Hydrogen Production Capacity Research Articles

Boosting intimate contact and charge transfer between carotenoid dye and Ti3C2Tx MXene for photocatalytic hydrogen production

Developing efficient heterojunction photocatalysts with improved light-harvesting capacity and high charge carrier separation rates for photocatalytic hydrogen production remains a challenge in the field of energy conversion. In this study, we synthesized two-dimensional Ti3C2Tx nanosheets through HF etching of Ti3AlC2 and combined them with carotenoid dyes (Car) with different structural characteristics using a solvent spontaneous volatilization method to construct novel Car@Ti3C2Tx Schottky heterojunctions. The intimate interface contacts between the two-dimensional Ti3C2Tx MXene and Car enhanced the light-harvesting capacity of the photocatalysts and promoted charge separation rates. The optimal sample, Car-3@Ti3C2Tx nanocomposite, exhibited excellent photocatalytic activity of 84.4 µmol h−1 g−1 for H2 production under visible light illumination. This work demonstrates the potential of earth-abundant organic Car dyes in constructing high-efficiency and low-cost photocatalysts for hydrogen production.

Enhancing green hydrogen production via improvement of an integrated double flash geothermal cycle; Multi-criteria optimization and exergo-environmental evaluation

The environmental advantages of hydrogen as a clean energy carrier are more prominent when it is produced utilizing renewable resources. In this regard, a novel geothermal energy driven electricity generation system integrated to hydrogen production plant is developed and investigated in this research. In the developed plant, a PEM electrolyzer is employed for hydrogen generation such that its required electricity is provided by an improved double-flash geothermal cycle. A self-superheater is applied for superheating the vapor at the steam turbine inlet using the geothermal resource to enhance the hydrogen production capacity. To evaluate feasibility of such superheating process and to examine its effects on hydrogen production, thermodynamic models are developed based on first and second laws. Also, environmental considerations are considered in evaluation of the proposed plant performance based on exergo-environmental indices. The influences of first and second flashing pressure, geothermal source temperature and current density of water electrolyzer on energy and exergy efficiency, hydrogen production rate, and environmental damage index are investigated. After carrying out a parametric study, the optimum operation point of the plant is determined via a two-objective optimization based on the hydrogen rate and environmental damage index (EDI). It is found that, under optimum operation, the system can produce 25.48 kg/h of hydrogen, while its environmental damage index is calculated to be as 0.00645.

Gully-like CQDs/In2O3/TiO2 composite with broad spectral response and its enhanced photocatalytic performance

The morphology and structure of photocatalytic materials often have a great influence on their photocatalytic performance. The photocatalytic degradation and hydrogen production capacity can be enhanced by optimizing the morphology and properties of the catalysts. In this paper, on the basis of carbon quantum dots (CQDs) with up-conversion photoluminescence (UCPL) properties and polystyrene colloid microspheres (PS) as templates, a kind of gully-like CQDs/In2O3/TiO2 composites with wide spectral response was prepared by vacuum impregnation and microwave-assisted hydrothermal method. The results show that CQDs/In2O3/TiO2 composites with PS colloid microsphere as templates have a gully structure, which provides more active sites for photocatalytic reaction. The heterostructure formed among components optimizes the charge transfer path, significantly improving the separation and transfer efficiency of photogenerated electrons and holes. In the multi-mode photocatalytic experiments, CQDs/In2O3/TiO2 composites show excellent photocatalytic activity for methyl orange, of which photocatalytic activity is much higher than that of pure TiO2, displaying a certain degree of degradation for the different kinds of dyes. In addition, the hydrogen evolution capacity of CQDs/In2O3/TiO2 composites is 1149.3 μmol/g for 8 h, which is 7 times of that of monomer TiO2. The results of the capture experiments show that the possible photocatalytic mechanism of CQDs/In2O3/TiO2 composites is more likely to be the result of a synergy between the traditional band theory and the "Z-scheme".

Small-scale industrial hydrogen liquefaction and refrigeration

As the hydrogen economy expands, the need for point of use production with smaller liquid hydrogen (LH2) production capacities will increase. Examples of this are transportation hubs in remote locations and numerous other applications where the required LH2 production is less than 5 MT/day. In response to this need, a small-scale industrial 1,000 kg/day hydrogen liquefaction plant is being developed and is planned for operation in 2024. The plant will achieve localized, efficient production, on-demand, in remote locations or any location advantageous for use in transportation, where complicated logistics, with associated transportation costs and tanker evaporative losses are eliminated or minimized. The chief advantages of the design are small size/footprint, safety, reliability, low cost, lack of restrictions on site location, and ability to make practical use of renewable energy. The liquefaction plant utilizes a closed-loop helium reverse-Brayton cycle refrigerator where refrigerant temperatures significantly less than the hydrogen liquefaction temperature cause the hydrogen gas stream to be liquefied. The liquefied hydrogen is maintained in the liquid state via a helium side stream taken from the refrigeration loop routed through the LH2 storage tank. This optional system can maintain LH2 temperatures in the storage tank lower than 18 K to eliminate boiloff and facilitate zero loss transload from tanker trucks and eliminate losses in transfer/dispensing. The hydrogen liquefaction plant does not require liquid nitrogen (LN2) pre-cooling and so can be located in remote areas wherever there is 480 V electricity and hydrogen production capacity available. A slightly modified reverse-Brayton cycle is also used in the refrigeration/storage plants. These plants can facilitate zero loss tanker transload and zero boiloff for LH2 storage plants of virtually any capacity. The smallest of these reverse-Brayton cycle refrigerators, currently in detailed design, refrigeration system RS1500 (1000 W heat lift @ 20K) will be capable of eliminating boiloff losses of the largest storage tanks currently in operation with very low electrical energy consumption.

TODAY'S REALITIES AND PROSPECTS OF THE FUTURE DEVELOPMENT OF HYDRO ENERGY IN THE WORLD AND IN UKRAINE

Traditional fossil fuels have a detrimental effect on the global environmental situation, which leads to stricter standards for environmental protection. Therefore, in recent years there has been a need to develop and master new technologies that make it possible to generate, store and transmit energy without or while minimizing emissions of greenhouse gases into the atmosphere, primarily CO2, which is referred to as the so-called “carbon footprint”. An emerging branch of global energy - hydrogen energy - is based on the use of a compound such as hydrogen as a means for accumulating, transporting, producing and consuming energy. Hydrogen is expected to transform the economy in four main application areas: transportation, industry, energy and utilities. The purpose of this review is to analyze the main trends and criteria for the successful development of global hydrogen energy, as well as to consider the state and prospects for the development of the emerging global and Ukrainian hydrogen energy markets. The article analyzes the development of the hydrogen energy market, discusses national programs to support this new branch of world energy and pilot hydrogen projects. Issues of production, consumption, accumulation, storage and transportation of hydrogen are considered. Ukraine is one of the EU's priority partners in the future hydrogen economy, as it has the necessary capacity for hydrogen production - both for domestic consumption and for export. In 2021, the Ministry of Energy of Ukraine joined the European Pure Hydrogen Alliance. Ukraine's potential for hydrogen production is currently being investigated. The possibility of using the national GTS for hydrogen transportation to Europe is also being studied. The results of the targeted comprehensive program of scientific research of the National Academy of Sciences of Ukraine regarding the creation of new materials, technological processes, structures and systems that could become the basis for the widespread introduction of hydrogen technologies in Ukraine are presented. An assessment of the state of the global and Ukrainian hydrogen markets and the prospects for their development in the coming years is provided.

Synthesis of rare earth MOF/CZS materials derived from aromatic tetracarboxylic acids and photocatalytic hydrogen production

With the increasing urgency of clean energy, photocatalytic hydrogen production serves as a sustainable hydrogen manufacturing method to improve the increasing scarcity of fossil fuels and environmental pollution. Herein, Cd0.2Zn0.8S (CZS)-modified Metal-Organic Framework (MOF) composites Pr–NO2–TPTC/CZS were successfully prepared through the reaction of Pr3+, aromatic tetracarboxylic acid, and Cd0.2Zn0.8S nanoparticles. Pr–NO2–TPTC/CZS composite materials exhibited enhanced photolysis performance compared to pure Pr–NO2–TPTC and Cd0.2Zn0.8S materials. With the decrease of Cd0.2Zn0.8S in Pr–NO2–TPTC/CZS composites, the photocatalytic performance of the synthesized composites is constantly improved. Pr–NO2–TPTC/CZS (1:1) photocatalyst exhibited excellent hydrogen evolution performance, with a hydrogen production capacity of 6321 μmol g−1 h−1. Photoluminescence spectroscopy (PL), photocurrent-time test (I-t), and electrochemical impedance spectroscopy (EIS) confirmed that the heterojunction interface formed between Pr–NO2–TPTC and CZS promoted electron-hole separation and transfer. Electron paramagnetic resonance (EPR) indicated that CZS-modified Pr–NO2–TPTC can promote the production of ·OH and ·O2− in the system, thereby increasing the photocatalytic hydrogen production performance. This work provides an effective solution for photocatalytic hydrogen production and a potential method for solving the energy crisis and environmental pollution.

Operation strategy optimization of an integrated proton exchange membrane water electrolyzer and batch reverse osmosis desalination system powered by offgrid wind energy

Operation strategy of the integrated wind-hydrogen system is the key to ameliorate the negative impacts of the fluctuated wind power on the hydrogen production capacity and durability ofelectrolyzer. However,the desalination system supplying pure water to electrolyzers was neglectedpreviously, with which the practical operation strategy of the hybrid wind-hydrogen-desalination system has yet to be investigated. In this work, we proposed a novel control strategy named step-by-step start for wind-hydrogen-desalination system consisting of wind turbine, proton exchange membrane water electrolyzer (PEMWE), battery and batch reverse osmosis (BRO) desalination system, which can produce hydrogen andfresh water. Real-time wind data from Shenzhen, Chinawere used as input to the integrated system. The results demonstratethe wind-hydrogen-desalination system with the proposed strategy can improve the hydrogen production by 17.55 %, the energy efficiency by 17.68 % in August, and increase hydrogen production by 10.29 %, the energy utilization efficiency by 10.44 % in December compared with traditional strategies. At low wind speeds, the switching times of PEMWE for this strategy is higher than the other strategies, while at high wind speeds, the switching times of PEMWE is significantly decreased. This work provides insights into the practical operation strategy for wind-hydrogen-desalination system depending on the real-time wind speed.

Exploring the capacity and economic viability of green hydrogen production by utilising surplus energy from wind farms and small hydropower plants in Southern Brazil

This study seeks to estimate the potential hydrogen production from the remaining energy in the small hydropower plants (SHPs). SHPs are plants with a reservoir of three-square miles and an installed capacity between 1 and 30 MW and wind plants in the south of Brazil. Subsequently, to evaluate the generation of chemical and electrical energy and the amount of stored hydrogen and to determine possible applications in the transport sector and its injection into the natural gas network of the regional mesh. Moreover, scenarios 1 and 2 represented 5% and 3% of the surplus power for hydrogen production. The results indicated that green hydrogen production from the remaining energy in the small hydroelectric and wind power plants proved viable. There was an average potential of 5.95 MNm3/day in SHPs and 7.66 MNm3/day in wind farms. Furthermore, the wind farms could generate an average of 16,000 MWh/day through H2 production, while the SHPs have the potential to produce an average of 9340 MWh/day. Further, the proposed scenarios were economically viable since the profit estimated ranged from 27.13 to 617.92 U$/kg in wind farms and from 162.87 to 342.42 U$/kg in SHPs.

A novel microbial community restructuring strategy for enhanced hydrogen production using multiple pretreatments and CSTR operation

To achieve rapid enrichment of the targeted hydrogen-producing bacterial population and reconstruction of the microbial community in the biological hydrogen-producing reactor, the activated sludge underwent multiple pretreatments using micro-aeration, alkaline treatment, and heat treatment. The activated sludge obtained from the multiple pretreatments was inoculated into the continuous stirred tank reactor (CSTR) for continuous operations. The community structure alteration and hydrogen-producing capability of the activated sludge were analyzed throughout the operation of the reactor. We found that the primary phyla in the activated sludge population shifted to Proteobacteria, Firmicutes, and Bacteroidetes, which collectively accounted for 96.69% after undergoing several pretreatments. This suggests that the multiple pretreatments facilitated in achieving the selective enrichment of the fermentation hydrogen-producing microorganisms in the activated sludge. The CSTR start-up and continuous operation of the biological hydrogen production reactor resulted in the reactor entering a highly efficient hydrogen production stage at influent COD concentrations of 4000 mg/L and 5000 mg/L, with the highest hydrogen production rate reaching 8.19 L/d and 9.33 L/d, respectively. The main genus present during the efficient hydrogen production stage in the reactor was Ethanoligenens, accounting for up to 33% of the total population. Ethanoligenens exhibited autoaggregation capabilities and a superior capacity for hydrogen production, leading to its prevalence in the reactor and contribution to efficient hydrogen production. During high-efficiency hydrogen production, flora associated with hydrogen production exhibited up to 46.95% total relative abundance. In addition, redundancy analysis (RDA) indicated that effluent pH and COD influenced the distribution of the primary hydrogen-producing bacteria, including Ethanoligenens, Raoultella, and Pectinatus, as well as other low abundant hydrogen-producing bacteria in the activated sludge. The data indicates that the multiple pretreatments and reactor's operation has successfully enriched the hydrogen-producing genera and changed the community structure of microbial hydrogen production.

Evaluating the Potential of Hydrogen Production from Agricultural Waste in Indonesia: A Comparative Techno-economic Analysis

Hydrogen production from agricultural waste is a potentially established industry in Indonesia, and the government aims to introduce innovative technologies to produce hydrogen. This study aimed to explore the feasibility of hydrogen production from agricultural waste using three different methods: SCWG, fermentation, and gasification. The analysis focuses on comparing the price of hydrogen as a product by setting the same value of the IRR at 30%. The simulation was conducted by analyzing the capacity of hydrogen production at 3650 tons/year. The results of this study demonstrate that fermentation is the most feasible technology for producing hydrogen from agricultural wastes in Indonesia. In this technology, the price of hydrogen obtained was $5.65/kg, with a total capital investment (TCI) and production cost (TPC) of $10,756,132.97 and $13,977,351.97, respectively. Based on this simulation, the other parameter values, including NPV, ROI, and PoT, were $15,387,688.72, 68%, and 2.27 years, respectively. These results indicate that the establishment of hydrogen production in Indonesia using fermentation technology and agricultural waste is economically viable.

Inhibition of norfloxacin on fermentative hydrogen production: Performance evaluation and metagenomic analysis

Toxic chemicals can inhibit the dark fermentation process for renewable biohydrogen production. Norfloxacin (NOR), a typical antibiotic, is present in various feedstocks of dark fermentation, which has excellent antibacterial properties. It is hypothesized that NOR could cause adverse effects on fermentative hydrogen production, while current understanding of this subject is scare. This study investigated the potential inhibitory effect of NOR on dark hydrogen fermentation, and explored the underlying mechanisms from the perspectives of bacterial community structure and functional gene abundance. The results showed that NOR significantly reduced the hydrogen-producing capacity upon exposure to concentrations exceeding 10 mg/L. The hydrogen yield decreased from 1.56 to 0.27 H2/mol-glucose at NOR concentrations of 50 mg/L. NOR also prolonged the hydrogen-producing lag period. Bacterial community analysis revealed that NOR reduced the abundance of high-yielding H2-generating bacteria, such as Clostridium sp., while increasing the abundance of H2-consuming bacteria (e.g. Enterococcus sp.). Metagenomic analysis further indicated that crucial genes involved in glycolysis (e.g. HK, tal-pgi, pfk and PK) and hydrogen formation (e.g. por and E1.12.7.2) were remarkably downregulated under NOR exposure, essentially causing the inhibition of hydrogen production. This study contributes to a better understanding of how antibiotics inhibit dark hydrogen fermentation and provides a theoretical basis for reducing potential inhibitory effects.

Coupling interface constructions of ZnO@ZnS@FeOOH for photocatalytic hydrogen production performance

Photocatalysis is a reliable method to solve energy crisis and generate green energy hydrogen. ZnO@ZnS (ZOS) formed heterojunction repressed carrier complexation and thus enhanced photocatalytic performance, but its low photoresponse efficiency limited its photocatalytic performance. Therefore, in this paper, ZnO@ZnS was modified with ethylene diamine tetraacetic acid (EDTA) to form ZnO@ZnS@FeOOH composites with coupling interface. The modification of EDTA could inhibite the oxidation of FeOOH during the synthesis process, and what’s more it could enhance the charge transfer at the heterojunction interface to promote the separation of electron-hole pairs and photoresponsive ability to further enhanced the hydrogen precipitation performance. The concentration of EDTA and Fe sources were regulated to investigate the photocatalytic hydrogen production capacity of the composites. The results indicated that the ternary composite ZnO@ZnS@FeOOH had the superior hydrogen evolution performance with the hydrogen evolution rate of 529.17 umol g−1 h−1, which was 2.4 times higher than that of ZOS. EDTA acts as an electron channel to enhance the inter-interfacial electron transfer capability, and the loading of FeOOH formed a heterojunction structure, which promoted carrier separation and enhanced the photoresponse. It’s the synergistic effect to enhanced the photocatalytic hydrogen production performance. This paper provided a method for the construction of ternary heterojunctions and interfacial charge transport channels.

Enhancing the Electrical and Photoelectrical Efficacy with the Synergistic SrO–ZnO Nano‐Heterosystem

Development of the sustainable materials for consolidation of the energy sustainability needs special emphasis in the current era of the increasing energy demand. In compliance with this, present investigation reports first investigation on the amended sustainable production conjugated with the microwave process of the strontium oxide (SrO) and zinc oxid (ZnO) forming SrO–ZnO nanoscale heterostructure. The band gap of the prepared green nanomaterial was tuned reducing it from 5.8 to 3.6 eV upon the formation of the nanocomposite. With the mixed cubic and hexagonal phase, these particles have average crystallite size of 66.4 nm and irregular shape. The electro‐catalytic assays have expressed the bifunctional role of the SrO–ZnO towards generation of the oxygen and hydrogen. However, it has an excellent hydrogen production capacity with the lower overpotential of 126 mV and Tafel slopes 123.6 mV dec−1. In addition, this nanomaterial has also exhibited superior electrochemical charge storage for batter applications with the unit capacity of 541.7 mAH g−1 and Rs = 0.4 Ω, reflecting facilitated diffusion at the interface. In terms of photovoltaic applications, SrO–ZnO nanocomposite has effectively passivated the perovskite solar cells by improving efficiency from 7.2% to 15.1%. Such an improved performance is associated with the chemical synergism.

ZIF-8 induced N, P double doped porous molybdenum phosphide hydrogen evolution catalyst

Molybdenum based phosphides have gradually become the investigation frontier of hydrogen evolution catalysts due to the platinum like electronic structure. In this paper, N, P double-doped graphite carbon layers wrapped with MoP nanoparticles (P–MoP@NPC), is directly compounded by one-step high-temperature carboning PMo12-APP@ZIF-8 precursor. P–MoP@NPC possesses splendid hydrogen production reactive, in two kinds of electrolytes, when the overpotentials of P–MoP@NPC are 132 mV and 161 mV, the slope of current density reaching 10 mA cm−2, Tafel slope are 67 and 79 mV dec−1, respectively. In the bargain, P–MoP@NPC displays satisfactory durability in acid and alkaline mediums and can continue to work for more than 24 h. The wonderful hydrogen production ability of P–MoP@NPC is ascribed to the synergistic effect of MoP nanoparticles, hierarchical porous structure as well as N, P double-doped carbon layers. The confinement effect of ZIF-8 makes most of the synthesized MoP nanoparticles evenly distributed. The hierarchical porous structure caused by the volatilization of Zn atoms with high temperature can expose more active centers. The N, P double-doped graphitic carbon layers not only protect the catalyst but also adjust the electronic structure of MoP, promoting the hydrogen production capacity. This work may provide a general way to study molybdenum phosphide catalysts synthesized by APP as a green phosphorus source for energy conversion.

Investigation of a community-based clean energy system holistically with renewable and hydrogen energy options for better sustainable development

This study develops a novel community-based integrated energy system where hydrogen and a combination of renewable energy sources are considered uniquely for implementation. In this regard, three different communities situated in Kenya, the United States and Australia are studied to cover their needs potentially by producing hydrogen, biogas, power, residential space and industrial heating, hot water and fresh water. where a multigenerational geothermal plant integrated with a solar power plant (using both concentrated solar power (CSP) and photovoltaic (PV) panels) is considered to provide the energy inputs. Innovations in hydrogen production and renewable energy are essential for reducing carbon emissions. By combining the production of hydrogen with renewable energy sources, this system seeks to move away from the reliance on fossil fuels and toward sustainability. The study investigates various research subjects using a variety of methods. The performance of the geothermal source is considered through energetic and exergetic thermodynamic analysis. The software System Advisor Model (SAM) and RETscreen software packages are used to analyze the other sub-systems, including CSP and PV units and a combined heat and power plant. The Australian, American, and Kenyan communities considered for this study are found to have promising potential for producing hydrogen and electricity from renewable sources. The geothermal output is expected to be 35.83 MW for electrical power, 122.8 MW for space heating, 151.9 MW for industrial heating, and 64.25 MW for hot water. The overall multigenerational geothermal energy and exergy efficiencies are reported as 65.15% and 63.54% respectively. These selected communities are expected to have annual solar power generation and hydrogen production capacities of 158 MW, 237 MW, 186 MW, 235 tons, 216 tons, and 313 tons respectively.

Comparative analysis of photo-fermentation hydrogen production from pretreated corn stover by deep eutectic solvents

To compare the pretreatment effect of deep eutectic solvents (DESs) on corn stover, three types of DESs (acid, neutral, and alkaline) were used to pretreat corn stover, and their effects on lignin removal were investigated. Then the performance of photo-fermentation hydrogen production (PFHP) using DESs pretreated corn stover was compared and analyzed. The results showed that acid DESs had the best lignin removal efficiency, and the lignin removal percentages of choline chloride/formic acid (ChCl/Fac) and choline chloride/oxalate (ChCl/Oac) were 64.7% and 65.6%, respectively. The alkaline DESs had the second highest removal of lignin, while the neutral DESs had a poor effect on lignin removal. The comparison of hydrogen production indicated that the corn stover pretreated with ChCl/Oac had the best hydrogen production effect. In conclusion, the DESs pretreatment can obviously remove the lignin in corn stover, and then improve the hydrogen production capacity and efficiency of photo-fermentation, which provides a potential pretreatment method for the efficient utilization of straw biomass.

Compounding or Curative? Investigating the impact of electrolyzer deployment on congestion management in the German power grid

Integrating large amounts of hydrogen production capacities for decarbonizing energy-intensive industries in Germany can be challenging for transmission system operators. This research investigates interactions of hydrogen production deployment pathways and associated congestion management policies with the operation of the German electricity transmission system for future market projections. Hydrogen electrolysis imputes additional electricity loads above conventional levels. A scenario framework is created representing different geographic electrolyzer deployment pathways and congestion management regulations for electrolyzer operation. Fundamental electricity market modeling and load flow optimization are proposed to evaluate resulting congestion management volumes to resolve grid bottlenecks associated with the market clearing dispatch. Overall results of this work highlight the importance of designing congestion management frameworks that enable efficient utilization of electrolyzers as a redispatch capacity, primarily if a demand-oriented deployment of electrolyzer installations near energy-intensive industries is assumed to support renewable energy integration. Differences in congestion management cost between demand- and supply-oriented deployment pathways of electrolyzer capacity lie in the range of 0.77–0.97 bn Euro if electrolyzers cannot be redispatched but almost diminish to 0.10–0.21 bn Euro in the scenarios that include electrolyzer as a redispatch capacity. The findings of this work assist policymakers and regulators with valuable insights into design options for future congestion management frameworks.

Impacts of EU Regulation on Green Hydrogen Production and Storage Capacity Design and Operation

In European Union green hydrogen production is regulated to guarantee that transition to green energy will really have positive effect on the mitigation of the climate change, and that the integration of hydrogen economy to existing energy system will be as smooth as possible. However, these regulations complicate the optimal design and operation of the hydrogen production. Requirement about one-hour temporal correlation between contracted variable renewable electricity production and green hydrogen production forces to invest in overcapacity of electrolyzers and high-capacity hydrogen storages to buffer variable hydrogen production to smooth supply flow to hydrogen end use processes. This paper explains these issues with a demonstrative example how different design parameters result to the operation performance of the hydrogen production process.

Assessing the potential of green hydrogen production from wind power: case of microgrid

In the context of a microgrid, green hydrogen production from wind power was assessed in this paper. A Wind-Hydrogen Integrated Power Grid Model was employed to address the intermittent nature of wind energy resources. Wind power generation was analyzed and integrated with hydrogen production to contribute to sustainable energy solutions. Meticulous estimation and scenarios analysis were performed to quantify the potential of green hydrogen production capacity achievable through wind energy integration. Additionally, sensitivity analyses were conducted to enhance the understanding of the system's dynamics and potential challenges. This paper significantly contributed to the understanding of this critical aspect and paved the way for the future development of a comprehensive Energy Management System (EMS) designed to optimize energy flow between the grid, wind power generation, and the electrolyzer.

Influence of the Zn/Al molar ratio over the photocatalytic hydrogen production by ZnS/ZnAl-LDH composites

In this work, ZnS/ZnAl-LDH composites were prepared by the sulfuration of pristine Zn–Al LDHs with Zn:Al molar ratios between 2 and 4. The sulfured samples (ZA2-S, ZA3-S, ZA4-S), were evaluated in the photocatalytic hydrogen production to verify the effect of the Zn:Al molar ratio. The X-ray powder diffraction revealed the presence of a well-crystallized hydrotalcite-like structure in all samples, but ZA4 also exhibited hydrozincite and Zn(OH)2 reflections. It was observed that as the Zn:Al ratio increased in the sulfured samples, more intense reflections of ZnS were detected. The sample with the highest amount of ZnS (ZA4-S) displayed the lowest bandgap value (3.54 eV) and the highest photocatalytic H2 production (4409.0 μmol g−1 h−1); although, it presented the lowest specific surface area (16 m2 g−1). Moreover, it was confirmed that after 5 cycles uses its activity not only was maintained but it increased slightly. As ZnS itself displayed a lower hydrogen production capacity compared to the ZA4-S composite, the photocatalytic activity of the prepared samples was explained in terms of the formation a type II heterojunction between ZnS and the LDH.