Hydrogen Production Research Articles

Highly efficient in-situ hydrogen generation from Al-ethanol reaction using NiCu bimetallic nanoparticles as catalysts

Highly efficient in-situ hydrogen generation from Al-ethanol reaction using NiCu bimetallic nanoparticles as catalysts

Bucket effect of Cobalt Nanoparticles and Single Atoms in Nitroarenes Transfer Hydrogenation

Synergetic metal nanoparticles (NPs) and single atoms hold significant potential in reactions that require activating multiple substrate molecules. However, due to the differences in adsorption, activation and kinetics among distinct substrates during the multistep reaction process, the synergy and matching relationship between metal NPs and single atoms remain unclear. In this work, we synthesized a series of Co1-NP/CNT@CN-X dual-site catalysts with tunable molar ratios (X%) of Co single atoms to total Co species through a coordination site regulation (CSR) strategy and investigated the bucket effect of the dual active sites in the transfer hydrogenation of nitro compounds. Density functional theory calculations reveal that active hydrogen generation from ammonia borane hydrolysis primarily occurs at the surface of Co NPs, while nitroarenes hydrogenation predominantly takes place at Co single atoms, which is consistent with experimental findings. The optimized Co1-NP/CNT@CN-7.6 maintains high selectivity for nitro hydrogenation (> 99.9%) and exhibits conversion (99.9%) nearly 3.7 times that of the original Co1-NP/CNT@CN-1.6 catalyst (27%), achieved by overcoming the bucket effect between Co NPs and single atoms. This work not only elucidates the synergistic mechanisms of dual sites in transfer hydrogenation, but also establishes that optimizing matching effect is an effective approach to significantly enhance their catalytic performance.

Controlled and Safe Hydrogen Generation from Waste Aluminum and Water, a New Approach to Hydrogen Generation

A new method is proposed to generate hydrogen in situ at low pressure from powder-pressed recycled aluminum turnings activated with small amounts of NaOH and drops of water. The contribution of this system is that the user can obtain small flows of high-purity hydrogen (>99%) to charge their portable electronic devices in remote places, in a simple, controlled, and safe way, since only water is used. Test tubes that contain tiny amounts of NaOH on their surface can be transported and used without contact. In addition to being a safer system, a smaller amount of NaOH and water is needed compared to other systems, there is no need to preheat the water, and the system can even generate heat. As the feeding is drop by drop, the hydrogen flow can be easily controlled by manual or automatic dosing. The waste obtained is solid and contains mostly aluminum hydroxide with some NaOH and impurities from the waste of origin, which are easy to sell and recycle. A study has been carried out to optimize the type of test tubes and establish critical parameters. The results show that a constant and controllable flow rate of hydrogen can be obtained depending on the drip frequency where the chemical reaction predominates over diffusion, that the optimal amount of NaOH is 20 wt%, that a finer grain size can increase the H2 yield with respect to the stoichiometric value but reduces the instantaneous flow with respect to that obtained with larger grains, and that it is very important to control the density and the impurities to increase porosity and therefore water diffusion. The estimated cost of the hydrogen produced is 3.15 EUR/kgH2 and an energy density of 1.12 kWh/kg was achieved with a test tube of 92% aluminum purity and 20 wt% NaOH.

Water process/treatment by a S-scheme Fe2O3/TiO2 heterojunction photocatalyst for excellent antibiotic degradation/CO2 reduction/H2 production; process optimization and mechanistic insights

A facile synthesis approach was employed to fabricate a binary Fe2O3/TiO2 nanocomposite (FeTi4-400) for enhanced photocatalytic hydrogen (H2) production, cephalexin degradation and CO2 reduction under visible light irradiation. Compared to pristine TiO2, FeTi4-400 exhibited improved visible light absorption and promoted charge carrier separation, leading to increased H2 production rate and CO2 conversion into CH4 and CO. This improvement can be attributed to the formation of an S-scheme heterojunction, along with the desirable properties of FeTi4-400, including visible light activity, high surface area, and strong CO2 adsorption. The photocatalyst achieved a maximum H2 production rate of 649 μmol/g·h−1, exceeding that of pure TiO2. Similarly, the highest CO production rate of 16.44 μmol/g·h−1 was attained with FeTi4-400. Furthermore, FeTi4-400 achieved excellent cephalexin degradation (96 %) under optimal conditions, with a degradation rate constant of 0.01 min−1. A plausible cephalexin degradation pathway over FeTi4-400 is proposed. Transient photocurrent measurements and EIS analysis corroborated a significant enhancement in photocatalytic activity for FeTi4-400, attributed to the efficient separation of photogenerated electron-hole pairs. Stability studies demonstrated consistent cephalexin degradation by FeTi4-400 over five consecutive cycles without noticeable photocatalyst deactivation. This work presents a novel strategy for fabricating low-cost, efficient, and readily synthesized nanomaterials for applications in solar energy conversion and environmental remediation.

Thermo-economic analysis of green hydrogen production onboard LNG carriers through solid oxide electrolysis powered by organic Rankine cycles

LNG carriers play a crucial role in the shipping industry meeting the global demand for natural gas (NG). However, the energy losses resulting from the propulsion system and the excess boil-off gas (BOG) cannot be overlooked. The present article investigates the H2 production on board LNG carriers employing both the engine's waste heat (WH) and the excess BOG. Conventional (ORC) and dual-pressure (2P-ORC) organic Rankine cycles coupled separately with a solid oxide electrolysis (SOEC) have been simulated and compared. The hydrogen (H2) produced is then compressed at 150 bar for subsequent use as required. According to the results, the 2P-ORC generates 14.79 % more power compared to ORC, allowing for an increased energy supply to the SOEC; hence, producing more H2 (34.47 kg/h compared to 31.14 kg/h). Including the 2P-ORC in the H2 production plant results in a cheaper H2 cost by 0.04 $/kgH2 compared to ORC, a 1.13 %LHV higher system efficiency when leveraging all the available waste heat. The plant including 2P-ORC exploits more than 86 % of the of the available waste compared to 70 % when using ORC. Excluding the compression system decreases the capital cost by almost the half regardless of the WH recovery system used, yet it plays in favour of the plant with ORC making the cost of H2 cheaper by 0.29 $/kgH2 in this case. Onboard H2 production is a versatile process independent from the propulsion system ensuring the ship's safety and availability throughout a sea journey.

Advanced modelling and optimization of steam methane reforming: From CFD simulation to machine learning - Driven optimization

Computational fluid dynamics simulations were utilized to investigate the steam methane reforming process with the aim to improve its efficiency. Key parameters examined for their impact on process performance included surface heat flux (73–108 kW/m2), tube length (1–16 m), steam-to-carbon ratio (1.4–4), and flow rate (0.22–0.38 kg/s). To analyze the simultaneous effects of these variables while reducing computational costs, Deep Neural Networks (DNN) were employed. An optimized DNN was designed to achieve acceptable performance, featuring an input layer with four neurons that represent reformer length, flow rate, heat flux, and steam-to-carbon ratio. The network includes four hidden layers with 32, 16, 8, and 8 neurons respectively, and concludes with an output layer comprising seven neurons for residual methane, water vapor, produced hydrogen, carbon dioxide, carbon monoxide, wall temperature, and gas outlet temperature. The results indicated that the proposed model achieved high accuracy, exceeding 99%, in predicting both training and test data. Following the DNN modeling, an optimization algorithm based on the random search method was developed. This algorithm searches a wide range of parameters to identify the optimal conditions for simultaneously maximizing hydrogen production and minimizing reformer length.

Unveiling the future: A simulation and analysis of hydrogen production using 1kW electrolyzer with MATLAB approach

This research concentrates on optimizing hydrogen production via a 1kW electrolyzer powered by renewable solar energy, specifically targeting efficiency enhancement through adjusting membrane area. The rising global demand for clean energy solutions has positioned hydrogen as a pivotal element in the shift toward sustainable energy systems. Nonetheless, the efficacy of hydrogen generation via electrolysis continues to pose a challenge, particularly at reduced scales. This research involved the creation of a comprehensive simulation model utilizing MATLAB Simulink to investigate the impact of membrane area variations on hydrogen production and overall system efficiency. The simulation results indicate that optimizing the membrane area can substantially enhance hydrogen production rates. The system was capable of producing up to 2.5 kg/h of hydrogen, signifying a substantial enhancement over traditional methods. Moreover, incorporating solar energy as the principal power source diminishes environmental repercussions while guaranteeing a sustainable and clean approach to hydrogen production. This research introduces an innovative method for optimizing small-scale electrolyzers, offering insights applicable to industrial hydrogen production and the integration of renewable energy. The findings facilitate the advancement of sustainable hydrogen production technologies, consistent with international initiatives to diminish dependence on fossil fuels.

Modeling and parametric study of tubular high temperature steam electrolysis (HTSE) cell for enhanced hydrogen production

High-temperature steam electrolysis (HTSE) achieves high efficiency in hydrogen production and plays a critical role in advancing hydrogen-based energy frameworks. Progression from single-cell to multi-cell stacks is essential, but this transition is hindered by the complex interplay of electrical, flow, and thermal management. Modeling is crucial for addressing these complexities, allowing for simulation of cell and stack performance. In this study, 2D axisymmetric modeling of HTSE cell in tubular configuration is performed. A tubular HTSE cell is fabricated and tested in solid oxide electrolysis (SOEC) mode and impedance modeling of the cell is conducted from 200 °C to 820 °C, analyzing cell behavior transition with temperature. Multiphysics modeling parameters are acquired experimentally and modeling results align well with the experimental data. Further cell analysis is carried out with the developed model by acquiring parameters that are challenging to measure experimentally. The study also determines optimal flow conditions for HTSE cells through parametric variations.

Holistic Idle Periodic Evaluation method for mass balance monitoring at hydrogen refuelling stations

Hydrogen refuelling station (HRS) is an intricate system consisting typically of compression, storage, and dispensing subsystems. Thus, monitoring of HRSs has become a challenge in a real-time operation. Mass balance analysis of such a system consists of evaluating for a given timespan the amount of hydrogen received (produced or delivered on-site) and the amount of hydrogen dispensed to the vehicles. Previous work focused on off-line evaluation of hydrogen losses of HRSs with on-site hydrogen production. This article proposed a solution to holistically evaluate hydrogen mass balance and periodically evaluate hydrogen losses at HRSs in a continuous operation environment. We applied the Holistic Idle Periodic Evaluation method on real-time operational data of two HRSs with off-site hydrogen production and deployed the system for online monitoring of the hydrogen losses. The two stations were found to have hydrogen mass balance of 94.2% and 83.6% with an uncertainty of ±5.0%. Our method can track normal and anomalous system operations in real time. It is applicable for HRSs with both off-site and on-site hydrogen production and only requires one mass flow meter used for metering hydrogen being dispensed to vehicles.

Tailored Ni(OH)2/CuCo/Ni(OH)2 Composite Interfaces for Efficient and Durable Urea Oxidation Reaction.

Electrocatalytic urea oxidation reaction is a promising alternative to water oxidation for more efficient hydrogen production due to its significantly lower thermodynamic potential. However, achieving efficient electrochemical urea oxidation remains a formidable challenge, and development of an improved electrocatalyst with an optimal physicochemical and electronic structure toward urea oxidation is desired. This can be accomplished by designing a tailored two-dimensional composite with an abundance of active sites in a favorable electronic environment. In this study, we demonstrate the fabrication of a self-supported, electrochemically grown metal/mixed metal hydroxide composite interface via a two-step electrodeposition method. Specifically, Ni(OH)2 was electrodeposited on the top of the CuCo layer (Ni(OH)2/CuCo/Ni(OH)2), and the resultant 2D composite structure required 1.333 ± 0.006 V to oxidize urea electrochemically to achieve a current density of 10 mA cm-2, which outperformed the potential required for individual components, Ni(OH)2 and CuCo. The high density of Ni3+ active sites in the composite structure facilitated high electrocatalyst activity and stability. Ni(OH)2/CuCo/Ni(OH)2 was stable for at least 50 h without any noticeable degradation in the activity or alteration of the morphology. As a bifunctional electrocatalyst, the material also exhibited excellent performance for water oxidation with 260 mV overpotential and 50 h stability. In a two-electrode configuration coupled with a NiMo cathode catalyst, the electrolyzer required 1.42 V cell voltage for overall urea splitting. Overall, the engineered Ni(OH)2/CuCo/Ni(OH)2 composite demonstrated exceptional potential as an efficient and stable electrocatalyst for both urea and water oxidation reactions, paving the way for more effective hydrogen production technologies.

Liquid-phase deposition of [formula omitted] heterojunction thin film photoanode for water splitting

The Liquid-phase deposition (LPD) method stands out as one of the most cost-effective techniques for fabricating thin films, due to its simple equipment requirements, low operational costs, and easy scalability while maintaining excellent film quality. In this work, we successfully demonstrate for the first time the synthesis of a heterojunction thin-film photoanode of hematite (α-Fe2O3) on an n-type silicon (n-Si) substrate using LPD. The α-Fe2O3/n-Si heterojunction photoanodes fabricated by LPD exhibited superior photocurrent responses for water splitting, with greater light absorption and enhanced performance compared to photoanodes prepared on fluorine-doped tin oxide (FTO) glass substrates, indicating the high quality of the heterojunction interface. The LPD-fabricated heterojunctions showed an early onset of photocurrent at lower applied potentials compared to Pt-based metal electrodes, demonstrating a reduction in overpotential voltage of 0.3 V. Overall, the LPD method shows promising potential for fabricating high-quality α-Fe2O3/n-Si thin films, with potential applications toward unassisted water splitting, offering an efficient and sustainable approach for green hydrogen production.

Techno-economic assessment of a green liquid hydrogen supply chain for ship refueling

Maritime transportation is an essential component of international trade and global economic growth: according to the 2021 Review of Maritime Transport, transportation by sea is responsible for more than 80% of the global product flow. To facilitate decarbonization and reduce pollutant emissions in the maritime sector, the International Maritime Organization (IMO) has set very ambitious targets, and hydrogen is one of the most promising energy vectors capable of supporting the required low-carbon energy transition. Recently, therefore, more attention has been paid to finding technical solutions for the development of hydrogen-based alternative propulsion systems and, at the same time, a hydrogen distribution infrastructure suitable for shipping. In this scenario, this study aims to analyze, through design, modeling and optimization approaches, the energy and economic performance of an offshore wind power plant integrated with a liquid hydrogen production system to be used for refueling ships far from ports. This study focuses on the development of an optimization procedure dedicated to finding the best technical solution in terms of component sizes and management strategies that ensure the minimum Levelized Cost of Hydrogen (LCOH). Resultshave highlighted that the proposed innovative plant configuration for the offshore liquid hydrogen production is able to produce 317 tons per year of green hydrogen with a LCOH of 16.77 €/kg by using 19 MW offshore wind farm and 5 MW PEM electrolyzer.

An up-to-date perspective of levelized cost of hydrogen for PV-based grid-connected power-to-hydrogen plants across all Italy

Green hydrogen holds potential for decarbonizing the energy sector, but high production costs are a major barrier. This study provides a comprehensive techno-economic-financial-environmental analysis of PV-based grid-connected hydrogen production plants, targeting hard-to-abate industries having constant hydrogen demand across all Italy. Using real hourly data, the Multi Energy System Simulator (MESS), an in-house developed rule-based tool, was employed and integrated with Genetic Algorithm for optimal plant sizing. The aim is to minimize the Levelized Cost of Hydrogen (LCOH) while complying with regulatory frameworks for green hydrogen incentives access. Key findings show that hydrogen storage is more advantageous than battery storage for supply-side flexibility, and the optimal PV-to-electrolyzer size ratio ranges from 1.8 in Southern Italy to 2.1 in Northern Italy, with hydrogen tank designed for daily storage. Considering photovoltaic, electrolyzer and battery aging models grid dependence increases by 60 % when comparing the first and worst year of operation and leads to a 7 % increase in LCOH. Transitioning from the strictest (hourly) to the least stringent (annual) temporal correlation increases certified green hydrogen by 22 %, while LCOH decreases by only 3 %, suggesting that the environmental benefits of stringent temporal requirements outweigh their moderate economic drawbacks. These findings underscore the need for additional national-level incentives to allow the deployment of this technology and achieving cost parity with grey hydrogen.

MXene-supported 2D bimetallic chalcogenide electrocatalyst: Enhanced electrochemical seawater splitting

Hydrogen energy holds immense potential for revolutionizing modern energy technologies. Seawater electrolysis is a promising strategy for hydrogen production; however, the lack of effective electrodes limits its widespread application. Therefore, developing high-performance, cost-effective catalysts for water splitting is essential for sustainable energy conversion. In this context, we report a novel hybrid bimetallic selenide (CoMoSe2) and MXene (Ti3C2Tx) electrocatalyst, which exhibits remarkable catalytic performance for seawater electrolysis. The CoMoSe2@Ti3C2Tx electrocatalyst demonstrates outstanding catalytic capabilities, achieving overpotentials of 82 mV for hydrogen evolution reaction (HER) and 329 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm⁻2 in alkaline conditions. The Tafel slope values are 124 mV dec⁻1 for hydrogen evolution and 69 mV dec⁻1 for oxygen evolution, outperforming their individual components. The enhanced bifunctional catalytic performance of the hybrid catalyst is attributed to the synergistic effect of Mo atoms within the CoSe2 crystal structure, which modifies the electronic structure and lowers the chemisorption energies of hydrogen and oxygen intermediates. The abundance of oxygen vacancies provides more reactive active sites and improves electrical conductivity. Additionally, the CoMoSe2@Ti3C2Tx composite has demonstrated remarkable bifunctional electrocatalytic performance for seawater splitting, achieving 10 mA cm⁻2 at overpotentials of 161 mV for HER and 354 mV for OER in alkaline seawater. The Volmer-Heyrovsky mechanism drives the remarkable long-term stability of the catalyst. This novel approach contributes to sustainable energy solutions by providing a fresh avenue for the development of effective catalysts to produce hydrogen from seawater.

Gallic acid assisted synthesis of novel CuO/Ni/Fe3O4 nanocomposite for catalytic CO2 methanation and photocatalytic hydrogen generation

Gallic acid assisted synthesis of novel CuO/Ni/Fe3O4 nanocomposite for catalytic CO2 methanation and photocatalytic hydrogen generation

Technoeconomic analysis of supercritical water gasification of canola straw for hydrogen production

Production of hydrogen from renewable sources is gaining popularity to reduce our dependency on non-renewable fossil fuels to meet growing hydrogen demand. However, despite the great prospect of production of hydrogen from sustainable sources such as lignocellulosic biomass via supercritical water gasification (SCWG), it has not been commercialized at a large industrial scale. This is due to the lack of detailed economic analysis of SCWG of lignocellulosic biomass, owing to the complexity of the SCWG process and the heterogeneous nature of biomass. Therefore, to address this knowledge gap, in this study, a detailed technoeconomic analysis (TEA) of a conceptual SCWG pilot having the capacity to process 200 tons/day of canola straw for the production of green hydrogen was conducted. Mass and energy balance of conceptual pilot was performed using Aspen Plus ® simulation by utilizing experimental data and hydrogen yield of 41.62 mmol/g was obtained at optimized reaction conditions of 500 °C, 23 MPa, and 10 wt%. Economic analysis based on calculated mass and energy balance was performed using SuperPro software. Cash flow analysis for capital expenses (CAPEX) of 81 Million USD showed a high internal rate of return (IRR) of 38.9% and an undiscounted net present value (NPV) of 548 million USD. A minimum selling price (MSP) of 3.38 USD/kg H2 for produced hydrogen was estimated, which is lower than other renewable hydrogen production processes and comparable to non-renewable hydrogen production technologies. A high positive IRR and NPV, while a lower MSP showed that despite having a low technological readiness level (TRL) of 4, SCWG of lignocellulosic biomass is a technically feasible and economically viable process for the production of hydrogen. Furthermore, sensitivity analysis also revealed that capital expenses (CAPEX) and canola straw price had the highest influence on net present value (NPV) and MSP. However, overall NPV and MSP were highly stable to changes in parameters highlighting the robustness of the economic analysis.

Mechanistic insights into the use of flotation tail coal for enhanced water electrolysis in hydrogen production

Coal-assisted water electrolysis for hydrogen production (CAWE) is a promising method for the efficient utilization of coal resources and the sustainable generation of hydrogen. However, identifying a cost-effective and efficient carbon source remains a critical and ongoing challenge. This study proposes the use of flotation tail coal as a novel and efficient carbon source for water electrolysis. Through a combination of electrochemical experiments, thermodynamic analysis, and comprehensive material characterization techniques, this research explores the effectiveness of tail coal-assisted water electrolysis for hydrogen production (TCAWE) in enhancing hydrogen production efficiency. It is found that the catalytic effect of minerals, particularly iron and manganese ions, is instrumental in significantly reducing energy consumption and enhancing the anodic oxidation reactions in the CAWE process. Flotation tail coal, with its high content of these catalytic minerals and favorable hydrophilic surface properties, not only lowers the electrolysis voltage but also increases the hydrogen yield compared to traditional coal sources. This research innovatively demonstrates that utilizing flotation tail coal in water electrolysis offers a dual benefit: it provides a cost-effective, abundant carbon source while promoting a more efficient and sustainable hydrogen production process. Additionally, this approach is expected to facilitate the resource utilization of waste flotation tail coal.

Electrochemical upgrading of PET plastic wastes for hydrogen production using porous Fe–Ni2P nanosheets

The electrochemical upgrading of PET plastic wastes-to-hydrogen is an important conversion system for achieving sustainable, low-cost and scalable hydrogen production. Designing cost-effective and highly active dual-function electrocatalysts for the ethylene glycol (PET monomer) oxidation reaction (EGOR) and hydrogen evolution reaction (HER) is very crucial for achieving practical application of PET plastic wastes upgrading assisted electrochemical water splitting technology. Herein, a simple hydrothermal-phosphating two-step method is implemented to achieve ultrathin porous iron (Fe) doped nickel phosphide (Ni2P) nanosheets attached to the nickel foam (named as Fe–Ni2P/NF). Profiting from the ample active sites provided by the ultrathin structure, porous structure and the optimized electronic structure caused by Fe doping, Fe–Ni2P/NF exhibits predominant electroactivity for HER and EGOR. Additionally, PET plastic wastes hydrolysate electrolyzer is assembled by using Fe–Ni2P/NF as a dual-functional electrode for the co-generation of hydrogen and formate. The constructed Fe–Ni2P/NF||Fe–Ni2P/NF electrolyzer only requires an electrolysis potential of 1.39 V to derive 10 mA cm−2 current density, which is lower than that of conventional water splitting (1.55 V). This work would afford a reference for constructing cost-efficient and steady plastic-assisted water electrolysis bifunctional catalysts, and expands the field of energy-saving co-generation of value-added chemicals and hydrogen.

Electrochemical exfoliation of graphite using aqueous ammonium hydrogen carbonate solution and the ability of the exfoliated product as a hydrogen production electrocatalyst support

Electrochemical exfoliation of graphite has attracted much attention as a practical mass production of two-dimensional graphene-like materials. There is an increasing desire to find new and improved methods to create unique exfoliated products with excellent functionality. We used aqueous ammonium hydrogen carbonate solution as a new electrolyte for anodic oxidative exfoliation of graphite. The exfoliated product has a porous two-dimensional structure, and it can be dispersed in water for over five years. The oxidized and defected porous surface serves as an ideal support for molecular metal complexes, effectively functioning as heterogeneous electrocatalysts for hydrogen production.

Study on the comprehensive influence of Si-Al-based additives on hydrogen production and K deposition during biomass gasification

Green hydrogen production through gasification is a prospective utilization of biomass. Operational issues (slagging, corrosion and catalyst poisoning) due to inherent alkali metal deposition are main factors affecting gasification. The adoption of Si-Al-based additives as alkali metal inhibitors is a promising approach. In this work, the influence of additive types and placement methods on K deposition and gasification characteristics were studied through a decoupled gasification with online analysis. As a result, separative placement (Sep) method could reduce K deposition without decreasing hydrogen yield compared to mechanical mixture (Mix) method. This advantage is particularly prominent in char gasification. SiO2 is recommended to be added by the Mix to react with alkali and alkaline earth metal species individually to inhibit K release. This match could reduce peak of K deposition content by 55.80 % with less impact on hydrogen yield. Meanwhile, Al2O3 is recommended to be added by the Sep due to its unique comprehensive performance, which could increase hydrogen yield by 4.34 % and reduce peak of K deposition content by 52.72 %. Two recommended addition strategies could be used in different scenarios. This study is expected to guide the design of corrosion-resistant reactors and multifunctional catalysts.