Advanced electrochemical synthesis of multicomponent metallic nanorods and nanowires: Fundamentals and applications

Abstract Intensive research efforts during the last few years have been performed to combine electrochemistry and nanotechnology in order to fabricate new 1D nanostructures with increasing potentiality for catalysis, sensing, energy, remediation and biomedicine. Here we describe, analyze and discuss the different electrochemical strategies developed to fabricate multicomponent metallic nanowires (NWs) and nanorods (NRs), by means of the so-called shape-controlled electrodeposition. The fabrication of compact NWs/NRs in no template, soft-template or hard-template electrodeposition has been recently revolutionized using micellar or microemulsion electrolytes to fabricate mesoporous NWs/NRs with extraordinary effective surface areas. Taking into account the experience in the electrochemical fabrication of unicomponent metallic NWs/NRs of different types, different researchers have developed new protocols for obtaining multicomponet metallic 1D structures in which the presence of more than one component defines new properties for the NWs/NRs, expanding their application fields. Therefore, core@shell NWs/NRs have been electrochemically fabricated and subsequently treated (superficial oxidation, galvanic displacement, etc.) to generate a superficial active shell, to combine the properties of the core and the shell, or to confer biocompatibility to the NWs/NRs. Bi- or multi-segmented NWs/NRs have also been designed recently, following different electrochemical strategies, to multiply the active surfaces in order to fabricate biomedical platforms or robotic nanostructures. Also, multicomponent composite NWs/NRs incorporating nanoparticles or formed by two combined materials can be fabricated. Electrochemical strategies have been also refined to form novel very complex structured NWs/NRs as bi- or multi-segmented NWs/NRs with core@shell, composite or porous segments alternated or combined, hybrid structures NW + particles at the end of the wire, or bioinorganic NWs/NRs structures. Finally, the review describes the utility of the electrochemically fabricated multicomponent metallic NWs/NRs in catalysis (for clean energy production, synthesis and remediation), medicine and health, sensing and biosensing, and as nanorobots.