Galvanic replacement synthesis of a Ni2Pd1 alloy aerogel nanozyme for sensitive colorimetric detection of L-cysteine

An efficient galvanic replacement synthesis strategy for the preparation of a bimetallic Ni 2 Pd 1 aerogel with remarkable peroxidase-mimicking activity is presented. By employing a non-precious Ni aerogel as a structural template, the precious Pd component is successfully incorporated and alloyed within its three-dimensional (3D) porous network through rational interfacial design. The combination of the intrinsic through-pore structure of metal aerogels with optimized bimetallic composition results in significantly enhanced peroxidase-like performance. Investigations involving radical quenching/trapping experiments and electrochemical tests confirm that the catalytic mechanism proceeds via an electron transfer pathway. Furthermore, based on the specific inhibitory effect of L-cysteine on the catalytic behavior of optimized Ni 2 Pd 1 alloy aerogel, a highly selective colorimetric sensing platform is developed, achieving a detection limit of 1.43 µM and robust anti-interference capability against various common amino acids. This study provides new design concepts and technical pathways for developing high-performance biomimetic sensing materials. Section Graphical abstract