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Glycerol is a renewable chemical that has become widely available and inexpensive due to the increased production of biodiesel. Noble metal materials have shown to be effective catalysts for the production of hydrogen and value-added products through the electrooxidation of glycerol. In this work we develop three platinum systems with distinct pore mesostructures, e.g., hierarchical pores (HP), cubic pores (CP) and linear pores (LP); all with high electrochemically active surface area (ECSA). The ECSA-normalized GEOR catalytic activity of the systems follows HPC > LPC > CPC > commercial Pt/C. Regarding the oxidation products, we observe glyceric acid as the main three-carbon product (3C), with oxalic acids as the main two-carbon oxidation product. DFT-based theoretical calculations support the glyceraldehyde route going through tartronic acid towards oxalic acid and also help understanding why the dihydroxyacetone (DHA) route is active despite the absence of DHA amongst the observed oxidation products.

Glycerol electrooxidation offers a dual benefit of producing clean hydrogen and valuable derived chemicals. Designer electrocatalysts with high performance need to be fine-tuned with the problem in achieving material reproducibility while varying their composition. Herein, we study the potential and stability of bimetallic Cu_1−xPt_x sputtered thin film electrocatalysts. Our findings reveal Cu_0.7Pt_0.3 as a promising effective, stable composition exhibiting a nine-fold increase in current density and 200 mV lower onset potential than pure Pt. Importantly, Cu_1−xPt_x demonstrates a composition dependent selectivity, favoring high glycerate/lactate at higher Cu at.%, and potential dependency with high lactate yield at higher applied potentials. Density functional theory and a combination of experimental methods clarify the detailed compositional and potential-dependent oxidation pathways. Additionally, we employ angle-dependent operando X-ray grazing incidence diffraction to look into the temporal variations of the catalyst surfaces during electrochemical reactions. The alloying of Pt with Cu results cost-effective catalyst with additional reaction pathway tunability compared to Pt, paving the way for more sustainable practices in alcohol electrooxidation.

The electrooxidation of glycerol into hydrogen gas and valuable chemicals is effectively carried out with Cu-Pt alloys. The stability of the catalysts is crucial to understand the chemistry underlying these reactions, improving catalyst performance, and elucidating degradation mechanisms. The temporal evolution of the catalyst composition was evaluated using angle-dependent grazing incidence X-ray diffraction under operando conditions in a dual-chamber flow cell. The cell is designed to allow for realistic conditions using synchrotron radiation. Analysis of the diffraction data shows that compositions rich in copper suffer surface oxidation and dealloying towards a Pt-rich composition after repeated cycling.

The development of alcohol-based electrolysis to enable the concurrent production of hydrogen with low electricity consumption still faces major challenges in terms of the maximum anodic current density achievable. Whilst noble metals enable a low electrode potential to facilitate alcohol oxidation, the deactivation of the catalyst at higher potentials makes it difficult for the obtained anodic current density to compete with water electrolysis. In this work the effect of significant parameters such as mass transport, glycerol and OH- concentration and electrolyte temperature on the glycerol electrooxidation reaction (GEOR) in alkaline conditions on a bimetallic catalyst PdNi/Ni-RDE (Pd0.9Ni0.1) has been studied to discern experimental conditions which maximise achievable anodic current density before deactivation occurs. The ratio of NaOH:glycerol in the electrolyte highly affects the rate of the GEOR. A maximum current density of 793 mA cm(-2) at-0.125 V vs. Hg/HgO through steady state polarisation curves was achieved at a moderate and intermediate rotation rate of 500 RPM in a 2 M NaOH and 1 M glycerol (ratio of 2) electrolyte at 80 & DEG;C. Shown here is a method of catalyst reactivation for enabling the longterm use of the PdNi/Ni-RDE for electrolysis at optimal conditions for extended periods of time (3 h at 300 mA cm(-2) and 10 h at 100 mA cm(-2)). Through scanning electron microscopy (SEM), X-ray photon electron spectroscopy (XPS) and X-ray diffraction (XRD) it is shown that the electrodeposition of Pd and Ni forms an alloy and that after 10 h of electrolysis the catalyst has chemical and structural stability. This study provides details on parameters significant to the maximising of the GEOR current density and the minimising of the debilitating effect that deactivation has on noble metal based electrocatalysts for the GEOR.& nbsp;(c) 2021 The Authors. Published by Elsevier Ltd.& nbsp;

The glycerol electrooxidation reaction (GEOR) has been increasingly studied for providing value-added chemical products whilst also facilitating a concurrent reduction process such as hydrogen evolution. Noble metals have been shown to be highly active for the GEOR in alkaline media. Here, to assess the effects of mass transport, catalyst layer thickness and pH on the GEOR, three thicknesses of Pd are electrodeposited onto a Ni rotating disk electrode and studied for a constant glycerol concentration of 0.50 M with NaOH to glycerol ratios of 1:2, 1:1 and 2:1. The electrodeposited catalysts are found to be morphologically similar with similar crystallographic structures. The activity, evaluated from the peak current density at the point of deactivation, shows that for every pH, the thinnest catalyst has the highest specific activity, whereas the thickest catalyst has the lowest. Therefore, there is a significant under utilisation of the thicker porous Pd electrodes for the GEOR. The thinnest catalyst layer is furthermore investigated in a solution of 1.0 M NaOH and 1.0 M glycerol. The doubling of the glycerol concentration in this case did not provide a significant increase in current density. Therefore, we propose that there is an optimal ratio of OHˉ to glycerol ratio in solution of around 2:1 due to the stoichiometry of the GEOR with the diffusion layer thickness and flux at higher glycerol concentrations considered.