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Recently, water oxidation or oxygen evolution reaction (OER) in electrocatalysis has attracted huge attention due to its prime role in water splitting, rechargeable metal–air batteries, and fuel cells. Here, we demonstrate a facile and scalable fabrication method of a rod-like structure composed of molybdenum disulfide and carbon (MoS2/C) from parent 2D MoS2. This novel composite, induced via the chemical vapor deposition (CVD) process, exhibits superior oxygen evolution performance (overpotential = 132 mV at 10 mA cm−2 and Tafel slope = 55.6 mV dec−1) in an alkaline medium. Additionally, stability tests of the obtained structures at 10 mA cm−2 during 10 h followed by 20 mA cm−2 during 5 h and 50 mA cm−2 during 2.5 h have been performed and clearly prove that MoS2/C can be successfully used as robust noble-metal-free electrocatalysts. The promoted activity of the rods is ascribed to the abundance of active surface (ECSA) of the catalyst induced due to the curvature effect during the reshaping of the composite from 2D precursor (MoS2) in the CVD process. Moreover, the presence of Fe species contributes to the observed excellent OER performance. FeOOH, Fe2O3, and Fe3O4 are known to possess favorable electrocatalytic properties, including high catalytic activity and stability, which facilitate the electrocatalytic reaction. Additionally, Fe-based species like Fe7C3 and FeMo2S5 offer synergistic effects with MoS2, leading to improved catalytic activity and durability due to their unique electronic structure and surface properties. Additionally, turnover frequency (TOF) (58 1/s at the current density of 10 mA cm−2), as a direct indicator of intrinsic activity, indicates the efficiency of this catalyst in OER. Based on ex situ analyzes (XPS, XRD, Raman) of the electrocatalyst the possible reaction mechanism is explored and discussed in great detail showing that MoS2, carbon, and iron oxide are the main active species of the reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 2D borophene-NiO composite electrocatalyst. • Composite exhibits low overpotential, high stability, and enhanced kinetics. • Borophene-NiO composite with exceptional Tafel slope and active sites. • Spectroscopic and microscopic analyses reveal facilitated electron transfer and new reaction intermediates. • Borophene functionalized by NiO opens new avenues in catalytic research. Electrochemical water splitting has great potential for converting electricity into clean energy through electrode reactions. However, the anodic oxygen evolution reaction (OER) exhibits serious drawbacks such as: (i) high overpotential, slow reaction dynamics, limited robustness at high current density, and (ii) high cost of standard catalysts in OER (IrO 2 or RuO 2). Therefore, in our study, we address those issues and present a new composite based on 2D borophene functionalized with nickel oxide nanoparticles with highly active electrocatalytic properties in OER, with a low overpotential of 191 mV reaching j = 10 mA/cm2 and Tafel slope of 44 mV/dec. Additionally, the structure showed electrochemical and physical stability during long-term measurements, with excellent potential retention of 99.9 % at 50 mA/cm2. The electrochemical surface area (ECSA) revealed an increase in the number of active sites available for the reaction to occur, with respect to individual components of composites. Detailed spectroscopic and microscopic analyses of the electrocatalyst conducted before and after OER allowed us to propose insight into the reaction mechanism indicating the synergy between borophene and NiO nanoparticles (facilitated electron charge transfer and additional reaction intermediate such as NiB 12 O 14 (OH) 10). The proposed fabrication process of borophene functionalized by NiO is facile, low-cost, and scalable. Moreover, this strategy offers an additional avenue to explore a 2D family of electrocatalysts in OER enriching the current state of the art in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Overpotential of ZIF-67 calcinated at 200 °C (ZIF-67 200) is 317.8 mV, lower than for RuO 2 (411.5 mV). • The robustness of ZIF-67 200 was proved in the stability test (potential retention of 99.6% at 20 mA·cm−2). • Optimal low-temperature calcination exposes coordinatively unsaturated Co sites and accelerates electrochemical activity. • Low-temperature calcination is a general approach to boost the electroactivity of metal-organic frameworks. An efficient electrocatalyst is crucial for sustainable hydrogen-fuel production, where cobalt oxyhydroxide is one of the most active catalysts for alkaline water splitting. Here, we designed a series of Co-based catalysts fabricated by direct low-temperature calcination of ZIF-67 for electrocatalytic oxygen evolution reaction (OER). Interestingly, the treatment of the pristine ZIF-67 by the temperature of only 200 °C was found to induce the most electroactive composition with a high electrochemically active surface of 373.5 cm2 and turnover frequency of 129.7 s−1, while a high specific surface area (1745 m2·g−1) is preserved. It resulted in a robust catalyst with a low overpotential of 317.8 mV at 10 mA·cm−2 and accelerated charge transfer, leading to improved performances in electrochemical energy conversion from water. Moreover, using in situ spectroscopy, XRD and microscopic techniques the active intermediates, for example, M-O, M-OH, and M-OOH were revealed and thus the exact mechanism of the reaction was proposed. Due to the formation of active species a lattice oxygen mechanism (LOM) was revealed. [ABSTRACT FROM AUTHOR]