Search

CdSe nanowires (NWs) were grown in solution under microwave irradiation with the catalysis of solid gold nanoparticles, following a solution–solid–solid (SSS) mechanism. The monocrystal CdSe nanowires distributed evenly on fluorine doped tin oxide (FTO) glass, exhibited intensive light absorption and degraded methyl blue efficiently. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuNi@Cu with porous core–shell structure is obtained in one step. • The CuNi@Cu self-supported electrode can be scaled up for industrial applications. • CuNi@Cu exhibits high activity and stability in alkaline Ampere-level HER. • Bubbles are fine and easy to release due to the confinement and capillary effects. • CuNi@Cu exhibits a good application prospect in seawater electrolysis. Designing cheap, efficient, and stable electrocatalysts for hydrogen evolution reaction (HER) under ampere-level current density is essential for the industrial water electrolysis technique. However, the large H 2 bubbles produced at high current density decrease the activity and stability of the catalyst. Here, a self-supported electrode with porous yolk-shell CuNi@Cu electrocatalyst is obtained via an alternant electrodeposition and replacement reaction during the pulse electrodeposition process. The porous Cu shell can boost electrolyte diffusion and serve as an H 2 bubble fining sieve to enhance the activity and stability of alkaline HER at high current density with the low overpotential of 326 mV @1 A cm−2. The CuNi@Cu electrocatalyst can work steadily for 1000 h at 1 A cm−2 with negligible attenuation. The porous Cu shell can also repel cations in natural seawater owing to the positively charged surface. The spontaneous alternant reaction paves an avenue to design electrocatalysts with porous yolk-shell structures for large-scale industrial applications. [ABSTRACT FROM AUTHOR]

Developing low‐cost and high‐activity pH‐universal hydrogen evolution reaction (HER) catalysts is very crucial to the industrialization of water electrolysis. However, the high price, low yield, and poor stability of current HER catalysts make them difficult to meet practical requirements. Herein, a plasma spraying technique is employed to prepare self‐supported Cu catalysts with tensile strain for the first time. The tensile strain upshifts the d‐band of Cu, improves the water dissociation and H* adsorption, eventually improves the intrinsic HER catalytic activity. As such, Cu electrode achieves overpotentials of 182 mV in 0.5 m H2SO4, 261 mV in 1 M PBS, and 121 mV in 1 M KOH at 10 mA cm–2. In addition, Cu electrode also performs well at high current densities, the overpotentials at 1 A cm–2 are much lower than those of Pt foil in acid, neutral, and alkaline solutions. [ABSTRACT FROM AUTHOR]

A self-supported silver electrode was prepared by plasma spraying and used for catalysing the hydrogen evolution reaction. Thanks to the non-equilibrium synthetic conditions, the silver catalyst exposes high-energy (200) crystal planes, which enhance the adsorption of hydrogen and improve the intrinsic catalytic activity. As a result, the silver catalyst delivers an overpotential of 349 mV at 10 mA cm−2, which was much lower than those of Ag foil (742 mV) and commercial Ag powder (657 mV). This work provides a new idea of preparing active electrocatalysts by traditional processes. [ABSTRACT FROM AUTHOR]

Exploiting low-cost and high-activity catalysts is crucial for lowering energy consumption for hydrogen evolution reaction (HER). Herein, we reported a pure Nickel catalyst with high activity and long-term stability at a large current density in an alkaline medium. We employed an industrial machining technology, turning processing, to generate Ni-chips, a self-supported catalyst, with mostly close-packed planes exposed and high compressive strain. The close-packed plane and compressive strain jointly lower the d -band center of the nickel catalyst and overcome the excessive adsorption for reactive intermediates. As such, Ni-chip achieves ultralow overpotentials of 70 mV at 10 mA cm−2 and 297 mV at 1000 mA cm−2. Particularly, the catalyst exhibits outstanding stability at high current density (1 A cm−2), after working for one and a half months (ca. 1070 h), the initial current density merely declined by 7.3%. With its remarkable catalytic activity, excellent stability, ease of synthesis, and utilization of metallic scraps, the Ni-chip catalyst may serve as a promising catalyst for industrial applications. Ni-chip catalysts with high compressive strain and predominantly close-packed planes were prepared through turning processing. This combination effectively mitigated the excessive adsorption of *OH and *H on the Ni surface, enabling an ultralow overpotential of 297 mV at 1000 mA cm-2, and excellent stability at 1 A cm-2 for 1070 h, demonstrating potential as an efficient and durable electrocatalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Metallic catalysts with nanopores are advantageous on improving both activity and selectivity, while the reason behind that remains unclear all along. In this work, porous Zn nanoparticles (P‐Zn) were adopted as a model catalyst to investigate the catalytic behavior of metallic nanopores. In situ X‐ray absorption spectroscopy, in situ Fourier transform infrared spectroscopy, and density functional theory (DFT) analyses reveal that the concave surface of nanopores works like a pincer to capture and clamp CO2 and H2O precursors simultaneously, thus lowering the energy barriers of CO2 electroreduction. Resultantly, the pincer mechanism endows P‐Zn with a high Faradic efficiency (98.1 %) towards CO production at the potential of −0.95 V vs. RHE. Moreover, DFT calculation demonstrates that Co and Cu nanopores exhibit the pincer behavior as well, suggesting that this mechanism is universal for metallic nanopores. [ABSTRACT FROM AUTHOR]

Metallic catalysts with nanopores are advantageous on improving both activity and selectivity, while the reason behind that remains unclear all along. In this work, porous Zn nanoparticles (P‐Zn) were adopted as a model catalyst to investigate the catalytic behavior of metallic nanopores. In situ X‐ray absorption spectroscopy, in situ Fourier transform infrared spectroscopy, and density functional theory (DFT) analyses reveal that the concave surface of nanopores works like a pincer to capture and clamp CO2 and H2O precursors simultaneously, thus lowering the energy barriers of CO2 electroreduction. Resultantly, the pincer mechanism endows P‐Zn with a high Faradic efficiency (98.1 %) towards CO production at the potential of −0.95 V vs. RHE. Moreover, DFT calculation demonstrates that Co and Cu nanopores exhibit the pincer behavior as well, suggesting that this mechanism is universal for metallic nanopores. [ABSTRACT FROM AUTHOR]

Catalyst support with good conductivity and stability is an eternal pursuit in the search for a high‐performance electrocatalyst. Here, an unusual catalyst support, laser‐modified boron nitride with C, O dopants (L‐BN), for the oxygen evolution reaction is reported. L‐BN exhibits unique advantages for electrocatalysis, namely, high corrosion resistance under oxidizing conditions, enhanced electrical conductivity arising from interlayer B–B dipolar interaction, and strong interaction with IrOx catalyst caused by NCN bonds. As an excellent substrate, L‐BN helps to achieve higher activity and stability than its carbon black counterpart. [ABSTRACT FROM AUTHOR]

Developing highly efficient and low‐cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble‐metal co‐catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so‐called L‐NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm. [ABSTRACT FROM AUTHOR]

Developing highly efficient and low‐cost photocatalysts for overall water splitting has long been a pursuit for converting solar power into clean hydrogen energy. Herein, we demonstrate that a nonstoichiometric nickel–cobalt double hydroxide can achieve overall water splitting by itself upon solar light irradiation, avoiding the consumption of noble‐metal co‐catalysts. We employed an intensive laser to ablate a NiCo alloy target immersed in alkaline solution, and produced so‐called L‐NiCo nanosheets with a nonstoichiometric composition and O2−/Co3+ ions exposed on the surface. The nonstoichiometric composition broadens the band gap, while O2− and Co3+ ions boost hydrogen and oxygen evolution, respectively. As such, the photocatalyst achieves a H2 evolution rate of 1.7 μmol h−1 under AM 1.5G sunlight irradiation and an apparent quantum yield (AQE) of 1.38 % at 380 nm. [ABSTRACT FROM AUTHOR]

FeCo2O4 nanoparticles with abundant oxygen vacancies were produced by laser fragmentation. The oxygen vacancies can lower the thermodynamic energy barriers as well as accelerate the electron transfer, eventually promoting oxygen evolution and reduction reactions simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: The spin state, specifically antibonding orbital (e g) occupancy, of transition‐metal ions is recognized as a descriptor for oxygen electrocatalysts with perovskite or spinel structures, and can be facilely adjusted by varying the valence states of transition metals. However, both perovskites and spinels show unsatisfactory performance even at the optimal spin states. In comparison, some oxides with a rock salt structure (e.g., NiIICoIIO2) exhibit higher activity than perovskites and spinels, nevertheless, the rock salt structure excludes valence changes of the transition metals, obstructing further e g optimization and performance enhancement. Herein, an innovative strategy is demonstrated to regulate the spin states of CoII in NiCoO2 via crystallinity manipulation, thus providing a new strategy for eg optimization. Remarkably, the catalyst (CNO‐8) with a moderate eg occupancy (≈1.2) achieves the best electrocatalytic activity, which is among the highest achieved by the state‐of‐the‐art electrocatalysts, namely, an overpotential of ≈269 mV at 10 mA cm−2 for oxygen evolution reaction and an onset potential of 935 mV for oxygen reduction reaction. As an efficient bifunctional catalyst for rechargeable Zn‐air batteries, CNO‐8 even outperforms the noble metal catalyst (Pt/C + RuO2), demonstrating high potential for practical applications in electrochemical energy conversion. [ABSTRACT FROM AUTHOR]

Introduction of lattice strain into catalysts is a facile way to modify catalytic behaviour. Here, we report the synthesis of Pd nanoparticles with compressive strain by pulsed laser ablation of a Pd target immersed in an aqueous solution. The intensive quenching effect induces obvious compressive strain which improves the ORR performance of the Pd nanoparticles significantly. [ABSTRACT FROM AUTHOR]

As a cheap and earth-abundant metal, copper is known highly conductive but inactive for catalyzing hydrogen evolution reaction (HER) due to its fully filled d orbital and weak adsorption for hydrogen intermediate. Herein, we adopt a mechanical stirring process to introduce a large number of dislocations into copper plate, and retain the dislocations by the quenching effect of dry ice. Theoretical computation indicates that dislocation can cause uneven distribution of charge density, and the electron-deficient area remarkably enhances the hydrogen adsorption, turning inactive copper into active HER catalyst. The product achieves high turnover frequency, low overpotential and long-term durability. Our work bridges mechanical process and functional materials, and exploits a powerful technology on producing self-supported catalysts in a rapid way : [Display omitted] [ABSTRACT FROM AUTHOR]

Water electrolysis has been proven as an effective means to produce clean hydrogen energy, and such a process can be accelerated by active bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we adopted a laser ablation technique to prepare a strawberry-like catalyst with Co 3 O 4 clusters embedded in Ag nanoparticles, realizing the ingenious mutual regulation of Co 3 O 4 and Ag. The Co 3 O 4 facilitates the water dissociation and optimizes the hydrogen adsorption of Ag by introducing tensile strain and low coordination number, resulting in a low HER overpotential of 51 mV at 10 mA cm−2. Meanwhile, the electron transfer from Co 3 O 4 to Ag facilitates the oxidization of Co 3 O 4 and improves the OER performance, leading to a low OER overpotential of 206 mV at 10 mA cm−2. Ultimately, an ultralow potential of 1.49 V for overall water splitting has been achieved at 10 mA cm−2, outperforming Pt/C+RuO 2 couple. [Display omitted] Utilizing the non-equilibrium synthesis method of the laser ablation, this work investigates a unique strawberry-like Co 3 O 4 -Ag composite with Co 3 O 4 clusters embedding in Ag substrate. Through the ingenious mutual regulation and synergic effect of the two components, the catalytic activity of the inactive component can be improved simultaneously, thereby achieving outstanding overall water splitting performance. • A novel strawberry-like structure with Co 3 O 4 clusters embedding in Ag substrate was prepared by laser ablation. • The embedded Co 3 O 4 clusters optimize the hydrogen adsorption of Ag, thus improving the HER performance. • The electron transfer from Co 3 O 4 to Ag facilitates the oxidization of Co 3 O 4 and then optimizes the OER performance. • Mutual regulation and synergic effect endow strawberry-like catalyst excellent water electrolysis performance. [ABSTRACT FROM AUTHOR]

• Single nickel atom is in-situ oxidized and embedded into Ru matrix. • NiRu-0.2 SAC exhibits a low overpotential of 17 mV @ 10 mA cm−2 which is much superior to that of commercial Pt/C (42 mV @ 10 mA cm−2) in alkaline media. • The introduction of oxidized single nickel atom creates a unique atomical interface which boosts water dissociation and H evolution during HER progress. [Display omitted] It is desirable but challenging to fine adjust the electronic structure of single atom to enhance the activity of single atom catalysts (SACs). Herein, we embedded an oxidized single nickel atom into pure ruthenium (Ru) metal (NiRu SAC), thereby constructing an atomic-level interface with high catalytic activity. NiRu SAC exhibits a long-term durability and an extremely low overpotential for hydrogen evolution reaction (optimal value reaches 17 mV) at 10 mA cm−2 which is superior to that of the commercial Pt/C catalyst and most reported Ru-based catalysts. NiRu-0.2 SAC also shows a remarkable oxygen evolution reaction (OER) performance of 210 mV at 10 mA cm−2, and a resulted excellent water splitting property (1.5 V vs. RHE @ 10 mA cm−2). Density functional theory (DFT) calculations demonstrate the fabricated oxidized single-nickel-atomic interface (between single nickel atom and neighboring Ru/O atom) not only lowers the energy barrier for water dissociation but also optimizes the H adsorption through the interaction between the interfacial Ru and O atoms. The single-atomic tailoring provides a new idea to further enhance the performance of single atom catalysts to satisfy the industrial applications. [ABSTRACT FROM AUTHOR]

GLO:OKZ/10mar20:adfm202000364-fig-0002.jpg PHOTO (COLOR): S2 a) Low-resolution transmission electron microscopy image of C-CO nanoparticles. The inset is size distribution pattern with an average particle size ~2.0 ± 0.5 nm. b) High-resolution transmission electron microscopy image of C-CO nanoparticles. gl. [Extracted from the article]

Engineering surface structure of catalysts is an efficient way towards high catalytic performance. Here, we report on the synthesis of regular iridium nanospheres (Ir NSs), with abundant atomic steps prepared by a laser ablation technique. Atomic steps, consisting of one-atom level covering the surface of such Ir NSs, were observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The prepared Ir NSs exhibited remarkably enhanced activity both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic medium. As a bifunctional catalyst for overall water splitting, they achieved a cell voltage of 1.535 V @ 10 mA/cm2, which is much lower than that of Pt/C-Ir/C couple (1.630 V @ 10 mA/cm2). [ABSTRACT FROM AUTHOR]

Ultrasmall size and abundant defects are two crucial factors for improving the performance of catalysts. However, it is a big challenge to introduce defects into ultrafine catalysts because of the surface tension and self‐purification effect of the nanoparticles. In the present work, physical laser fragmentation with chemical oxidization reaction is combined to synthesize Co3O4 nanoparticles (L‐CO) with ultrasmall size (≈2.1 nm) as well as abundant oxygen vacancies, thus providing an effective solution to the long‐standing contradiction between the size reduction and defect generation. The ultrasmall particle size allows more catalytic sites to be exposed. The surficial oxygen vacancies enhance the intrinsic activity, while the internal oxygen vacancies improve the electron transfer, and all of these benefits make L‐CO an active and durable bifunctional catalyst for oxygen reduction/evolutions. As the air cathode of zinc–air battery, L‐CO displays excellent rechargeable performance with a power density of ≈337 mW cm−2, outperforming the commercial noble metal couple (Pt/C+RuO2). [ABSTRACT FROM AUTHOR]

Highly efficient and stable catalysts for the hydrogen evolution reaction, especially in alkaline conditions are crucial for the practical demands of electrochemical water splitting. Here, the synthesis of a novel RuAu single‐atom alloy (SAA) by laser ablation in liquid is reported. The SAA exhibits a high stability and a low overpotential, 24 mV@10 mA cm−2, which is much lower than that of a Pt/C catalyst (46 mV) in alkaline media. Moreover, the turnover frequency of RuAu SAA is three times that of Pt/C catalyst. Density functional theory computation indicates the excellent catalytic activity of RuAu SAAs originates from the relay catalysis of Ru and Au active sites. This work opens a new avenue toward high‐performance SAAs via fast quenching of immiscible metals. [ABSTRACT FROM AUTHOR]