Speaker
Description
Three-dimensional (3D) nanoarchitectures have attracted growing interest as a powerful platform for enhancing the efficiency of electrochemical energy conversion systems [1]. Among the various materials, nickel-based structures stand out due to their natural abundance, cost-effectiveness, and well-documented electrocatalytic activity toward the hydrogen evolution reaction (HER) under alkaline conditions [2]. Three-dimensional nickel nanowire networks (Ni NWNWs) are promising electrode architectures for alkaline hydrogen evolution because they combine a high geometric surface area with interconnected electron-conduction pathways and mechanical stability. However, the electrochemically active surface area may not scale directly with the geometric surface area, particularly in dense nanowire networks where nanowire overlap and restricted electrolyte transport can limit surface utilization. Understanding and controlling these effects is therefore important for optimizing the performance of 3D Ni nanowire electrodes. In addition, electrodeposition of Ni inside high-aspect-ratio ion-track-etched nanochannels can be complicated due to slow pore filling, hydrogen evolution, non-uniform growth, and premature cap formation.
Here, we investigate the controlled potentiostatic electrodeposition of Ni NWNWs using tailored track-etched templates and examine how nanowire density influences their electrochemically active surface area. Preliminary results show that increasing network density can reduce the fraction of the geometrical surface area that is electrochemically active, likely due to nanowire overlapping and restricted electrolyte penetration. These findings indicate that maximizing the geometrical surface area does not necessarily maximize electrochemical surface utilization, emphasizing the importance of optimizing the geometry of porous electrodes for electrochemical applications. Future work will correlate active surface area and morphology with alkaline HER activity, charge-transfer kinetics, and long-term stability.
References
[1] M. F. P. Wagner, K.-O. Voss, C. Trautmann, M. E. Toimil-Molares, EPJ Tech. Instrum. 10(2023).
[2] P. C. Chen, Y. M. Chang, P. W. Wu, Y. F. Chiu, Int. J. Hydrogen Energy 34 (2009) 6596–6602