Browsing by Author "Gooding, J. Justin"

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    Combining Nanoconfinement in Ag Core/Porous Cu Shell Nanoparticles with Gas Diffusion Electrodes for Improved Electrocatalytic Carbon Dioxide Reduction
    (ChemElectroChem, 2021) Junqueira, João R. C.; O’Mara, Peter B.; Wilde, Patrick; Dieckhöfer, Stefan; Benedetti, Tania M.; Andronescu, Corina; Tilley, Richard D.; Gooding, J. Justin; Schuhmann, Wolfgang
    Bimetallic silver-copper electrocatalysts are promising materials for electrochemical CO2 reduction reaction (CO2RR) to fuels and multi-carbon molecules. Here, we combine Ag core/porous Cu shell particles, which entrap reaction intermediates and thus facilitate the formation of C2+ products at low overpotentials, with gas diffusion electrodes (GDE). Mass transport plays a crucial role in the product selectivity in CO2RR. Conventional Hcell configurations suffer from limited CO2 diffusion to the reaction zone, thus decreasing the rate of the CO2RR. In contrast, in the case of GDE-based cells, the CO2RR takes place under enhanced mass transport conditions. Hence, investigation of the Ag core/porous Cu shell particles at the same potentials under different mass transport regimes reveals: (i) a variation of product distribution including C3 products, and (ii) a significant change in the local OH- activity under operation.
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    Feasibility of Silicon Quantum Dots as a Biomarker for the Bioimaging of Tear Film
    (Nanomaterials, 2022) Sarwat, Sidra; Stapleton, Fiona Jane; Perry Willcox, Mark Duncan; O’Mara, Peter B.; Tilley, Richard David; Gooding, J. Justin; Roy, Maitreyee
    This study investigated the fluorescence and biocompatibility of hydrophilic silicon quantum dots (SiQDs) that are doped with scandium (Sc-SiQDs), copper (Cu-SiQDs), and zinc (Zn-SiQDs), indicating their feasibility for the bioimaging of tear film. SiQDs were investigated for fluorescence emission by the in vitro imaging of artificial tears (TheraTears®), using an optical imaging system. A trypan blue exclusion test and MTT assay were used to evaluate the cytotoxicity of SiQDs to cultured human corneal epithelial cells. No difference was observed between the fluorescence emission of Sc-SiQDs and Cu-SiQDs at any concentration. On average, SiQDs showed stable fluorescence, while Sc-SiQDs and Cu-SiQDs showed brighter fluorescence emissions than Zn-SiQDs. Cu-SiQDs and Sc-SiQDs showed a broader safe concentration range than Zn-SiQDs. Cu-SiQDs and Zn-SiQDs tend to aggregate more substantially in TheraTears® than Sc-SiQDs. This study elucidates the feasibility of hydrophilic Sc-SiQDs in studying the tear film’s aqueous layer.
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    Is Cu instability during the CO2 reduction reaction governed by the applied potential or the local CO concentration?
    (Chemical science, 2021) Wilde, Patrick; O'Mara, Peter B.; Junqueira, Joao R. C.; Tarnev, Tsvetan; Benedetti, Tania M.; Andronescu, Corina; Chen, Yen-Ting; Tilley, Richard D.; Schuhmann, Wolfgang; Gooding, J. Justin
    have shown structural instability during the electrochemical CO2 reduction reaction (CO2RR). However, studies on monometallic Cu catalysts do not allow a nuanced differentiation between the contribution of the applied potential and the local concentration of CO as the reaction intermediate since both are inevitably linked. We first use bimetallic Ag-core/porous Cu-shell nanoparticles, which utilise nanoconfinement to generate high local CO concentrations at the Ag core at potentials at w