Active sites engineering leads to exceptional ORR and OER bifunctionality in P,N Co-doped graphene frameworks

Bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly desirable for rechargeable metal-air batteries and regenerative fuel cells. However, the commercial oxygen electrocatalysts (mainly noble metal based) can only exhibit either ORR or OER activity, and also suffer from inherent cost and stability issues. It remains challenging to achieve efficient ORR and OER bifunctionality on a single catalyst. Metal-free structures offer relatively large scope for such bifunctionality to be enginnered within one catalyst, together with improved cost-effectiveness and durablility. Herein, by closely coupled computational design and experimental development, highly effective bifunctionality is achieved in a phosphorus and nitrogen co-doped graphene framework (PNGF) - with both ORR and OER activities reaching the theoretical limits of metal-free catalysts, superior to the noble metal counterparts in both (bi)functionality and durability. In particular, with the identification of active P-N sites for OER and N-doped sites for ORR , we successfully intensified such sites by one-pot synthesis to tailor the PNGF. The resulting catalyst reaches an ORR potential of 0.845 V vs. RHE at 3 mA cm-2 and an OER potential of 1.55 V vs. RHE at 10 mA cm-2, respectively. Its combined ORR and OER overpotential of 705 mV is significantly lower than those reported previously for metal-free bifunctional catalysts

Cost-Effective In-Context Learning for Entity Resolution: A Design Space Exploration

Entity resolution (ER) is an important data integration task with a wide spectrum of applications. The state-of-the-art solutions on ER rely on pre-trained language models (PLMs), which require fine-tuning on a lot of labeled matching/non-matching entity pairs. Recently, large languages models (LLMs), such as GPT-4, have shown the ability to perform many tasks without tuning model parameters, which is known as in-context learning (ICL) that facilitates effective learning from a few labeled input context demonstrations. However, existing ICL approaches to ER typically necessitate providing a task description and a set of demonstrations for each entity pair and thus have limitations on the monetary cost of interfacing LLMs. To address the problem, in this paper, we provide a comprehensive study to investigate how to develop a cost-effective batch prompting approach to ER. We introduce a framework BATCHER consisting of demonstration selection and question batching and explore different design choices that support batch prompting for ER. We also devise a covering-based demonstration selection strategy that achieves an effective balance between matching accuracy and monetary cost. We conduct a thorough evaluation to explore the design space and evaluate our proposed strategies. Through extensive experiments, we find that batch prompting is very cost-effective for ER, compared with not only PLM-based methods fine-tuned with extensive labeled data but also LLM-based methods with manually designed prompting. We also provide guidance for selecting appropriate design choices for batch prompting.Comment: 14 pages, 7 figure

Preparation of Antibacterial Color-Coated Steel Sheets

A simple method to fabricate antibacterial color-coated steel sheet was presented. The Ag-loaded TiO2 was well dispersed in steel coil coating coupled with some special additives, such as plasticizer, wetting dispersant, and flow agent, and finally became the part of coil coating without any negative influence on the properties of final products. The best process parameters were obtained by substantive trial experiments. Ag-loaded TiO2 with the addition of 2% (w/w) in steel coil coating not only improved antibacterial efficiency of the antibacterial color-coated sheet by reaching 99.99%, but also greatly increased the degradation percentage of methyl orange to 88% without decreasing physical properties. The antibacterial color-coated sheets are expected to be used as antimicrobial products in the construction industry considering its low cost and high effectiveness in inhibiting the growth of bacteria

Psychological support for public-funded normal students engaged in teaching profession

Among primary and secondary school teachers in China, 70% of teachers believe that they are facing greater occupational pressure. 63.8% of teachers clearly stated that occupational pressure has caused a great or great impact on themselves. And this has had negative effects on them such as mental, physical and personal development. This article studies the group of public-funded normal students from the perspective of psychological support. This article uses the SCL-90 form to investigate the professional psychology of teachers for the psychological support of public-funded normal students engaged in the teaching profession. And it conducts a survey on the curriculum setting and satisfaction of the public-funded normal students during their study stage. The experimental results of this article show that only 11.9% of public-funded normal students are very willing to take root and serve township education. Moreover, the psychological pressure of teachers at different educational stages is quite different

Palladium alloys used as electrocatalysts for the oxygen reduction reaction

Palladium-based alloy materials as cathodes for the reduction of oxygen are regarded as potential substitutes for platinum-based catalysts in fuel cells. In this work, we present the scientometric analysis and critically review the use of Pd alloys for the oxygen reduction reaction (ORR). Through scientometric analysis, publication information, research fronts and hotspots are identified. For the critical review, reaction mechanisms in different media are discussed, with the aid of volcano plots to show the general principles for catalyst modifications to maximise the ORR. Influencing factors, including alloying, structure, strain and ligand, particle size, crystal facet and dealloying are considered with a view to informing the theoretical feasibility to enhance ORR activity. In addition, Pd-based alloys synthesized by different methods are presented and compared in terms of ORR activities. Future research directions are discussed and possible approaches to the mass production for industrialization are also proposed

Enhancing Hydrogen Evolution Electrocatalytic Performance in Neutral Media via Nitrogen and Iron Phosphide Interactions

It remains a challenge to develop efficient electrocatalysts in neutral media for hydrogen evolution reaction (HER) due to the sluggish kinetics and switch of the rate determining step. Although metal phosphides are widely used HER catalysts, their structural stability is an issue due to oxidization, and the HER performance in neutral media requires improvement. Herein, a new material, i.e., grapevine-shaped N-doped iron phosphide on carbon nanotubes, as an efficient HER catalyst in neutral media is developed. The optimized catalyst shows an overpotential of 256 mV at a large current density of 65 mA cm−2, which is even 10 mV lower than that of the commercial 20% Pt/C catalyst. The excellent performance of the catalyst is further studied by combined computational and experimental techniques, which proves that the interaction between nitrogen and iron phosphides can provide more efficient active structures and stabilize the metal phosphide electrocatalysts for HER

Copper-surface-mediated synthesis of acetylenic carbon-rich nanofibers for active metal-free photocathodes

The engineering of acetylenic carbon-rich nanostructures has great potential in many applications, such as nanoelectronics, chemical sensors, energy storage, and conversion, etc. Here we show the synthesis of acetylenic carbon-rich nanofibers via copper-surface- mediated Glaser polycondensation of 1,3,5-triethynylbenzene on a variety of conducting (e.g., copper, graphite, fluorine-doped tin oxide, and titanium) and non-conducting (e.g., Kapton, glass, and silicon dioxide) substrates. The obtained nanofibers (with optical bandgap of 2.51eV) exhibit photocatalytic activity in photoelectrochemical cells, yielding saturated cathodic photocurrent of ca. 10μAcm−2 (0.3–0V vs. reversible hydrogen electrode). By incorporating thieno[3,2-b]thiophene units into the nanofibers, a redshift (ca. 100 nm) of light absorption edge and twofold of the photocurrent are achieved, rivalling those of state-of- the-art metal-free photocathodes (e.g., graphitic carbon nitride of 0.1–1 μA cm−2). This work highlights the promise of utilizing acetylenic carbon-rich materials as efficient and sustainable photocathodes for water reductio

Planar cell polarity genes in motor axon guidance in the limb

The assembly of neuronal circuits depends on the correct wiring of axons and dendrites. Studies in our laboratory revealed a critical role of seven-pass atypical cadherin Celsr3, a member of planar cell polarity (PCP) proteins, in the development of axonal tracts in the central nervous system, such as the anterior commissure, internal capsule and corticospinal tract. Celsr3 deficiency does not alter axonal growth, but affects axon guidance in cell-autonomous or non-cell-autonomous manners, causing axon stalling at intermediate targets or rerouting. Notably, all axon guidance defects in Celsr3−/− were observed in mice bearing mutations in the PCP gene Fzd3, and some errors were reported in mice with mutations of Vangl2, another PCP gene. Despite their unequivocally role, underlying molecular mechanisms remain elusive. Furthermore, their functions in the peripheral nervous system are still largely unexplored. Here we show that Celsr3 cooperates with Fzd3 in spinal motor neurons to mediate pathfinding of motor axons innervating the dorsal limb. Celsr3 is expressed in postmitotic neurons in the developing spinal cord. Specific inactivation of Celsr3 in spinal motor neurons severely perturbs peroneal nerve development, leading to absent innervation of the tibialis anterior muscle and stiff hindlimb. Deletion of Celsr3 affects neither the specification of motor neurons nor neuronal survival or neurite outgrowth. Celsr3-deficient axons of the peroneal nerve segregate from those of the tibial nerve but fail to extend dorsally, and they stall just after the branch point of the sciatic nerve. Mutant axons respond to repulsive ephrinA-EphA forward signaling and attractive glial cell–derived neurotrophic factor (GDNF). However, they are insensitive to attractive EphA-ephrinA reverse signaling. In transfected cells, Celsr3 immunoprecipitates with ephrinA2, ephrinA5, Ret, GDNF family receptor a1 (GFRa1) and Fzd3. The function of Celsr3 in motor axons is Fzd3 dependent but Vangl2 independent. Our results thus revealed the crucial roles of Celsr3 and Fzd3 in motor axon guidance, and provide evidence for the first time that the Celsr3-Fzd3 pathway interacts with EphA-ephrinA reverse signaling to guide motor axons in the hindlimb, which may help us better understand their molecular mechanisms of action.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 201