Reinvestigation of Water Oxidation Catalyzed by a Dinuclear Cobalt Polypyridine Complex: Identification of CoO_<i>x</i> as a Real Heterogeneous Catalyst

Recently, a dinuclear cobalt complex, [(TPA)­Co^III(μ-OH)­(μ-O₂)­Co^III(TPA)]­(ClO₄)₃ (<b>1</b>; TPA = tris­(2-pyridylmethyl)­amine), has been reported as a homogeneous catalyst for electrochemical and photochemical water oxidation (Angew. Chem. Int. Ed. 2014, 53, 14499). During the reinvestigation of the reported water oxidation catalyst (WOC) of <b>1</b>, several characterizations such as EDTA and bipyridine titrations, electrochemistry, SEM, EDX, ICP-AES, TEM, XPS, and UV–vis spectroscopy have revealed that the water oxidation may happen due to the formation of CoO_<i>x</i> as a real heterogeneous WOC, and <b>1</b> itself lacks the ability to catalyze water oxidation. This paper presents a practical and simple procedure to clarify whether the water oxidation is truly catalyzed by a molecular catalyst or not

Syngas Production with a Highly-Robust Nickel(II) Homogeneous Electrocatalyst in a Water-Containing System

Syngas (CO and H₂) is an essential raw material for producing various chemicals in industry. The reduction of CO₂ in a water-containing system can serve as a more sustainable pathway to obtain syngas than the transformation of fossil fuels, while the modulation of the H₂/CO ratios is a challenge. Herein a nickel­(II) tripodal complex is employed as a homogeneous electrocatalyst for CO₂ and H₂O reduction. With this catalyst, selective CO formation with negligible H₂ evolution can be accomplished in the presence of 5.0 M H₂O in <i>N,N′</i>-dimethylformamide (DMF). By further varying the applied potentials, the H₂/CO ratio can be delicately tuned. The catalyst is appreciably robust with a high turnover number of 1.9 × 10⁶ in 1 day operation with negligible deactivation, which can be attributed to the redox innocence of the used ligand. Based on the results of electrochemistry and DFT calculation, the catalytic mechanism is proposed

Cognitive and Psychiatric Effects of STN versus GPi Deep Brain Stimulation in Parkinson's Disease: A Meta-Analysis of Randomized Controlled Trials

<div><p>Background</p><p>Deep brain stimulation (DBS) of either the subthalamic nucleus (STN) or the globus pallidus interna (GPi) can reduce motor symptoms in patients with Parkinson’s disease (PD) and improve their quality of life. However, the effects of STN DBS and GPi DBS on cognitive functions and their psychiatric effects remain controversial. The present meta-analysis was therefore performed to clarify these issues.</p><p>Methods</p><p>We searched the PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials databases. Other sources, including internet-based clinical trial registries and grey literature sources, were also searched. After searching the literature, two investigators independently performed literature screens to assess the quality of the included trials and to extract the data. The outcomes included the effects of STN DBS and GPi DBS on multiple cognitive domains, depression, anxiety, and quality of life.</p><p>Results</p><p>Seven articles related to four randomized controlled trials that included 521 participants were incorporated into the present meta-analysis. Compared with GPi DBS, STN DBS was associated with declines in selected cognitive domains after surgery, including attention, working memory and processing speed, phonemic fluency, learning and memory, and global cognition. However, there were no significant differences in terms of quality of life or psychiatric effects, such as depression and anxiety, between the two groups.</p><p>Conclusions</p><p>A selective decline in frontal-subcortical cognitive functions is observed after STN DBS in comparison with GPi DBS, which should not be ignored in the target selection for DBS treatment in PD patients. In addition, compared to GPi DBS, STN DBS does not affect depression, anxiety, and quality of life.</p></div

Self-Template Synthesis of Co–Se–S–O Hierarchical Nanotubes as Efficient Electrocatalysts for Oxygen Evolution under Alkaline and Neutral Conditions

We develop a facile self-template synthetic method to construct hierarchical Co–Se–S–O (CoSe_<i>x</i>S_2–<i>x</i>@Co­(OH)₂) nanotubes on a carbon cloth as a self-standing electrode for electrocatalytic oxygen evolution reaction (OER). In the synthetic process, separate selenization and sulfurization on the Co­(OH)F precursor in different solvents have played an important role in constructing CoSe_<i>x</i>S_2–<i>x</i> (Co–Se–S) hierarchical nanotubes, which was further transformed into the nanotube-like Co–Se–S–O via an in situ electrochemical oxidation process. The Co–Se–S–O obtained by the Kirkendall effect through two stepwise anion-exchange reactions represents the first quaternary Co–Se–S–O nanotube array, which dramatically enhances its surface area and conductivity. Further, it only requires low overpotentials of 230 and 480 mV to achieve a 10 mA cm^–2 current density. The OER performance of Co–Se–S–O is much more efficient than that of its monochalcogenide counterparts, as well as the commercial benchmark catalyst IrO₂

Flow chart used to include studies in the present meta-analysis.

<p>Flow chart used to include studies in the present meta-analysis.</p

Risk-of-bias assessment of the included trials.

<p>Risk-of-bias assessment of the included trials.</p

Results for the neuropsychological domains.

<p>Results for the neuropsychological domains.</p

Baseline characteristics of the included trials.

<p>Baseline characteristics of the included trials.</p

Tests included in each neuropsychological domain.

<p>Tests included in each neuropsychological domain.</p

Conjugation Effect Contributes to the CO₂‑to-CO Conversion Driven by Visible-Light

Structural modification of a ligand is an effective way to improve the catalytic activity of molecular catalysts for photocatalytic CO₂ reduction. In this study, we designed and synthesized three tripodal ligands with different conjugate groups (L¹ = tris­{2-[(9′ - anthrylmethyl)­amino)­ethyl}­amine, L² = tris­{2-[(1′-naphthylmethyl)­amino]­ethyl}­amine, L³ = tris­[2-(benzylamino)­ethyl]­amine), and their corresponding mononuclear cobalt complexes, [CoL¹(OH)]­ClO₄ (<b>1</b>), [CoL²­(OH)]­ClO₄ (<b>2</b>), and [CoL³­(OH)]­ClO₄ (<b>3</b>). Control experiments showed that <b>1</b> and <b>2</b> possess higher efficiency than <b>3</b> for the photocatalytic CO₂-to-CO conversion, with TON and TOF for CO of 58 000 and 1.61 s^–1 for <b>1</b>, and 49 200 and 1.37 s^–1 for <b>2</b>, respectively, greatly higher than those of <b>3</b>. Compounds <b>1</b> and <b>2</b> also display higher CO selectivity (≥97%) than <b>3</b>. Control experiments and DFT calculations revealed that the excellent catalytic performances of <b>1</b> and <b>2</b> can be ascribed to the extended conjugation substituent in L¹ and L², which endows the Co^II catalytic center with low reduction potential, accelerates the intermolecular electron transfer, and thus dramatically boosts the CO₂-to-CO conversion. This study demonstrates that the improvement of the electron transfer between photosensitizer and catalysts is the key for enhancing the activity of catalyst for CO₂-to-CO conversion