Aprotic solvent-assisted local Lewis acid etching for the efficient doping of Cu ions into Ni foam with enhanced electrochemical sensing performance

Nickel-based electrodes are attractive candidates for electrochemical sensing owing to their abundance and rich redox chemistry, but their moderate intrinsic catalytic activity and limited conductivity still hamper high-performance applications. In this work, we propose an aprotic solvent-assisted Lewis acid etching strategy for the efficient doping of Cu ions into pure Ni to construct an electrochemical sensor based on Cu ions-doped Ni foam electrode (Cu_DA-NF). In contrast to conventional protic media, the aprotic solvent regulates ion solvation and migration during the Lewis acid etching process, suppresses parasitic redox reactions, and markedly improves the efficiency and uniformity of metal doping. The resulting Cu_DA-NF electrode exhibits enhanced electrical conductivity and electrocatalytic activity, contributing to the high sensitivity, a low detection limit and a wide linear range in the electrochemical detection of dopamine hydrochloride (DAH). The sensor also shows excellent selectivity, reproducibility, and operational stability, and it enables accurate determination of DAH in animal feed samples with satisfactory recoveries. This aprotic solvent–assisted metal-doping strategy provides a simple and general route to engineering highly active transition-metal electrodes for electrochemical DAH analysis and can be extended to the construction of electrochemical sensors for other hazardous substances.