Electrochemical Hydrogen Evolution Reaction Evaluation of CoNi(Cr/V) Medium-Entropy Alloys in an Acidic Environment

Abstract

Developing nonprecious metal-based electrocatalysts with outstanding performance has been the focal point of the scientific community for the past decade. Multiprinciple element medium-and high-entropy alloys have recently been known to exhibit a range of superior mechanical, physical, electrocatalytic, and anticorrosive properties, which are superior to traditional alloys. In this study, the electrocatalytic properties of equiatomic single-phase medium-entropy alloy electrodes with equiatomic compositions CoNiCr, CoNiV, and CoNi(Cr/V) are investigated for the hydrogen evolution reaction in 0.5 M H 2 SO 4 at room temperature. Electrochemical measurements revealed operational overpotentials of 50 and 228 mV at current densities of 10 and 100 mA/cm 2 with a Tafel slope of 46 mV/dec for the CoNi(Cr/V) alloy, while CoNiCr and CoNiV exhibited Tafel slopes of 78 and 82 mV/dec, respectively. The long-term durability of all specimens in the acidic phase was further tested at room temperature using cyclic voltammetry degradation and chronoamperometry methods, and it was found that all samples exhibited good stability with a shift in overpotential of just 6 mV@50 mA/cm 2 after 2000 cycles and stable multistep current density values for 20 h. X-ray photoelectron spectroscopy analysis showed an increase in the surface oxidation number of Ni and Co through Cr and V doping, which is in agreement with the higher electrocatalytic activity of the CoNi(Cr/V) alloy. The spin-polarized first-principles calculations within the context of the plane wave self-consistent field method were performed to evaluate the mechanism of electrochemical experimental results.

Nickel(II)–N-Heterocyclic Carbene Complex and its Carbon Nanotube Composites as Efficient Bifunctional Electrocatalysts for Hydrogen and Oxygen Evolution Reactions and Mercury-Sensing Applications

“…The 2000th LSV polarization curve shifted slightly toward the positive potential side with a slight change in the onset potential compared with the first curve. The oxidation potentials and corresponding current responses for nickel­(II) oxidation in both curves are almost similar to the overpotentials at a current density of 10 mA cm –2 . However, the overpotential at 50 mA cm –2 for the 2000th curve is 525 mV vs RHE with a slight loss in the OER potential by ca.…”

“…In addition, the double-layer capacitance of complex 4 (1.23 mF cm −2 ) was lower than that of the 4b composite (2.11 mF cm −2 ), which is probably due to the formation of stable π−π and synergetic interactions between the coumarin ring of the complex 4 and MWCNTs, while other composites displayed similar capacitance values as that of the bare complex. 40 However, the overpotential at 50 mA cm −2 for the 2000th curve is 525 mV vs RHE with a slight loss in the OER potential by ca. 2.2% with a Δη 50 of 11 mV vs RHE.…”

Review of Laser-Based Surface Nanotexturing for Enhanced Light Absorption and Photoelectrochemical Water Splitting

“…This technique of 3D printing and laser ablation can be extended to a broad range of photoactive materials for fabricating nanostructured photoelectrodes. Figure shows the developmental path of stable photocatalytic systems and electrode fabrication methods with an aim to achieve the highest solar energy conversion efficiency. − …”

Lacunary Keggin-Type Phosphomolybdate Functionalized with Ru(acac)3 Complex for Electrocatalytic H2 Production in Aqueous Media

“…However, this process suffers from high energy requirements and the production of CO 2 , which cause further environmental issues. − Recently, electrocatalytic water splitting for efficient production of H 2 has been considered a propitious solution for achieving a clean energy system. , It has been shown that noble metals like Pt, Ru, and Pd can be used as the best choices for catalysis of the hydrogen evolution reaction (HER) due to their high current density and low overpotential . In order to achieve low-cost catalysts while maintaining high efficiency, some noble metal-free systems, like metal phosphides, , chalcogenides, , oxides and alloys, − have been introduced in recent years. However, there is still great research attention to develop and design new efficient and low-cost electrocatalysts for the HER process.…”