Engineered V2C MXene Anchored Cu Nanoparticles for Selective Nitrate/Nitrite Sensing and Magneto-Electrocatalytic Hydrogen Evolution Reaction

The pursuit of developing electrode materials that can seamlessly integrate both sensing and catalytic functions remains a key goal in the field of electrochemical materials research. This study introduces a hybrid electrochemical platform that utilizes copper nanoparticles on delaminated V2CTx MXene to explore the material's inherent electrochemical and catalytic characteristics. The two-dimensional V2CTx structure offers a substantial accessible surface area, excellent electrical conductivity, and surface terminations that can be chemically adjusted, while the electrodeposited Cu nanoparticles provide additional catalytic active sites and enhance charge transfer efficiency. The resulting V2C@Cu composite exhibits highly selective electrochemical detection of nitrate and nitrite ions in alkaline conditions, showing two linear concentration ranges (0.1-10 mM and 10-30 mM) with detection limits of 0.232 and 0.475 mM for nitrate and 0.08 and 0.45 mM for nitrite, respectively. Beyond its sensing capabilities, the material also demonstrates magneto-electrocatalytic activity for the hydrogen evolution reaction under low external magnetic fields (0-2000 G), where the overpotential decreases from 465.49 to 374.94 mV at 10 mA cm-2 and the Tafel slope improves from 126.78 to 93.25 mV dec-1. The composite electrode also shows remarkable electrochemical stability during repeated cycling and extended potentiostatic operation. Its practical applicability was further validated by successfully detecting nitrate and nitrite in environmental water samples with high recovery efficiencies. These results reveal the potential of V2C@Cu MXene as a versatile materials platform for combined electrochemical sensing and magneto-electrocatalytic applications.