Revealing the Impact of Pulsed Laser-Produced Single-Pd Nanoparticles on a Bimetallic NiCo₂O₄ Electrocatalyst for Energy-Saving Hydrogen Production via Hybrid Water Electrolysis

Abstract

Nowadays, the assembling of hybrid water electrolysis using a hydrazine oxidation reaction (HzOR) instead of a slow anodic oxygen evolution reaction (OER) has been established as a favorable technology for efficient hydrogen (H 2 ) production. Nevertheless, it is still critical to develop highly effective bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and HzOR. In this work, we propose a facile approach for the design and synthesis of single-Pd-nanoparticles-decorated bimetallic NiCo 2 O 4 nanoplates as a bifunctional electrocatalyst for both HER and HzOR. Initially, the NiCo 2 O 4 nanoplates are synthesized by a combination of hydrothermal reaction and high-temperature calcination. Subsequently, single-Pd nanoparticles with varying proportions are decorated on NiCo 2 O 4 nanoplates via facile pulsed laser irradiation (PLI), leading to the formation of Pd/NiCo 2 O 4 composites. The optimized Pd/NiCo 2 O 4 composite shows a remarkable electrocatalytic ability with a low overpotential of 294 mV for the HER and an ultrasmall working potential of −6 mV (vs RHE) for the HzOR at 10 mA cm −2 in a 1 M KOH electrolyte. Thus, an overall hydrazine splitting (OHzS) electrolyzer with the Pd/NiCo 2 O 4 ∥Pd/NiCo 2 O 4 system presents the current densities of 10 and 100 mA cm −2 at respective low cell voltages of 0.35 and 0.94 V. Notably, in situ/operando Raman spectroscopy confirms the surface formation of α-Co(OH) 2 during the HER and γ-NiOOH during the HzOR. Furthermore, the density function theory (DFT) calculations demonstrate that the decoration of Pd onto NiCo 2 O 4 facilitates the optimization of both the hydrogen adsorption free energy (ΔG H* ) and enhancement of hydrazine dehydrogenation kinetics. This work introduces a facile strategy for fabricating bifunctional electrocatalysts, potentially useful in energy-saving H 2 production.

Taking Advantage of Potential Coincidence Region: Insights into Gas Production Behavior in Advanced Self-Activated Hydrazine-Assisted Alkaline Seawater Electrolysis

“…Specifically, an ultralow overpotential of 10 mV is required to reach a current density of 10 mA cm –2 for FeCoP/NF, which is better than FeP/NF (35 mV), CoP/NF (97 mV), commercial Pt/C catalyst supported on Ni foam, pure Ni foam, and many other recently reported (non)­noble metal-based HER electrocatalysts (Figure g and Table S1). − Besides, FeCoP/NF can deliver 100, 200, and 500 mA cm –2 at overpotentials of 57, 86, and 119 mV, respectively (Figure S10), which is better than FeP/NF (204, 305, and 467 mV) and CoP/NF (182, 227, and 331 mV).…”

Recent Progress and Challenges in Hybrid Water Electrolysis through Economic Evaluation

“…The high overpotential mainly arises from the mechanistic limitations of OER, a slow four-electron transfer process, which makes the commercial development of electrolysis difficult. − High required cell potential is a critical problem because electricity cost is reported as the largest portion of cost in water electrolysis . OER carries the additional risk of generating explosive gas mixtures due to cross-hydrogen reactions, which are a major cause of safety concerns and shortened lifetime of electrocatalysts and membranes. ,, The generated oxygen also has the possibility to consume energy and degrade the membrane from hydrogen peroxides generated by oxygen reduction reaction …”