Rational Design of Polymers for Selective CO2 Reduction Catalysis.

A series of copolymers comprising a terpyridine ligand and various functional groups were synthesized toward integrating a Co-based molecular CO2 reduction catalyst. Using porous metal oxide electrodes designed to host macromolecules, the Co-coordinated polymers were readily immobilized via phosphonate anchoring groups. Within the polymeric matrix, the outer coordination sphere of the Co terpyridine catalyst was engineered using hydrophobic functional moieties to improve CO2 reduction selectivity in the presence of water. Electrochemical and photoelectrochemical CO2 reduction were demonstrated with the polymer-immobilized hybrid cathodes, with a CO:H2 product ratio of up to 6:1 compared to 2:1 for a corresponding "monomeric" Co terpyridine catalyst. This versatile platform of polymer design demonstrates promise in controlling the outer-sphere environment of synthetic molecular catalysts, analogous to CO2 reductases.the Woolf Fisher Trust in New Zealand, the Winston Churchill Foundation of the United States, the Christian Doppler Research Association (Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development), the OMV Grou

Cucurbit[8]uril-derived graphene hydrogels

The scalable production of uniformly distributed graphene (GR)-based composite materials remains a sizable challenge. While GR-polymer nanocomposites can be manufactured at large scale, processing limitations result in poor control over the homogeneity of hydrophobic GR sheets in the matrices. Such processes often result in difficulties controlling stability and avoiding aggregation, therefore eliminating benefits that might have otherwise arisen from the nanoscopic dimensions of GR. Here, we report an exfoliated and stabilized GR dispersion in water. Cucurbit[8]uril (CB[8])-mediated host guest chemistry was used to obtain supramolecular hydrogels consisting of uniformly distributed GR and guest-functionalized macromolecules. The obtained GR-hydrogels show superior bioelectrical properties over identical systems produced without CB[8]. Utilizing such supramolecular interactions with biologically-derived macromolecules is a promising approach to stabilize graphene in water and avoid oxidative chemistry.Marie Sklodowska-Curie individual research grant (H2020-MSCAIF- 2017, P.ID: 797106) The Winston Churchill Foundation of the United States EPSRC Doctoral Training Grant EP/N509620/1 EPSRC Programme Grant NOtCH (EP/L027151/1

Electrodeposited MnO_<i>x</i>/PEDOT Composite Thin Films for the Oxygen Reduction Reaction

Manganese oxide (MnO_<i>x</i>) was anodically coelectrodeposited with poly­(3,4-ethylenedioxythiophene) (PEDOT) from an aqueous solution of Mn­(OAc)₂, 3,4-ethylenedioxythiophene, LiClO₄ and sodium dodecyl sulfate to yield a MnO_<i>x</i>/PEDOT composite thin film. The MnO_<i>x</i>/PEDOT film showed significant improvement over the MnO_<i>x</i> only and PEDOT only films for the oxygen reduction reaction, with a >0.2 V decrease in onset and half-wave overpotential and >1.5 times increase in current density. Furthermore, the MnO_<i>x</i>/PEDOT films were competitive with commercial benchmark 20% Pt/C, outperforming it in the half-wave ORR region and exhibiting better electrocatalytic selectivity for the oxygen reduction reaction upon methanol exposure. The high activity of the MnO_<i>x</i>/PEDOT composite is attributed to synergistic charge transfer capabilities, attained by coelectrodepositing MnO_<i>x</i> with a conductive polymer while simultaneously achieving intimate substrate contact

Cucurbit[8]uril-Derived Graphene Hydrogels

The scalable production of uniformly distributed graphene (GR)-based composite materials remains a sizable challenge. While GR-polymer nanocomposites can be manufactured at large scale, processing limitations result in poor control over the homogeneity of hydrophobic GR sheets in the matrices. Such processes often result in difficulties controlling stability and avoiding aggregation, therefore eliminating benefits that might have otherwise arisen from the nanoscopic dimensions of GR. Here, we report an exfoliated and stabilized GR dispersion in water. Cucurbit[8]uril (CB[8])-mediated hostguest chemistry was used to obtain supramolecular hydrogels consisting of uniformly distributed GR and guest-functionalized macromolecules. The obtained GR-hydrogels show superior bioelectrical properties over identical systems produced without CB[8]. Utilizing such supramolecular interactions with biologically-derived macromolecules is a promising approach to stabilize graphene in water and avoid oxidative chemistry.</div

Nanoscale Carbon Modified α‑MnO₂ Nanowires: Highly Active and Stable Oxygen Reduction Electrocatalysts with Low Carbon Content

Carbon-coated α-MnO₂ nanowires (C-MnO₂ NWs) were prepared from α-MnO₂ NWs by a two-step sucrose coating and pyrolysis method. This method resulted in the formation of a thin, porous, low mass-percentage amorphous carbon coating (<5 nm, ≤1.2 wt % C) on the nanowire with an increase in single-nanowire electronic conductivity of roughly 5 orders of magnitude (α-MnO₂, 3.2 × 10^–6 S cm^–1; C-MnO₂, 0.52 S cm^–1) and an increase in surface Mn³⁺ (average oxidation state: α-MnO₂, 3.88; C-MnO₂, 3.66) while suppressing a phase change to Mn₃O₄ at high temperature. The enhanced physical and electronic properties of the C-MnO₂ NWsenriched surface Mn³⁺ and high conductivityare manifested in the electrocatalytic activity toward the oxygen reduction reaction (ORR), where a 13-fold increase in specific activity (α-MnO₂, 0.13 A m^–2; C-MnO₂, 1.70 A m^–2) and 6-fold decrease in charge transfer resistance (α-MnO₂, 6.2 kΩ; C-MnO₂, 0.9 kΩ) were observed relative to the precursor α-MnO₂ NWs. The C-MnO₂ NWs, composed of ∼99 wt % MnO₂ and ∼1 wt % carbon coating, also demonstrated an ORR onset potential within 20 mV of commercial 20% Pt/C and a chronoamperometric current/stability equal to or greater than 20% Pt/C at high overpotential (0.4 V vs RHE) and high temperature (60 °C) with no additional conductive carbon

Treating Hoarding Disorder in a real-world setting: Results from the Mental Health Association of San Francisco.

Hoarding Disorder (HD) is associated with substantial distress, impairment, and individual and societal costs. Cognitive-behavioral therapy (CBT) tailored to HD is the best-studied form of treatment and can be led by mental health professionals or by non-professionals (peers) with specific training. No previous study has directly compared outcomes for therapist-led and peer-led groups, and none have examined the effectiveness of these groups in a real-world setting. We used retrospective data to compare psychologist-led CBT groups (G-CBT) to groups led by peer facilitators using the Buried in Treasures workbooks (G-BiT) in individuals who sought treatment for HD from the Mental Health Association of San Francisco. The primary outcome was change in Hoarding Severity Scale scores. Approximate costs per participant were also examined. Both G-CBT and G-BiT showed improvement consistent with previous reports (22% improvement overall). After controlling for baseline group characteristics, there were no significant differences in outcomes between G-CBT and G-BiT. For G-CBT, where additional outcome data were available, functional impairment and severity of hoarding symptoms improved to a similar degree as compared to previous G-CBT studies, while hoarding-related cognition improved to a lesser degree (also consistent with previous studies). G-BiT cost approximately $100 less per participant than did G-CBT

Role of Cu-Ion Doping in Cu-α-MnO₂ Nanowire Electrocatalysts for the Oxygen Reduction Reaction

The role of Cu-ion doping in α-MnO₂ electrocatalysts for the oxygen reduction reaction in alkaline electrolyte was investigated. Cu-doped α-MnO₂ nanowires (Cu-α-MnO₂) were prepared with varying amounts (up to ∼3%) of Cu²⁺ using a hydrothermal method. The electrocatalytic data indicate that Cu-α-MnO₂ nanowires have up to 74% higher terminal current densities, 2.5 times enhanced kinetic rate constants, and 66% lower charge transfer resistances that trend with Cu content, exceeding values attained by α-MnO₂ alone. The observed improvement in catalytic behavior correlates with an increase in Mn³⁺ content at the surface of the Cu-α-MnO₂ nanowires. The Mn³⁺/Mn⁴⁺ couple is the mediator for the rate-limiting redox-driven O₂/OH^– exchange. O₂ adsorbs via an axial site (the e_g orbital on the Mn³⁺ d⁴ ion) at the surface or at edge defects of the nanowire, and the increase in covalent nature of the nanowire with Cu-ion doping leads to stabilization of O₂ adsorbates and faster rates of reduction. A smaller crystallite size (roughly half) for Cu-α-MnO₂ leading to a higher density of (catalytic) edge defect sites was also observed. This work is applicable to other manganese oxide electrocatalysts and shows for the first time there is a correlation for manganese oxides between electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline electrolyte and an increase in Mn³⁺ character at the surface of the oxide

Halide Perovskites Breathe Too: The Iodide–Iodine Equilibrium and Self-Doping in Cs₂SnI₆

The response of an oxide crystal to the atmosphere can be personified as breathinga dynamic equilibrium between O2 gas and O2– anions in the solid. We characterize the analogous defect reaction in an iodide double-perovskite semiconductor, Cs2SnI6. Here, I2 gas is released from the crystal at room temperature, forming iodine vacancies. The iodine vacancy defect is a shallow electron donor and is therefore ionized at room temperature; thus, the loss of I2 is accompanied by spontaneous n-type self-doping. Conversely, at high I2 pressures, I2 gas is resorbed by the perovskite, consuming excess electrons as I2 is converted to 2I–. Halide mobility and irreversible halide loss or exchange reactions have been studied extensively in halide perovskites. However, the reversible exchange equilibrium between iodide and iodine [2I–(s) ↔ I2(g) + 2e–] described here has often been overlooked in prior studies, though it is likely general to halide perovskites and operative near room temperature, even in the dark. An analysis of the 2I–(s)/I2(g) equilibrium thermodynamics and related transport kinetics in single crystals of Cs2SnI6 therefore provides insight toward achieving stable composition and electronic properties in the large family of iodide perovskite semiconductors