Heterointerface MnO2/RuO2 with rich oxygen vacancies for enhanced oxygen evolution in acidic media.

The design and synthesis of oxygen evolution reaction (OER) electrocatalysts that operate efficiently and stably under acidic conditions are important for the preparation of green hydrogen energy. The low intrinsic catalytic activity and poor acid resistance of commercial RuO2 limit its further development, and the construction of heterointerface structures is the most promising strategy to break through the intrinsic activity limitation of electrocatalysts. Herein, we synthesized spherical and oxygen vacancy-rich heterointerface MnO2/RuO2 using morphology control, which promoted the kinetics of the oxygen evolution reaction with the interaction between oxygen vacancies and the oxide heterointerface. MnO2/RuO2 was reported to be an acidic OER catalyst with excellent performance and stability, requiring only an ultra-low overpotential of 181 mV in 0.5 M H2SO4 to achieve a current density of 10 mA cm-2. The catalyst activity remained essentially unchanged in a 140 h stability test with an ultra-high mass activity (858.9 A g-1@ 1.5 V), which was far superior to commercial RuO2 and most previously reported noble metal-based acidic OER catalysts. The experimental results showed that the effect of more oxygen vacancies and the heterointerfaces of manganese ruthenium oxides broke the intrinsic activity limitation, provided more active sites for the OER, accelerated reaction kinetics, and improved the stability of the catalyst. The excellent performance of the catalyst suggests that MnO2/RuO2 provides a new idea for the design and study of heterointerfaces in metal oxide nanomaterials.

Grafting Ultra-fine Nanoalloys with Amorphous Skin Enables Highly Active and Long-lived Acidic Hydrogen Production.

Large-scale deployment of proton exchange membranes water electrolysis (PEM-WE) requires a substantial reduction in usage of platinum group metals (PGMs) as indispensable electrocatalyst for cathodic hydrogen evolution reaction (HER). Ultra-fine PGMs nanocatalysts possess abundant catalytic sites at lower loading, but usually exhibit reduced stability in long-term operations under corrosive acidic environments. Here we report grafting the ultra-fine PtRu crystalline nanoalloys with PtxRuySez "amorphous skin" (c-PtRu@a-PtxRuySez) by in situ atomic layer selenation to simultaneously improve catalytic activity and stability. We found that the c-PtRu@a-PtxRuySez-1 with ~0.6 nm thickness amorphous skin achieved an ultra-high mass activity of 26.7 A mg-1 Pt+Ru at -0.07 V as well as a state-of-the-art durability maintained for at least 1000 h at -10 mA cm-2 and 550 h at -100 mA⋅cm-2 for acid HER. Experimental and theoretical investigations suggested that the amorphous skin not only improved the electrochemical accessibility of the catalyst surface and increasing the intrinsic activity of the catalytic sites, but also mitigated the dissolution/diffusion of the active species, thus resulting in improved catalytic activity and stability under acidic electrolyte. This work demonstrates a direction of designing ultra-fine PGMs electrocatalysts both with high utilization and robust durability, offers an in situ "amorphous skin" engineering strategy.

Synergistic Effects of Dual-Doping with Ni and Ru in Monolayer VS2 Nanosheet: Unleashing Enhanced Performance for Acidic HER through Defects and Strain.

Amidst the escalating quest for clean energy, the hydrogen evolution reaction (HER) in acidic conditions has taken center stage, catalyzing the search for advanced electrocatalysts. The efficacy of these materials is predominantly dictated by the active site density on their surfaces. The propensity is leveraged for monolayer architectures to introduce defects, enhancing surface area, and increasing active sites. Doping enhances defects and fine-tunes catalyst activity. In this vein, defect-enriched monolayer nanosheets doped with nickel and a trace amount of ruthenium in VS2 (SL-Ni-Ru-VS2 ) are engineered and characterized. Evaluation in 0.5 m H2 SO4 solution unveils that the catalyst achieves overpotentials as low as 20 and 41 mV at current densities of -10 and -100 mA cm⁻2 . Impressively, the catalyst maintains a mass activity of 13.08 A mg⁻¹Ru , even with minimal Ru incorporation, indicating exceptional catalytic efficiency. This monolayer catalyst sustains its high activity at lower overpotentials, demonstrating its practical applicability. The comprehensive analysis, which combines experimental data and computational simulations, indicates that the co-doping of Ni and Ru enhances the electrocatalytic properties of VS2 . This research offers a strategic framework for crafting cutting-edge electrocatalysts specifically designed for enhanced performance in the HER.

Self-regulating bioinspired supramolecular photonic hydrogels based on chemical reaction networks for monitoring activities of enzymes and biofuels.

Inspired by the way many living organisms utilize chemical/biological reactions to regulate their skin and respond to stimuli in the external environment, we have developed a self-regulating hydrogel design by incorporating chemical reaction networks (CRNs) into biomimetic photonic crystal hydrogels. In this hydrogel system, we used host-guest supramolecular non-covalent bonds between beta-cyclodextrin (ß-CD) and ferrocene (Fc) as partial crosslinkers and designed a CRN involving enzyme-fuel couples of horseradish peroxidase (HRP)/H2O2 and glucose oxidase (GOD)/d-glucose, by which the responsive hydrogel was transformed into a glucose-driven self-regulating hydrogel. Due to the biomimetic structural color in the hydrogel, the progress of the chemical reaction was accompanied by a change in the color of the hydrogel. Based on this principle, the designed supramolecular photonic hydrogel (SPH) can not only achieve naked-eye detection of H2O2 and glucose concentrations with the assistance of a smartphone but also monitor the reactions of HRP and GOD enzymes and determine their activity parameters. The sensitivity and stability of the sensor have been proven. In addition, due to the reversibility of the chemical reaction network, the sensor can be reused, thus having the potential to serve as a low-cost point-of-care sensor. The SPH was ultimately used to detect glucose in human plasma and H2O2 in liver tumor tissue. The results are comparable with commercial assay kits. By redesigning the chemical reaction network in the hydrogel, it is expected to be used for detecting other enzymes or fuels.

Enriched Fe Doped on Amorphous Shell Enable Crystalline@Amorphous Core-Shell Nanorod Highly Efficient Electrochemical Water Oxidation.

The rational design of efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER) with sluggish kinetics, is imperative to diverse clean energy technologies. The performance of electrocatalyst is usually governed by the number of active sites on the surface. Crystalline/amorphous heterostructure has exhibited unique properties and opens new paradigms toward designing electrocatalysts with abundant active sites for improved performance. Hence, Fe doped Ni-Co phosphite (Fe-NiCoHPi) electrocatalyst with cauliflower-like structure, comprising crystalline@amorphous core-shell nanorod, is reported. The experiments uncover that Fe is enriched in the amorphous shell due to the flexibility of the amorphous component. Further density functional theory calculations indicate that the strong electronic interaction between the enriched Fe in the amorphous shell and crystalline core host at the core-shell interface, leads to balanced binding energies of OER intermediates, which is the origin of the catalyst-activity. Eventually, the Fe-NiCoHPi exhibits remarkable activity, with low overpotentials of only 206 and 257 mV at current density of 15 and 100 mA cm-2 . Unceasing durability over 90 h is achieved, which is superior to the effective phosphate electrocatalysts. Although the applications at high current remain challenges , this work provides an approach for designing advanced OER electrocatalysts for sustainable energy devices.

Ultra-Low Pt Doping and Pt-Ni Pair Sites in Amorphous/Crystalline Interfacial Electrocatalyst Enable Efficient Alkaline Hydrogen Evolution.

Noble metal doping can achieve an increase in mass activity (MA) without sacrificing catalysis efficiency and stability, so that alkaline hydrogen evolution reaction (HER) performance of the catalyst can be optimized to the maximum degree. However, its excessively large ionic radius makes it difficult to achieve either interstitial doping or substitutional doping under mild conditions. Herein, a hierarchical nanostructured electrocatalyst with enriched amorphous/crystalline interfaces for high-efficiency alkaline HER is reported, which is composed of amorphous/crystalline (Co, Ni)11 (HPO3 )8 (OH)6 homogeneous hierarchical structure with an ultra-low doped Pt (Pt-a/c-NiHPi). Benefiting from the structural flexibility of the amorphous component, extremely low Pt (0.21 wt.%, totally 3.31 µg Pt on 1 cm-2 NF) are stably doped on it via a simple two-phase hydrothermal method. The DFT calculations show that due to the strongly electron transfer between the crystalline/amorphous components at the interfaces, electrons finally concentrate toward Pt and Ni in the amorphous components, thus the electrocatalyst has near-optimal energy barriers and adsorption energy for H2 O* and H* . With the above benefits, the obtained catalyst exhibits an exceptionally high MA (39.1 mA µg-1 Pt ) at 70 mV, which is almost the highest level among the reported Pt-based electrocatalysts for alkaline HER.

Multiple roles for LaFeO3 in enhancing the Photoelectrochemical performance of WO3.

For photoelectrochemical (PEC) water splitting, constructing heterojunctions and loading co-catalysts are effective means to realizing sufficient light absorption, effective photogenerated carrier separation and fast charge transport. However, during implementation, the PEC performance of the catalyst is affected by both parasitic light absorption and reflection and the change in energy band structure due to the creation of new interfaces. Herein, in order to minimize the effect of recombination of photogenerated electron-hole pairs on the catalyst PEC performance due to the nascent interface arising from the co-catalyst compounding, WO3 and Ni/Co co-doped LaFeO3 (LFO) are constructed as heterojunctions, in which NiCo-LFO acts both as a part of the heterojunction to enhance photogenerated carrier separation and a co-catalyst to enhance the conductivity and modulate the surface state density at the catalyst-electrolyte interface. The current density of NiCo-LFO/WO3 reaches 3.92 mA cm-2, which is more than 7 times that of LFO/WO3. This work provides a reference for the efficient water splitting of B-site doped, especially the co-doped perovskite oxide as multifunctional roles integrated with conventional photoelectrodes.

Interfacial Engineering of Polycrystalline Pt5 P2 Nanocrystals and Amorphous Nickel Phosphate Nanorods for Electrocatalytic Alkaline Hydrogen Evolution.

Electrocatalytic hydrogen evolution reaction (HER) in alkaline media is important for hydrogen economy but suffers from sluggish reaction kinetics due to a large water dissociation energy barrier. Herein, Pt5 P2 nanocrystals anchoring on amorphous nickel phosphate nanorods as a high-performance interfacial electrocatalyst system (Pt5 P2 NCs/a-NiPi) for the alkaline HER are demonstrated. At the unique polycrystalline/amorphous interface with abundant defects, strong electronic interaction, and optimized intermediate adsorption strength, water dissociation is accelerated over abundant oxophilic Ni sites of amorphous NiPi, while hydride coupling is promoted on the adjacent electron-rich Pt sites of Pt5 P2 . Meanwhile, the ultra-small-sized Pt5 P2 nanocrystals and amorphous NiPi nanorods maximize the density of interfacial active sites for the Volmer-Tafel reaction. Pt5 P2 NCs/a-NiPi exhibits small overpotentials of merely 9 and 41 mV at -10 and -100 mA cm-2 in 1 M KOH, respectively. Notably, Pt5 P2 NCs/a-NiPi exhibits an unprecedentedly high mass activity (MA) of 14.9 mA µgPt -1 at an overpotential of 70 mV, which is 80 times higher than that of Pt/C and represents the highest MA of reported Pt-based electrocatalysts for the alkaline HER. This work demonstrates a phosphorization and interfacing strategy for promoting Pt utilization and in-depth mechanistic insights for the alkaline HER.

The effects of metals and mixture exposure on lung function and the potential mediating effects of oxidative stress.

Exposure to metals is associated with lung function decline. However, limited data are available about effects of co-exposure of metals on lung function. Additionally, the mechanism of the association between metals and lung function remains unclear. We conducted a longitudinal panel study in 2017-2018 among 45 healthy college students. Urinary 15 metals, lung function, biomarkers of oxidative stress and inflammation of participants were measured. Linear mixed effect (LME) and Bayesian kernel machine regression (BKMR) models were applied to explore the associations of urinary metals and mixture with lung function. Furthermore, we analyzed the mediating effect of biomarkers in the association between urinary metals and lung function. LME models showed the negative associations of aluminum (Al), vanadium (V), manganese (Mn), cobalt (Co), nickel (Ni), cadmium (Cd) or antimony (Sb) with Forced vital capacity (FVC), and V, Co, Ni, and Sb with Forced expiratory volume in one second (FEV1). BKMR models indicated the overall effect of metals mixture was negatively associated with FEV1 and FVC; urinary Sb was identified as the major contributor to decreased FVC and FEV1. Urinary 8-hydroxydeoxyguanosine mediated the association of Al, Mn, or Sb with FVC and the relationship of V with FEV1. The results revealed the longitudinal dose-response relationships of urinary metals with pulmonary function among healthy adults. Oxidative stress may be the underlying mechanisms of metals exposure associated with decreased lung function. Due to the small sample size, the interpretation of the results of this study should be cautious, and more studies are needed to verify the findings of this study.

Manganese Cadmium Sulfide Nanoparticles Solid Solution on Cobalt Acid Nickel Nanoflakes: A Robust Photocatalyst for Hydrogen Evolution.

Photocatalytic water splitting for hydrogen evolution is one of the most promising methods to mitigate environmental and energy-related issues. In this study, manganese cadmium sulfide (Mnx Cd1-x S) solid solution is used to construct a p-n heterostructure with NiCo2 O4 through a hydrothermal method. The Mn0.25 Cd0.75 S/NiCo2 O4 composites are used for photocatalytic hydrogen evolution reaction, and the optimal hydrogen rate with 40 mg of Mn0.25 Cd0.75 S/NiCo2 O4 40 mg (MCS/NCO 40) is 61159 µmol g-1 h-1 , which is about 16.3 times than that of pure Mn0.25 Cd0.75 S. After combining with NiCo2 O4 , the light absorption scale, the separation efficiency of photogenerated carriers, and the reaction kinetics are enhanced. Moreover, the band offset of MCS/NCO composites is calculated by the core level alignment method, demonstrating the formation of a p-n heterostructure. The built-in electric field from the p-n heterostructure drives charge transfer and enhances separation efficiency, which results in improved photocatalytic performance.

Amorphous Fe(OH)3 Passivating CeO2 Nanorods: A†Noble-Metal-Free Photocatalyst for Water Oxidation.

Noble-metal-free composites with good photocatalytic property are of great interest. Here, CeO2 nanorods composites loaded with amorphous Fe(OH)3 cocatalyst were designed and prepared via a secondary water bath at 100 °C. The as-synthesized CeO2 /amorphous Fe(OH)3 composites exhibited superior light photocatalytic activities compared to pure CeO2 , especially the sample with a loading time of 60 min. The photocatalytic oxygen generation rate could reach to 357.2 µmol h-1 g-1 , and the average apparent quantum yield (AQY) was 24.67 %, which was a 5.5-fold increase compared to the CeO2 sample. The improvement of photocatalytic performance could be ascribed to three main reasons: First, loading the amorphous Fe(OH)3 enlarged the specific surface area and passivated the surface of the pristine CeO2 . Second, the amorphous Fe(OH)3 ,which acted as a cocatalyst, provided many active sites, and reduced the reaction activation energy. Thirdly, the maximum interface with intimate contact between CeO2 and amorphous Fe(OH)3 cocatalyst accelerated the photogenerated charge separation efficiency and thus improved the photocatalytic performance of CeO2 in photocatalytic water oxidation.

Mn3-x Fex O4 Hollow Nanostructures for High-Performance Asymmetric Supercapacitor Applications.

Design of hollow nanostructure and controllable phase of mixed metal oxides for improving performance in supercapacitor applications is highly desirable. Here we demonstrate the rational design and synthesis of Mn3-x Fex O4 hollow nanostructures for supercapacitor applications. Owing to high porosity and the specific surface area that provides more active sites for electrochemical reactions, the electrochemical performance of Mn3-x Fex O4 hollow nanostructure substantially enhanced comparing with pristine Mn3 O4 . Particularly, in 1.0 M KOH electrolyte, Mn0.16 Fe2.84 O4 with a typical diameter of 20 nm exhibits excellent specific capacitance of 2675, 2320, 1662, 987 F g-1 at current densities of 1, 2, 5, 10 A g-1 , respectively, which is significantly superior to those of other transition metal oxides. Besides, an asymmetric supercapacitor is assembled by using Mn0.16 Fe2.84 O4 and activated carbon as a positive and a negative electrode, respectively. Electrochemical results indicate a high energy density of 42 Wh kg-1 at a power density of 0.75 kW kg-1 , which makes this hollow nanostructure a highly promising electrode for achieving high-performance next-generation supercapacitors.

Fe doped amorphous single layered vanadyl phosphate nanosheets as highly efficient electrocatalyst for water oxidation.

The search for earth-abundant water oxidation electrocatalysts with low-cost and high-performance is essential to the energy conversion field. Well defined, rational designed two-dimensional materials have attracted enormous interest in light of much more specific surface areas and unique electronic properties. Herein, we report a facile two-phase solvothermal approach for the synthesis of Fe doped amorphous single-layered (~0.85 nm) vanadyl phosphate nanosheets (Fe-Am VOPO4). The obtained electrocatalyst exhibits excellent OER electrocatalytic performance, only require overpotential of 215 mV and 270 mV to reach current densities of 10 and 100 mA cm-2 in 1.0 M KOH electrolyte, and long-term electrochemical stability of 40 h. This work strikes out a path of synthesis of graphene-like materials with amorphous phase, and explores a new type of phosphate for efficient OER electrocatalysts.

Two-dimensional (2D) MnIn2Se4 nanosheets with porous structure: a novel photocatalyst for water splitting without sacrificial agents.

Novel 2D porous MnIn2Se4 nanosheet photocatalysts have been synthesized for the first time via a simple hydrothermal method, which exhibit promising activity for photocatalytic water splitting without any sacrificial agent due to their large specific surface area, 2D layered morphology, porous structure and suitable energy gap.

Vertical 1T/2H-WS2 nanoflakes grown on 2D-C3N4: Multiple charge transfer channels designed for enhanced photocatalytic activity.

Two-dimensional (2D) sulfides have attracted much attention as a promising photocatalyst for the hydrogen evolution reaction. In this work, a highly active and stable vertical 1T/2H-WS2 nanoflakes grown on 2D-C3N4 with multiple charge transfer channels through a simple and efficient colloidal strategy is reported. This three-dimensional (3D) composite presents the usual semiconducting 2H phase WS2 as well as the unusual distorted octahedral 1T phase WS2, which vertically connect 2D-C3N4 constructing an interesting 3D structure with more active sites. The H2 production rate of the optimal product has reached 350.75 µmol·g-1·h-1, which is 66.8 and 8.2 times higher than the rate of 2D-C3N4 and 1T/2H-WS2 respectively. The predominant charge transfer occurs between 2D-C3N4 and 2H-WS2 nanoflakes due to their vertical connection and the matched energy structure while the existence of the metallic 1T-WS2 acts as a cocatalyst with an enhanced conductivity to provide multiple charge transfer channels over its basal and edge sites for H+ reduction.

Synthesis and characterization of Mn-doped CsPb(Cl/Br)3 perovskite nanocrystals with controllable dual-color emission.

Metal-halide perovskite nanocrystals (NCs) are considered to be promising types of optoelectronic and photonic materials. The emission colors of the cesium lead halide perovskite (CsPbX3, X = Cl, Br, I) NCs depend on the joint influence of the emission peaks of the host and its dopant ions. Herein, we report a phosphine-free strategy to synthesize Mn-doped CsPb(Cl/Br)3 NCs to tune their optical properties in a wide color gamut. Colloidal Mn-doped CsPb(Cl/Br)3 NCs were synthesized by injecting Cs-oleate solution into the MnCl2 and PbBr2 precursor solution. The as-prepared Mn-doped CsPb(Cl/Br)3 NCs are highly crystalline and uniform sized nanocubes with two emission peaks, including the host emission around 450 nm and the Mn2+ dopant emission around 600 nm, which are sensitive to the MnCl2-to-PbBr2 molar feed ratio and the reaction temperature. By varying the MnCl2-to-PbBr2 molar feed ratio or the reaction temperature, the relative PL intensities of dual color emission can be manipulated, showing their ability in tunable color output.

Vertical Growth of 2D Amorphous FePO4 Nanosheet on Ni Foam: Outer and Inner Structural Design for Superior Water Splitting.

Rational design of highly efficient bifunctional electrocatalysts based on 3D transition-metal-based materials for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of great importance for sustainable energy conversion processes. Herein, a novel strategy involving outer and inner structural engineering is developed for superior water splitting via in situ vertical growth of 2D amorphous FePO4 nanosheets on Ni foam (Am FePO4 /NF). Careful experiments and density functional theory calculations show that the inner and outer structural engineering contributing to the synergistic effects of 2D morphology, amorphous structure, conductive substrate, and Ni-Fe mixed phosphate lead to superior electrocatalytic activity toward OER and HER. Furthermore, a two-electrode electrolyzer assembled using Am FePO4 /NF as an electrocatalyst at both electrodes gives current densities of 10 and 100 mA cm-2 at potentials of 1.54 and 1.72 V, respectively, which is comparable to the best bifunctional electrocatalyst reported in the literature. The strategies, introduced in the present work, may open new opportunities for the rational design of other 3D transition-metal-based electrocatalyst through an outer and inner structural control to strengthen the electrocatalytic performance.

Rapid synthesis of CuInTe2 ultrathin nanoplates with enhanced photoelectrochemical properties.

Ultrathin (2.1 ± 0.1 nm) single-crystal CuInTe2 two-dimensional (2D) nanoplates were synthesized via a rapid colloidal synthesis method. The growth mechanism was investigated in detail. Crystal seeds grew via a 2D assembly process of initially formed small CuInTe2 nanoparticles followed by recrystallization into single crystal nanoplates. The obtained CuInTe2 nanoplates exhibited significantly enhanced photoelectrochemical properties compared with the CuInTe2 nanoparticles, benefitting from their ultrathin 2D characteristics.

Controllable synthesis and luminescent properties of rare earth doped Gd2(MoO4)3 nanoplates.

For the first time, we have successfully synthesized rare-earth doped Gd2(MoO4)3: RE3+ (RE=Eu, Tb) nanoplates by solvothermal method. The morphology of Gd2(MoO4)3 can be manipulated by changing the reaction times and reaction temperatures. The composition and surface morphology have been investigated by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), respectively. Under the excitation of UV, Photoluminescence (PL) has been used to explore the excellent luminescence properties of the synthesized nanophosphors. The Gd2(MoO4)3: Eu3+ phosphors shows a hypersensitive red emission (612nm) when excitation wavelength within the scope of 200-350nm corresponding to a 5D0-7F2 transition. Similarly, the Gd2(MoO4)3: Tb3+ phosphors certificate a highly strong green emission at 544nm at an excitation wavelength of 298nm corresponding to a 5D4-7F5 transition. Furthermore, the characteristic spectrum peak of the Gd2(MoO4)3: Eu3+/Tb3+ nanophosphor exhibits the corresponding spectra position (green emission at 544nm and red emission at 612nm). Hence, the obtained Gd2(MoO4)3: RE3+ nanoplates may establish highly potentiality in light field applications.

Colloidal synthesis of VSe2 single-layer nanosheets as novel electrocatalysts for the hydrogen evolution reaction.

We present a one-pot colloidal route to synthesize VSe2, a new type of metallic single-layer nanosheet. The ∼0.4 nm thick VSe2 single-layer nanosheets possess extraordinary electrocatalytic hydrogen evolution reaction (HER) performance with a low onset overpotential of 108 mV, a small Tafel slope of 88 mV per decade, and an exceptional overpotential of 206 mV at a current density of 10 mA cm(-2).