A Water-Promoted Mars-van Krevelen Reaction Dominates Low-Temperature CO Oxidation over Au-Fe2O3 but Not over Au-TiO2.

We provide experimental evidence that is inconsistent with often proposed Langmuir-Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au-Fe2O3. Passing CO and H2O, but no O2, over Au-γ-Fe2O3 at 25 °C, we observe significant CO2 production, inconsistent with LH mechanistic hypotheses. Experiments with H218O further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-γ-Fe2O3. Guided by density functional theory, we instead postulate a water-promoted Mars-van Krevelen (w-MvK) reaction. Our proposed w-MvK mechanism is consistent both with observed CO2 production in the absence of O2 and with CO oxidation in the presence of H218O and 16O2. In contrast, for Au-TiO2, our data is consistent with previous LH mechanistic hypotheses.

Operando probing of the surface chemistry during the Haber-Bosch process.

The large-scale conversion of N2 and H2 into NH3 (refs. 1,2) over Fe and Ru catalysts3 for fertilizer production occurs through the Haber-Bosch process, which has been considered the most important scientific invention of the twentieth century4. The active component of the catalyst enabling the conversion was variously considered to be the oxide5, nitride2, metallic phase or surface nitride6, and the rate-limiting step has been associated with N2 dissociation7-9, reaction of the adsorbed nitrogen10 and also NH3 desorption11. This range of views reflects that the Haber-Bosch process operates at high temperatures and pressures, whereas surface-sensitive techniques that might differentiate between different mechanistic proposals require vacuum conditions. Mechanistic studies have accordingly long been limited to theoretical calculations12. Here we use X-ray photoelectron spectroscopy-capable of revealing the chemical state of catalytic surfaces and recently adapted to operando investigations13 of methanol14 and Fischer-Tropsch synthesis15-to determine the surface composition of Fe and Ru catalysts during NH3 production at pressures up to 1 bar and temperatures as high as 723 K. We find that, although flat and stepped Fe surfaces and Ru single-crystal surfaces all remain metallic, the latter are almost adsorbate free, whereas Fe catalysts retain a small amount of adsorbed N and develop at lower temperatures high amine (NHx) coverages on the stepped surfaces. These observations indicate that the rate-limiting step on Ru is always N2 dissociation. On Fe catalysts, by contrast and as predicted by theory16, hydrogenation of adsorbed N atoms is less efficient to the extent that the rate-limiting step switches following temperature lowering from N2 dissociation to the hydrogenation of surface species.

Multi-spectroscopic study of electrochemically-formed oxide-derived gold electrodes.

Oxide-derived metals are produced by reducing an oxide precursor. These materials, including gold, have shown improved catalytic performance over many native metals. The origin of this improvement for gold is not yet understood. In this study, operando non-resonant sum frequency generation (SFG) and ex situ high-pressure X-ray photoelectron spectroscopy (HP-XPS) have been employed to investigate electrochemically-formed oxide-derived gold (OD-Au) from polycrystalline gold surfaces. A range of different oxidizing conditions were used to form OD-Au in acidic aqueous medium (H3PO4, pH = 1). Our electrochemical data after OD-Au is generated suggest that the surface is metallic gold, however SFG signal variations indicate the presence of subsurface gold oxide remnants between the metallic gold surface layer and bulk gold. The HP-XPS results suggest that this subsurface gold oxide could be in the form of Au2O3 or Au(OH)3. Furthermore, the SFG measurements show that with reducing electrochemical treatments the original gold metallic state can be restored, meaning the subsurface gold oxide is released. This work demonstrates that remnants of gold oxide persist beneath the topmost gold layer when the OD-Au is created, potentially facilitating the understanding of the improved catalytic properties of OD-Au.

Facilitating critical discourse through "meaningful disagreement" online.

This paper is concerned with identifying ways of facilitating "meaningful disagreement" amongst students in interprofessional online discussion forums. It builds on previous research that identified a trend toward polite agreement and only limited evidence of disagreement in this setting. Given the suggestion that disagreement indicates a deeper level of engagement in group discussion and therefore leads to deeper learning, our aim was to critique the pedagogical approach adopted by analyzing whether we were promoting a particular interprofessional discourse amongst students that favored agreement and therefore limited potential learning. Agreement in this context has been conceptualized as a form of online interprofessional "netiquette" existing amongst participants. Findings suggest that creating an online context for critical discourse is challenging; however, the careful construction of learning outcomes, trigger material/resources and learning activities, as well as attention to students' stage of study and life experience, can provoke the desired effects.

"Understanding where you're coming from": discovering an [inter]professional identity through becoming a peer facilitator.

Peer facilitation offers an innovative and effective means of promoting interprofessional learning (IPL) between health and social care students. This paper highlights the benefits that peer facilitators themselves experience from involvement in assisting junior colleagues to engage with IPL in an online context. The setting for the inquiry is an online interprofessional learning pathway shared by two higher education institutions in the UK. Insights have been developed over a 3-year period through collaborative inquiry with 41 peer facilitators, academic tutors and the students who benefitted from their input. This paper which focuses on peer facilitators' application data, interview data and written reflections explores the instrumental, cognitive and personal gains experienced. However, more fundamentally, theorizing findings in relation to identity theory we substantiate the claim that the role provides opportunity for testing and refining important aspects of both professional and interprofessional identities.

An investigation of "agreement" in the context of interprofessional discussion online: a "netiquette" of interprofessional learning?

This article suggests that "agreement" is a predominant feature of online discussions amongst undergraduate health and social care professionals, which is an area of concern. The context for the research is an online interprofessional learning pathway completed by ~2,800 students each year. The concept of agreement, how and why it is reached and what it indicates in an online interprofessional group is examined. The underpinning educational rationale for instigating online interprofessional dialogue was the potential to provide a powerful interface for bringing together students across a wide range of professional groups, which is necessary to promote interprofessional learning. Discourse analysis was used to analyze digital texts of interaction in online forums. The discussion forum discourse shows evidence of increased interprofessional knowledge and understanding, as well as capacity for interprofessional dialogue. Discussions were largely characterized by agreement, although some disagreement was evident. These findings support previous research in online dialogue. However, they are interpreted in an interprofessional context as constituting a specific type of "netiquette" in relation to the participants and their identification with professional discourses and to the learning activities that shaped discussions. The research has significance for teachers, researchers, and practitioners involved in promoting interprofessional learning through online discussion forums.