International audienc

Simple guidelines to develop water splitting photocatalysts using multi-scale simulations

International audienc

Simple guideline for water splitting: an interdisciplinary multi-scale approach

International audienc

Cu-Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO2 to CO

We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO2 to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of -1.0 mA cm(-2) at -0.6 V vs RHE, compared to the CO FE of 63% and -2.1 mA cm(-2) for OD-Cu. Excess Sn on the surface caused H-2 evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu Sn alloy. Auger electron spectroscopy of the sample surface exhibits zerovalent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multifold sites on pure Cu, disfavoring the adsorption of H and leaving the adsorption of CO relatively unperturbed. Our catalytic results along with DFT calculations indicate that the presence of Sn on reduced OD-Cu diminishes the hydrogenation capability-i.e., the selectivity toward H-2 and HCOOH-while hardly affects the CO productivity. While the pristine monometallic surfaces (both Cu and Sn) fail to selectively reduce CO2, the Cu Sn bimetallic electrocatalyst generates a surface that inhibits adsorbed H*, resulting in improved CO FE. This study presents a strategy to provide low-cost non-noble metals that can be utilized as a highly selective electrocatalyst for the efficient aqueous reduction of CO2

Modelling heterogeneous photocatalyst for water splitting: What can we ask from quantum chemistry?

International audienc

Computational methodology for full in silico design of new semiconductors for water splitting: A DFT study of YTaON2 and YTiO2N

International audienc

Cu–Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO₂ to CO

We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO₂ to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of −1.0 mA cm^–2 at −0.6 V vs RHE, compared to the CO FE of 63% and −2.1 mA cm^–2 for OD-Cu. Excess Sn on the surface caused H₂ evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu–Sn alloy. Auger electron spectroscopy of the sample surface exhibits zerovalent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multifold sites on pure Cu, disfavoring the adsorption of H and leaving the adsorption of CO relatively unperturbed. Our catalytic results along with DFT calculations indicate that the presence of Sn on reduced OD-Cu diminishes the hydrogenation capabilityi.e., the selectivity toward H₂ and HCOOHwhile hardly affects the CO productivity. While the pristine monometallic surfaces (both Cu and Sn) fail to selectively reduce CO₂, the Cu–Sn bimetallic electrocatalyst generates a surface that inhibits adsorbed H*, resulting in improved CO FE. This study presents a strategy to provide low-cost non-noble metals that can be utilized as a highly selective electrocatalyst for the efficient aqueous reduction of CO₂

Modelling heterogeneous photocatalysts for water splitting: What can we ask from quantum chemistry?

International audienc

Revealing the bonding of solvated Ru complexes with valence-to-core resonant inelastic X-ray scattering

Ru-complexes are widely studied because of their use in biological applications and photoconversion technologies. We reveal novel insights into the chemical bonding of a series of Ru(ii)- and Ru(iii)-complexes by leveraging recent advances in high-energy-resolution tender X-ray spectroscopy and theoretical calculations. We perform Ru 2p4d resonant inelastic X-ray scattering (RIXS) to probe the valence excitations in dilute solvated Ru-complexes. Combining these experiments with a newly developed theoretical approach based on time-dependent density functional theory, we assign the spectral features and quantify the metal-ligand bonding interactions. The valence-to-core RIXS features uniquely identify the metal-centered and charge transfer states and allow extracting the ligand-field splitting for all the complexes. The combined experimental and theoretical approach described here is shown to reliably characterize the ground and excited valence states of Ru complexes, and serve as a basis for future investigations of ruthenium, or other 4d metals active sites, in biological and chemical applications

Tethering Metal Ions to Photocatalyst Particulate Surfaces by Bifunctional Molecular Linkers for Efficient Hydrogen Evolution

A simple and versatile method for the preparation of photocatalyst particulates modified with effective cocatalysts is presented; the method involves the sequential soaking of photocatalyst particulates in solutions containing bifunctional organic linkers and metal ions. The modification of the particulate surfaces is a universal and reproducible method because the molecular linkers utilize strong covalent bonds, which in turn result in modified monolayer with a small but controlled quantity of metals. The photocatalysis results indicated that the CdS with likely photochemically reduced Pd and Ni, which were initially immobilized via ethanedithiol (EDT) as a linker, were highly efficient for photocatalytic hydrogen evolution from Na2S-Na2SO3-containing aqueous solutions. The method developed in this study opens a new synthesis route for the preparation of effective photocatalysts with various combinations of bifunctional linkers, metals, and photocatalyst particulate materials