Oxalic Acid-Assisted Vacancy Engineering Promotes Iron-Copper Sulfide Nanosheets for High-Current Density Water Oxidation.

The effective defect and interface coupling are pivotal for the promotion of the catalytic activity for the oxygen evolution reaction. Herein, we report novel hybrid nanosheets with sulfur vacancies composed of FeS2 and Cu39S28 grown on Cu foam (Vs-FeS2/Cu39S28). The optimal Vs-FeS2/Cu39S28 exhibits a high current output of 500 mA cm-2 at a low overpotential of 370 mV and robust stability for 60 h at 100 mA cm-2, surpassing the values of most previously reported Cu-based catalysts. Furthermore, a two-electrode electrolyzer made by pairing the prepared catalyst with commercial Pt/C requires a low cell voltage of 1.75 V at 100 mA cm-2 and is retained over 80 h. Key to its excellent performance is the synergism between intertwined FeS2 and Cu39S28 domains, enriched by the deliberate introduction of sulfur vacancies, thus optimizing the electronic structure and causing the proliferation of catalytic active sites. This work presents a potent Cu-based electrocatalyst and emphasizes the leveraging of non-precious metals for efficient water oxidation.

Geometric and Electronic Engineering in Co/VN Nanoparticles to Boost Bifunctional Oxygen Electrocatalysis for Aqueous/Flexible Zn-Air Batteries.

Modulating metal-metal and metal-support interactions is one of the potent tools for augmenting catalytic performance. Herein, highly active Co/VN nanoparticles are well dispersed on three-dimensional porous carbon nanofoam (Co/VN@NC) with the assistance of dicyandiamide. Studies certify that the consequential disordered carbon substrate reinforces the confinement of electrons, while the coupling of diverse components optimizes charge redistribution among species. Besides, theoretical analyses confirm that the regulated electron configuration can significantly tune the binding strength between the active sites and intermediates, thus optimizing reaction energy barriers. Therefore, Co/VN@NC exhibits a competitive potential difference (ΔE, 0.65 V) between the half-wave potential of ORR and OER potential at 10 mA cm-2, outperforming Pt/C+RuO2 (0.67 V). Further, catalyst-based aqueous/flexible ZABs present superior performances with peak power densities of 156 and 85 mW cm-2, superior to Pt/C-based counterparts (128 and 73 mW cm-2). This research provides a pivotal foundation for the evolution of bifunctional catalysts in the energy sector.

A novel probe based on rhodamine 101 spirolactam and 2-(2'-hydroxy-5'-methylphenyl)benzothiazole moieties for three-in-one detection of paramagnetic Cu2+, Co2+ and Ni2.

A novel probe based on rhodamine 101 spirolactam and 2-(2'-hydroxy-5'-methylphenyl)benzothiazole moieties (probe 1) was developed as a three-in-one platform for detection of paramagnetic Cu2+, Co2+ and Ni2+ through different processes. Ratiometric changes in emission intensities at 565 nm and 460 nm for 1 (λex = 350 nm) were observed in presence of Co2+, Cu2+ and Ni2+ respectively. This probe displayed ratiometric colorimetric responses and 'turn-on' fluorescence responses (λex = 540 nm) toward Cu2+ and Co2+. Whereas probe 1 exhibited very weak absorption around 480 nm, no 'turn-on' emission (λex = 540 nm) in presence of Ni2+. The detection limits were 0.11 µM and 0.17 µM for Cu2+ and Co2+ ions respectively from ratiometric colorimetric measurements and 26 nM, 54 nM and 101 nM for Cu2+, Co2+ and Ni2+ respectively from ratiometric fluorometric measurements. The excited-state intramolecular proton transfer (ESIPT)-prohibited coupled ring-open process for 1-Cu2+ (1-Co2+) and ESIPT-prohibited irreversible process for 1-Ni2+ were proposed according to the spectral results. Furthermore, probe 1 was utilized to determine Cu2+ and Co2+ in real-life samples with good recoveries.