Unveiling Copper Vanadium Sulfide Nanocrystals as a Next-Generation Electrocatalyst for Selective Nitrate Remediation...

The Haber-Bosch process dominates ammonia production but is energy-intensive and a major source of COx emissions. Electrochemical nitrate reduction (NORR) presents a sustainable alternative by simultaneously remediating nitrate pollution and enabling carbon-neutral, or even carbon-negative, ammonia synthesis. However, NORR still suffers from high overpotentials, limited selectivity, and poor catalyst durability. Here, a one-pot hydrothermal strategy is reported for synthesizing ternary copper-vanadium sulfide (CVS) nanocrystals as a robust, heavy-metal-free NORR electrocatalyst operating under ambient conditions. The synergistic Cu-V interactions within the sulvanite framework enhance reduction activity, while vertical stacking and high crystallinity provide a large electrochemically active surface area and efficient charge transport. CVS delivers a significantly low onset potential (-0.476 V) and overpotential (-0.596 V at 10 mA cm^-2 vs RHE), rapid kinetics (Tafel slope: 34.1 mV dec^-1), and a high Faradaic efficiency (FE) of 91%, outperforming binary counterparts such as VS₂ and CuS. Importantly, its potential efficacy is validated using real agricultural runoff water, demonstrating practical relevance beyond laboratory conditions. Further, detailed computational studies including catalytic free energy calculations on the CVS (110) surface reveal favorable reaction energetics, consistent with experimental observations. Overall, this unique work positions ternary chalcogenides as promising platforms for decentralized and sustainable green ammonia synthesis.