Curvature-programmed nitrate electroreduction via single-atom protrusions on quantum dots.

Local geometric constraints have a substantial influence on electronic structure renormalization, offering a promising approach to enhance single-atom catalysts (SACs) beyond traditional limits. Conventional SACs typically feature planar-confined sites, but three-dimensional configurations remain underexplored. This study introduces a "curvature-programming" strategy to drive electrochemical nitrate reduction by assembling FeCu dual single-atom protrusions on molybdenum carbide quantum dots (FeCu/MoCx-5 QDs). The high-curvature QDs and protruding geometries mimic active vertex sites, enhancing electric fields to polarize N─O bonds. This delivers nearly 100% NH3 Faradaic efficiency over a wide potential window (-0.1 to -0.4 V versus reversible hydrogen electrode), with an ultralow overpotential (300 mV) and energy consumption (7.52 Wh gNH3-1 mgcat-1). FeCu/MoCx-5 effectively reduces nitrate levels in wastewater, producing scalable (NH4)2SO4, thus integrating environmental remediation with renewable energy storage. This work provides a promising strategy for developing SACs for broader energy applications.