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The oxygen evolution reaction (OER) is critical to solar production of fuels, but the reaction mechanism underlying the performance for a best OER catalyst, Fe-doped NiOOH [(Ni,Fe)OOH], remains highly controversial. We used grand canonical quantum mechanics to predict the OER mechanisms including kinetics and thus overpotentials as a function of Fe content in (Ni,Fe)OOH catalysts. We find that density functional theory (DFT) without exact exchange predicts that addition of Fe does not reduce the overpotential much. However, DFT with exact exchange predicts dramatic improvement in performance for (Ni,Fe)OOH, leading to an overpotential of 0.42 V and a Tafel slope of 23 mV/decade (dec), in good agreement with experiments, 0.3–0.4 V and 30 mV/dec. We reveal that the high spin d⁴ Fe(IV) leads to efficient formation of an active O radical intermediate, while the closed shell d⁶ Ni(IV) catalyzes the subsequent O–O coupling, and thus it is the synergy between Fe and Ni that delivers the optimal performance for OER.

Beta oscillations (15-29Hz) are among the most prominent signatures of brain activity. Beta power is predictive of healthy and abnormal behaviors, including perception, attention and motor action. In non-averaged signals, beta can emerge as transient high-power 'events'. As such, functionally relevant differences in averaged power across time and trials can reflect changes in event number, power, duration, and/or frequency span. We show that functionally relevant differences in averaged beta power in primary somatosensory neocortex reflect a difference in the number of high-power beta events per trial, i.e. event rate. Further, beta events occurring close to the stimulus were more likely to impair perception. These results are consistent across detection and attention tasks in human magnetoencephalography, and in local field potentials from mice performing a detection task. These results imply that an increased propensity of beta events predicts the failure to effectively transmit information through specific neocortical representations.

Rationally manipulating the in situ formed catalytically active surface of catalysts remains a tremendous challenge for a highly efficient water electrolysis. Here we present a cationic redox-tuning method to modulate in situ catalyst leaching and to redirect the dynamic surface restructuring of layered LiCoO 2– x Cl x ( x  = 0, 0.1 or 0.2), for the electrochemical oxygen evolution reaction (OER). Chlorine doping lowered the potential to trigger in situ cobalt oxidation and lithium leaching, which induced the surface of LiCoO 1.8 Cl 0.2 to transform into a self-terminated amorphous (oxy)hydroxide phase during the OER. In contrast, Cl-free LiCoO 2 required higher electrochemical potentials to initiate the in situ surface reconstruction to spinel-type Li 1± x Co 2 O 4 and longer cycles to stabilize it. Surface-restructured LiCoO 1.8 Cl 0.2 outperformed many state-of-the-art OER catalysts and demonstrated remarkable stability. This work makes a stride in modulating surface restructuring and in designing superior OER electrocatalysts via manipulating the in situ catalyst leaching. Rationally manipulating the in-situ-formed catalytically active surface of catalysts is a challenging but promising endeavour. Now, the surface of LiCoO 2 during water oxidation is engineered by Cl doping via a cationic redox-tuning method that modulates in situ leaching and redirects the dynamic surface restructuring.

Efficient electrocatalysts for the oxygen evolution reaction (OER) are paramount to the development of electrochemical devices for clean energy and fuel conversion. However, the structural complexity of heterogeneous electrocatalysts makes it a great challenge to elucidate the surface catalytic sites and OER mechanisms. Here, we report that catalytic single-site Co in a well-defined brookite TiO 2 nanorod (210) surface (Co-TiO 2 ) presents turnover frequencies that are among the highest for Co-based heterogeneous catalysts reported to date, reaching 6.6 ± 1.2 and 181.4 ± 28 s −1 at 300 and 400 mV overpotentials, respectively. Based on grand canonical quantum mechanics calculations and the single-site Co atomic structure validated by in situ and ex situ spectroscopic probes, we have established a full description of the catalytic reaction kinetics for Co-TiO 2 as a function of applied potential, revealing an adsorbate evolution mechanism for the OER. The computationally predicted Tafel slope and turnover frequencies exhibit exceedingly good agreement with experiment. The rational design of efficient water oxidation electrocatalysts is paramount to the development of electrochemical devices. Now, a Co-TiO 2 single-site catalyst is presented for alkaline water oxidation with high intrinsic activity, and its mechanism has been studied by grand canonical quantum mechanics calculations and in situ techniques.

Understanding the phase separation mechanism of solid-state binary compounds induced by laser–material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (∼2.5 nm) and polycrystalline silicon (∼5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system. Laser beam-induced processing is industrially relevant but often challenging to study in terms of underlying phase transformations. Here authors characterize formation of thin, phase-separated carbon and silicon layers on a silicon carbide substrate by laser-induced melting and solidification.

Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO2 reduction reaction (CO2RR). However, an efficient CO2RR electrocatalyst doesn't ensure an effective co‐catalyst on the semiconductor surface for photoelectrochemical CO2RR. Herein, Bi2S3 nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CO2RR. Compared with commercial‐Bi, the Bi2S3‐derived Bi (S‐Bi) nanoplates on carbon paper exhibit superior electrocatalytic activity and selectivity for formate (HCOO−) in the electrochemical CO2RR, achieving a Faradaic efficiency exceeding 93%, with minimal H2 production over a wide potential range. This highly selective S‐Bi catalyst is being employed on the Si photocathode to investigate the behavior of electrocatalysts during photoelectrochemical CO2RR. The strong adhesion of the S‐Bi nanoplates to the Si nanowire substrate and their unique catalytic properties afford exceptional activity and selectivity for HCOO− under simulated solar irradiation. The selectivity observed in electrochemical CO2RR using the S‐Bi catalyst correlates with that seen in the photoelectrochemical CO2RR system. Combined pulsed potential methods and theoretical analyses reveal stabilization of the OCHO* intermediate on the S‐Bi catalyst under specific conditions, which is critical for developing efficient catalysts for CO2‐to‐HCOO− conversion. The study demonstrates the transformation of Bi2S3 nanorods into Bi nanoplates (S‐Bi), yielding catalysts highly effective in CO2‐to‐HCOO− conversion in electrochemical and photoelectrochemical systems. Defect states in the catalysts significantly aid HCOO− production. S‐Bi/SiNWs photocathodes show remarkable activity and selectivity, suppressing H2 generation via pulsed electrolysis. These findings highlight the effectiveness of S‐Bi as a catalyst for CO2 reduction reactions.

Despite numerous reports on the beneficial effects of catechin or epicatechin contained in tea and cacao extract on human health, a conclusive and precise molecular mechanism has not been elucidated. Metabolism of chemical compounds in gut microbiota recently gained significant attention, and extensive studies have been devoted in this field. In conjunction with these results, our group focused on the anti-inflammatory effects of both enantiomers of DHPV (5-(3′,4′-dihydroxyphenyl)-γ-valerolactone), produced in the intestine by microbiota metabolism, on IEC-6 cells. Divergent and efficient enantioselective synthesis of (S)- and (R)-DHPV was efficiently achieved by cross-metathesis and Sharpless asymmetric dihydroxylation as a key reaction for four steps in 16% and 14% overall yields, respectively. The anti-inflammatory effects of two enantiomers were tested on IEC-6 cells, and we found that (S)-DHPV was more active than (R)-DHPV. This result implicates that the metabolite produced in the gut has beneficial effects on IEC-6 cells of rat intestines, and the chirality of the metabolite is important for its anti-inflammatory activity. This also provided information for the future discovery of novel small molecular therapeutics for the treatment of inflammatory bowel disease.

Hydrogen spillover has been studied for several decades, but its nature, catalytic functions and even its existence remain topics of vigorous debate. This is a consequence of the lack of model catalysts that can provide direct evidences of the existence of hydrogen spillover and simplify the catalytic interpretation. Here we use platinum encapsulated in a dense aluminosilicate matrix with controlled diffusional properties and surface hydroxyl concentrations to elucidate the catalytic functions of hydrogen spillover. The catalytic investigation and theoretical modelling show that surface hydroxyls, presumably Brønsted acids, are crucial for utilizing the catalytic functions of hydrogen spillover on the aluminosilicate surface. The catalysts with optimized nanostructure show remarkable activities in hydro-/dehydrogenation, but virtually no activity for hydrogenolysis. This distinct chemoselectivity may be beneficial in industrially important hydroconversions such as propane dehydrogenation to propylene because the undesired hydrogenolysis pathway producing light hydrocarbons of low value (methane and ethane) is greatly suppressed. The hydrogen spillover mechanism has been studied for several decades, although its exact elucidation has been hampered by the lack of suitable model catalyst systems. Here, the authors combine experimental and computational techniques to probe the role of surface hydroxyls in the mechanism.

The oxygen evolution reaction (OER) is critical to solar production of fuels, but the reaction mechanism underlying the performance for a best OER catalyst, Fe-doped NiOOH [(Ni,Fe)OOH], remains highly controversial. We used grand canonical quantum mechanics to predict the OER mechanisms including kinetics and thus overpotentials as a function of Fe content in (Ni,Fe)OOH catalysts. We find that density functional theory (DFT) without exact exchange predicts that addition of Fe does not reduce the overpotential much. However, DFT with exact exchange predicts dramatic improvement in performance for (Ni,Fe)OOH, leading to an overpotential of 0.42 V and a Tafel slope of 23 mV/decade (dec), in good agreement with experiments, 0.3–0.4 V and 30 mV/dec. We reveal that the high spin d4 Fe(IV) leads to efficient formation of an active O radical intermediate, while the closed shell d6 Ni(IV) catalyzes the subsequent O–O coupling, and thus it is the synergy between Fe and Ni that delivers the optimal performance for OER.

Plastics are a serious cause of environmental pollution, and microplastics pose a threat to human health. To solve this problem, the plastic-degrading mechanism of insect larvae is being investigated. The aim of this study was to examine the metabolic pathways involved in polyethylene metabolism, the interaction between the host and microorganisms, and the role of superworms in promoting plastic degradation in polyethylene-fed superworms. Through host transcriptomic analysis, we identified 429 up-regulated and 777 down-regulated genes and analyzed their functions using the Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases. We found that insects promote the degradation of polyethylene through two main mechanisms. First, polyethylene metabolites activate the lipid metabolism pathway in insects, promoting the synthesis of carboxylic ester hydrolases and accelerating polyethylene degradation. Second, insect larvae generate reactive oxygen species (ROS) which are critical for insect immune responses and for the initial oxidation of polyethylene. In metagenomic analysis, bacterial species, such as Citrobacter sp. and Raoultella sp., which are known to be involved in the degradation of polyethylene and its metabolites, were more abundant in the guts of insects that consumed polyethylene. In addition, increases in the concentration of peroxide in the gut and the activity of esterase (lipase) acting on lipophilic substrates were observed. Furthermore, we suggest that xenobiotic metabolism is critical for polyethylene metabolism in superworm guts. In particular, enzymes involved in xenobiotic metabolism phase 2, such as glutathione S-transferase and uridine diphosphate glycosyltransferase, convert lipophilic plastic degradation intermediates into water-soluble forms and promote polyethylene degradation.