Ruthenium triazine composite: a good match for increasing hydrogen evolution activity through contact electrification

The development of Pt‐free catalysts for the alkaline hydrogen evolution reaction (HER), which is widely used in industrial scale water‐alkali electrolyzers, remains a contemporary and pressing challenge. Ruthenium (Ru) has excellent water‐dissociation abilities and could be an alternative water splitting catalyst. However, its large hydrogen binding energy limits HER activity. Here, a new approach is proposed to boost the HER activity of Ru through uniform loading of Ru nanoparticles on triazine‐ring (C3N3)‐doped carbon (triNC). The composite (Ru/triNC) exhibits outstanding HER activity with an ultralow overpotential of ≈2 mV at 10 mA cm−2; thereby making it the best performing electrocatalyst hitherto reported for alkaline HER. The calculated metal mass activity of Ru/triNC is >10 and 15 times higher than that of Pt/C and Pt/triNC. Both theoretical and experimental studies reveal that the triazine‐ring is a good match for Ru to weaken the hydrogen binding on Ru through interfacial charge transfer via increased contact electrification. Therefore, Ru/triNC can provide the optimal hydrogen adsorption free energy (approaching zero), while maintaining the strong water‐dissociation activity. This study provides a new avenue for designing highly efficient and stable electrocatalysts for water splitting

Spatiotemporal Variation in Extreme Climate in the Yellow River Basin and its Impacts on Vegetation Coverage

Global warming and extreme climate events (ECEs) have grown more frequent, and it is essential to investigate the influences of ECEs on vegetation in the Yellow River Basin (YRB) and other environmentally fragile areas. This study was based on data from 86 meteorological stations in the YRB for the period 2000–2020. Twenty-five extreme climate indices (ECIs) were chosen, encompassing four dimensions: extreme value, intensity, duration, and frequency. The trend analysis approach was used to examine the spatiotemporal characteristics of extreme climate conditions. Additionally, geographical detectors and Pearson correlation analysis methods were employed to quantitatively assess the influence of ECEs on the Normalized Difference Vegetation Index (NDVI). The Multiscale Geographically Weighted Regression (MGWR) method was adopted to analyze the regression of twenty-five ECIs. The findings revealed the following: (1) Over the last 21 years, there has been a distinct rise in both the extreme precipitation indices (EPIs) and the extreme temperature indices (ETIs). (2) The spatial distribution of the NDVI throughout the year displayed the characteristic of being high in the south and low in the north. The annual NDVI demonstrated a noteworthy increase at a rate of 0.055/decade, with the enhancement encompassing an extensive area of 87.33%. (3) The investigation revealed that EPIs, including PRCPTOT, R10mm, CWD, R95p, and CDD, had explanatory values surpassing 0.4. This implied that the intensity, frequency, and duration of extreme precipitation played pivotal roles in steering vegetation alterations in the YRB. (4) The correlation between the EPIs and vegetation was greater than the ETIs. Grassland meadows exhibited greater sensitivity to precipitation than woody plants. The EPIs (excluding CDD and SDII) and the ETIs (TXn) displayed a substantial positive correlation with the NDVI in regions hosting grasslands, broadleaf forests, and shrubs. Desert vegetation and cultivated plants were less affected by ECEs. This study underscores the importance of the interplay between extreme climate and vegetation in the YRB. Additionally, it provides a scientific basis for formulating environmental safeguarding strategies

A Medium-Frequency Fiber Bragg Grating Accelerometer Based on Flexible Hinges

Mediumfrequency fiber Bragg grating (FBG) acceleration sensors are used in important applications in mechanical, aerospace and weapon equipment, and have strict requirements in terms of resonance frequency and sensitivity. A novel medium-frequency accelerometer, based on fiber Bragg grating and flexible hinges, is proposed in this paper. The differential structure doubles the sensitivity of the sensor while avoiding temperature effects. The structure model and principle for the sensor are introduced, the sensor’s sensing characteristics are theoretically analyzed, and the structure parameters for the sensor are determined through numerical analysis. The sensing experiments show that the resonance frequency of the sensor is approximately 2800 Hz, the sensitivity is 21.8 pm/g in the flat frequency range of 50–1000 Hz, and the proposed sensor has a good temperature self-compensation function and lateral anti-interference capability

Dual-doping of ruthenium and nickel into Co3O4 for improving the oxygen evolution activity

Spinel oxides Co3O4 with mixed valence cations Co2+ and Co3+ make it possible to improve the catalytic activity by regulating the distribution of cations via additional doping. Controllable synthesis of nanosized Co3O4 with excellent catalytic properties and stability towards the oxygen evolution reaction (OER) is critical for conversion and storage of sustainable source-derived electricity. Herein, Ru and Ni co-doped Co3O4 nanoparticles (Ru/Ni-Co3O4) with abundant active sites and oxygen vacancies were synthesized by a one-step hydrothermal method. Ru atoms doped into the octahedral sites improve the intrinsic activity of spinel oxide Co3O4, while the introduction of Ni creates abundant oxygen vacancies, thus exposing more active sites at the surface and accelerating the OER kinetics. The optimized Ru/Ni-Co3O4 nanoparticles possess a low overpotential (290 mV at 10 mA cm(-2)) and excellent stability (only 1% activity decay after 10 h), significantly superior to the state-of-the-art IrO2 and most OER electrocatalysts reported before. This work provides a new strategy to increase the density of the active sites and generate surface oxygen vacancies simultaneously without destroying the crystallinity/microstructure and use of any additional complicated treatments (such as plasma techniques and multi-step pyrolysis)

Interface catalysis by Pt nanocluster@Ni3N for bifunctional hydrogen evolution and oxygen evolution

Due to their importance for practical applications in energy conversion, resolving the kinetic issues of water-dissociation in alkaline media for Pt-based electrocatalysts remains an ongoing challenge. Herein, the electronic properties of Pt could be modified with a nickel nitride (Ni3N) support through forming an interface of a low ratio of Pt nanoclusters (Pt NCs)viaa simple impregnation approach combined with nitridation. 1.5Pt@Ni3N-360 can offer excellent bifunctional performance for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) which is competitive with commercial IrO(2)and Pt/C catalysts under alkaline media. It shows a low overpotential at 10 mA cm(-2)(285 and 71 mV) and a small Tafel slope (57 and 48 mV dec(-1)) for OER and HER, respectively. The excellent bifunctional electrochemical activity of 1.5Pt@Ni3N-360 is due to the interface and synergetic effect between Ni3N and dispersed Pt clusters, which changes the electron distribution of the material, so that the hydrogen adsorption energy tends to the optimal value (Delta G(H*)similar to 0). It is believed that the utilization of low-ratio Pt as an co-electrocatalyst with a variety of metal nitrides opens new horizons and opportunities to fabricate more efficient electrocatalysts for broad applications in energy-related devices

Increased activity of nitrogen-doped graphene-like carbon sheets modified by iron doping for oxygen reduction

Increased activity of nitrogen-doped graphene-like carbon sheets modified by iron doping for oxygen reductio

Ruthenium Triazine Composite: A Good Match for Increasing Hydrogen Evolution Activity through Contact Electrification

The development of Pt-free catalysts for the alkaline hydrogen evolution reaction (HER), which is widely used in industrial scale water-alkali electrolyzers, remains a contemporary and pressing challenge. Ruthenium (Ru) has excellent water-dissociation abilities and could be an alternative water splitting catalyst. However, its large hydrogen binding energy limits HER activity. Here, a new approach is proposed to boost the HER activity of Ru through uniform loading of Ru nanoparticles on triazine-ring (C3N3)-doped carbon (triNC). The composite (Ru/triNC) exhibits outstanding HER activity with an ultralow overpotential of approximate to 2 mV at 10 mA cm(-2); thereby making it the best performing electrocatalyst hitherto reported for alkaline HER. The calculated metal mass activity of Ru/triNC is >10 and 15 times higher than that of Pt/C and Pt/triNC. Both theoretical and experimental studies reveal that the triazine-ring is a good match for Ru to weaken the hydrogen binding on Ru through interfacial charge transfer via increased contact electrification. Therefore, Ru/triNC can provide the optimal hydrogen adsorption free energy (approaching zero), while maintaining the strong water-dissociation activity. This study provides a new avenue for designing highly efficient and stable electrocatalysts for water splitting

Mechanochemical synthesis of multi-site electrocatalysts as bifunctional zinc-air battery electrodes

Mechanochemical synthesis of multi-site electrocatalysts as bifunctional zinc-air battery electrode

Interface Engineering with Ultralow Ruthenium Loading for Efficient Water Splitting

Developing high-performance and cost-effective bifunctional electrocatalysts for water splitting is the key to large-scale hydrogen production. How to achieve higher performance with a lower amount of noble metal is still a major challenge. Herein, using a facile wet-chemistry strategy, we report the ultralow amount loading of ruthenium (Ru) on porous nickel foam (NF) as a highly efficient bifunctional electrocatalyst for water splitting. Theoretical simulations reveal that the coupling effect of Ru and Ni can significantly reduce the d-band center of the composite. The Ru-modified NF exhibits a very high level of HER activity with only 0.3 wt% of Ru, far surpassing commercial Pt/C. It only requires an extremely low overpotential (eta(10)) of 10 mV to achieve a current density of 10 mA cm(-2). in alkaline solution and a quite low Tafel slope of 34 mV dec(-1). This catalyst also shows remarkable performance for overall water splitting with a low voltage of 1.56 V at 10 mA cm(-2). These findings indicate the potential of this material in water-alkali electrolyzers, providing a new approach for fabrication of low-cost advanced electrocatalysts