Sustainable wet-chemical sintering of metal-based 3D-printed electrodes enables high-performance electrochemical transducers

Fused Filament Fabrication (FFF) enables rapid and low-cost manufacturing of metal-based 3D-printed components with customizable geometries. However, as-printed metallic systems typically suffer from poor electrical conductivity, necessitating tedious activation post-treatments, such as high-temperature annealing or electroplating technologies, to make them suitable for electrochemical applications. While effective, these methods are costly, time-consuming, and environmentally unfriendly, also requiring specialized equipment. Herein, we report a green wet-chemical activation strategy based on sodium borohydride (NaBH), as a mild reducing agent, which induces room-temperature chemical sintering in 3D-printed copper electrodes (3D-CuEs). As a proof-of-concept, the NaBH-activated 3D-CuEs have been successfully applied to the voltammetric determination of nitrate (NO ) in water via nitrate reduction reaction (NRR), exhibiting a wide linear range (1.5-2553 ppm), a low detection limit of 1.5 ppm, and excellent recoveries in real water samples. Overall, this sustainable and scalable activation method provides a versatile route toward the large-scale fabrication of high-performance metal-based 3D-printed electrodes, opening new opportunities for advanced electrochemical applications.