Developing highly active and stable electrocatalysts is essential for the large-scale production of hydrogen from alkaline water. In this work, Ag single atoms and nanoparticles co-decorated Co hydro(oxy)oxide (Ag SAs&NPs@CoO(O)H) is synthesized by a facile one-step approach. Notably, the overpotential of Ag SAs&NPs@CoO(O)H is 200 mV at current density of 50 mA cm(-2) during oxygen evolution reaction (OER). Meanwhile, it can display the mass activity of 637.47 A g(Ag)(-1) under 300 mV, which is 212.49 times higher than that of commercial IrO2. Moreover, the assembled Pt/C // Ag SAs&NPs@CoO(O)H system only requires 1.9 V to reach an industrial current density of 1000 mA cm(-2) in alkaline water electrolyzer and exhibits excellent stability at large current density of 1000 mA cm(-2). Furthermore, in situ Raman spectroscopy analysis coupled with theoretical calculations reveals an novel active site switching mechanism is found on Ag SAs&NPs@CoO(O)H. Specifically, the O* preferentially generates on the Ag NPs and then switches toward the Co3+ site in CoO(O)H to produce OOH* and O-2. Meanwhile, the Ag SAs in the lattice of CoO(O)H can exert an inhibitory force on the reconstruction process of CoOOH to Co(OH)(2), resulting in excellent anti-dissolution stability.

Constructing efficient and stable catalysts is the key to achieving green hydrogen production through electrolysis of water. Atomically dispersed catalysts have received widespread attention due to their high atomic utilization and catalytic efficiency. Herein, Pt 1 Mo 1 dual‐atom catalysts anchored on the nickel selenide nanoisland (Pt 1 Mo 1 /Ni 3 Se 2 ) are prepared by a two‐step method. It only needs 53 mV to deliver the current density of 10 mA cm −2 in 1 M KOH media, and the mass activity at 200 mV is approximately 4.13 times higher than that of Pt/C. In addition, the Pt 1 Mo 1 /Ni 3 Se 2 also exhibits electrochemical stability of nearly 60 h at 20 mA cm −2 . It is shown in the studies that the synergistic effect between Pt and Mo atoms enables the migration of electrons around Mo atoms toward Pt, thus realizing charge redistribution. Further density functional theory calculations verify that synergistic effect of Pt and Mo atoms could optimize the adsorption of H*, enhancing the hydrogen evolution reaction activity. Moreover, the Ni 3 Se 2 nanoisland prevents the aggregation of Pt and Mo dual atom, effectively improving the stability of the catalyst. In this work, a nanoisland confined strategy is provided to construct atomically dispersed catalysts with high activity and stability for water splitting.

Atomically dispersed catalysts (ADCs), including single atoms and sub-nanoclusters, simultaneously, are considered as the most promising candidate to boost the reaction kinetics of hydrogen evolution reaction (HER). However, the correlation between the coordination environment of single atoms and catalytic activity has not been clearly discussed in ADCs system. Herein, Pt ADCs with the different coordination structures were fabricated by a facile sulfurate route coupling deposition strategy. Importantly, Pt ADCs, including Pt-O1Ni1 single atoms and Pt sub-nanoclusters (Pt1+n/Ni3S2), show good basic HER activity, which just need 17 mV at 10 mA cm(-2). Meanwhile, the turnover frequency for Pt1+n/Ni3S2 is 0.49 H-2 s(-1) under the overpotential of 100 mV, which is 8.6 times higher than Pt/C. Besides, the assembled RuO2 ||Pt1+n/Ni3S2 system could get 100 mA cm(-2) current density under 1.7 V cell voltage in alkaline water electrolyzer. Notably, in-situ Raman and attenuated total reflection-surface enhanced infrared absorption spectroscopy reveal that Pt-O1Ni1 coordination is conducive to promoting the fracture of H-O-H bond, realizing the rapid transform of Pt-H* intermediates. Further, density functional theory calculations confirm Pt single atoms with Pt-O1Ni1 coordination environment in Pt1+n/Ni3S2 serves as the main role for HER because Pt-O1Ni1 are more likely to accelerate the production of Pt-H* at the Pt sites, extremely achieving the rapid HER progress. This work discloses the structure-activity relationship in ADCs system, which is essential for the development of highly active electrocatalysts.

Engineering noble metal‐based electrocatalysts (NMEs) with high activity is of vital importance to accelerate the hydrogen production from proton exchange membrane water electrolyzers (PEMWEs). However, the poor stability and high price of NMEs greatly restrict the practical application. In this review, a series of strategies are summarized to boost the activity and reduce the cost of NMEs under acidic condition from the perspective of composition and structure optimization. The composition regulation through doping of metals or nonmetals can effectively inspire alloy effect or cocktail effect of NMEs, which provides an essential guidance to reduce the cost and enhance the stability of NMEs. Meanwhile, the structure optimization also directly improves the intrinsic activity of NMEs, which is comprehensively elaborated based on size, defect, and geometric effects. In addition, to extend the industrial application of PEMWEs, critical scientific issues behind the formulating of electrocatalyst slurry and coating method–PEMWEs performance relationships are fully clarified. Finally, the challenges for survivability of active center, catalytic mechanism research, and construction of membrane electrode are concluded. This review offers comprehensive and targeted guidelines for the rational design of NMEs for PEMWEs application.

A NiMoP nanorod array catalyst with excellent hydrogen evolution reaction (HER) activity under both acidic and alkaline conditions is constructed. Mechanism studies reveal that the Ni 2 P/NiMoP 2 heterointerface is the main active site of HER.

The OER activity diversity among Ni-based chalcogenides is related to the in situ -formed oxyanions from anions.

Developing bifunctional electrocatalysts with lowcontent noble metals and high activity and stability is crucial for water splitting. Herein, we reported a novel Ru doped FeP4/Fe2PO5 heterogeneous interface catalyst (Ru@FeP4/Fe2PO5) for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by heat treatment coupling electrodeposition strategy. Experiments disclosed that Ru@FeP4/Fe2PO5 proclaimed excellent catalytic activity for the OER (249 mV@100 mA cm(-2)) and HER (49 mV@ 10 mA cm(-2)) in a 1 M KOH environment. More importantly, the mass activity and turnover frequency of Ru@FeP4/Fe2PO5 were 117 and 108 times higher than that of commercial RuO2 at an overpotential of 300 mV during the OER, respectively. In addition, the assembled Ru@FeP4/Fe2PO5 || Ru@FeP4/Fe2PO5 system could retain superior durability in a two-electrode system for 134 h at 300 mA cm(-2). Further mechanism studies revealed that Ru atoms in Ru@FeP4/Fe2PO5 act in a key role for the excellent activity during water splitting because the electronic structure of Ru sites could be optimized by the interaction between Ru and Fe atoms at the interface to strengthen the adsorption of reaction intermediates. Besides, the introduction of Ru atoms could also enhance the charge transfer, which effectually accelerates the reaction kinetics. The strategy of anchoring Ru atom on novel heterostructure provides a promising path to boost the overall activity of electrocatalysts for water splitting.

Constructing efficient bifunctional electrocatalysts for both cathode and anode is of great importance for obtaining green hydrogen by water splitting. Herein, sulfuration of hierarchical Mn-doped NiCo LDH heterostructures (Mn-NiCoS2/NF) is constructed as a bifunctional electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) via a facile hydrothermal-annealing strategy. Mn-NiCoS2/NF shows an overpotential of 310 mV at 50 mA cm-2 for OER and 100 mV at 10 mA cm-2 for HER in 1.0 M KOH. Moreover, only 1.496 V@10 mA cm-2 is required for overall water splitting by using Mn-NiCoS2/NF as catalyst dual electrodes in a two-electrode system. The excellent performance of Mn-NiCoS2/NF should be attributed to the ameliorative energy barriers of adsorption/desorption for HO-/H2O through the modification of electronic structure of NiCo basal plane by Mn-doping and the acceleration of water dissociation steps via rich delocalized electron inside sulfur vacancies. The construction of hierarchical Mn-NiCoS2/ NF heterostructures provides new prospects and visions into developing efficientadvanced electrocatalysts for overall water splitting. & COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Layered perovskite oxides have attracted great attention in the electrochemical-energy field due to fast oxygen kinetics at low temperature and high electronic/ionic conductivity. Developing low-cost, high-performance electrocatalysts is a necessary path for the commercialization of electrochemical energy devices. In the current research study, PrBaCo2O5+delta codoping with Ca to substitute Pr and Ba is prepared by a modified complexing sol-gel process. New perovskite oxides Pr0.9Ca0.1Ba1-xCaxCo2O5+delta (x = 0-0.2, PCBCx) remained in a pure-phase tetragonal (P4/mmm) structure. PCBCx exhibit good chemical compatibility with Ce0.8Sm0.2O1.9 (SDC) after calcining at 1000 degrees C for 10 h. The doping of calcium ions at the Ba-site effectively improved the electrical conductivity. XPS analysis indicate that Co ions exist at +3 and +4 valence states in PCBCx samples. The thermal-expansion coefficients (TECs) of PCBCx samples decrease as the calcium ion doping concentration increasing. The polarization resistance of a PCBCx cathode on the SDC electrolyte, where x = 0-0.3 at 700 degrees C, are 0.097, 0.076, 0.069, and 0.106 Omega cm(2), respectively. The x = 0.2 cathode reveals the best electrochemical performance. The maximum power densities of the PCBC2 cathode are 712, 541, and 392 mW cm(-2) at 800, 750, and 700 degrees C, respectively. The results demonstrate an effective codoping strategy to improve conductivity, thermal stability, and electrochemical performance, and provide evidence for the great potential of prepared novel double-perovskite oxides PCBCx as solid-oxide fuel cell cathodes. (C) 2020 Elsevier Ltd. All rights reserved.

This paper investigates the complicated dynamic behavior and power generation efficiency of the cantilevered laminated composite piezoelectric beam with the unilateral layer separate. The effect of the external excitation on the voltage output, the impacts of the layered length of composite layers and the influence of the magnetic distance on the voltage output and the effective frequency bandwidth are examined. Simultaneously, the output voltage and the effective frequency bandwidth of the traditional cantilevered laminated composite piezoelectric beam are measured experimentally to verify the developed model. The amplitude of the harmonic excitation is given the certain value and is not changed. Experimental results show that the developed structure has lower natural frequency, great voltage output and great effective frequency bandwidth when the length of the separate parts between composite layers is in the range. For the different layered lengths of the developed bistable piezoelectric beam, there exist the optimal magnetic distance and an optimal layered length, respectively. The power generation efficiency of the developed bistable piezoelectric beam is better than that of the developed monostable piezoelectric beam. When the layered length of the separate parts between composite layers is optimal, the voltage output of the piezoelectric beam has four peak voltages. In addition, the power generation efficiency of the developed structure are superior to that of the traditional one. The maximum peak voltage of this structure is 6.73 times than that of the traditional piezoelectric beam, and its effective frequency bandwidth promotes 8.4 times.

Silicate garnet phosphors (Lu[Formula: see text]Ce[Formula: see text]Ca[Formula: see text]Mg 2 Si 3 O[Formula: see text] with [Formula: see text], 0.05, 0.1, and 0.15 were prepared by high-temperature solid-state reaction in a reducing atmosphere. The crystal structure, photoluminescence and luminescence of the phosphors were investigated. The optimum excitation peak wavelength of the phosphors ranged from 450[Formula: see text]nm to 490[Formula: see text]nm, matching the emission spectra of a blue light-emitting diode chip. The phosphors emit orange-red light after excitation that can be tuned from 589[Formula: see text]nm to 597[Formula: see text]nm by changing the concentration of calcium ions. In addition, their emission made them suitable for use in warm-white LEDs with a high-color rendering index.

Sr 3 SiO 5 :Eu[Formula: see text] phosphors were synthesized rapidly through a microwave sintering method with the presence of activated carbon powder. The detailed composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of sintering time, fluxing agent (BaF[Formula: see text] content and rare earth ion doping concentration on its photoluminescence (PL) properties were also investigated. It was clear in PL spectra that a broad emission band peaking at 570[Formula: see text]nm was obtained in as-prepared phosphors under a blue light excitation. Meanwhile, non-radiative transitions between Eu[Formula: see text] ions in the Sr 3 SiO 5 host had also been demonstrated to be attributable to dipole–dipole interactions, and the critical distance calculated by the quenching concentration was estimated to be 10.56 Å. The samples were uniform in diameter and regular in morphology. In other words, the Sr 3 SiO 5 :Eu[Formula: see text] phosphors possessed a potential application for white light emitting diodes (LEDs).