Synthesis, Optimisation, and Characterisation of Non-Noble Low-Cost Ni-Mo Electrocatalysts for Green Hydrogen Production via Anion Exchange Membrane Water Electrolysis
Date
2023-11-01
Authors
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Journal ISSN
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Publisher
Saudi Digital Library
Abstract
Anion 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.
Description
Anion Exchange Membrane Water Electrolysis (AEMWE) holds great promise for sustainable hydrogen production but faces challenges in stability and catalytic efficiency. This research project is dedicated to investigating and optimizing Ni-Mo catalysts for the Hydrogen Evolution Reaction (HER) within AEMWE systems. The study focuses on understanding and refining key synthesis conditions, including pH, applied potential, and plating methods on a carbon cloth substrate.
Objectives:
1. Synthesis Condition Evaluation:
• Use advanced techniques such as Electrochemical Quartz Crystal Microbalance (EQCM) to monitor metal deposition-induced quartz crystal frequency changes.
• Employ Scanning Electron Microscopy (SEM) to examine morphology and surface properties.
• Apply Energy Dispersive Spectroscopy (EDS) to determine the elemental composition of synthesized materials.
2. Electrocatalytic Performance Characterization:
• Characterize the electrocatalytic performance using the Rotating Disk Electrode (RDE) technique for catalyst activity analysis via linear sweep voltammetry.
• Extract information about reaction kinetics and electron transfer rates to understand the catalyst's efficiency.
3. Catalyst Deposition and Morphology Analysis:
• Plate Ni-Mo catalysts onto carbon cloth substrates using various electrodeposition techniques.
• Analyze resulting catalyst morphology and composition to identify optimal deposition conditions.
4. Electrocatalytic Performance Evaluation in AEMWE:
• Deposit synthesized electrodes into an AEMWE setup to evaluate their electrocatalytic performance.
• Focus on assessing activities in the Hydrogen Evolution Reaction (HER) to understand the catalyst's effectiveness in real-world AEMWE conditions.
Expected Outcomes:
• Observe variances in composition, morphology, and surface properties of Ni-Mo catalysts due to variations in pH and potential during electrodeposition.
• Gain insights into the influence of pH and potential on catalytic performance, understanding how different conditions affect the catalytic activity and morphology of Ni-Mo catalysts.
Significance:
The findings of this research will contribute to optimizing the synthesis of Ni-Mo catalysts, providing guidelines to enhance catalytic performance in various chemical reactions. The study's outcomes will have practical applications in industrial processes, including energy conversion, environmental remediation, and chemical synthesis. The proposed Ni-Mo catalyst, if successful, holds the potential to be a cost-effective alternative to Pt in AEMWE for hydrogen evolution, contributing to the ongoing quest for affordable and environmentally friendly hydrogen fuel production.
Keywords
anion exchange membrane, water electrolyser, green hydrogen, HER, Ni-Mo, electrocatalyst, catalyst preparation