Cathodic Hydrogen Evolution Research Articles

Enhancing the Stability of Cu‐Based Electrocatalyst via Fe Alloy in Electrocatalytic Formaldehyde Oxidation with Long Durability

AbstractElectrocatalytic formaldehyde oxidation with metal Cu electrocatalyst has attracted significant interest since it can produce H2 at the anode and make it possible to construct a bipolar hydrogen production cell with low voltage. However, the activity of the Cu electrocatalyst will be greatly weakened after oxidizing it to Cu+ or Cu2+. Here, a CuFe bimetallic catalyst is developed to efficiently catalyze the electro‐oxidation process of HCHO to produce H2 at a potential of 0.10 VRHE with a current density of 100 mA cm−2. It is confirmed that introducing Fe in a CuFe catalyst can regulate the electron configuration to prevent Cu0 oxidation and improve the stability of the catalysts. The introduction of Fe can reduce the energy barrier of the reaction process, and make the C─H bond more easily split on CuFe. A bipolar hydrogen production device is constructed by combining the anodic oxidation of HCHO with the cathodic hydrogen evolution. The current density of 500 mA cm−2 is achieved at a cell voltage of 0.6 V. The faradaic efficiency is ≈100% and the device is stable for ≈50 h. The research provides a promising path toward the secure, effective, and expandable generation of high‐purity H2 at both anodic and cathodic electrodes.

In Situ Anodic Transition and Cathodic Contamination Affect the Overall Voltage of Alkaline Water Electrolysis

NiFe (oxy)hydroxide has been widely used as a benchmark anodic catalyst for oxygen evolution reactions (OERs) in alkaline water electrolysis devices; however, the energy saving actually takes contributions from both the anodic OER and cathodic hydrogen evolution reaction (HER). In this work, we observe the catalytic promotion upon the in situ-derived NiFe (oxy)hydroxide from the NiFe alloy monolithic electrode and also point out that the coupled nickel cathode is contaminated, leading to the loss of HER activity and a reduction in overall efficiency. It is found that Ni2+ and Fe3+ cations are inevitably detached from the anode into the electrolyte and electrodeposited on the nickel cathode after the three-month industrial simulation. This research presents the significant enhancement of the oxygen evolution catalysis using an in situ aging process and emphasizes that the catalytic application should not only be isolated on the half reaction, but a reasonable coupled electrode match to get rid of the contamination from the electrolyte is also of great significance to sufficiently present the intrinsic catalytic yielding for the real application.

Review of Ni-Based Materials for Industrial Alkaline Hydrogen Production.

Hydrogen has been recognized as a green energy carrier, which can relieve energy shortage and environmental pollution. Currently, alkaline water electrolysis (AWE) driven by renewable energy to produce large-scale green hydrogen is a mainstream technology. However, tardy cathodic hydrogen evolution reaction (HER) and stability issue of catalysts make it challenging to meet the industrial requirements. Ni-based materials have attracted wide attention, thanks to their low cost and rich tuning possibilities, and many efforts have focused on their activity and stability. However, due to the significant discrepancy between laboratory and industrial conditions, these catalysts have not been widely deployed in industrial AWE. In this review, we first introduce the differences between laboratory and industrial stage, especially concerning equipment, protocols and evaluation metrics. To shorten these gaps, some strategies are proposed to improve the activity and stability of the Ni-based catalysts. Besides, some key issues related to the catalysts in industrial AWE device are also emphasized, including reverse-current and foreign ions in the electrolyte. Finally, the challenges and outlooks on the industrial alkaline AWE are discussed.

A sustainable approach for the corrosion control of mild steel using Cocous nucifera gum: An electrochemical investigation

The study of corrosion inhibition on mild steel (MS) in an acid medium (1 M HCl) solution was performed using a crude extract of Cocousnucifera gum (CNG). Cocousnucifera develops gum exudates on its palm, the exudate process occurs mainly after some physical or microbiological injuries and is formed on the fruit of the palm. The gum was utilized to study the corrosion inhibition of MS by electrochemical and surface studies. The characterization of the crude gum was done by Fourier transform infrared spectroscopy (FT-IR) which revealed the presence of several active components (aromatic and oxygen-containing functional groups) in its structure. The electrochemical studies resulted in the maximum inhibition efficiency value of 75.64 % at the highest inhibitor concentration of 4000 ppm at 308 K. It was inferred that both the anodic dissolution of the metal and cathodic hydrogen evolution were effectively decreased in the presence of Cocous nucifera gum extract, revealing that inhibitor is of mixed type. From the adsorption studies, it was found that the best fit with R2 ∼ 0.9 followed Langmuir adsorption isotherm indicating the monolayer adsorption of the inhibitor on the metal surface. Gibb’s free energy of adsorption values was found <−20 kJ/mol, a characteristic of predominant physical adsorption. To support the electrochemical data SEM (scanning electron microscopy), AFM (Atomic force microscopy), and X-ray diffraction analysis were performed and these are in good agreement.

Natural DNA-Derived Ultrafine Ir/Ir2P Hybrid on Porous N, P-Codoped Carbon for pH-Universal Energy-Saving Hydrogen Production Assisted by Electrocatalytic Hydrazine Oxidation

Due to the intrinsic slow kinetics and high potential of the anodic oxygen evolution reaction (OER), hydrazine oxidation reaction (HzOR) with ultralow potential is a viable substitute to combine the cathodic hydrogen evolution reaction (HER) for the energy-saving hydrogen generation. Therefore, it is a compelling demand to explore high-performance electrocatalysts for bifunctional HER and HzOR. Herein, natural DNA was employed to prepare the uniform and ultrafine Ir/Ir2P hybrids loaded on N, P-codoped porous carbon (Ir/PNPC) through a facile “mix-and-pyrolyze” approach. Benefitting from abundant heteroatom doping, large surface area and high degree of graphitization, Ir/PNPC only requires the ultrasmall potentials of -22/-347/-54 mV at 100 mA cm-2 for HER, 46/172/227 mV at 10 mA cm-2 for HzOR, and 167/836/864 mV at 100 mA cm−2 for the constructed two-electrode overall hydrazine splitting (OHzS) in the alkaline, neutral and acidic electrolytes, respectively, all exceeding Pt/C and also showing the remarkable energy-efficient superiority over the conventional water splitting. Furthermore, the OHzS system can be readily driven by the as-prepared direct N2H4/H2O2 fuel cell and commercial solar cell with decent H2 generation rate of 1.245 and 1.392 mmol h-1, respectively. This study provides lights on the preparation of the advanced pH-universal HER and HzOR bifunctional electrocatalysts by natural DNA and is also encouraging for the energy-saving H2 production.

Research on the corrosion protection of in-situ prepared Li[sbnd]Al layered double hydroxides on AZ31 Mg alloy under standard atmospheric pressure and low temperature

This work successfully prepared LiAl LDHs coatings on AZ31 Mg alloy under standard atmospheric pressure and low temperature. The whole process did not require a hydrothermal autoclave reactor and high pressure. Electrochemical test results showed that the coating was able to provide good corrosion protection performance. The LiAl LDHs coatings provided a large low-frequency impedance on AZ31. When the treatment time was 24 h, the maximum |Z|0.01Hz at pH = 12 was 5.14 × 104 Ω∙cm2, which is more than an order of magnitude higher than the |Z|0.01Hz of 1.81 × 103 Ω∙cm2 for the bare sample. Under the same treatment conditions, the potentiodynamic polarization test results showed that the LiAl LDHs coated samples had a lower corrosion current density and a higher breakdown potential. The icorr was 1.78 × 10−7 A/cm2 and Ebr was −0.82 VSCE compared to the Mg substrate (icorr of 1.13 × 10−5 A/cm2 and Ebr of −1.53 VSCE). Additionally, LiAl LDHs coatings also had a significant inhibitory effect on cathodic hydrogen evolution, providing targeted protection to the cathodic areas.

Strain effects on corrosion inhibition in stress corrosion of tubing steel

In this investigation, we explored the corrosion inhibition mechanism of an imidazoline quaternary ammonium salt (IQA) on J55 steel in simulated annulus environment through a series of experiments, including electrochemical testing, stress corrosion immersion experiments, and hydrogen permeation testing. Our findings reveal that IQA functions as a mixed-type inhibitor, exerting its inhibitory action through chemical adsorption. Notably, it exhibits a stronger inhibitory effect on the anodic dissolution reaction compared to the cathodic hydrogen evolution reaction. Despite the minor influence of tensile plastic strain on the average inhibition efficiency, it notably exacerbates pitting and initiates stress corrosion cracking. This underscores the limitation of average inhibition efficiency in accurately assessing IQA's efficacy against stress corrosion. Additionally, hydrogen permeation experiments and electrochemical testing demonstrate that plastic strain diminishes IQA's inhibitory effect on the cathodic hydrogen evolution reaction, facilitating hydrogen diffusion into the steel substrate and thereby exacerbating stress corrosion in J55 steel. Consequently, at low IQA inhibitor concentrations (as in this study, 12.5 mg L−1), despite high average inhibition efficiency, it proves ineffective in mitigating stress corrosion.

Engineering active and robust alloy-based electrocatalyst by rapid Joule-heating toward ampere-level hydrogen evolution

Rational design of bimetallic alloy is an effective way to improve the electrocatalytic activity and stability of Mo-based cathode for ampere-level hydrogen evolution. However, it is still critical to realise desirable syntheses due to the wide reduction potentials between different metal elements and uncontrollable nucleation processes. Herein, we propose a rapid Joule heating method to effectively load RuMo alloy onto MoOx matrix. As-prepared catalyst exhibits excellent stability (2000 h @ 1000 mA cm−2) and ultralow overpotential (9 mV, 18 mV and 15 mV in 1 M KOH, 1 M PBS, 0.5 M H2SO4 solution, respectively) at 10 mA cm−2. Based on first-principle simulations and operando measurements, the impressive electrocatalytic stability and activity are investigated. And the role of rapid Joule heating method is highlighted and discussed in details. This study showcases rapid Joule heating as a feasible strategy to construct highly efficient alloy-based electrocatalysts.

Scale-Up, Continuous and Low-Temperature Production of Multimetal Based Electrocatalysts toward Water Electrolysis.

Electrocatalytic water splitting is a crucial strategy for advancing hydrogen energy and addressing the global energy crisis. Despite its significance, the need for a straightforward and swift method to synthesize electrocatalysts with exceptional performance remains pressing. In this study, we demonstrate a novel approach for the preparation of multimetal-based electrocatalysts in a continuous flow reactor, enabling the quick synthesis of a large number of products through a streamlined process. The resultant NiFe-LDH comprises nanoflakes with a high specific surface area and requires only 255.4 mV overpotential to achieve a current density of 10 mA·cm-2 in 1 M KOH, surpassing samples fabricated by conventional hydrothermal methods. Our method can also be applied to craft a spectrum of other multimetal-based electrocatalysts, including CoFe-LDH, CoAl-LDH, NiMn-LDH, and NiCoFe-LDH. Additionally, the NiFe-LDH electrocatalyst is further applied to anodic methanol electrooxidation coupled with cathodic hydrogen evolution. Moreover, the simplicity and generality of our fabrication method render it applicable for the facile preparation of various multimetal-based electrocatalysts, offering a scalable solution to the quest for high-performance catalysts in advancing sustainable energy technologies.

Energy-saving and benign hydrogen production by coal gasification fine slag-assisted Water electrolysis

ABSTRACT Integrating anodic coal gasification fine slag oxidation with cathodic hydrogen evolution reaction presents an environmentally friendly and energy-efficient solution for solid waste recycling and hydrogen production. This innovative approach exhibits higher activity and stability than conventional water electrolysis, while also preventing anode degradation due to its benign reaction conditions. The kinetic investigations have revealed that slag oxidation occurs more rapidly than water oxidation. Specifically, slag undergoes direct and indirect oxidation within the potential regions below and above those of water oxidation, respectively. This study has the potential to shed light on the mechanisms underlying slag electrolysis and offer valuable insights for the simultaneous recycling of solid waste and hydrogen production.

Glucose oxidation on monoclinic Co2V2O7 nanorods: Intuitions on cell potential reduction in hybrid electrolyzer

The deleterious impact of burning fossil fuels has led to a strategic shift towards exploring the environmentally benign energy generation technologies and renewable green sources. From the prospect of energy-saving hydrogen generation approach, alkaline hybrid electrolyzer using an anodic glucose oxidation reaction in conjunction with cathodic hydrogen evolution reaction catalyzed by monoclinic Co2V2O7 nanorods (NRs) is investigated. The Co2V2O7 was prepared by facile thermal treatment (500 °C/1 h) and displayed a nanorod-like morphology. The results derived from X-ray photoelectron spectroscopy confirmed the presence of multivalence states for both V (+4 and + 5) and Co (+2 and + 3) species. The Co2V2O7 exhibits superior glucose oxidation performance with very low onset potential of 1.2 V (vs RHE) and very high current density of 400 mA cm−2 at an overpotential of 1.51 V (vs RHE) in 1 M KOH. Furthermore, the Co2V2O7 exhibits an onset potential of −0.054 V (vs RHE) and an overpotentials of −75 mV and −190 mV to achieve the current densities of 10 mA cm−2 and 100 mA cm−2 respectively in hydrogen evolution reactions (HER). The Co2V2O7-NRs perform well in both the HER and glucose oxidation reactions, with a smaller hybrid water splitting potential of ∼1.46 V, which is 260 mV less than the analogous value in the conventional electrolyzer. The proposed electrocatalyst Co2V2O7 opens new possibilities for the production enediol together with hydrogen generation at low energy consumption.

Assembly of low-voltage driven co-production of hydrogen and sulfur via Ru nanoclusters on metal-sulfur coordination: Insights from DFT calculations

Herein, we propose a simple and rapid approach for synthesizing a CuS/Ru composite that serves as a bifunctional electrocatalyst to promote hydrogen production and concurrently convert sulfion into a value-added sulfur product. This composite comprises Ru nanoclusters supported on the CuS nanostructure, achieved through simple pulsed laser irradiation in liquid approach. The optimized CuS/Ru-30 electrocatalyst demonstrates remarkable bifunctional electrocatalytic activity, exhibiting a negligible working potential of 0.28 V (vs. RHE) for the anodic sulfion oxidation reaction (SOR) and a minimal overpotential of 182 mV for cathodic hydrogen evolution reaction (HER) to achieve 10 mA cm−2 of current density. Moreover, the CuS/Ru-30 electrocatalyst shows exceptional selectivity for converting sulfion into valuable sulfur during anodic oxidation reactions. Remarkably, in a two-electrode electrolyzer system utilizing CuS/Ru-30 as both the anode and cathode, the SOR + HER coupled water electrolysis system demands only 0.52 V to reach 10 mA cm−2, which is considerably lesser compared to the OER + HER coupled water electrolysis (1.85 V). The experimental results and density function theory (DFT) calculations reveal that the strong electron interaction between CuS and Ru nanoclusters generates a built-in electric field, greatly enhancing electron transfer efficiency. This significantly boosts the HER performance and facilitates the adsorption and production of sulfur intermediates. This study presents a rapid and simple strategy for synthesizing a dual-functional catalyst suitable for low-voltage hydrogen generation while facilitating the recovery of valuable sulfur sources.

Electronic Structure Investigation of BSCF Catalysts during Electrochemical Water Electrolysis by Using Time Zero Analysis and Advanced Operando X-Ray Absorption Spectroscopy

The rapid increase in global energy demands and environmental awareness regarding the excessive use of fossil fuel has spurred significant academic interest in the development of alternative energy conversion and storage technologies that prioritize both efficiency and environmental sustainability. Among all kinds of renewable energy, hydrogen energy holds the potential to create a carbon free clean society, and a possible solution to the environmental issues.1 Electrochemical water splitting is considered as a greener approach for pure H2, which involved cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). The anodic OER is kinetically sluggish and considered as a rate determining step of the water splitting reaction. Therefore, it is necessary to develop OER catalysts with high activities.Perovskite oxides knows as a promising oxygen electrode catalyst due to their low cost, flexibility, and tailorable properties. However, most perovskite oxides possess poor electrical conductivity at room temperatures, and this limits their oxygen catalytic activity. In our work Ba0.5Sr0.5CoxFe1-xO3-δ (BSCF) catalysts with different cobalt and iron amounts where X=0, 0.2, 0.8, 1 were synthesized and investigated by time zero analysis and flow rate infinitization analysis which are electrochemical testing method that uses pressure to remove generated oxygen gas bubbles and provides accurate activity of the catalyst.2We find the volcano plot of the Fe amount and the OER activities, showing samples with X=0.8 have the best OER activities as Figure 1. Electronic structure of B-Site transition metal elements, oxygen vacancies, crystal structures and electrical conductivity are the key factors for determining the activities of Perovskite catalysts in OER.3Also it is quite important to determine the real active sites during the OER process by using advance operando techniques.Therefore, in order to investigate the in-depth mechanism of OER activities of Perovskite catalysts, the newly designed operando soft X-ray Absorption Spectroscopy (XAS) cells was utilized to analyze the subtle change as shown in Figure 2 on the oxygen K-edge (531 eV - 532 eV). Ba0.5Sr0.5Co0.8Fe0.2O3-δ has the most obvious changes in integral surface area at the O K-edge pre-edge region, which leads to the best activity among other BSCF samples. According to the Energy Dispersive X-ray Spectroscopy and Lattice Oxygen Evolution Mechanism, ions on the A sites (Ba2+,Sr2+) tend to dissolve and ions on the B sites (Co, Fe) are forming hydroxides (BOOH).Keywords: oxygen evolution reaction, BSCF catalysts, Time zero analysis, operando X-ray absorption spectroscopy Acknowledgements This work is based on results obtained from a project (JPNP14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. Reference: (1) Rose, P. K.; Neumann, F. Hydrogen refueling station networks for heavy-duty vehicles in future power systems. Transportation Research Part D: Transport and Environment 2020, 83, 102358.(2) Nagasawa, K.; Matsuura, I.; Kuroda, Y.; Mitsushima, S. A Novel Evaluation Method of Powder Electrocatalyst for Gas Evolution Reaction. Electrochemistry 2022, 90 (1), 017012-017012.(3) Zhu, Y.; Zhou, W.; Shao, Z. Perovskite/carbon composites: applications in oxygen electrocatalysis. Small 2017, 13 (12), 1603793. Figure 1

Application of Bifunctional Layered Double Hydroxide Electrocatalysts to Water Splitting

Water splitting is an area of research which is of pressing interest in addressing climate change. Water splitting provides oxygen and hydrogen as products, with hydrogen finding use as a potential high-density fuel to replace fossil fuels. Water splitting manifests as two half-cell reactions, namely the anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction. The purpose of this project is to synthesise a bifunctional electrocatalyst to use in the water splitting reaction, replacing the rare and expensive transition metals catalysts currently in use such as platinum and ruthenium. The ideal material would exhibit strong performance for both the oxygen evolution reaction and the hydrogen evolution reaction.In this project, Layered Double Hydroxides (LDHs) have been synthesised for use in water splitting. LDHs are a group of ionic compounds characterised by their layered structure of positively charged sheets and an interlayer region consisting of the corresponding anions. LDHs typically contain a bivalent and a trivalent metal as part of the generic formula [M2+ 1–xM3+ x(OH)2][An–]x/n·zH2O. In this project the bivalent metal in use is typically cobalt and the trivalent metal is typically iron. The synthesis developed is a simple, one pot hydrothermal synthesis which can be seen in Figure 1. In this synthesis, the process begins with the precursor materials dissolved in solution. These solutions are mixed and stirred until homogenous. The resultant solution is then heated to form an impure product. Following washing steps and centrifugation a purified powder product is obtained. A variety of metallic salts have been tested for their use in these LDHs with the optimum LDHs selected for further study. The metallic salts used to provide the metals for the LDHs are typically hydrated transition metal nitrates.The LDHs have been characterised and their structure confirmed by a variety of analytical techniques including X-Ray Diffraction and Scanning Electron Microscopy. Simple qualitative analysis has been performed with FTIR spectroscopy. These LDHs have been immobilised on a variety of porous, high surface area materials, including nickel foam and copper foam, to enhance the properties seen in the screening study. These materials allow synthesis of high surface area, reactive electrocatalysts. To enhance the stability of the LDHs, carbon materials have been integrated with the LDHs. Examination of a variety of carbon materials involved post-synthesis mixing of the carbon material and the LDH product or inclusion of the carbon material in the LDH synthesis to form a composite. A variety of carbon materials have been analysed including graphene oxide, carbon black and carbon nanotubes. Figure 1

High‐entropy Sulfide Catalyst Boosts Energy‐saving Electrochemical Sulfion Upgrading to Thiosulfate Coupled with Hydrogen Production

Electrochemical sulfion oxidation reaction (SOR) offers a sustainable strategy for sulfion‐rich wastewater treatment, which can couple with cathodic hydrogen evolution reaction (HER) for energy‐saving hydrogen production. However, the corrosion and passivation of sulfur species render the inferior catalytic SOR performance, and the oxidation product, polysulfide, requires further acidification to recover cheap elementary sulfur. Here, we reported an amorphous high‐entropy sulfide catalyst of CuCoNiMnCrSx nanosheets in‐situ growth on the nickel foam (CuCoNiMnCrSx/NF) for SOR, which achieved an ultra‐low potential of 0.25 V to afford 100 mA cm‐2, and stable electrolysis at as high as 1 A cm‐2 for 100 h. These were endowed by the manipulated chemical environments surrounding Cu+ sites and the constructed “soft‐acid” to “hard‐acid” adsorption/desorption sites, enabling synergistically boosted adsorption/desorption process of sulfur species during SOR. Moreover, we developed an electrochemical‐chemical tandem process to convert sulfions to value‐added thiosulfate, providing a good choice for simultaneous wastewater utilization and hydrogen production.

High-Entropy Sulfide Catalyst Boosts Energy-Saving Electrochemical Sulfion Upgrading to Thiosulfate Coupled with Hydrogen Production.

Electrochemical sulfion oxidation reaction (SOR) offers a sustainable strategy for sulfion-rich wastewater treatment, which can couple with cathodic hydrogen evolution reaction (HER) for energy-saving hydrogen production. However, the corrosion and passivation of sulfur species render the inferior catalytic SOR performance, and the oxidation product, polysulfide, requires further acidification to recover cheap elementary sulfur. Here, we reported an amorphous high-entropy sulfide catalyst of CuCoNiMnCrSx nanosheets in situ growth on the nickel foam (CuCoNiMnCrSx/NF) for SOR, which achieved an ultra-low potential of 0.25 V to afford 100 mA cm-2, and stable electrolysis at as high as 1 A cm-2 for 100 h. These were endowed by the manipulated chemical environments surrounding Cu+ sites and the constructed "soft-acid" to "hard-acid" adsorption/desorption sites, enabling synergistically boosted adsorption/desorption process of sulfur species during SOR. Moreover, we developed an electrochemical-chemical tandem process to convert sulfions to value-added thiosulfate, providing a good choice for simultaneous wastewater utilization and hydrogen production.

Bimodal Trending in Corrosion Loss of Magnesium Alloys

Data for the mass loss of a variety of magnesium alloys as a function of an exposure period show that corrosion loss follows bimodal trending with time for different exposure environments, with both laboratory and field supporting these findings. For datasets sufficient to discriminate bimodal behavior, the instantaneous rate of corrosion at the commencement of the second mode is (close to) four times the instantaneous rate of corrosion at the end of the first mode (i.e., through the transition period). This observation is consistent with the theoretical relative diffusivities of oxygen and hydrogen through the corrosion product layer as it exists during the transition period. These findings support the notion that the bimodal model has corrosion in mode 1 rate-controlled by the cathodic oxygen reduction reaction and the inward diffusion of oxygen while in mode 2 corrosion is rate-controlled by the cathodic hydrogen evolution reaction and the outward diffusion of hydrogen. Similar findings have been made previously for various ferrous and other alloys and thus throws new light on the development of corrosion of magnesium alloys. It also provides reasons for measurements of hydrogen evolution and electrochemical techniques underestimating magnesium corrosion rates. A new procedure for combining these is proposed.

Pre-Adsorbed H-Mediated Electrochemiluminescence.

In conventional electrochemiluminescence (ECL) systems, the presence of the competitive cathodic hydrogen evolution reaction (HER) in aqueous electrolytes is typically considered to be a side reaction, leading to a reduced ECL efficiency and stability due to H2 generation and aggregation at the electrode surface. However, the significant role of adsorbed hydrogen (H*) as a key intermediate, formed during the Volmer reaction in the HER process, has been largely overlooked. In this study, employing the luminol-H2O2 system as a model, we for the first time demonstrate a novel H*-mediated coreactant activation mechanism, which remarkably enhances the ECL intensity. H* facilitates cleavage of the O-O bond in H2O2, selectively generating highly reactive hydroxyl radicals for efficient ECL reactions. Experimental investigations and theoretical calculations demonstrate that this H*-mediated mechanism achieves superior coreactant activation compared to the conventional direct electron transfer pathway, which unveils a new pathway for coreactant activation in the ECL systems.

Combined effect of cathodic potential and calcareous deposits on hydrogen evolution and permeation in Q460 steel

Cathodic protection is widely employed to prevent the corrosion of steel in marine environments. However, an inappropriate cathodic potential may lead to the generation of hydrogen and consequently induce cracking. Therefore, this study investigates the relationships between cathodic deposition potential, calcareous deposits, hydrogen evolution, and hydrogen permeation. Combining scanning electron microscopy, Raman spectroscopy, coupled focused ion beam lithography, and energy dispersive X-ray spectroscopy, it is observed that all calcareous deposits formed in artificial seawater at the potential range of −1.0 to −1.3 VSCE have calcium-rich inner and magnesium-rich outer layers, respectively. The thickness and compactness of each layer of the double-layer deposits vary with the cathodic deposition potential. Combining potentiodynamic polarization, hydrogen permeation experiments, and the morphology of calcareous deposits, we can find that the deposits formed at the cathodic deposition potential of −1.1 VSCE exhibit a thin inner layer and a condensed outer layer, which is effective in balancing hydrogen recombination and absorption, thus, inhibiting hydrogen entry. This study provides guidelines for the cathodic protection of steel materials in marine environments.

Rational design of porous vanadium-based alloys modified with a Ni-Cu-Mo coating for alkaline water electrolysis

The development of a hydrogen evolution catalyst with both catalytic activity and stability is critical for hydrogen production from electrolytic water. Herein, a V-based porous alloy was prepared via high-energy ball milling and solid-state sintering. Then, the V-based porous alloy was modified with a Ni-Cu-Mo ternary alloy coating by direct current electrodeposition to obtain a composite hydrogen evolution cathode with high hydrogen evolution activity. The substrate has a certain hydrogen storage capacity combined with a high-activity Ni-Cu-Mo coating. The composite hydrogen evolution cathode exhibited high electrocatalytic activity toward the HER. It can afford a lower overpotential of 93 mV and a smaller Tafel slope of 97.4 mV/dec with a current density of 10 mA/cm2 in 1.0 M KOH. The composite hydrogen evolution cathode demonstrated outstanding stability after 2000 cycles and good durability after intermittent electrolysis for 20 h. Hydrogen protons can protect the components of the cathode composite from dissolution during discontinuous constant potential electrolysis. The composite hydrogen evolution cathode also exhibited a strong catalytic capacity for hydrogen evolution during intermittent electrolysis under alkaline conditions.