Saudi Cultural Missions Theses & Dissertations
Permanent URI for this communityhttps://drepo.sdl.edu.sa/handle/20.500.14154/10
Browse
1 results
Search Results
Item Restricted Synthesis, Optimisation, and Characterisation of Non-Noble Low-Cost Ni-Mo Electrocatalysts for Green Hydrogen Production via Anion Exchange Membrane Water Electrolysis(Saudi Digital Library, 2023-11-01) Alotaibi, Mohammed; Hankin, AnnaAnion exchange membrane water electrolysis (AEMWE) encounters challenges related to stability and catalytic efficiency. This research investigates the use of Ni-Mo catalysts for the hydrogen evolution reaction (HER) within AEMWE, with a focus on optimising preparation conditions, including pH, applied potential, and plating methods on a carbon cloth substrate. An investigation employing electrochemical quartz crystal microbalance with energy dispersive spectroscopy reveals that a more alkaline environment (pH≈10), combined with a more negative applied potential (≤ −1.8 VSCE), results in increased Ni-Mo deposition. Consequently, increased the Mo mass fraction in NiMo alloy reported to be better for catalysis. HER electrocatalytic activity assessment, conducted via a rotating disk electrode, demonstrates a notable enhancement in catalytic performance within the pH range of 9 to 10, reaffirming the pH-dependent nature of catalysis. However, catalytic efficacy diminishes beyond pH 10. Notably, an overpotential analysis pinpoints the catalyst prepared at pH 10, with an applied potential of −2.2 VSCE, as exhibiting superior performance in the HER (with an overpotential of 88.9 mV at 10 mA/cm2 ). Diverse plating techniques were employed to regulate morphology, with the custom-built reactor displaying exceptional performance and yielding a smooth surface structures with a remarkable Mo to Ni mass ratio of approximately 0.22. The proposed Ni-Mo catalyst delivers a current density of 1.6 A/cm2 at a 1.8 cell potential, surpassing pure Ni by 76%, and demonstrating comparable performance to commercial Pt in an AEMWE setup, operating under conditions of 1M KOH and 60 ◦C. This achievement was obtained with a pH of 10, utilising 0.2 M nickel(II) sulfate, 0.12 M sodium molybdate, 0.7 M ammonia, and 0.25 M sodium citrate, plated on carbon cloth using a custom-built reactor with pulse plating at −2.2 VSCE applied potential for 15 min. Collectively, this study underscore the potential of Ni-Mo as a cost-effective alternative to Pt in AEMWEn for H2 evolution, bolstering the quest for affordable and environmentally friendly hydrogen fuel production. Keywords: anion exchange membrane, water electrolyser, green hydrogen, HER, electrocatalyst preparation, Ni-Mo.49 0