Au@AuPd Core-Alloyed Shell Nanoparticles for Enhanced Electrocatalytic Activity and Selectivity under Visible Light Excitation.

Plasmonic catalysis has been employed to enhance molecular transformations under visible light excitation, leveraging the localized surface plasmon resonance (LSPR) in plasmonic nanoparticles. While plasmonic catalysis has been employed for accelerating reaction rates, achieving control over the reaction selectivity has remained a challenge. In addition, the incorporation of catalytic components into traditional plasmonic-catalytic antenna-reactor nanoparticles often leads to a decrease in optical absorption.

Impact of NiCoO/SrTiO p-n Heterojunctions on the Interface of Photoelectrochemical Water Oxidation.

Forming semiconductor heterojunctions is a promising strategy to boost the efficiency of solar-driven photoelectrochemical (PEC) water splitting by accelerating the separation and transport of photogenerated charge carriers via an interfacial electric field. However, there is limited research considering the influence of electrolytes on the band alignment of the heterojunction under PEC conditions. In this work, we use a single crystal NiCoO/SrTiO (NCO/STO) heterojunction with atomic-precision controlled thickness as a model photoelectrode to study the band structure modulations upon getting in contact with the electrolyte and the correlation with the PEC activity.

Synergistic binding sites in a metal-organic framework for the optical sensing of nitrogen dioxide.

Luminescent metal-organic frameworks are an emerging class of optical sensors, able to capture and detect toxic gases. Herein, we report the incorporation of synergistic binding sites in MOF-808 through post-synthetic modification with copper for optical sensing of NO at remarkably low concentrations. Computational modelling and advanced synchrotron characterization tools are applied to elucidate the atomic structure of the copper sites.

Highly Active and Stable Ni/La-Doped Ceria Material for Catalytic CO Reduction by Reverse Water-Gas Shift Reaction.

The design of an active, effective, and economically viable catalyst for CO conversion into value-added products is crucial in the fight against global warming and energy demand. We have developed very efficient catalysts for reverse water-gas shift (rWGS) reaction. Specific conditions of the synthesis by combustion allow the obtention of macroporous materials based on nanosized Ni particles supported on a mixed oxide of high purity and crystallinity.

Laser-Reduced BiVO for Enhanced Photoelectrochemical Water Splitting.

The present study proposes a laser irradiation method to superficially reduce BiVO photoelectrodes and boost their water oxidation reaction performance. The origin of this enhanced performance toward oxygen evolution reaction (OER) was studied using a combination of a suite of structural, chemical, and mechanistic advanced characterization techniques including X-ray photoelectron (XPS), X-ray absorption spectroscopy (XAS), electrochemical impedance spectroscopy (EIS), and transient absorption spectroscopy (TAS), among others. We found that the reduction of the material is localized at the surface of the sample and that this effect creates effective n-type doping and a shift to more favorable energy band positions toward water oxidation.

Improved Methane Production by Photocatalytic CO Conversion over Ag/InO/TiO Heterojunctions.

In this work, the role of InO in a heterojunction with TiO is studied as a way of increasing the photocatalytic activity for gas-phase CO reduction using water as the electron donor and UV irradiation. Depending on the nature of the employed InO, different behaviors appear. Thus, with the high crystallite sizes of commercial InO, the activity is improved with respect to TiO, with modest improvements in the selectivity to methane.

Twin boundary migration in an individual platinum nanocrystal during catalytic CO oxidation.

At the nanoscale, elastic strain and crystal defects largely influence the properties and functionalities of materials. The ability to predict the structural evolution of catalytic nanocrystals during the reaction is of primary importance for catalyst design. However, to date, imaging and characterising the structure of defects inside a nanocrystal in three-dimensions and in situ during reaction has remained a challenge.

Electronic Structure and Interface Energetics of CuBiO Photoelectrodes.

CuBiO exhibits significant potential for the photoelectrochemical (PEC) conversion of solar energy into chemical fuels, owing to its extended visible-light absorption and positive flat band potential vs the reversible hydrogen electrode. A detailed understanding of the fundamental electronic structure and its correlation with PEC activity is of significant importance to address limiting factors, such as poor charge carrier mobility and stability under PEC conditions. In this study, the electronic structure of CuBiO has been studied by a combination of hard X-ray photoemission spectroscopy, resonant photoemission spectroscopy, and X-ray absorption spectroscopy (XAS) and compared with density functional theory (DFT) calculations.

An Fe stabilized metallic phase of NiS for the highly efficient oxygen evolution reaction.

This work reports a fundamental study on the relationship of the electronic structure, catalytic activity and surface reconstruction process of Fe doped NiS (FeNiS) for the oxygen evolution reaction (OER). A combined photoemission and X-ray absorption spectroscopic study reveals that Fe doping introduces more occupied Fe 3d states at the top of the valence band and thereby induces a metallic phase. Meanwhile, Fe doping also significantly increases the OER activity and results in much better stability with the optimum found for FeNiS.

Water-Dispersible Copper Sulfide Nanocrystals via Ligand Exchange of 1-Dodecanethiol.

In colloidal Cu S nanocrystal synthesis, thiols are often used as organic ligands and the sulfur source, as they yield high-quality nanocrystals. However, thiol ligands on Cu S nanocrystals are difficult to exchange, limiting the applications of these nanocrystals in photovoltaics, biomedical sensing, and photocatalysis. Here, we present an effective and facile procedure to exchange native 1-dodecanethiol on Cu S nanocrystals by 3-mercaptopropionate, 11-mercaptoundecanoate, and S in formamide under inert atmosphere.

Marrying SPR excitation and metal-support interactions: unravelling the contribution of active surface species in plasmonic catalysis.

Plasmonic catalysis takes advantage of the surface plasmon resonance (SPR) excitation to drive or accelerate chemical transformations. In addition to the plasmonic component, the control over metal-support interactions in these catalysts is expected to strongly influence the performances. For example, CeO2 has been widely employed towards oxidation reactions due to its oxygen mobility and storage properties, which allow for the formation of Ce3+ sites and adsorbed oxygen species from metal-support interactions.

Electronic Structure and Band Alignment at the NiO and SrTiO p-n Heterojunctions.

Understanding the energetics at the interface, including the alignment of valence and conduction bands, built-in potentials, and ionic and electronic reconstructions, is an important challenge in designing oxide interfaces that have controllable multifunctionalities for novel (opto-)electronic devices. In this work, we report detailed investigations on the heterointerface of wide-band-gap p-type NiO and n-type SrTiO (STO). We show that despite a large lattice mismatch (∼7%) and dissimilar crystal structure, high-quality NiO and Li-doped NiO (LNO) thin films can be epitaxially grown on STO(001) substrates through a domain-matching epitaxy mechanism.

Electronic basis of visible region activity in high area Sn-doped rutile TiO2 photocatalysts.

The influence of Sn doping on the anatase-to-rutile phase transition has been investigated in high area powders prepared by a sol-gel route involving alkoxide precursors. Sn doping facilitates conversion of anatase to rutile at lower temperatures than observed for undoped material. At the same time Sn-doping inhibits sintering as gauged by line widths in X-ray diffraction and gas-adsorption surface area measurements.

A critical evaluation of the mode of incorporation of nitrogen in doped anatase photocatalysts.

A range of sol-gel synthesis conditions were used to prepare high surface area N-doped TiO(2) in the anatase phase. The N dopant was derived either from NH(3) in solution or from NH(3) gas bubbled through solution. Bulk N doping levels were determined by an inert gas fusion method and were compared with surface N doping levels determined by X-ray photoelectron spectroscopy.