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Impurity tolerance of unsaturated Ni-N‑C active sites for practical electrochemical CO2 reduction
(American Chemical Society (ACS), 2022-02-09) Leverett, J; Yuwono, JA; Kumar, P; Tran-Phu, T; Qu, JT; Cairney, JM; Wang, X; Simonov, AN; Hocking, RK; Johannessen, B; Dai, L; Daiyan, R; Amal, R
Demonstrating the potential of the electrochemical carbon dioxide reduction reaction (CO2RR) in industrially relevant conditions is a promising route for achieving net-zero emissions through decarbonization. This requires a catalyst system that displays not only high activity and stability but also the capacity to deliver a consistent performance in the presence of waste stream impurities. To explore these opportunities, we investigate the role that the Ni coordination structure plays on the impurity tolerance of highly active single-atom catalysts (SACs) during CO2RR. The as-synthesized materials are highly active for CO2RR to CO, achieving a current density of 470 mA cm-2 and a CO selectivity of 99% in a CO2 electrolyzer. We demonstrate, through high-temperature pyrolysis, that a higher concentration of “unsaturated” Ni-N4-x-Cx sites significantly improves the tolerance to NOx, SOx, volatile organic compounds, and SCN- impurities in aqueous electrolyte, paving the way for SACs capable of CO2RR in industrial conditions. © 2022 American Chemical Society.
6th Design and Engineering of Neutron Instruments Meeting Organized by ANSTO in Sydney (Australia) 28 November – 1 December 2017
(SAGE Publications, 2018-10) Anderson, DC; Désert, S; Hadad, N; Sutton, I; Olsen, SR; Eltobaji, A; Darmann, FA; Pullen, SA; Rule, KC
The Design and Engineering of Neutron Instruments Meeting series began at the Rutherford Appleton Labs, Oxford (UK) in 2012. This annual series brings together a wide range of technical staff, principally engineers, responsible for designing and operating neutron scattering facilities. Since then, this yearly event has been held in ORNL (Oak-Ridge TN, USA) in 2013, FRM II (Munich, Germany) in 2014, BNC (Budapest, Hungary) in 2015, ESS (Lund, Sweden) in 2016 and recently was held at ANSTO, Sydney (Australia).
Ecological engineering of iron ore tailings into useable soils for sustainable rehabilitation
(Elsevier, 2023-07-21) Wu, SL; Liu, YJ; Southam, G; Nguyen, TAH; Konhauser, KO; You, F; Bougoure, JJ; Paterson, DJ; Chan, TS; Lu, YR; Haw, SC; Yi, Q; Li, Z; Robertson, LM; Hall, M; Saha, N; Ok, YS; Huang, LB
Ecological engineering of soil formation in tailings is an emerging technology toward sustainable rehabilitation of iron (Fe) ore tailings landscapes worldwide, which requires the formation of well-organized and stable soil aggregates in finely textured tailings. Here, we demonstrate an approach using microbial and rhizosphere processes to progressively drive aggregate formation and development in Fe ore tailings. The aggregates were initially formed through the agglomeration of mineral particles by organic cements derived from microbial decomposition of exogenous organic matter. The aggregate stability was consolidated by colloidal nanosized Fe(III)-Si minerals formed during Fe-bearing primary mineral weathering driven by rhizosphere biogeochemical processes of pioneer plants. From these findings, we proposed a conceptual model for progressive aggregate structure development in the tailings with Fe(III)-Si rich cements as core nuclei. This renewable resource dependent eco-engineering approach opens a sustainable pathway to achieve resilient tailings rehabilitation without resorting to excavating natural soil resources. © 2024 The Authors - open access article under the CC BY-NC-ND license.
Pentavalent manganese luminescence: designing narrow-band near-infrared light-emitting diodes as next-generation compact light sources
(American Chemical Society, 2023-11-30) Rajendran, V; Chen, KC; Huang, WT; Majewska, N; Leśniewski, T; Grzegorczyk, M; Mahlik, S; Leniec, G; Kaczmarek, SM; Pang, WK; Peterson, VK; Lu, KM; Chang, H; Liu, RS
Manganese in the pentavalent state (Mn5+) is both rare and central in materials exhibiting narrow-band near-infrared (NIR) emission and is highly sought after for phosphor-converted light-emitting diodes as promising candidates for future miniature solid-state NIR light source. We develop the Ca14Zn6Ga10-xMnxO35 (x = 0.3, 0.5, 1.0, 1.25, 1.5, and 3.0) series that exhibit simultaneous Mn4+ (650-750 nm) and Mn5+ (1100-1250 nm) luminescence. We reveal a preferential occupancy of Mn in regular octahedral and tetrahedral environments, with the short bond length between these responsible for luminescence. We present a theoretical spin-orbital interaction model in which breaking the spin selection rule permits the luminescence of Mn4+ and Mn5+. A total photon flux of 87.5 mW under a 7 mA driving current demonstrates its potential for real-time application. This work pushes our understanding of achieving Mn5+ luminescence and opens the way for the design of Mn5+-based narrow-band NIR phosphors. © 2022 American Chemical Society.
Underscreening in concentrated electrolytes: re-entrant swelling in polyelectrolyte brushes
(Royal Society of Chemistry, 2023-09-30) Robertson, H; Elliott, GR; Nelson, ARJ; Le Brun, AP; Webber, GB; Prescott, SW; Craig, VSJ; Wanless, EJ; Willott, JD
Hypersaline environments are ubiquitous in nature and are found in myriad technological processes. Recent empirical studies have revealed a significant discrepancy between predicted and observed screening lengths at high salt concentrations, a phenomenon referred to as underscreening. Herein we investigate underscreening using a cationic polyelectrolyte brush as an exemplar. Poly(2-(methacryloyloxy)ethyl)trimethylammonium (PMETAC) brushes were synthesised and their internal structural changes and swelling response was monitored with neutron reflectometry and spectroscopic ellipsometry. Both techniques revealed a monotonic brush collapse as the concentration of symmetric monovalent electrolyte increased. However, a non-monotonic change in brush thickness was observed in all multivalent electrolytes at higher concentrations, known as re-entrant swelling; indicative of underscreening. For all electrolytes, numerical self-consistent field theory predictions align with experimental studies in the low-to-moderate salt concentration regions. Analysis suggests that the classical theory of electrolytes is insufficient to describe the screening lengths observed at high salt concentrations and that the re-entrant polyelectrolyte brush swelling seen herein is consistent with the so-called regular underscreening phenomenon. © the Owner Societies 2023 This article is Open Access - CC-BY-NC

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