Engineering electronic properties is a promising way to design nonprecious-metal or earth-abundant catalysts toward hydrogen evolution reaction (HER). Herein, we deposited catalytically active MoS flakes onto black phosphorus (BP) nanosheets to construct the MoS-BP interfaces. In this case, electrons flew from BP to MoS in MoS-BP nanosheets because of the higher Fermi level of BP than that of MoS. MoS-BP nanosheets exhibited remarkable HER performance with an overpotential of 85 mV at 10 mA cm. Due to the electron donation from BP to MoS, the exchange current density of MoS-BP reached 0.66 mA cm, which was 22 times higher than that of MoS. In addition, both the consecutive cyclic voltammetry and potentiostatic tests revealed the outstanding electrocatalytic stability of MoS-BP nanosheets. Our finding not only provides a superior HER catalyst, but also presents a straightforward strategy to design hybrid electrocatalysts.

The reaction between Fe 2+ and HClO constitutes a promising advanced oxidation process (AOP) for removing pollutants from wastewater, and • OH has been considered the dominant reactive oxidant despite limited evidence for this. Herein, we demonstrate that the Fe 2+ /HClO reaction enables the production of Fe IV O 2+ rather than • OH in acid medium, a finding that is strongly supported by multiple lines of evidence. Both X-ray absorption near-edge structure spectroscopic tests and Mossbauer spectroscopic tests confirmed the appearance of Fe IV O 2+ as the reactive intermediate in the reaction between Fe 2+ and HClO. The determination of Fe IV O 2+ generation was also derived from the methyl phenyl sulfoxide (PMSO)-based probe experiments with respect to the formation of PMSO 2 without • OH adducts and the density functional theory studies according to the lower energy barrier for producing Fe IV O 2+ compared with • OH. A dual-anode electrolytic system was established for the in situ generation of Fe 2+ and HClO that allows the production of Fe IV O 2+ . The system exhibits an enhanced capacity for oxidizing a model pollutant (e.g., phosphite) from industrial wastewater, making it an attractive and promising AOP for the abatement of aqueous contaminants.

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Core–shell nanostructures have received widespread attention because of their potential usage in various technological and scientific fields. However, they still face significant challenges in terms of fabrication of core–shell nanostructure libraries on a controlled, and even programmed scale. This study proposes a general approach to systematically fabricate core–shell nanohybrids using liquid‐metal Ga alloys as reconfigurable templates, and the initiation of a local galvanic replacement reaction is demonstrated utilizing an ultrasonic system. Under ultrasonic agitation, the hydrated gallium oxides generated on the liquid metal droplets, simultaneously delaminated themselves from the interfaces. Subsequently, single‐metal or bimetallic components are deposited on fresh smooth Ga‐based alloys via galvanic reactions to form unique core–shell metal/metal nanohybrids. Controlled and quantitative regulation of the diversity of the non‐homogeneous nanoparticle shell layer composition is achieved. The obtained core–shell nanostructures are used as efficient microwave absorbers to dissipate unwanted electromagnetic wave pollution. The effective absorption bands (90% absorption) of core–shell GaNi and GaCoNi nanohybrids are 3.92 and 3.8 GHz at a thickness of 1.4 mm, respectively. This general and advanced strategy enables the growth of other oxides or sulfides by spontaneous interfacial redox reactions for the fabrication of functional materials in the future.

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Abstract:The phase transformation of iron minerals induced by aqueous Fe(II) (Fe(II) aq ) is a critical geochemical reaction which greatly affects the geochemical behavior of soil elements. How the geochemical behavior of rare earth elements (REEs) is affected by the Fe(II) aq -induced phase transformation of iron minerals, however, is still unknown. The present study investigated the adsorption and immobilization of REEs during the Fe(II) aq -induced phase transformation of ferrihydrite. The results show that the heavy REEs of Ho(III) were more efficiently adsorbed and stabilized compared with the light REEs of La(III) by ferrihydrite and its transformation products, which was due to the higher adsorptive affinity and smaller atomic radius of Ho(III). Both La(III) and Ho(III) inhibited the Fe atom exchange between Fe(II) aq and ferrihydrite, and sequentially, the Fe(II) aq -induced phase transformation rates of ferrihydrite, because of the competitive adsorption with Fe(II) aq on the surface of iron (hydr)oxides. Owing to the larger amounts of adsorbed and stabilized Ho(III), the inhibition of the Fe(II) aq -induced phase transformation of ferrihydrite affected by Ho(III) was higher than that by La(III). Our findings suggest an important role for the Fe(II) aq -induced phase transformation of iron (hydr)oxides in assessing the mobility and transfer behavior of REEs, as well as for their occurrence in earth surface environments.

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