Promotion of borophene/NiO-based electrocatalyst for oxygen evolution reaction

Promotion of borophene/NiO-based electrocatalyst for oxygen evolution reaction


Electrochemical water splitting has great potential for converting electricity into clean energy through electrode reactions. However, the anodic oxygen evolution reaction (OER) exhib its 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 (IrO2 or RuO2). 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 NiB12O14(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.

Summary for Non-Scientists

The study relates to electrochemicalwater splitting, a process that can turn electricity into clean energy by using reactions at electrodes. A key part of this process is the oxygenevolution reaction (OER), which has some problems: it requires a lot of extra energy (high overpotential), it’s slow, it doesn’t work well at highpower, and the catalysts (like IrO2 or RuO2) are expensive. The study introduces a new material to improve OER. It’s a composite made of 2Dborophene (a flat form of boron) with nickel oxidenanoparticles attached. This combo works really well for OER, needing much less extra energy (a low overpotential of 191 millivolts) to achieve a current density of 10 milliamperes per square centimeter, and it has a Tafel slope of 44 millivolts per decade, which is a measure of how quickly the reaction speeds up with increasing voltage. This new material is also stableover time, keeping 99.9% of its potential even at a high current density of 50 milliamperes per square centimeter. It has a larger electrochemical surface area (ECSA), meaning it has more active spots where the reaction can happen compared to its individual parts. The researchers looked closely at the material before and after OER using various techniques and found that the borophene and nickel oxide work together really well, making electrons move easily and creating helpful intermediate compounds like NiB12O14(OH)10 during the reaction. Making this borophene-nickel oxide material is straight forward, cheap, and can be done on a large scale. Plus, it opens up new possibilities for exploring other 2D materials as catalysts in OER, which could significantly advance the field.

Source :
Chemical Engineering Journal
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