Hydrogen Evolution Reaction Performance of Ni-Co-Coated Graphene-Based 3D Printed Electrodes.

Additive manufacturing has been a very promising topic in recent years for research and development studies and industrial applications. Its electrochemical applications are very popular due to the cost-effective rapid production from the environmentally friendly method. In this study, three-dimensional (3D) printed electrodes are prepared by Ni and Co coatings in different molar ratios. Different Ni/Co molar ratios (x:y) of the Ni/Co/x:y alloys are prepared as 1:1, 1:4, and 4:1 and they are named Ni/Co/1:1, Ni/Co/4:1, and Ni/Co/1:4, respectively. According to the results, when the 3D electrode samples are coated with Ni and Co at different molar ratios, the kinetic performance of the NiCo-coated 3D electrode samples for hydrogen evolution reaction is enhanced compared to that of the uncoated 3D electrode sample. The results indicate that the Ni/Co/1:4-coated 3D electrode has the highest kinetic activity for hydrogen evolution reactions (HERs). The calculated Tafel's slope and overpotential value (η10) for HER are determined as 164.65 mV/dec and 101.92 mV, respectively. Moreover, the Ni/Co/1:4-coated 3D electrode has an 81.2% higher current density than the other electrode. It is observed that the 3D printing of the electrochemical electrodes is very promising when they are coated with Ni-Co metals in different ratios. This study provides a new perspective on the use of 3D printed electrodes for high-performance water electrolysis.