Fabrication of Ni-alloy nanostructured elecrodes for alkaline electrolizers

In last years, renewable energy sources are becoming more and more important owing to the progressive decarbonization of energy processes to reduce CO2 emissions [1,2]. In this view, governments and authorities all around the world are encouraging the use of renewable energies by promoting laws and initiatives for the most sustainable energy transition [3,4]. One of the main drawbacks of renewable sources is their unpredictability, consequently, interest in hydrogen has drastically increased. One way to produce green hydrogen is by water electrolysis using only electricity from renewable sources. It is a viable strategy to take advantage of the surplus electricity. The most relevant part of the cost of electrochemical hydrogen comes from the electricity cost and catalysts. For this reason, research is focused on improving the performance of the electrolyzer, using more efficient and less expensive materials, such as transition metal alloys like Nickel-based alloy [5]. One of the possible ways to improve the performance of electrolyzers is based on the development and fabrication of nanostructured electrodes with a low cost and high electrocatalytic activity. In previous works, Ni nanowires were fabricated by template electrosynthesis, featuring by very high surface area. Starting from the best-performing nickel-iron alloy previously studied [6], this work focuses on the fabrication of nickel-iron-sulfur electrodes. In an aqueous solution containing nickel and iron, a third element was added in different concentrations in order to obtain electrodes with different compositions. The chemical and morphological features of these nanostructured electrodes were studied through scanning electrode microscopy (SEM) and energy diffraction spectroscopy (EDS) analyses, and those results will be presented and discussed. Electrochemical and electrocatalytic tests (Cyclic Voltammetry (CV), Quasi Steady State Polarization (QSSP) and Galvanostatic Step) were carried out to establish the best alloy composition for both hydrogen and oxygen evolution reactions. Long-term tests performed at a constant current density in an aqueous solution of potassium hydroxide (30% w/w) will be also reported. Acknowledgments This research was funded by CNMS, Centro Nazionale per la Mobilità sostenibile (MUR, PNRR-M4C2, CN00000023), spoke 12 – innovative propulsion. References [1] A.T.D. Perera, R.A. Attalage, K.K.C.K. Perera, V.P.C.Dassanayake, “Designing standalone hybrid energy systems minimizing initialinvestment, life cycle cost and pollutant emission” Energy, 54, 2013, 237-248. [2] K. Bandara, T. Sweet, J. Ekanayake, “Photovoltaic applications for off-grid electrification using novel multi-level inverter technology with energy storage”, Renewable Energy, 37, 2012, 82-88 [3] P. Balcombe, D. Rigby, A. Azapagic, “Motivations and barriers associated with adopting microgeneration energy technologies in the UK”, Renewable and Sustainable Energy Reviews, 22, 2013, 655-666. [4] H. Meyar-Naimi, S. Vaez-Zadeh, “Sustainable development-based energy policy making frameworks, a critical review”, Energy Policy, 43, 2012, 351-361. [5] F. Safizadeh, E. Ghali, G. Houlachi, “Electrocatalysis developments for hydrogen evolution reaction in alkaline solutions – A Review”, International Journal of Hydrogen Energy, 40, 2015, 256–274. [6] B. Buccheri, F. Ganci, B. Patella, G. Aiello, P. Mandin, R. Inguanta, “Ni-Fe alloy nanostructured electrodes for water splitting in alkaline electrolyser”, Electrochimica Acta, Volume 388, 2021, 0013-4686.