Fluorine-free synthesized tantalum carbide (Ta2C Mxene) as an efficient electrocatalyst for water reduction and nitro compound reduction

Abstract

One of the eco-sustainable sustainable ways to generate hydrogen, which is considered a clean energy source, involves the electrochemical process. On the other hand, identifying the most effective heterogeneous catalyst is crucial for amine synthesis from nitro compounds in order to determine the optimum catalytic activity, stability, and reusability. Herein, we report the preparation of a 2D tantalum carbide MXene via the fluorine-free etching method and its application in catalysis (nitro reduction) and electrocatalysis (HER and nitro reduction). It is well-known that due to their layered structure, MXenes show better catalytic activities, and hence they find applications in catalysis. Ta₂AlC (MAX phase) and Ta₂C (MXene) were evaluated for their electrocatalytic activity in the hydrogen evolution reaction. The electrocatalyst Ta₂C MXene exhibited overpotentials of 223 mV to reach 10 mA cm⁻² current density when tested under standard HER conditions (0.5 M H₂SO₄), and furthermore, the electrocatalytic reduction behavior of Ta₂C MXene towards the electrochemical reduction of 4-NP was tested in 1 M KOH. Galvanostatic electrolysis was performed in a divided cell using Ta₂C modified carbon cloth as the cathode, and Pt as the anode separated by a Nafion membrane, and it showed 72% product conversion and 96% faradaic efficiency. The progress of the galvanostatic electrolysis was monitored using ex situ Raman and UV-Vis spectroscopy. Similarly, the reducing behavior of Ta₂C towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH₄ was tested. The Ta₂C MXene displayed improved catalytic activity with pseudo-first-order kinetics. Ta₂C nanoparticles completely reduced all three nitro compounds (10 mL each), 4-NP (216 μM–17 min), 2,4-dinitrophenol DNP (163 μM–25 min) and 2,4,6-trinitrophenol TNP (131 μM–36 min). Furthermore, in all these studies, the Ta₂C MXene exhibited improved catalytic performance and stability.