Oxygen-Coordinated Single Mn Sites for Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection. Here, we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen (O) coordination on bacterial cellulose-converted graphitic carbon (Mn-O-C). Evidence of the atomically dispersed Mn-(O-C2)4 moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy. As a result, the as-synthesized Mn-O-C catalyst exhibits superior NitRR activity with an NH3 yield rate (RNH3) of 1476.9 ± 62.6 µg h-1 cm-2 at - 0.7 V (vs. reversible hydrogen electrode, RHE) and a faradaic efficiency (FE) of 89.0 ± 3.8% at - 0.5 V (vs. RHE) under ambient conditions. Further, when evaluated with a practical flow cell, Mn-O-C shows a high RNH3 of 3706.7 ± 552.0 µg h-1 cm-2 at a current density of 100 mA cm-2, 2.5 times of that in the H cell. The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn-(O-C2)4 sites not only effectively inhibit the competitive hydrogen evolution reaction, but also greatly promote the adsorption and activation of nitrate (NO3-), thus boosting both the FE and selectivity of NH3 over Mn-(O-C2)4 sites.

Environmental Effects of Surfactant-Free Silver Nanoparticles on Enzyme Activities, Bacterial Diversity, and Soil Function.

The effects of silver nanoparticles (Ag NPs) on the soil environment have attracted considerable research attention. Previous studies mainly focused on agent-coated Ag NPs, which inevitably introduce additional disturbance of chemical agents to the intrinsic property of Ag NPs. We investigated the environmental effects induced by pure surfactant-free Ag NPs (SF-Ag NPs), including soil enzyme activities (urease, sucrase, phosphatase, and ß-glucosidase), bacterial community structure, and functional profile, over different exposure periods in the present study. The results indicated that these enzymes, especially urease and phosphatases, exhibit different responses to SF-Ag NPs and are more susceptible to SF-Ag NPs than other enzymes. Surfactant-free Ag NPs can also induce a decrease in bacterial diversity and a change of bacterial community structure. The abundance of SF-Ag NPs in Proteobacteria increased, but decreased in Acidobacteria after 14 days of exposure. Moreover, the abundance of genus Cupriavidus was significantly higher than those of the respective controls. By contrast, SF-Ag NP exposure for 30 days could attenuate these negative effects. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) prediction revealed that SF-Ag NPs exert a negligible effect on bacterial function, thereby suggesting that functional redundancy is conduced to bacterial community tolerance to SF-Ag NPs. These findings will help us further understand the environmental toxicity of Ag NPs. Environ Toxicol Chem 2023;42:1685-1695. © 2023 SETAC.

Selenium nanoparticles improve nickel-induced testosterone synthesis disturbance by down-regulating miR-708-5p/p38 MAPK pathway in Leydig cells.

The present study was designed to investigate the role of miR-708-5p/p38 mitogen-activated protein kinase (MAPK) pathway during the mechanism of selenium nanoparticles (Nano-Se) against nickel (Ni)-induced testosterone synthesis disorder in rat Leydig cells. We conducted all procedures based on in vitro culture of rat primary Leydig cells. After treating Leydig cells with Nano-Se and NiSO4 alone or in combination for 24 h, we determined the cell viability, reactive oxygen species (ROS) levels, testosterone production, and the protein expression of key enzymes involved in testosterone biosynthesis: steroidogenic acute regulatory (StAR) and cytochrome P450 cholesterol side chain cleavage enzyme (CYP11A1). The results indicated that Nano-Se antagonized cytotoxicity and eliminated ROS generation induced by NiSO4 , suppressed p38 MAPK protein phosphorylation and reduced miR-708-5p expression. Importantly, we found that Nano-Se upregulated the expression of testosterone synthase and increased testosterone production in Leydig cells. Furthermore, we investigated the effects of p38 MAPK and miR-708-5p using their specific inhibitor during Nano-Se against Ni-induced testosterone synthesis disorder. The results showed that Ni-inhibited testosterone secretion was alleviated by Nano-Se co-treatment with p38 MAPK specific inhibitor SB203580 and miR-708-5p inhibitor, respectively. In conclusion, these findings suggested Nano-Se could inhibit miR-708-5p/p38 MAPK pathway, and up-regulate the key enzymes protein expression for testosterone synthesis, thereby antagonizing Ni-induced disorder of testosterone synthesis in Leydig cells.

Facile room temperature synthesis of a NiFe2O4-based magnetic covalent organic framework for the extraction of tetracycline residues in environmental water samples prior to HPLC.

In this study, a functionalized magnetic covalent organic framework (NiFe2O4@TAPB-TPA) was fabricated with NiFe2O4 nanoparticles as the magnetic core, and 1,3,5-tris(4-aminophenyl)benzene (TAPB) and terephthalaldehyde (TPA) as building blocks by a facile room temperature strategy. Benefitting from the π-π stacking and hydrogen bond interaction, NiFe2O4@TAPB-TPA showed great potential as a magnetic adsorbent for the extraction of tetracyclines (TCs). Under optimal conditions, good linearities (R2 > 0.9990) were obtained between the peak area and TC concentration in the range of 1-500 µg L-1 with limits of detection ranging from 0.09 to 0.26 µg L-1. The intra-day and inter-day relative standard deviations were less than 2.2% and 4.7%, respectively. The established method was successfully applied for the determination of TCs in diverse environmental water samples with satisfactory recoveries in the range of 91.6-102.7%. In addition, NiFe2O4@TAPB-TPA showed good reusability with the recoveries for TCs higher than 73.1% after nine recycles, indicating potential application of NiFe2O4@TAPB-TPA as an ideal adsorbent for the enrichment of TCs.

Hydrogen Peroxide Assisted Electrooxidation of Benzene to Phenol over Bifunctional Ni-(O-C2 )4 Sites.

Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high-value phenol product, but remaining a huge challenge. Here an oxygen-coordinated nickel single-atom catalyst (Ni-O-C) is reported with bifunctional electrocatalytic activities toward the two-electron oxygen reduction reaction (2e- ORR) to H2 O2 and H2 O2 -assisted benzene oxidation to phenol. The Ni-(O-C2 )4 sites in Ni-O-C ar proven to be the catalytic active centers for bifunctional 2e- ORR and H2 O2 -assisted benzene oxidation processes. As a result, Ni-O-C can afford a benzene conversion as high as 96.4 ± 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 ± 3.2% with the help of H2 O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni-O-C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 ± 2.2% with a phenol selectivity of 100% and a FE of 44.8 ± 3.0% at 10 mA cm-2 .

Triazine-based porous organic polymer as pipette tip solid-phase extraction adsorbent coupled with HPLC for the determination of sulfonamide residues in food samples.

In this work, triazine-based porous organic polymer (TAPT-BPDA) synthesized by simple solvothermal method with stable chemical properties was employed as pipette tip solid-phase extraction (PT-SPE) adsorbent for the extraction of sulfonamides for the first time. Under the optimal conditions, good linearities (1-300 µg L-1, R2 ≥ 0.9987) and low limits of detection (0.10-0.28 µg L-1) were obtained. The recoveries of sulfonamides in meat, egg and milk samples were in the range of 76.1-114.0 %. The prepared TAPT-BPDA showed good reusability with the recoveries of sulfonamides remained above 80.0 % after eight recycles. The adsorption mechanism between SAs and adsorbent might be the combined effects of electrostatic interactions, hydrogen bonding and π-π interactions. The results demonstrated potential applications of a TAPT-BPDA-based PT-SPE-HPLC method for the analysis of trace sulfonamide residues in food samples.

Surface-Plasmon-Mediated Alloying for Monodisperse Au-Ag Alloy Nanoparticles in Liquid.

Plasmonic noble-metal nanoparticles with broadly tunable optical properties and catalytically active surfaces offer a unique opportunity for photochemistry. Resonant optical excitation of surface-plasmon generates high-energy hot carriers, which can participate in photochemical reactions. Although the surface-plasmon-driven catalysis on molecules has been extensively studied, surface-plasmon-mediated synthesis of bimetallic nanomaterials is less reported. Herein, we perform a detailed investigation on the formation mechanism and colloidal stability of monodisperse Au-Ag alloy nanoparticles synthesized through irradiating the intermixture of Au nanochains and AgNO3 solution with a nanosecond pulsed laser. It is revealed that the Ag atoms can be extracted from AgNO3 solution by surface-plasmon-generated hot electrons and alloy with Au atoms. Particularly, the obtained Au-Ag alloy nanoparticles without any surfactants or ligands exhibit superior stability that is confirmed by experiments as well as DLVO-based theoretical simulation. Our work would provide novel insights into the synthesis of potentially useful bimetallic nanoparticles via surface-plasmon-medicated alloying.

Electrochemical Hydrogen Peroxide Synthesis from Selective Oxygen Reduction over Metal Selenide Catalysts.

Se-based nanoalloys as an emerging class of metal chalcogenide with tunable crystalline structure, component distribution, and electronic structure have attracted considerable interest in renewable energy conversion and utilization. In this Letter, we report a series of nanosized M-Se catalysts (M = Cu, Ni, Co) as prepared from laser ablation method and screen their electrocatalytic performance for onsite H2O2 generation from selective oxygen reduction reaction (ORR) in alkaline media. A flexible control on 2e-/4e- ORR pathway has been achieved by engineering the alloying component. Moreover, through a feedback loop between theory and experiment an optimized scaling relationship between oxygenated ORR intermediates has been discovered on cubic Cu7.2Se4 nanocrystals, that is, the ensemble effect of isolated Cu component destabilizes O* binding while the ligand effect of Se to Cu fine-tunes the binding strength of OOH*, leading to a superb H2O2 selectivity above 90% over a wide potential window even after 1400 potential cycles.

Nano-selenium attenuates mitochondrial-associated apoptosis via the PI3K/AKT pathway in nickel-induced hepatotoxicity in vivo and in vitro.

The aim of this study was to investigate the protective effects of Nano-Se against nickel (Ni)-induced hepatotoxicity and the potential mechanism. Hence, we constructed in vivo and in vitro models of Ni-induced hepatotoxicity. Sprague-Dawley (SD) rats were exposed to nickel sulfate (NiSO4 , 5.0 mg/kg, i.p.) with or without Nano-Se (0.5, 1, and 2 mg/kg, oral gavage) co-administration for 14 days, and HepG2 cells were exposed to NiSO4 (1500 µM) with or without Nano-Se (20 µM) for 24 h. Nano-Se obviously prevented Ni-induced hepatotoxicity indicated by ameliorating pathological change and decreasing Ni accumulation in rat livers. Ni induced a significant increase in hepatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GSH-Px), and malondialdehyde (MDA) level, decreased the glutathione (GSH) content while compared to those in the control group. Nano-Se administration improved the hepatic antioxidant capacity through increase hepatic GSH contents and GSH-Px activity, decrease the activities of SOD, CAT, and MDA level. Nano-Se improved the cell viability, decreased active oxygen (ROS) generation and ameliorated morphological changes of nuclear structures in Ni-treated HepG2 cells. In addition, Nano-Se inhibited the Ni-induced increases of cytochrome c, caspase-9, cleaved caspase-3, increased PI3K and AKT phosphorylation both in vivo and in vitro. Besides, the PI3K inhibitor Y294002 could inhibit the protective effects of Nano-Se on apoptosis. Thus, Nano-Se significantly activates PI3K/AKT signaling to ameliorate apoptosis in Ni-induced hepatotoxicity.

Two-Dimensional IV-V Monolayers with Highly Anisotropic Carrier Mobility and Electric Transport Properties.

Two-dimensional (2D) semiconductors with anisotropic properties (e.g., mechanical, optical, and electric transport anisotropy) have long been sought in materials research, especially 2D semiconducting sheets with strong anisotropy in carrier mobility, e.g., n-type in one direction and p-type in another direction. Here, we report a comprehensive study of the carrier mobility and electric transport anisotropy of a class of 2D IV-V monolayers, XAs (X = Si or Ge), by using density functional theory methods coupled with deformation potential theory and non-equilibrium Green's function method. We find that the polarity of room-temperature carrier mobility µ of the 2D XAs monolayer is highly dependent on the lattice direction. In particular, for the SiAs monolayer, the µ values of the electron (e) and hole (h) are 1.25 × 103 and 0.39 × 103 cm2 V-1 s-1, respectively, in the a direction and 0.31 × 103 and 1.12 × 103 cm2 V-1 s-1, respectively, for the b direction. The computed electric transport properties also show that the SiAs monolayer exhibits strong anisotropy in the biased voltage in the range of -1 to 1 V. In particular, the current reflects the ON state in the a direction but the OFF state in the b direction. In addition, we find that the uniaxial strain can significantly improve the electric transport performance and even lead to the negative differential conductance at 10% strain. The unique transport properties of the 2D XAs monolayers can be exploited for potential applications in nanoelectronics.

Efficient electrocatalytic nitrogen reduction to ammonia with aqueous silver nanodots.

The electrocatalytic nitrogen (N2) reduction reaction (NRR) relies on the development of highly efficient electrocatalysts and electrocatalysis systems. Herein, we report a non-loading electrocatalysis system, where the electrocatalysts are dispersed in aqueous solution rather than loading them on electrode substrates. The system consists of aqueous Ag nanodots (AgNDs) as the catalyst and metallic titanium (Ti) mesh as the current collector for electrocatalytic NRR. The as-synthesized AgNDs, homogeneously dispersed in 0.1 M Na2SO4 solution (pH = 10.5), can achieve an NH3 yield rate of 600.4 ± 23.0 µg h-1 mgAg-1 with a faradaic efficiency (FE) of 10.1 ± 0.7% at -0.25 V (vs. RHE). The FE can be further improved to be 20.1 ± 0.9% at the same potential by using Ti mesh modified with oxygen vacancy-rich TiO2 nanosheets as the current collector. Utilizing the aqueous AgNDs catalyst, a Ti plate based two-electrode configured flow-type electrochemical reactor was developed to achieve an NH3 yield rate of 804.5 ± 30.6 µg h-1 mgAg-1 with a FE of 8.2 ± 0.5% at a voltage of -1.8 V. The designed non-loading electrocatalysis system takes full advantage of the AgNDs' active sites for N2 adsorption and activation, following an alternative hydrogenation mechanism revealed by theoretical calculations.

Stability evolution of ultrafine Ag nanoparticles prepared by laser ablation in liquids.

Understanding the stability evolution of the silver nanoparticles (Ag NPs) in colloid has great benefits for its controllable preparation, storage and application. Herein, uncapped Ag NPs with diameter of 1.66 ± 0.37 nm are obtained by laser ablation of Ag target in deionized water, corresponding surface plasma resonance (SPR) bands, ζ potential and particle size distribution are monitored to investigate uncapped Ag NPs' stability evolution. Due to negatively charged surface, uncapped Ag NPs show an excellent dispersion stability in 70 days without any external disturbance. But its dispersion stability and structure stability are destroyed easily by an oscillation treatment, resulting in a tardy growth and the formation of one-dimensional Ag nanochain. In addition, the chemical stability of uncapped Ag NPs is dramatically varied by a displacement reaction with an inserted copper wire. As comparison, two typical cationic and anionic surfactant molecules, N-hexadecyl trimethyl ammonium chloride (CTAC) and sodium dodecyl benzene sulfonate (SDBS) are severally used to prepare surface capped Ag NPs. With same treatment of Ag colloid, both two kinds of capped Ag NPs display better dispersion stability and structure stability than uncapped Ag NPs. Moreover, CTAC capped Ag NPs keep a better chemical stability than SDBS capped Ag NPs.

Laser ablation in liquids for the assembly of Se@Au chain-oligomers with long-term stability for photothermal inhibition of tumor cells.

For the potential use of Au nanoparticles (NPs) in photothermal therapy, it is important and effective to achieve the uniaxial assembly of Au NPs to allow enhanced absorption in the near infrared (NIR) region. Herein, we first presented the construction of amorphous selenium encapsulated gold (Se@Au) chain-oligomers by successive laser ablation of Au and Se targets in sodium chloride solution without other toxic precursors, stabilizers, or templating molecules. Se@Au chain-oligomers showed evidently enhanced NIR absorption and excellent photothermal transduction efficiency (η), which was higher than 47% at 808 nm. After being stored for 1 year, the Se@Au colloids still exhibited outstanding photothermal performance. The cytotoxicity assay demonstrated that there is negligible toxicity of Se@Au chain-oligomers in cells, but cell viability declined to only 1% in phototherapeutic experiments that were implemented in vitro. In intracellular Reactive Oxygen Species (ROS) generation measurements, Se@Au chain-oligomers could trigger a 35.9% increment of ROS upon laser irradiation. The possible synergetic effects between the anticancer function of Se and photothermal behaviors of Se@Au oligomers were intended to increase ROS level in cells. Therefore, such designed Se@Au chain-oligomers of high stability exhibit promising potential for their use as in vivo photothermal therapeutic agents.

Laser-synthesized graphite carbon encased gold nanoparticles with specific reaction channels for efficient oxygen reduction.

Developing novel electrocatalysts with desirable activity and stability is always full of challenge in electrochemical energy conversion. Here, specific carbon shell encapsulated Au (Au@C) nanoparticles are prepared by a laser ablation in liquids method and used as the oxygen reduction reaction (ORR) electrocatalysts. Such Au@C nanoparticles exhibit excellent catalytic activity toward ORR with an onset potential of 0.98 V and a half-wave potential of 0.87 V, better than that of commercial Pt/C. More importantly, the Au@C catalyst exhibits unrivalled stability for 3000 CV cycles for ORR in 0.1 M KOH, dramatically superior to Pt/C and pure Au catalysts. The density functional theory (DFT) calculations and SCN- ions to poison metal-based active sites are conducted to Au@C catalyst, and the results indicate that the structural defects of carbon shells supply an access for the reactants to contact the core Au nanoparticles, causing the catalytic reaction, meanwhile the carbon shells prevent the degeneration of core Au nanoparticles in the harsh electrolytes enhancing the durability of Au effectively.

Ambient Electrosynthesis of Ammonia Using Core-Shell Structured Au@C Catalyst Fabricated by One-Step Laser Ablation Technique.

This work reports the synthesis of core-shell structured Au@C composite through a simple one-step laser ablation technique. The results demonstrate that the Au@C with a mean nanosphere size of ∼8.0 nm is composed of a spherical shaped Au core and 1-2 layered graphitic carbon shell with abundant defects. As a nitrogen reduction reaction (NRR) electrocatalyst, the Au@C gives a large NH3 yield rate of 241.9 µg h-1 mgcat.-1 with a high faradaic efficiency of 40.5% at -0.45 V versus reversible hydrogen electrode in a 0.1 M Na2SO4 electrolyte (pH = 6.3) under ambient conditions, surpassing the performances of most aqueous-based NRR electrocatalysts recently reported. The 15N labeling experimental results demonstrate that the produced NH3 is undoubtedly originated from the NRR process catalyzed by Au@C. The superior NRR performance of Au@C can be ascribed to the ultrathin carbon layer, effectively inhibiting the aggregation of Au nanospheres during the NRR, and the abundant defects such as carbon vacancies existed in the ultrathin carbon layer, providing additional NRR catalytic active sites. Our theoretical calculation results further confirm the role of carbon vacancies in the electrocatalytic NRR.

Interface and defect engineer of titanium dioxide supported palladium or platinum for tuning the activity and selectivity of electrocatalytic nitrogen reduction reaction.

Electrocatalytic N2 reduction reaction (NRR) under ambient condition is considered as an alternative and environmental-friendly technique to substitute the conventional process of Haber-Bosch for NH3 production. However, there are still hurdles for researchers to control the balance between N2 activation and competitive hydrogen evolution reaction (HER) to obtain high selectivity of NRR. Herein, we synthesized Pt/TiO2 and Pd/TiO2 hybrids by using laser ablation in liquid (LAL) technology combined with hydrothermal treatment and compared their activity and selectivity of N2 reduction. The results concluded that Pt/TiO2 exhibited a higher NH3 yield rate whereas Pd/TiO2 achieved a better FE for artificial N2 fixation, confirming that enhanced activity surely needs more electrons and protons to participate in the reaction, but the limited protons and electrons furnishing could restrain HER activity and improve selectivity of NRR. Comparing with Pt/TiO2, Pd/TiO2 hybrids could serve as a superior catalyst for keeping a balance relationship between HER and NRR to realize excellent selectivity and high yield rate simultaneously in an alkaline solution. Overall, this work will provide a significant practice to rational design electrocatalysts for NRR at ambient conditions and Pd-based materials might open an electrocatalyst paradigm to solve the global energy and ecological crisis.

Ameliorative effects of nano-selenium against NiSO4-induced apoptosis in rat testes.

Nickel (Ni) is a common environmental pollutant, which has toxic effects on reproductive system. Nowadays, nano-selenium (Nano-Se) has aroused great attention due to its unique antioxidant effect, excellent biological activities and low toxicity. The aim of this study was to explore the protective effects of Nano-Se on NiSO4-induced testicular injury and apoptosis in rat testes. Nickel sulfate (NiSO4) (5 mg/kg b.w.) was administered intraperitoneally and Nano-Se (0.5, 1, and 2 mg Se/kg b.w., respectively) was given by oral gavage in male Sprague-Dawley rats. Histological changes in the testes were determined by H&E staining. The terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and immunohistochemistry were performed to evaluate the apoptosis in testes. Expression levels of mitochondrial apoptosis-related genes and proteins were analyzed by RT-qPCR and Western blot. The results showed that Nano-Se improved lesions of testicular tissue induced by NiSO4. Nano-Se significantly alleviated NiSO4-induced apoptosis in rat testes, as well as significantly downregulated the Bak, cytochrome c, caspase-9 and caspase-3 and upregulated Bcl-2 expression levels, all of which were involved in mitochondria-mediated apoptosis. Altogether, we concluded that Nano-Se may potentially exert protective effects on NiSO4-induced testicular injury and attenuate apoptosis, at least partly, via regulating mitochondrial apoptosis pathways in rat testes.

Nano-selenium attenuates nickel-induced testosterone synthesis disturbance through inhibition of MAPK pathways in Sprague-Dawley rats.

The aim of this study was to investigate the protective effects of Nano-Se against Ni-induced testosterone synthesis disorder in rats and determine the underlying protective mechanism. Sprague-Dawley rats were co-treated with Ni (5.0 mg/kg, i.p.) and Nano-Se (0.5, 1.0, and 2.0 mg/kg, oral gavage) for 14 days after which various endpoints were evaluated. The Ni-induced abnormal pathological changes and elevated 8-OHdG levels in the testes were attenuated by Nano-Se administration. Importantly, decreased serum testosterone levels in the Ni-treated rats were significantly restored by Nano-Se treatment, particularly at 1.0 and 2.0 mg/kg. Furthermore, the mRNA and protein levels of testosterone synthetase were increased by Nano-Se compared to the Ni group, whereas phosphorylated protein expression levels of mitogen-activated protein kinase (MAPK) pathways were suppressed by Nano-Se administration in the Ni-treated rats. Overall, the results suggest that Nano-Se may ameliorate the Ni-induced testosterone synthesis disturbance via the inhibition of ERK1/2, p38, and JNK MAPK pathways.

Strong Fe3+-O(H)-Pt Interfacial Interaction Induced Excellent Stability of Pt/NiFe-LDH/rGO Electrocatalysts.

Agglomeration-triggered deactivation of supported platinum electrocatalysts markedly hinders their application in methanol oxidation reaction (MOR). In this study, graphene-supported nickel-iron layered double hydroxide (NiFe-LDH/rGO), in which Fe3+ was introduced to replace Ni2+ partially in the Ni(OH)2 lattice to provide stronger metal-support bonding sites, was utilized to immobilize Pt nanoparticles (NPs). Given the optimized metal-support interfacial contact (Fe3+-O(H)-Pt) between Pt NPs and NiFe-LDH/rGO nanosheets for Pt/NiFe-LDH/rGO electrocatalysts, the Pt/NiFe-LDH/rGO electrocatalysts displayed dramatically enhanced durability than that of Pt/Ni(OH)2/rGO counterpart as well as commercial Pt/C, and 86.5% of its initial catalytic activity can be maintained even after 1200 cycles of cyclic voltammetry (CV) tests during MOR. First-principle calculations toward the resultant M-O(H)-Pt (M = Fe3+, Ni2+) interfacial structure further corroborates that the NiFe-LDH nanosheets can provide stronger bonding sites (via the Fe3+-O(H)-Pt bonds) to immobilize Pt NPs than those of Ni(OH)2 nanosheets (via the Ni2+-O(H)-Pt bonds).

Pure Ni nanocrystallines anchored on rGO present ultrahigh electrocatalytic activity and stability in methanol oxidation.

Pure Ni nanoparticles with ultrafine size (2.3 ± 0.4 nm) embedded on rGO present ultrahigh catalytic activity (1600 mA mg-1), excellent stability (1020 mA mg-1 retained after 1000 cycles), and a saturation concentration (4 M) of methanol for methanol oxidation reactions, which is better than that of all previously reported Ni-based catalysts.