Origin of Electrocatalytic Activity in Amorphous Nickel–Metalloid Electrodeposits

Abstract

In transition metal-based alloys, the nonlinearity of the current at large cathodic potentials reduces the credibility of the linear Tafel slopes for the evaluation of electrocatalytic hydrogen activity. High-precision nonlinear fitting at low current densities describing the kinetics of electrochemical reactions due to charge transfer can overcome this challenge. To show its effectiveness, we introduce a glassy alloy with a highly asymmetric energy barrier: amorphous NiP electrocoatings (with different C and O inclusions) via changing the applied DC and pulsed current and NaH2PO2 content. The highest hydrogen evolution reaction (HER) activity with the lowest cathodic transfer coefficient α = 0.130 with high J 0 = −1.07 mA cm–2 and the largest surface areas without any porosity are observed for the pulsed current deposition. The calculated α has a direct relation with morphology, composition, chemical state and coating thickness defined by the electrodeposition conditions. Here, a general evaluation criterion with practicality in assessment and high accuracy for electrocatalytic reactions applicable to different metallic alloy systems is presented.

Magnetron Sputtered Non‐Toxic and Precious Element‐Free TiZrGe Metallic Glass Nanofilms with Enhanced Biocorrosion Resistance

“…For the as-sputtered sample, this value equals ≈90 Ω cm −2 . The difference between the before and after polarization is not visible for composition (1), where the stabilization is reached at ≈35 Ω cm −2 and a frequency of ≈1500 Hz. |Z| is only ≈5 Ω cm −2 for composition (3) with a stabilization frequency of ≈15 000 Hz.…”

“…The same composition exhibits the lowest corrosion and passivation resistance and corrosion potential, indicating its tendency for oxide formation. On the other hand, Ti 62 Zr 13 Ge 25(1) has a relatively larger passive region (η pit = 1.323 V) followed by (2) (η pit = 1.213 V), hinting their high stability at low currents compared to the already discovered Ti-based metallic glasses tested in PBS solution at 37 °C.…”

“…Their exclusive combination of the high elasticity, mechanical strength, corrosion stability, and good resistance against hydrogen embrittlement renders metallic glasses for use as alternative materials for hydrogen storage, electrocatalytic converters, and lithium-ion rechargeable batteries. [1][2][3][4][5][6][7] Besides, due to their minimal stress shielding and anti-biocorrosion, biocompatibility with the promotion of cell adhesion, and in some cases, biodegradability, these advanced amorphous alloys have started to be used in daily healthcare applications such as orthopedics and dental implants, screws for bone fracture fixation, and stents for cardiovascular repair. [8][9][10][11][12][13][14][15] Promising antimicrobial properties of thin film metallic glass (TFMG) coatings have been shown in the literature.…”

Pd-based Metallic Glasses as Promising Materials for Hydrogen Energy Applications

“…6) is used to define the sole kinetics of a reaction without transport limitations for small overpotentials η when the effects of the mass transfer due to large η, e.g., linear Tafel polarization curves, are negligible. 218 The B-V model is widely used to describe redox systems such as ferrocene or hexacyanoferrate (ferro/ferricyanide), electrode kinetics at planar electrodes coated with films of micro-and nanoparticles, H 2 and O 2 electrocatalytic processes, and energy storage device reactions (lithium-ion batteries, vanadium redox-flow batteries). 219 The WE in a typical electrochemical hydrogen sensor is a noble metal, such as platinum or gold, which can establish a bounded interface with the electrolyte and has porosity to permit efficient diffusion of the hydrogen to a large-area and reactive electrodeelectrolyte interface.…”