Pure Hydrogen Research Articles

Thermodynamic property calculation for pure component hydrogen isotopologues considering tritium processing technologies in fusion fuel cycle

In this study, the thermodynamic properties calculation methods for hydrogen isotopes are presented to be used in the process simulation of tritium handling processes in the fusion fuel cycle. To define appropriate temperature and pressure ranges for the calculations, applicable technologies of subsystems are investigated. Among various approaches, specific calculation methods and models for each property are suggested based on data gathered from a literature survey. Commonly used cubic equations of state, Peng-Robinson and Redlich-Kwong-Soave, are evaluated to ensure applicability in commercial simulation software. Hydrogen and deuterium data in the NIST REFPROP database are used as validation sets for proposed calculation approaches. The results show that Peng-Robinson and Redlich-Kwong-Soave equations of state have good agreement with NIST REFPROP in saturated liquid and gas states, as well as gas conditions up to 10 bar and 1000K. Finally, the proposed methods are applied to other isotopologues, and the trends of the properties are analyzed.

A computational-fluid-dynamics study on scaling up a single flat membrane reactor for on-site hydrogen production

The accessibility of hydrogen stations has been problematic for remote areas, although the demand for fuel-cell electric vehicles has risen. We propose a 50-Nm3/h on-site hydrogen production system using the accessible liquid-fuel infrastructure. The system integrates a pressurized steam reformer and a catalytic membrane reactor to produce high-purity hydrogen. This study focuses on scaling up our membrane reactor for enhanced hydrogen permeation while maintaining acceptable similarity and performance to make the system compact and effective. We compare three scale-up methods, which keep the inlet Reynolds number, gas hour space velocity, and Damköhler-Peclet number constant, respectively. After selecting the third case for its best similarity, we increase the scale to eight and conclude that any scale beyond four is not ideal for our specific membrane reactor. By increasing the scale to four, we reduce the number of reactors for the 50 Nm3/h target by 91% while achieving a hydrogen recovery of 91%. Future studies can refer to the scale-up process that maintains the reactor similarity and high performance in this work for choosing an appropriate scale for membrane reactors.

Thermal quench induced by a composite pellet-produced plasmoid

Injecting shattered pellets is the critical concept of the envisaged ITER disruption mitigation system (DMS). Rapid deposition of large amounts of material should presumably result in controlled cooling of the entire plasma. A considerable transfer of thermal energy from the electrons of the background plasma to the ions accompanies a localized material injection due to the ambipolar expansion along the magnetic field line of the cold and dense plasmoid produced by the ablated pellet. Radiation initially plays the dominant role in the energy balance of a composite plasmoid containing high-Z impurities. A competition between the ambipolar expansion and the radiative losses defines the Thermal Quench scenario, including the amount of pre-quench thermal energy radiated on a short collisional timescale—possibly detrimental for the plasma-facing components. The present work quantifies plasmoid energy balance for disruption mitigation parameters. For pure hydrogen injection, up to 90% of the pre-pellet electron thermal energy may go to the newly injected ions. We also demonstrate that a moderate high-Z impurity content within the plasmoid can reduce highly localized radiation at the beginning of the expansion. The thermal energy will then dissipate on the much longer ion collisional timescale, which would be attractive for ITER DMS.

Evaluation of Oxygen Carrier Performance in a Packed‐Bed Reactor during Chemical Looping Hydrogen Generation

AbstractChemical looping hydrogen generation (CLHG) has attracted much attention owing to its simple operation, low carbon capture cost, and high hydrogen purity. The performance of oxygen carrier plays an important role in the CLHG. In this work, considering the variation of internal reaction and coke deposition inside the oxygen carrier during the CLHG process, a packed‐bed reactor model is established. The temperature, gas composition, and coke deposition distribution inside the particle and reactor are explored. The results indicate that the reaction progress of the oxygen carrier near the wall is slightly faster than that at the center. The overall conversion rate and coke accumulation of the oxygen carrier near the wall are greater than those at the center.

ZnCrXFe2-XO4 (X = 0–2) porous powder prepared through self-combustion glycine nitrate process and applied to methyl alcohol steam reforming for production of pure hydrogen

Climate change, global warming, and energy crisis have become an important problem due to the environmental impact of fossil fuels. Hence, alternate energy source is needed for environmental remediation. One such source could be hydrogen (H2). H2 is used as an alternate energy carrier due to it is non-toxic, clean, and efficient. Steam reforming of methyl alcohol (or) methanol (SRM) is a widely available and low-cost hydrogen production method. In this stream-reforming process, mostly commercial zinc-supported catalyst is used, these have some economic defect. Therefore, we need to find alternate suitable catalysts for the SRM process. In this study, ZnCrXFe2-XO4 (X = 0–2) porous catalyst powders of different ratios were synthesized by the glycine nitrate process (GNP) for hydrogen production by SRM. The specific surface areas of the ZnCrXFe2-XO4 powders ranged from 15.75 m2/g to 45.16 m2/g. The ZnCr0.4Fe1.6O4 powder had the highest H2 production without activation, reaching 6850.33 ml STP min−1 g-cat−1 at a reaction temperature of 450 °C. ZnCr0.4Fe1.6O4 porous powders prepared using the GNP method have simple, rapid process steps, low cost, high catalytic activity, and they can be applied to hydrogen fuel cells or other related catalysis applications in the future. The pure hydrogen production performance of these ZnCrXFe2-XO4 catalysts could be of great importance in industry and economic impact.

DETERMINATION OF ECOTOXIC SUBSTANCES IN WASTEWATER FORMED IN THE PURIFICATION PROCESS OF PETROLEUM OILS WITH HYDROGEN BY SPECTRAL METHODS

The article analyzes the determination of the amount of dissolved ecotoxicants in the sample taken from the industrial wastewater obtained during the process of hydrogen treatment of petroleum oils. During the hydrogenation process, different types of wastes are formed, depending on the nature of each compound contained in petroleum distillates. Every gas, liquid, solid waste formed during the process of hydrogen purification of petroleum distillates by the oil refining industry has a negative impact on the environment in various ways. One of the main directions of our scientific research is the ecological assessment of the environmental impact of wastewater formed in the process of hydrogen treatment of petroleum distillates.Based on the results obtained, the environmental impact of the wastewater was assessed. The amount of volatile ecotoxicants in the wastewater sample was determined by spectral methods and is shown in the table. We used gas chromatography-mass spectrometry method for the polycyclic aromatic hydrocarbons; optical emission spectrometry method for metals; spectrometry method for phenols, dyes and fluorine; nephelometry method for turbidity; the gravimetry method for total suspended particles. Based on the results obtained, it is possible to assess the environmental impact of wastewater generated during the technological process at the hydrogen treatment plant. According to the results of the research, it can be noted that the industrial wastewater discharged from the oil refinery's facility № 501 has a content that will damage the ecosphere and biosphere, despite the fact that the discharge standards meet the permissible discharge limits

Green hydrogen Production from the oxidative reform of clean biogas over Ni/MgO-Nb2O5 catalysts

Synthesis gas has a variety of applications ranging from its transformation into Fischer-Tropsch fuels, its processing to produce pure hydrogen, and even its direct combustion to generate energy, among many other applications. The objective of this work was the conversion of a model of biogas (clean biogas) into synthesis gas, H2 /CO, through oxidative reforming of methane over NiO/MgO/Nb2O5 catalysts. The catalysts in this work were prepared by impregnation and calcination (at 750ºC) and subsequently characterized by Energy Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Nitrogen Adsorption-Desorption (BET method) and Temperature Programmed Reduction with H2 (TPR). Finally, these catalysts were tested in the oxidative reform of methane (molar ratio of 1.5CH4:1CO2:0.25O2) at 750 ºC, 100mg of catalyst at a total flow of 110 mL.min-1, and 1 atm (inside the reactor). According to the results, it was verified that the catalyst composed of the NiO/MgO mixture is composed of the NiO-MgO solid solution, whereas the NiO/MgO/Nb2O5 catalysts are also formed by nickel niobate (NiNb2O6). All catalysts showed catalytic activity in the oxidative form of biogas, NiMg, Ni60NbMg, and Ni40NbMg catalysts showed the highest conversion value. The efficiency of the catalysts in the oxidative reforming of biogas improved gradually as the %MgO increased in the NiO/MgO/Nb2O5 system. The characterization of the catalyst after the reaction demonstrated that the carbon formed is of the filamentous type.

The effect of concentration polarization and chemical interactions on electrochemical hydrogen pump

Electrochemical hydrogen pump is expected to play an important role in, e.g., H2 extraction from natural gas pipelines, by-product hydrogen purification. The influence of typical concomitant CH4 and CO2 on electrochemical hydrogen pump is systematically investigated in this study over a wide range of gas content (CH4 or CO2: 10-80 %) and temperature (26-60 °C), with the focus on two main inhibition effects, i.e., concentration polarization and chemical interaction. An Faradaic efficiency of 86–96 %, i.e., below 100 %, is obtained as to the H2/CH4 mixture separation due to concentration polarization effect, which is even lower in case of H2/CO2, due to additional chemical interactions between CO2 and Pt anode catalysts. The inhibition of concentration polarization is more significant than that of chemical interactions, and the former can be suppressed by increasing the operating temperature and pressure due to enhance catalytic activity and proton conductivity. As to these two gas mixtures, the energy consumption ranged from 0.2 to 2.0 kWh/m3 with the increase of applied current from 125 to 1250 mA. The electrochemical pump exhibits limited H2 purity of 98.6 %–99.7 % due to the existence of nafion membrane defects, which requires to be further improved.

Excellent gas separation performance of hybrid carbon molecular sieve membrane derived from polyimide/10X zeolite for hydrogen purification

Membrane-based gas separation is attracting more and more attention in hydrogen purification and CO2 separation. One critical challenging remaining for large-scale production is fabricating a high-performance membrane with both inexpensive and excellent separation performance. In this work, a novel hybrid-carbon molecular sieve (CMS) membranes were reported for hydrogen purification by pyrolysis of commercial polyimide precursor (PMDA-ODA) with incorporation of modified 10X zeolite. The addition of modified 10X zeolite provided additional gas transport channels to the CMS mixed matrix membrane (MMM), and contained a significant fraction of micropores within the 0.6–0.8 nm range, which greatly enhance hydrogen adsorption capacity. Interestingly, despite this, the selectivity for H2/N2 and H2/CH4 also increases with higher zeolite content. This unexpected phenomenon may be attributed to the partial blocking of zeolite pores by CMS strand, which narrows the 10X pore size to a dimension smaller than CH4 and N2, enabling differentiation between H2 and CH4 gas pairs. Therefore, the permeability and selectivity of H2 was significantly enhanced. The CMS/10X-7.5 (with 7.5 wt % 10X zeolite) exhibited an advanced H2 permeability (1709 Barrer) and high gas selectivity of 551 for H2/CH4 and 105 for H2/N2, respectively, which is higher than other samples and exceed the 2015 trade-off lines. Furthermore, the CMS/10X-7.5 delivered excellent stability after 20 cycles. Therefore, this hybrid CMS/10X-7.5 obtained by carbonization of zeolite-doped polymer precursors has great potential for larger industrial applications.

Engineering dual MoC–Mo2C heterostructure–knotted CNTs for efficient direct seawater electrolysis

Considering the abundant reserves of seawater and limited resources of freshwater, seawater electrolysis is a more economically competitive technology for producing high-purity hydrogen, but remains a challenging approach. Herein, we report an innovative strategy for constructing dual MoC–Mo2C heterostructure–knotted CNTs nanorods (MoC–Mo2C/CNTs) to improve the electrocatalytic performance and durability in alkaline seawater, in which the hybrid electrode achieves 10 mA cm−2 at low overpotentials of 95 and 279 mV for HER and OER, respectively. For overall simulated and natural seawater splittings, a low cell voltage of 1.57 and 1.61 V, respectively, is necessary to drive 10 mA cm−2 and outstanding durability over 50 h at a high current density of 50 mA cm−2. The experimental results indicate that the unique boundary interface of MoC–Mo2C/CNTs could result in rich exposed active sites, corrosion resistance layer, and electronic redistribution, thus leading to high-performance HER and OER activities. This work provides an ultimate approach to the rational design of multi-component transition metal carbide-based heterogeneous electrocatalysts for seawater electrolysis.

Rapid room-temperature synthesis of porous Sulfur-doped nickel-chromium-Layered Double Hydroxide for oxygen evolution catalysis in seawater splitting

Seawater splitting is a promising and sustainable technology for producing high-purity hydrogen, but its commercial application remains a major challenge due to the kinetically slow oxygen evolution reaction (OER) and severe corrosion in practical applications. In this work, we report a single-step approach to grow a highly porous Sulfur-doped nickel-chromium-Layered Double Hydroxide (S-doped NiCr-LDH) catalyst on Ni foam at room temperature. This rapid approach efficiently designs the surface of Ni foam into a porous S-doped NiCr-LDH layer with outstanding hydrophilic characteristics. The catalyst exhibits outstanding OER performance in alkaline freshwater and alkaline seawater electrolytes, requiring overpotentials of only 270 and 342 mV to achieve current densities of 100 mA cm−2, while also exhibiting an extremely long endurance of over 80 h. This simple OER catalyst preparation method could advance the development of hydrogen production from seawater splitting.

Evaluation of a novel coupling process for the simultaneous production of syngas and ultra-pure hydrogen from natural gas with in situ utilization of carbon dioxide

Recently, with the aim of developing clean and efficient energy systems, various designs based on chemical looping combustion and reforming have been suggested. This study proposed and investigated the production of ultra-pure hydrogen in dual-purpose integrated zero-emission reforming (UPH2-DPIZER) process based on the sorption-enhanced chemical looping steam methane reforming (SECLSMR). This process is proposed on the basis of reduction in the emissions of carbon dioxide as well as the simultaneous generation of pure hydrogen and syngas for use in a wide range of applications. One of the most novel aspects of this research is that the proposed UPH2-DPIZER process can reduce or eliminate carbon dioxide emissions because all the produced and chemisorbed CO2 can be applied directly in the reforming process without any additional purification. Furthermore, the synthesized 30 wt%NiO-5wt.%CeO2/Al2O3 oxygen carrier was examined using the X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques along with evaluation in SECLSMR process. The attained results of experimental tests are applied to adapt and validate the simulations of novel proposed process. The other objectives of this study are the reduction in required energy for the whole process along with reduction in the direct consumption of fossil fuels. The experiments showed high H2/CO molar ratio of 36 at 550 °C with appropriate methane conversion of about 74 %, while at 750 °C, nearly a complete conversion of CH4 occurs. The obtained results from the simulation of proposed UPH2-DPIZER showed the production of ultra-pure hydrogen along with syngas with H2/CO molar ratio of about 1 with negligible CO2 release.

Acceleration of Pd-V intermetallic diffusion by hydrogen

Vanadium-based membranes have great potential for hydrogen purification due to their perfect selectivity, high permeability, and relatively low cost. With appropriate surface cleaning, V efficiently permeates hydrogen at elevated temperature, but performance declines due to its affinity to absorb impurities. The application of palladium thin films maintains a clean surface that catalyzes hydrogen dissociation and recombination. Hydrogen permeation in Pd-V-Pd membranes initially reach theoretical permeability, but declines due to Pd-V interdiffusion. The objective of this work was to quantify the intermetallic diffusion process as a function of temperature and ambient. Pd-V composites were subjected to various annealing treatments and characterized using Auger electron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy, as well as correlated to measurements of membrane permeability. In an inert environment Pd-V interdiffusion was observable as low as 300 °C, and the diffusion coefficient had an activation energy of 44 kJ/mol. Furthermore, the presence of hydrogen at partial pressures > 10 kPa accelerated interdiffusion six-fold at T = 400 °C. Membrane performance degraded with an activation energy 75 kJ/mol, suggesting that intermetallic diffusion leads to both a loss of catalytic activity and as well as degradation of bulk permeability. These findings provide a baseline for evaluating hydrogen permeable interdiffusion barriers to overcome these challenges.

The Role of Diffusion on Reservoir Performance in Underground Hydrogen Storage

Summary Underground hydrogen storage (UHS) has the potential to balance fluctuating sustainable energy generation and energy demand by offering large-scale seasonal energy storage. Depleted natural gas fields or underground gas storage fields are attractive for UHS as they might allow for cost-efficient hydrogen storage. The amount of cushion gas required and the purity of the backproduced hydrogen are important cost factors in UHS. This study focuses on the role of molecular diffusion within the reservoir during UHS. Although previous research has investigated various topics of UHS such as microbial activity, UHS operations, and gas mixing, the effects of diffusion within the reservoir have not been studied in detail. To evaluate the composition of the gas produced during UHS, numerical simulation was used here. The hydrogen recovery factor and methane-to-hydrogen production ratio for cases with and without diffusive mass flux were compared. A sensitivity analysis was carried out to identify important factors for UHS, including permeability contrast, vertical-to-horizontal permeability ratio, reservoir heterogeneity, binary diffusion coefficient, and pressure-dependent diffusion. Additionally, the effect of numerical dispersion on the results was evaluated. The simulations demonstrate that diffusion plays an important role in hydrogen storage in depleted gas reservoirs or underground gas storage fields. Ignoring molecular diffusion can lead to the overestimation of the hydrogen recovery factor by up to 9% during the first production cycle and underestimation of the onset of methane contamination by half of the back production cycle. For UHS operations, both the composition and amount of hydrogen are important to design facilities and determine the economics of UHS, and hence diffusion should be evaluated in UHS simulation studies.

Experimental Control of a Methanol Catalytic Membrane Reformer

A simple proportional integral (PI) controller with scheduled gain has been developed and implemented in a catalytic membrane reactor (CMR) to obtain pure hydrogen from a methanol steam reforming process. The controller is designed to track the setpoint of the pure hydrogen flow rate in the permeate side of the CMR via the manipulation of the fuel inlet flow rate. Therefore, the controller actuator is the liquid pump that provides the mixture of methanol and water to the reactor. Within the CMR, the catalytic pellets of PdZn/ZnAl2O4/Al2O3 have been used to facilitate the methanol steam-reforming reaction under stoichiometric conditions (S/C = 1), and Pd–Ag metallic membranes have been employed to simultaneously separate the generated hydrogen. The PI controller design is based on a mathematical model constructed using transfer functions acquired from dynamic experiments conducted with the CMR. The controller has been successfully implemented, and experimental validation tests have been carried out at 450 °C and relative pressures of 6, 8, 10, and 12 bar.

Study on effect of vanadium doping in cesium tungsten bronze system and application in HER

Increasing demand for energy and the crisis of fossil fuels have led researchers to search for an alternative energy source. Hydrogen is the cleanest energy source producing water as fuel cells exhaust. However, producing hydrogen could be crucial as only some active catalysts produce pure hydrogen. The expense due to the scarcity of the state-of-the-art catalyst (platinum) for the Hydrogen Evolution Reaction (HER) is the main reason for the higher price of pure hydrogen as a fuel. In our present research, we chose the less expensive cesium tungsten bronzes (CTB) doped with various percentages of vanadium (5 mol% - 20 mol%) to study their HER performance. The materials were prepared hydrothermally at 180 °C at different reaction times. XRD revealed that, upon increasing the vanadium amount, the hexagonal phase of the CTB is transformed to the cubic phase at a higher reaction time. However, the hexagonal phase was retained after vanadium introduction with a lower reaction time. FT-IR, Raman, EDX, SIMS, XPS, and XRF spectroscopy confirmed the incorporation of vanadium into the bronze system. Vanadium-doped samples showed enhanced HER activity compared to the pure CTB. The 20% vanadium-doped hexagonal bronze showed the best HER performance in 0.5 M H2SO4 among all the vanadium-doped materials, which lowered the HER potential of the pure CTB (-0.665 V vs RHE) to -0.288 V vs RHE at -10 mA cm−2. This increase in activity was correlated with a higher surface area, higher electrochemical surface area, faster reaction kinetics with a lower Tafel slope, and a small charge-transfer resistance of the samples after V5+ incorporation compared to the pure CTB.

The defective C3N monolayers as high-efficient hydrogen purification membranes: DFT calculations and MD simulations

The design of new high-performance membranes for separation and purification of hydrogen remains highly desirable for industrial applications. Herein, using the density functional theory calculations along with MD simulations, we demonstrated firstly a new 2D membrane based C3N monolayer (D-C3N) with intrinsic pores and then investigated its potential as gas separation membranes for H2 purification. The cohesive energy and ab initio MD simulations confirmed that the D-C3N monolayer is structurally and thermodynamically stable under 1800 K. All considered gas molecules are physisorbed on the D-C3N monolayer with small interaction energy. At room temperature, the D-C3N membrane for H2 gas has high selectivity over other gases such as 1.5 × 103, 1.8 × 105, 8.8 × 109, 1.4 × 1012, and 1.3 × 1019 for H2/N2, H2/CO2, H2/O2, H2/H2O, and H2/CH4 at 300 K, respectively, and the H2 permeance is as high as 2.2 × 10−5 mol·m−2·s−1·Pa−1, exceeding the industrially acceptable value and most of the carbon-based separation membranes. In addition, MD simulations further confirmed that the defective porous C3N monolayer has ideal selectivity and permeation as a promising separation membrane for H2 purification from other gases for industrial applications.

Economic analysis with multiscale high-throughput screening for covalent organic framework adsorbents in ammonia-based green hydrogen separation

Because green ammonia is an emerging transportation medium for carbon-free hydrogen, technologies for efficient and cost-effective separation and purification of green hydrogen have attracted significant attention in recent years. Among the various options for hydrogen separation, pressure swing adsorption (PSA) has the highest technology readiness level, but the optimal adsorbent for this application is still under investigation. This study evaluates the viability of covalent organic framework (COF) adsorbents for ammonia-based green hydrogen separation processes. The feasibility of the adsorbents was estimated based on the economic analysis of the entire green hydrogen production process with a newly proposed multiscale high-throughput screening (HTS) approach. This approach addresses an existing knowledge gap, where the molecular- and process-scale viewpoints are not fully considered together during adsorbent evaluation. The proposed HTS approach incorporates a new algorithm for simulations with reduced computational cost and a procedure for estimating the economic viability of the adsorbents. The results show that among 648 COFs in a COF database, MPCOF was the most efficient for ammonia-based green H2 separation with a H2 recovery of 72% and levelized cost of USD 8.30/kg H2. This result was obtained with only 31% of the computational cost required by an existing HTS approach.

Electrochemical synthesis of trimetallic nickel-iron-copper nanoparticles via potential-cycling for high current density anion exchange membrane water-splitting applications

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels. Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen. Nevertheless, electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods, such as sol–gel, hydrothermal, or surfactant-assisted approaches, which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination. Therefore, this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam. The synthesized material exhibited remarkable performance, requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm−2 current density in alkaline solution. Furthermore, this material was integrated into an anion exchange membrane water-splitting device and achieved an exceptionally high current density of 1 A cm−2 at a low cell voltage of 2.13 V, outperforming the noble-metal benchmark (2.51 V). Additionally, ex situ characterizations were employed to detect transformations in the active sites during the catalytic process, revealing the structural transformations and providing inspiration for further design of electrocatalysts.

Operational and design parameters evaluation to improve hydrogen production using a low-cost alkaline water electrolysis cell in direct combination with a photovoltaic cell

Hydrogen production from renewable sources such as photovoltaic solar energy can contribute to a more sustainable energy scenario worldwide. The present work aimed to evaluate hydrogen production via alkaline water electrolysis by finding the optimal operational conditions with electrodes, alkaline electrolyzers, and solar energy with a photovoltaic panel. Firstly, graphite, stainless steel 304, and Monel 400 electrodes were evaluated using a direct voltage source, resulting in maximum hydrogen flow rates of 4.86, 10.40, and 8.12 mL/min, respectively. Then, hydrogen generation was analyzed with electrolytes of KOH, NaOH, and LiOH in 1-10 mol/L concentrations. The highest hydrogen flow rates were found for KOH electrolytes, attributed to their higher electrical conductivity. Therefore, stainless steel electrodes and KOH electrolyte were evaluated with the photovoltaic panel. The optimized conditions were a KOH concentration of 6.18 mol/L and a solar radiation of 900 W/m2 for a hydrogen production of 71.83 mL/min. The hydrogen purity remained at 98.96 ± 0.10%.