The hydrogen evolution reaction (HER) of molybdenum disulfide (MoS 2 ) is limited in alkaline and acid solution because the active sites are on the finite edge with extended basal plane remaining inert. Herein, we activated the interfacial S sites by coupling with Ru nanoparticles on the inert basal plane of MoS 2 nanosheets. The density functional theory (DFT) calculation and experimental results show that the interfacial S electronic structure was modulated. And the results of Δ G H* demonstrate that the adsorption of H on the MoS 2 was also optimized. With the advantage of interfacial S sites activation, the Ru-MoS 2 needs only overpotential of 110 and 98 mV to achieve 10 mA·cm −2 in both 0.5 M H 2 SO 4 and 1 M KOH solution, respectively. This strategy paves a new way for activating the basal plane of other transition metal sulfide electrocatalysts for improving the HER performance.
Lei Wang,Cunzhi Zhang,Hui He,Hongxiang Zhu,Wei Guo,Shile Zhou,Shuangfei Wang,Joe R. Zhao,Jian Zhang
A novel cellulose-based colorimetric sensor (DAC-Tu) with N, S sites for Ag + was prepared. The DAC-Tu exhibited excellent selectivity and sensitivity for Ag + with a naked eyes color change from white to black in mixed metal ions aqueous solutions. The naked-eye in-situ detection limit of DAC-Tu for Ag + was 10 −6 mol/L within 10 min. The cellulose matrix and the grafted functional groups ( C S, NH 2 ) of DAC-Tu all contributed to the low naked-eye in-situ detection limit. The mechanism of the visual recognition of DAC-Tu sensor for Ag + was proposed, the N and S atoms of DAC-Tu preferentially coordination chelated with Ag + to form N Ag, S Ag, and Ag 2 S, and enriched on the cellulose matrix, thus the DAC-Tu presented different color change in response to different concentrations of Ag + . The as-prepared DAC-Tu colorimetric sensor showed a great application prospect for in-situ naked eyes detection of Ag + .
Min Lu,Li An,Jie Yin,Jing Jin,Rui Yang,Bolong Huang,Yang Hu,Yong-Qing Zhao,Pinxian Xi
The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are key electrochemical processes in metal–air batteries and water splitting devices. Aluminium–air batteries, as an important type of metal–air battery, have been considered to be promising power candidates for flexible electronics. Here, we describe electronically engineered amorphous Fe–Co–S sites embedded in Prussian blue analogue (FeCoSx-PBA) hetero-nanoframes. The experimental results and DFT calculations reveal the critical role of the introduced FeCoSx layer to PBA, which enhances the electron transfer and alleviates the overbinding effect of OH* during the OER. The FeCoSx-PBA hybrid system supplies an optimized electronic structure for the alkaline OER, which is also confirmed by the much-lowered overpotential (266 mV at 10 mA cm−2) for the alkaline OER. Furthermore, a flexible Al–air battery based on an FeCoSx-PBA cathode catalyst exhibits a high peak power density (58.3 mW cm−2) and energy density (1483 W h kgAl−1), and outstanding stability for more than 50 h of operation under bending or stretching conditions, demonstrating its potential in the practical application of flexible electronic devices. Our results may provide a new strategy of modulating the electronic structure of air electrode catalysts to efficiently promote the reactivity of alkaline OER and Al–air battery processes.
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