In situ growth of copper oxide on MXene by combustion method for electrochemical ammonia production from nitrate

Abstract

The elimination of the nitrogen pollutant nitrate ions through the electrochemical synthesis of ammonia is an important and environment friendly strategy. Electrochemical nitrate reduction requires highly efficient, selective, and stable catalysts to convert nitrate to ammonia. In this work, a composite of copper oxide and MXene was synthesized using a combustion technique. As reported, nitrate ions are effectively adsorbed by Cu_xO (CuO & Cu₂O) nanoparticles. Herein, MXene is an excellent assembly for anchoring Cu_xO on its layered surface because it has a strong support structure. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses show the presence of oxidation states of metal ions and the formation of Cu_xO nanofoam anchors on the surface of MXene (Ti₃C₂T_x). The optimized Cu_xO/Ti₃C₂T_x composite exhibits an improved nitrate reduction reaction. The electrochemical studies of Cu_xO/Ti₃C₂T_x show an interesting nitrate reduction reaction (NO₃RR) with a current density of 162 mA cm⁻². Further, Cu_xO/Ti₃C₂T_x shows an electrocatalytic activity with an ammonia production of 41 982 μg h⁻¹ m_cat⁻¹ and its faradaic efficiency is 48% at −0.7 V vs. RHE. Thus, such performance by Cu_xO/Ti₃C₂T_x indicates a well-suitable candidate for nitrate ion conversion to ammonia.