Hydrogen Production Methods Research Articles

Rational synthesis of highly efficient dual–Z–scheme InVO4/FeVO4/Ex–CQDs–g–C3N4 heterojunction for photo(electro)chemical water splitting and pollutant removal applications

BackgroundThe ever–growing concern for environmental pollution and the need for clean energy sources have driven research toward sustainable technologies. Semiconductor photocatalysis has emerged as a promising approach for both environmental remediation and clean energy generation due to its efficiency and environment–friendly nature. This work focuses on developing a novel photocatalyst capable of addressing two crucial environmental challenges: Cr(VI) removal and water splitting for clean hydrogen production. MethodsThis study presents the development of a dual–Z–scheme heterojunction photo(electro)catalyst based on a combination of metal vanadates (FeVO4 and InVO4) and ultrasound–exfoliated carbon–rich graphitic carbon nitride (Ex–C–g–CN), denoted as IVO/FVO/Ex–C–g–CN. The synthesized nanocomposite was thoroughly characterized using various spectroscopic and microscopic techniques (such as XRD, XPS, UV–DRS, FESEM, EDX, and PL) to understand its material properties and structure. These techniques are crucial for elucidating the relationship between the composition of the material and its photocatalytic performance. Significant findingsThe key innovation of this work lies in the design of the dual–Z–scheme heterojunction within the IVO/FVO/Ex–C–g–CN photo(electro)catalyst. This design fosters efficient separation of photogenerated charges, a critical factor for enhancing photocatalytic activity. The effectiveness of this approach is evident in the achieved removal efficiency of 97.17 % for 100 ppm Cr(VI) within just 60 min of visible light irradiation. This demonstrates the superior ability of the developed photocatalyst to address chromium contamination. Furthermore, the photocatalyst exhibits a remarkable photocurrent of 3.16 mA and a low onset potential of 112 mV for the photoelectrochemical oxygen evolution (OER) reaction. These findings highlight the potential of this material for solar–driven water splitting, a clean and sustainable method for hydrogen production. Additionally, the IVO/FVO/Ex–C–g–CN composite demonstrates excellent recyclability, maintaining high Cr(VI) removal efficiency over multiple cycles, indicating its reusability and cost-effectiveness. Overall, the exceptional photo(electro)catalytic performance of the IVO/FVO/Ex–C–g–CN dual–Z–scheme heterojunction positions it as a promising candidate for tackling environmental pollution and generating clean energy.

Integrating Experimental and Numerical Data for Improved Steam Reforming Simulation with Deep Learning

Abstract In this paper, a data-driven methane steam reforming simulation is developed and used to predict the post-reaction mixture composition. Until today, methane steam reforming remains a predominant hydrogen production method, yet modeling its complex reactions remains a significant challenge due to the intricate interplay of process variables. Here, we show an artificial neural network simulator that can effectively model these reactions, offering precise predictions based on parameters like temperature, inlet gas composition, methane flow, and nickel catalyst mass. Our approach to data curation integrates experimental, interpolated, and theoretically calculated values and refining the model by assessing the relative importance of each data category. Various neural network structures were tested before ultimately identifying an optimal architecture with a 5-6-8-6-4 network structure. The network underwent 6000 epochs of training, leading to a model that demonstrates excellent agreement with experimental observations, as evidenced by the mean squared error of 0.000217 and the Pearson correlation coefficient of 0.965. Moreover, all process trajectories predicted by the network are characterized by a smooth course and are within a physical range of values. Therefore, this work overcomes a common challenge in chemical process simulation using neural networks and also sets a possible direction for future research in this field.

Development of a hydrogen permselective silica membrane and its application to the thermochemical water splitting method

Abstract The thermochemical water splitting IS process is one of the hydrogen production method to use a heat directly. The temperature of the thermal decomposition of water (4000 K) can be reduced under 700 K by introducing I2 and SO2 as recycling catalysts. One of the problems in the IS process is that the conversion of the HI decomposition reaction is low at about 20%. If a membrane reactor with the H2 permselective membrane is applied to the HI decomposition reaction, the hydrogen can be extracted to improve the HI conversion. We focus on a counter diffusion CVD method for the preparation method of the membranes. Two reactants (e.g. silica precursor and oxidant) are provided at the opposite side of the porous substrates and hybrid silica is deposited inside the pore of the substrate. The pore sizes are controlled by introducing organic functional groups to silica precursor. In this study, the silica hybrid membrane with high H2 permeation performance and high H2/HI selectivity were developed by introducing organic functional groups. Effects of the organic functional groups were summarized by using a pore model. The HI gas and other inorganic gases permeation performance were tested through silica hybrid membranes.

Modeling and design of a combined electrified steam methane reforming-pressure swing adsorption process

Steam methane reforming (SMR) is the most widely used hydrogen (H2) production method, converting natural gas and steam into H2 and carbon dioxide (CO2). SMR is a mature industrial technology that burns fossil fuels to provide heat to the endothermic reforming reaction and to generate steam, which contributes to the production of greenhouse gas emissions. In order to reduce heating-based emissions, an electrically-heated steam methane reforming process has been proposed. Conventional SMR uses a packed bed catalyst and receives heat through radiation from hot flames in the surrounding furnace; on the other hand, an electrified SMR employs a washcoated catalyst, and is resistively-heated through the wall of the reactor coil. To gain further insight into the scalability of hydrogen production processes using electrically-heated reformers, this paper takes experimental data from an electrified reformer built at UCLA, extracts kinetic parameters, and uses these parameters to model and scale up a hydrogen production plant with a hydrogen production capacity of 231 kg/h (2607 Nm3/h). The simulated plant includes a reformer, two water gas shift reactors, pressure swing adsorption (PSA) for separation, and a heat exchange network to make steam for the reformer. A two-column-PSA process is dynamically modeled to output 99% H2 purity, and the pressures necessary for separation and H2 recovery are calculated using steady-state simulation data. A sensitivity analysis is conducted for the most energy-efficient H2 production conditions (e.g., operating pressure, heat flux), and CO2 production amounts are compared to a conventional SMR process, demonstrating that electrified SMR can potentially be a significantly cleaner alternative. The optimization of electrified reformers must target high mass and heat transfer along the full length of the reformer to achieve near full methane conversion that will minimize off-gas generation from the PSA unit.

Integration of Concentrating Solar Power With High Temperature Electrolysis for Hydrogen Production

Hydrogen has been identified as a leading sustainable contender to replace fossil fuels for transportation or electricity generation, and hydrogen generated from renewable sources can be an energy carrier for a carbon-free economy. Several hydrogen production methods are under development or deployment with various technical readiness levels and technoeconomic potentials. This study focuses on integrating concentrating solar thermal power (CSP) with high temperature electrolysis (HTE) using solid oxide electrolysis cells (SOEC). The CSP-HTE integration approach provides the benefits of thermal energy storage for continuous operation, improved capacity, and reduced thermal cycling for improved SOEC life. The CSP-HTE system analysis utilizes a Python-based system modeling program in connection with solar receiver thermal output derived from the NREL System Advisor Model (SAM) software. The system model facilitates component sizing, performance simulation, and evaluation of operation modes on an annual basis for various CSP-HTE configurations including CSP with thermal energy storage (TES). The SOEC operation conditions were simulated to assess component sizing and performance and to derive system capacity factors.

Machine learning-based predictive control of an electrically-heated steam methane reforming process

Hydrogen plays a crucial role in improving sustainability and offering a clean and efficient energy carrier that significantly reduces greenhouse gas emissions. However, the primary method of industrial hydrogen production, steam methane reforming (SMR), relies on the combustion of hydrocarbons as the heating source for the reforming reactions, resulting in significant carbon emissions. To address this issue, an experimental setup of an electrically-heated steam methane reformer (e-SMR) has been constructed at UCLA, and a lumped first-principle dynamic process model was built based on parameters estimated from the experimental data in a previous study. Subsequently, the first-principle dynamic process model was implemented into the computational model predictive control (MPC) scheme, successfully driving the hydrogen production rate to the desired setpoint. While these works are important and pave the way for developing MPC for large-scale e-SMR processes, the first-principle process model may not accurately reflect the actual process behavior, particularly as the process behavior changes with time. Therefore, the development and establishment of an adaptive data-driven approach for implementing model predictive control in the e-SMR process is necessary. To address this need, the present work investigates the construction of recurrent neural network (RNN) models for an e-SMR process in-depth, utilizing data from an experimentally-validated first-principle model. Specifically, a long short-term memory (LSTM) layer was utilized in the RNN model to effectively capture the complex correlations present in long-term sequential data. Subsequently, this LSTM-based RNN process model was employed to design an MPC, and its performance was evaluated through comparison with proportional–integral (PI) control. To address potential disturbances and variability in a typical e-SMR process, three distinct approaches were developed: MPC with an integrator, MPC with real-time online retraining (transfer learning), and offset-free MPC. These approaches effectively eliminated the offset caused by disturbances. Overall, this study underscores the effectiveness of utilizing RNN models to capture process dynamics in an experimental e-SMR process. It also outlines strategies for employing RNN-based control and multiple approaches to address disturbances in general processes with partially infrequent and delayed measurement feedback. This approach is particularly valuable in scenarios where developing first-principle models for a new process may be challenging.

Design of dual-channel Swiss-roll reactor for high-performance hydrogen production from ethanol steam reforming through waste heat valorization

Steam reforming is one of the most economical and efficient methods for hydrogen production. However, one of its glaring issues is the heat supply, which is used to maintain the reactions. Among reactors for hydrogen production, Swiss-roll reactors have exhibited exceptional performance in sustaining the heat required for reactions. Furthermore, heat supply via waste heat recovery has been an attractive industrial prospect for improving the sustainability of hydrogen production. This study proposes a design of a novel Swiss-roll reactor with dual channels to harvest waste heat from the flue gas to sustain the steam reforming reactions. Ethanol is used as a feedstock due to its environmentally benign properties. Numerical simulations are conducted to establish the reactor's catalytic reactions and heat transfer phenomena under the variations of gas hourly space velocity (GHSV), steam-to-ethanol (S/E) ratio, and inlet flue gas temperature. Heat recovery improves at higher GHSVs and lower S/E ratios at the cost of less efficient hydrogen production, while high inlet flue gas temperature improves heat recovery and hydrogen production. The novel reactor design can fulfill complete ethanol conversion maintained by heat recovered from waste flue gas, achieving 86.6 % hydrogen production efficiency and 72.7 % heat recovery under optimal operating conditions.

Marine predators algorithm with deep learning based solar photovoltaic system modelling and optimization of green hydrogen production

Green hydrogen production depends on solar energy contains employing renewable solar power to purpose the electrolysis of water, causing the separation of hydrogen and oxygen molecules. This method contains a high potential to address the energy transition challenges caused by weather changes and vital carbon-neutral alternatives. Photovoltaic (PV) based combined energy systems performance as a potential new technological solution for clean and affordable green hydrogen production. Optimizing solar PV systems for the effectual generation of green hydrogen includes maximizing the energy output of solar panels and increasing the entire hydrogen production method. Several researchers and scientists are paid attention to the optimizer and modelling of many blocks developing the PV electrolysis method to acquire the optimum solution. With this motivation, the study presents a new Marine Predator Algorithm with Deep Learning-based Modelling and Optimization of the Green Hydrogen Production (MPADL-MOGHP) technique. The MPADL-MOGHP technique can be employed for determining the optimum operational variables of the water electrolysis procedure relevant to hydrogen (H2) production. Catalyst amount (μg), electrolysis time (min), and electric voltage (V) are the three controlling factors that should be properly detected to increase hydrogen production. The MPADL-MOGHP technique comprises two major stages of operations such as modelling and optimization. Primarily, the DBN model is applied for simulating the water electrolysis procedure designed based on electric voltage, quantity of catalyst, and electrolysis time. Next, the MPA is applied for determining the optimum parameters of the water electrolysis process to maximize the generation rate of the hydrogen. The quantity of catalyst, the electrolysis time, and the electric voltage are applied as decision parameters during the optimization process. The performances of the MPADL-MOGHP system are tested on different aspects. The experimental values highlighted the promising results of the MPADL-MOGHP method over other existing techniques.

Nanocomposite engineering: Tailoring MXene/Cobalt oxide for efficient electrocatalytic hydrogen and oxygen evolution reactions

Electrocatalytic water splitting has become a significant method of hydrogen production to overcome the energy scarcity and increased rate of pollution caused by the extreme consumption of fossil fuels. Pure cobalt oxide is a potential option for electrocatalytic water splitting due to its higher OER activity but lacks stability, conductivity, and active sites which impair its electrocatalytic performance. In this study, Ti3C2Tx/Co3O4 nanocomposite is synthesized to address the previously noted difficulties along with detailed study of both combinations in three different ratios (1:1, 1:2, 2:1). The outcomes demonstrated that the combination of Ti3C2Tx and Co3O4 in the ratio 1:2 outperformed the component materials in terms of electrocatalytic activity with the lowest overpotential of 270 mV at 50 mA cm‐2−2 for the oxygen evolution reaction (OER), having the least Tafel slope (85 mV dec−1) and Ti3C2Tx/Co3O4 in the ratio 2:1 showed overpotential of 235 mA cm−2, with lowest Tafel slope of 97 mV dec−1 which is the lowest among all electrodes for hydrogen evolution reaction (HER). In Ti3C2Tx MXene with increased O functional group providing adsorption site for hydrogen enables HER in a faster rate. While cobalt oxide enables charge transfer to electronegative MXene which in turn result in stability of the electrocatalyst. In the case of OER, Ti3C2Tx/Co3O4 (1:2) shows the better performance as Co centres act as the active sites for OER while MXene has the role of support matrix for the Co3O4 nanoparticles and prevent aggregation. By choosing these two particular composites, Ti3C2Tx/Co3O4 (2:1) as cathode and Ti3C2Tx/Co3O4 (1:2) as anode overall water splitting was done. For total electrolysis, a potential of 1.73 V was required to provide a current density of 10 mA cm−2 with satisfactory stability. Thus, the produced material is a promising contender for producing green hydrogen in the future.

Advanced Methods for Hydrogen Production, Storage and Utilization

Renewable hydrogen plays a critical role in the current energy transition and can facilitate the decarbonization and defossilization of hard-to-abate sectors, such as the industrial, power and mobility sectors [...]

Rigorous development and comparison of multi-dimensional reactor models encompassing the catalyst domains for steam methane reforming

Hydrogen is being considered as a possible large-scale carbon-free industrial combustion and transportation fuel. Steam methane reforming (SMR) reaction is the most dominant industrial hydrogen production method. This paper develops comprehensive models and delves into the influences of the multi-dimensional reactor and catalyst domains in SMR. Several single-scale or multi-scale SMR packed-bed reactor models are developed with the Aspen Custom Modeler and solved by the built-in finite difference method. These models are categorized into pseudo-homogeneous and heterogeneous models. This study thoroughly compares and discusses the effects of axial and/or radial mixing due to mass/heat dispersion as well as interfacial and intraparticle mass/heat transport phenomena across various types of reactor-catalyst configurations. Furthermore, insights into the prediction accuracy of each model under various operating conditions are provided. This research fills a gap in the existing literature by developing rigorous dynamic models for SMR reactors to investigate their profiles and performances, offering a clearer understanding of the relative importance of different modeling approaches in predicting the behavior of SMR reactors. The findings provide valuable guidelines for researchers and industry professionals in selecting the appropriate model for their design, analysis, optimization, and control tasks.

Enhanced Oxygen Evolution Reaction Performance in Co–Fe Hydroxides through Boron Doping

Among hydrogen production methods, water electrolysis stands out, but its efficiency is hampered by the substantial energy barrier of the oxygen evolution reaction (OER). To address this, incorporating electron‐deficient boron (B) into Co–Fe hydroxide (CoFeOxHy) promotes higher oxidation states of involved metals, greatly enhancing OER activity and charge transfer capabilities. Herein, the synthesis of a range of amorphous CoFeB nanoparticles with varying Fe to (Co+Fe) atomic ratios achieved through a simple chemical reduction method using CoFe‐Prussian blue analogs as precursors and employing Mössbauer spectroscopy to observe structural characteristics before and after transformation is reported. Among these nanoparticles, the CoFe0.25B variant, exhibiting favorable electrochemical properties, is chosen and subsequently subjected to hydrolysis to yield CoFe0.25BOH nanoparticles, serving as an active catalyst for OER. At a current density of 10 mA cm−2, the overpotentials for CoFe0.25OxHy and CoFe0.25BOH are 362 and 310 mV, respectively, with Tafel slopes decreasing from 393 to 93 mV dec−1. Furthermore, the i–t test reveals no significant loss of electrochemical performance within 24 h, substantiating the efficacy of enhancing the electrocatalytic performance of CoFeOxHy through the introduction of electron‐deficient elements. This research offers novel insights into the development of efficient and stable water electrolysis catalysts.

Highly effective hydrogen evolution reaction in alkaline conditions using a sputtered bimetal Ni-Mo system: Experimental and computational evidence

Electrocatalytic water splitting is a promising method for large-scale green hydrogen production. Nevertheless, the electrodes used remain costly and exhibit limited adherence. We should develop alternative techniques using cost-effective materials to achieve robust catalyst-substrate adherence. Herein, we systematically investigate the HER performance of the bimetal Ni-Mo system fabricated by scalelable magnetron sputtering. The formation of the bimetal Ni-Mo system not only significantly increased the HER activity, but it also accelerated the kinetic reaction. The optimal ratio Ni/Mo of 6 enables the achievement of ultra-low overpotentials of 39 and 172 mV at current densities of −10 and −100 mA/cm2, respectively, in alkaline conditions. The performance of the electrode is also evaluated using the single-stack electrolyzer and further assessed in natural seawater. The long-term stability test at 1.6 and 4 A for each 50 hours shows stable performance. The HER improvement mechanism is systematically investigated through experimental and computational calculations.

Silicon-doped cobal–aluminum layered double hydroxide electrocatalyst with high catalytic activity for oxygen evolution reactions

Electrochemical water splitting is a zero-carbon-emission and environmentally friendly method for hydrogen production. However, the process requires electrocatalysts to lower its energy requirements. In this study, Si-doped cobalt–aluminum layered double hydroxide (Si-CoAl-LDH) had been successfully synthesized by SiCl4 chemical etching at room temperature. The Co-O-Si chemical bonds promoted the formation of γ-CoOOHx during the process of water oxidation, thereby increasing the number of active sites. Moreover, Theoretical calculations revealed the overlap of atomic orbitals on the Si-CoAl-LDH catalyst surface and the improved electronic structure due to Co–O–Si chemical bonds. The Si-CoAl-LDH exhibited overpotentials of 295, 336, and 363 mV for oxygen evolution reactions (OERs) at current densities 10, 50, and 100 mA cm−2, respectively. The Tafel slope of the sample was 74.16 mV·dec−1. Physical characterization and in situ Raman analysis revealed the formation of intermediate hydroxylated cobalt species, which act as active centers during OER. This study serves as a basis for the surface reconstruction and activity enhancement of other electrocatalysts through Si doping.

State-of-the-art review on hydrogen's production, storage, and potential as a future transportation fuel.

Global energy consumption is expected to reach 911 BTU by the end of 2050 as a result of rapid urbanization and industrialization. Hydrogen is increasingly recognized as a clean and reliable energy vector for decarbonization and defossilization across various sectors. Projections indicate a significant rise in global demand for hydrogen, underscoring the need for sustainable production, efficient storage, and utilization. In this state-of-the-art review, we explore hydrogen production methods, compare their environmental impacts through life cycle analysis, delve into geological storage options, and discuss hydrogen's potential as a future transportation fuel. Combining electrolysis to make hydrogen and storing it in porous underground materials like salt caverns and geological reservoirs looks like a good way to balance out the variable supply of renewable energy and meet the demand at peak times. Hydrogen is a key component of our sustainable economy, and this article gives a broad overview of the process from production to consumption, touching on technical, economic, and environmental concerns along the way. We have made an attempt in this paper to compile different methods for the production of hydrogen and its storage, the challenges faced by current methods in the manufacturing of hydrogen gas, and the role of hydrogen in the future. This review paper will serve as a very good reference for hydrogen system engineering applications. The paper concludes with some suggestions for future research to help improve the technological efficiency of certain production methods, all with the goal of scaling up the hydrogen economy.

An Overview of the Efficiency and Long-Term Viability of Powered Hydrogen Production

This work studies the efficiency and long-term viability of powered hydrogen production. For this purpose, a detailed exploration of hydrogen production techniques has been undertaken, involving data collection, information authentication, data organization, and analysis. The efficiency trends, environmental impact, and hydrogen production costs in a landscape marked by limited data availability were investigated. The main contribution of this work is to reduce the existing data gap in the field of hydrogen production by compiling and summarizing dispersed data. The findings are expected to facilitate the decision-making process by considering regional variations, energy source availability, and the potential for technological advancements that may further enhance the economic viability of electrolysis. The results show that hydrogen production methods can be identified that do not cause significant harm to the environment. Photolysis stands out as the least serious offender, producing 0 kg of CO2 per kg of H2, while thermolysis emerges as the major contributor to emissions, with 20 kg of CO2 per kg of H2 produced.

Decarbonization frameworks to industrial-scale ammonia production: Techno-economic and environmental implications

Ammonia production traditionally relies on steam methane reforming (SMR), but it emits carbon and harms the environment. To address decarbonization frameworks of industrial-scale ammonia production process, a 100,000-ton ammonia manufacturing plant is presented using green ammonia synthesis methods. This study presents two promising hydrogen production methods for ammonia production, utilizing water electrolysis as scenario 1 and biomass gasification as scenario 2, while nitrogen is supplied using a cryogenic air separation unit (CASU). The techno-economic analysis shows that the ammonia production via SMR as the base case has lower total costs than Scenarios 1 and 2 due to not using green electricity. Through the environmental impact assessment of climate change, ozone depletion, terrestrial ecotoxicity, and natural land transformation, it is shown that Scenario 1 has lower impacts than the base case and Scenario 2 due to using green electricity. It is noted that the base case and Scenario 1 ensure the lowest production cost and environmental impacts, respectively, and Scenario 2 is the best balance between the economy and the environment.

Techno-economics and environmental assessment of sorbitol and itaconic acid production from sugarcane-based feedstock

Production of sorbitol or itaconic acid from sugarcane feedstocks in energy self-sufficient biorefinery scenarios were investigated, via Aspen Plus® simulations, techno-economic and environmental assessments. Sorbitol co-produced with fructose from A-molasses had a minimum selling price (MSP) (0.81 $/kg) similar to technical-grade sorbitol market prices (0.5 to 1.1$/kg), and an internal rate of return (IRR) of 19.65%. Sorbitol co-produced with mannitol from A-molasses had a lower MSP (0.48 $/kg), below food-grade sorbitol prices (0.58$/kg) and a higher IRR (23.63%). Combining A-molasses with lignocelluloses for the co-production of sorbitol and mannitol increased the MSP (0.63 $/kg) above the market price and decreased the IRR (18.46%). This scenario also had greenhouse gas emissions lower than that of its A-molasses only counterpart, mainly due to the method of hydrogen production. Itaconic acid production from sugarcane feedstocks in similar scenarios was unattractive due to lower IRRs (4.49% to 11.61%).

Nagynyomású hidrogénatmoszférás kemence gyártása szénacélok elridegedésének vizsgálatához

Összefoglalás. A hidrogén tárolása iránti igény egyre növekszik, melynek oka az, hogy a hidrogén mint alternatív energiahordozó jelentős szerepet játszik a szén-dioxidkibocsátás-csökkentési törekvésekben. Azonban, az elridegedési folyamatok körében a hidrogén által előidézett károsodások jelentik a legkomolyabb problémát az acélokra nézve. Kutatómunkánk során egy nagynyomású hidrogénatmoszférás hőkezelésre alkalmas autoklávot terveztünk, majd gyártottunk. Az autoklávban P355 NH minőségű alapanyagból kimunkált szabványos Charpy-féle ütőpróbatesteket hőkezeltünk 150 °C-on, 40 bar túlnyomáson, 200 órán keresztül, tiszta hidrogén atmoszférában. A vizsgálatok eredményei alapján megállapítottuk, hogy a jelentős mértékű elridegedés a hidrogénezési folyamat után sem történt. Summary. The demand for hydrogen storage is growing. The primary reason for this is that hydrogen as an alternative energy carrier is playing a significant role in carbon reduction efforts as a fuel for road and maritime transport. In addition, hydrogen can be seen as a long-term flexible energy storage option. Hydrogen as an energy carrier is expected to play a significant role in residential and industrial use in the future. A first step in this development is the mixing of hydrogen with natural gas in small quantities. Increasing the share of hydrogen would not only reduce CO2 emissions, but would also facilitate the development of different hydrogen production methods and thus reduce production costs. The upper safety limit for hydrogen blending with natural gas is set by the national specification of the natural gas supply, possible material quality restrictions and the tolerance of the most sensitive equipment in the network. For this reason, the maximum allowable hydrogen content in natural gas is generally limited to 2,5%. However, among the embrittlement processes, hydrogen-induced damage is the most serious problem for both non-alloy and low-alloy steels. Atomic hydrogen diffuses in steel at high rates. The diffusion rate is orders of magnitude higher than that of other elements; this is due to the small atomic diameter of hydrogen. To investigate the degradation of different carbon steels in a high-pressure hydrogen atmosphere, a hydrogenation furnace was designed and fabricated at the Department of Materials Science and Engineering at BME. The hydrogenation furnace is the main part of a complex mechanical engineering system, for the operation of which the mechanical, heating, electrical supply, control and gas handling components are indispensable. The entire design process of the furnace was led by József Blücher, Professor Emeritus at BME, with the help of the engineers and technicians working on the project. Standard Charpy impact test specimens were machined from P355 NH grade material to test the embrittlement of carbon steels. The hydrogenation temperature was 150 °C, the internal overpressure in the chamber was 40 bar, the hydrogenation time was 200 hours and the atmosphere was hydrogen gas of purity 5.0. The impact test was carried out at -20, 0 and +20 °C. Based on the results of the tests, it can be concluded that there was no significant degree of degradation both before hydrogenation and after prolonged exposure to hydrogen. It can be concluded that the tube material used as a sample is suitable for operation in a hydrogen medium. Based on the analysis of the burst areas and impact values of the impact test specimens, it was concluded that hydrogen did not cause any observable damage to the test material.

Recent Advances in Vanadium-Based Electrocatalysts for Hydrogen and Oxygen Evolution Reactions: A Review

With the intensification of global resource shortages and the environmental crisis, hydrogen energy has garnered significant attention as a renewable and clean energy source. Water splitting is considered the most promising method of hydrogen production due to its non-polluting nature and high hydrogen concentration. However, the slow kinetics of the two key reactions, the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER), have greatly limited the development of related technologies. Meanwhile, the scarcity and high cost of precious metal catalysts represented by Pt and Ir/RuO2 limit their large-scale commercial application. Thus, it is essential to develop catalysts based on Earth’s transition metals that have abundant reserves. Vanadium (V) is an early transition metal with a distinct electronic structure from late transition metals such as Fe, Co, and Ni, which has been emphasized and studied by researchers. Numerous vanadium-based electrocatalysts have been developed for the HER and OER. In this review, the mechanisms of the HER and OER are described. Then, the compositions, properties, and modification strategies of various vanadium-based electrocatalysts are summarized, which include vanadium-based oxides, hydroxides, dichalcogenides, phosphides, nitrides, carbides, and vanadate. Finally, potential challenges and future perspectives are presented based on the current status of V-based electrocatalysts for water splitting.