Role of vanadium ions substitution on spinel MnCo2O4 towards enhanced electrocatalytic activity for hydrogen generation

Abstract

Improving efficient electrocatalysts (ECs) for hydrogen generation through water splitting is of significant interest in tackling the upcoming energy crisis. Sustainable hydrogen generation is the primary prerequisite to realizing the future hydrogen economy. This work examines the electrocatalytic activity of hydrothermally prepared vanadium doped MnCo spinel oxide microspheres (MC), MnVxCo2−xO4 (Vx-MnCo MC, where x ≤ 0.4) in the HER (hydrogen evolution reaction) process. Magnetization measurements demonstrated a paramagnetic (at high temperatures) to a ferrimagnetic (at low temperatures) transition below the Curie temperature (Tc) in all the samples. The magnetization is found to intensify with the rising vanadium content of MCs. The optimized catalyst Vx-MnCo MCs (x = 0.3) outperformed other prepared ECs with a Tafel slope of 84 mV/dec, a low onset potential of 78.9 mV, and a low overpotential of 85.9 mV at a current density of 10 mA/cm2, respectively. The significantly improved HER performance of hydrothermally synthesized Vx-MnCo MCs (x = 0.3) is principally attributable to many exposed active sites, accelerated electron transport at the EC/electrolyte interface, and remarkable electron spectroscopy for chemical analysis (ECSA) value was found ~ 11.4 cm2. Moreover, the Vx-MnCo MCs (x = 0.3) electrode exhibited outstanding electrocatalytic stability after exposure to 1000 cyclic voltametric cycles and 36 h of chronoamperometric testing. Our results suggest a feasible route for developing earth-abundant transition metal oxide-based EC as a superior electrode for future water electrolysis applications.

Chestnut-like Molybdenum-Doped Nickel Cobaltite Spinel Oxide Nanoparticles Grown on Ni Foam as the Electrocatalyst for the Hydrogen Evolution Reaction

“…The Tafel slope has been widely employed to investigate the rate-determining steps in the HER mechanism process for enhanced comprehension. The Volmer, Heyrovsky, and Tafel reactions are widely recognized as the three primary steps involved in converting hydrogen protons into molecular hydrogen. ,,,, Based on the underlying mechanisms, the amalgamation of the Volmer pathway alongside either the Heyrovsky or Tafel pathway could produce molecular hydrogen. Typically, when the slope is approximately 120 mV/dec, the Volmer step mechanism is the reaction rate’s limiting factor.…”

“…They observed the significant enhancement in the HER performance of hydrothermally synthesized MnV x Co 2−x O 4 MCs. 13 Jiang et al fabricated ZnCo 2 O 4 nanospheres with bifunctional catalysis on nickel foam, and they observed excellent performance for hydrogen production due to the multiple redox couplings and a three-dimensional porous structure of the product to simplify the release of gases from the surface. 14 Moreover, Faid et al found that heterojunctions in mixed MOs allowed them to be more exposed active sites than alloys or oxide composites.…”

“…Mohamed et al studied the electrocatalytic activity of hydrothermally prepared MnV x Co 2– x O 4 ( x ≤ 0.4) microspheres (MCs) in the HER process. They observed the significant enhancement in the HER performance of hydrothermally synthesized MnV x Co 2– x O 4 MCs . Jiang et al fabricated ZnCo 2 O 4 nanospheres with bifunctional catalysis on nickel foam, and they observed excellent performance for hydrogen production due to the multiple redox couplings and a three-dimensional porous structure of the product to simplify the release of gases from the surface .…”

Effective Hydrogen Production from Alkaline and Natural Seawater using WO3–x@CdS1–x Nanocomposite-Based Electrocatalysts

“…So far, despite an outstanding hydrogen evolution activity of platinum (Pt)-based electrocatalysts owing to almost zero Gibbs free energy, the scarcity and high cost of Pt limits their widespread applications . To surmount this shortcoming, intensive research efforts have been made to develop highly stable, durable, nontoxic, efficient, and low-cost alkali metal-based HER electrocatalysts, including various oxides, sulfides, phosphides, carbides, and hydroxides, in the past decades. − …”

“…In light of this, hydrogen has emerged as a prospective fuel for the future, offering the potential to address various challenges associated with environmental and energy crises. 1,2 It is established that hydrogen can efficiently be produced at low cost via the electrolysis of water, offering a versatile resource of renewable energy like solar and wind. 3 Research revealed that the alkaline electrocatalytic hydrogen evolution reaction (HER) is preferable with acidic and neutral electrolytes because of less corrosion for equipment and transition metal-based electrodes.…”