Statistical and Electrochemical Insights of Hexagonal NiCoMg-LDH Nanosheets toward Overall Water Splitting and Methanol Oxidation Reactions

Abstract

The primary obstacle in electrochemical water splitting for hydrogen (H2) production is the sluggish anodic oxygen evolution reaction (OER). However, a promising approach to overcome this barrier involves replacing the OER with the more energetically favorable methanol oxidation reaction (MOR), providing a practical avenue for efficient and energy-saving H2 generation. This paper proposes a bifunctional electrocatalyst, successfully synthesizing a trimetallic hybrid NiCoMg-LDH composite via a one-step hydrothermal method supported on 3-DCF (carbon felt). Additionally, the stability of the electrolyzer was assessed by the statistical modeling and predictive time series analysis (LSTM) technique. The synthesized multimetallic self-supported NiCoMg-LDH composition formed porous hexagonal sheet-like structures, demonstrating outstanding bifunctional activity toward the hydrogen evolution reaction (HER) and OER, achieving low overpotentials of 0.185 and 0.161 V for HER and OER at an applied current density of 100 mA/cm2, respectively. Additionally, when employed parallel as the anode and cathode for total water splitting, it necessitated only 1.56 V to achieve 100 mA/cm2, surpassing the compared benchmark Pt/C parallel to RuO2 electrodes. Furthermore, the cell voltage of the NiCoMg-LDH parallel to NiCoMg-LDH-based methanol-water electrolyzer at 100 mA/cm2 was notably reduced by 250 mV compared to that of the OER alone at the anode. Therefore, from these results, the superior electroactivity of the trimetallic NiCoMg-LDH catalyst is primarily attributed to its high electrochemical active surface area (ECSA), abundant active sites, and rapid electron transfer from the catalyst surface to the electrolyte. Therefore, this study represents a significant advancement in the design and development of stable, highly active, and economical hybrid catalysts for green energy harvesting applications.