The development of highly efficient and durable non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) is significant for clean and renewable energy research. This work reports the synthesis of N-doped graphene nanosheets supported N-doped carbon coated cobalt phosphide (CoP) nanoparticles via a pyrolysis and a subsequent phosphating process by using polyaniline. The obtained electrocatalyst exhibits excellent electrochemical activity for HER with a small overpotential of -135 mV at 10 mA cm and a low Tafel slope of 59.3 mV dec in 0.5 m H SO . Additionally, the encapsulation of N-doped carbon shell prevents CoP nanoparticles from corrosion, exhibiting good stability after 14 h operation. Moreover, the as-prepared electrocatalyst also shows outstanding activity and stability in basic and neutral electrolytes.
Waves that are perfectly confined in the continuous spectrum of radiating waves without interaction with them are known as bound states in the continuum (BICs). Despite recent discoveries of BICs in nanophotonics, full routing and control of BICs are yet to be explored. Here, we experimentally demonstrate BICs in a fundamentally new photonic architecture by patterning a low-refractive-index material on a high-refractive-index substrate, where dissipation to the substrate continuum is eliminated by engineering the geometric parameters. Pivotal BIC-based photonic components are demonstrated, including waveguides, microcavities, directional couplers, and modulators. Therefore, this work presents the critical step of photonic integrated circuits in the continuum, and enables the exploration of new single-crystal materials on an integrated photonic platform without the fabrication challenges of patterning the single-crystal materials. The demonstrated lithium niobate platform will facilitate development of functional photonic integrated circuits for optical communications, nonlinear optics at the single photon level as well as scalable photonic quantum information processors.
We report on the surface behavior of a hydrophobic, cationic peptide, [lysine-(leucine)4]4-lysine (KL4), spread at the air/water interface at 25 degrees C and pH 7.2, and its effect at very low molar ratios on the surface properties of the zwitterionic phospholipid 1,2-dipalmitoylphosphatidylcholine (DPPC), and the anionic forms of 1-palmitoyl-2-oleoylphosphatidylglycerol (POPG) and palmitic acid (PA), in various combinations. Surface properties were evaluated by measuring equilibrium spreading pressures (pi(e)) and surface pressure-area isotherms (pi-A) with the Wilhelmy plate technique. Surface phase separation was observed with fluorescence microscopy. KL4 itself forms a single-phase monolayer, stable up to a surface pressure pi of 30 mN/m, and forms an immiscible monolayer mixture with DPPC. No strong interaction was detected between POPG and KL4 in the low pi region, whereas a stable monolayer of the PA/KL4 binary mixture forms, which is attributed to ionic interactions between oppositely charged PA and KL4. KL4 has significant effects on the DPPC/POPG mixture, in that it promotes surface phase separation while also increasing pi(e) and pi(max), and these effects are greatly enhanced in the presence of PA. In the model we have proposed, KL4 facilitates the separation of DPPC-rich and POPG/PA-rich phases to achieve surface refinement. It is these two phases that can fulfill the important lung surfactant functions of high surface pressure stability and efficient spreading.
By grafting butyl or ethyl onto tetramethylethylenediamine, quaternary ammonium salts with two positive charge centers were formed at the first step. Metathesis with Ag(2)O followed. Through neutralization with glycine, l-alanine, or valine, a series of new ditetraalkylammonium amino acid ionic liquids (DILs) for CO(2) capture were generated. The structures of DILs, as shown in Figure 1, were verified by using (1)H NMR and EA. These DILs were found to be of quite high viscosity which militated against their industrial application in CO(2) removal. Drawing on the experience of mixed amines' aqueous solutions, these DILs were blended with water or N-methyldiethanolamine (MDEA) aqueous solutions to act as special absorbents of CO(2). Using a Double-Tank Absorption System, the absorption performance of these DIL solutions was investigated in detail. The experimental results indicated that among the three aqueous solutions of DILs (20%, 40%, and 80 wt %), the solution of 40% DIL had a higher absorption rate of CO(2) than the other two, demonstrating the different effects of concentration and viscosity on the absorption. The solution of 40% DIL or the 15% DIL + 15% MDEA had much higher capacity for CO(2) than the corresponding monocation tetraalkylammonium AAILs, due to the special structure of the dication which could influence the solubility of CO(2) in the aqueous solution.
Metal phosphides are promising efficient non-Pt electrocatalysts for hydrogen evolution reaction (HER). Herein, we report a simple strategy to controllably synthesize pure RuP and RuP 2 and evaluate their HER performances in all pH range. Different from other transition metal phosphides, the HER performance of the RuP x in all pH range obviously improves as the phosphorus content decreases. By systematic research, it has been found that the RuP-475 with more Ru had much better conductivity and more catalytically active sites than the P rich RuP 2 -550. In addition, the RuP-475 exhibits excellent HER performance with small overpotential at a current density of 10 mA cm −2 (46, 47, 22 mV in pH 0, 7, and 14, respectively).
Deep eutectic solvents (DESs) have been regarded as promising alternative absorbents for CO 2 capture recently. In this work, a series of novel superbase/acylamido-based DESs with low viscosity were synthesized and used for CO 2 capture. 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN)/2-imidazolidone (EU) (2:1) exhibited fairly high absorption capacity up to 23.02 wt % (1.75 mol CO 2 per mol DES) at 45 °C and 1 bar. Furthermore, the absorbent showed high desorption efficiency and excellent recycling performance during five absorption−desorption cycles. Fourier transform infrared, 1 H NMR, and 13 C NMR spectra analyses and quantum chemical calculations were used to investigate the interaction mechanism between the DES and CO 2 . The enhanced CO 2 absorption capacity can be ascribed to the strong multiple-site interaction between the N atom of EU and CO 2 . This work supplies a new strategy to design and optimize high-efficiency superbase/acylamido-based DESs for CO 2 capture.
Valley pseudospin, a new degree of freedom in photonic lattices, provides an intriguing way to manipulate photons and enhance the robustness of optical networks. Here, topological waveguiding, refracting, resonating, and routing of valley‐polarized photons in integrated circuits are experimentally demonstrated. Specifically, it is shown that at the domain wall between photonic crystals of different topological valley phases, there exists a topologically protected valley kink state that is backscattering‐free at sharp bends and terminals. These valley kink states are further harnessed for constructing high‐Q topological photonic crystal cavities with tortuously shaped cavity geometries. A novel optical routing scheme at an intersection of multiple valley kink states is also demonstrated, where light splits counterintuitively due to the valley pseudospin of photons. These results can not only lead to robust optical communication and signal processing, but also open the door for fundamental research of topological photonics in areas such as lasing, quantum photon‐pair generation, and optomechanics.
Herein, a series of imidazole derived task-specific deep eutectic solvents (DESs) based on a protic ionic liquid were synthesized and used for CO 2 capture. These DESs exhibited excellent CO 2 absorption capacity up to 1.00 mol CO 2 /mol DES, and the absorption process could be adjusted by the mole ratio of hydrogen-bond acceptor and hydrogen-bond donor. The effect of temperature on the absorption process was also investigated. To deeply investigate the absorption mechanism of these DESs, the corresponding protic ionic liquid was studied and in situ IR analysis was applied for recording the absorption process. With the help of experimental results, NMR spectra analysis, and theoretical calculations, it was found that these DESs captured CO 2 via a synergism of cation and anion, and the protonated superbase played a key role in the absorption process. In addition, the DESs studied in this work showed high thermal stability and excellent recyclability.
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