Hydrogen Production Experiments Research Articles

Fabrication of Ceramic Microchannels with Periodic Corrugated Microstructures as Catalyst Support for Hydrogen Production via Diamond Wire Sawing.

Hydrogen energy is the clean energy with the most potential in the 21st century. The microchannel reactor for methanol steam reforming (MSR) is one of the effective ways to obtain hydrogen. Ceramic materials have the advantages of high temperature resistance, corrosion resistance, and high mechanical strength, and are ideal materials for preparing the catalyst support in microchannel reactors. However, the structure of ceramic materials is hard and brittle, and the feature size of microchannel is generally not more than 1 mm, which is difficult to process using traditional processing methods. Diamond wire saw processing technology is mainly used in the slicing of hard and brittle materials such as sapphire and silicon. In this paper, a microchannel with a periodic corrugated microstructure was fabricated on a ceramic plate using diamond wire sawing, and then as a catalyst support when used in a microreactor for MSR hydrogen production. The effects of wire speed and feed speed on the amplitude and period size of the periodic corrugated microstructure were studied using a single-factor experiment. The microchannel surface morphology was observed via SEM and a 3D confocal laser microscope under different processing parameters. The microchannel samples obtained under different processing parameters were supported by a multiple impregnation method. The loading strength of the catalyst was tested via a strong wind purge experiment. The experimental results show that the periodic corrugated microstructure can significantly enhance the load strength of the catalyst. The microchannel catalyst support with the periodic corrugated microstructure was put into the microreactor for a hydrogen production experiment, and a good hydrogen production effect was obtained. The experimental results have a positive guiding effect on promoting ceramic materials as the microchannel catalyst support for the development of hydrogen energy.

Interfacial engineering between carbon vacancies modified graphitic carbon nitride and CoAl-LDH formed heterojunctions for improved photocatalytic performance: Degradation pathway, DFT calculations, and mechanism insights

The construction of green, low-cost heterojunctions with interfacial interaction is crucial to enhance their photocatalytic performance and broaden their utility in practical applications. Here, we prepared CoAl-LDH/Carbon Nitride with carbon vacancies (Cv-CN) heterojunction by electrostatic self-assembly strategy to explore its photocatalytic properties. 30 wt% CoAl-LDH/70 wt% Cv-CN (CCN-2) exhibited the optimal photocatalytic degradation performance after 120 min of light exposure, with a degradation efficiency of 93.1 %. Fukui function calculations, in conjunction with LC-MS/MS analysis, were employed to explore potential degradation pathways during the photocatalytic degradation of tetracycline. The photocatalytic performance of CoAl-LDH/Cv-CN heterojunction was further analyzed by photocatalytic hydrogen production experiments, and after five hours, the hydrogen production rate of CCN-2 was 2515 µmol/g (Cv-CN: 1554 µmol/g, CoAl-LDH: hardly produced any hydrogen). According to the experimental results and data analysis, an effective charge-carrier separation and transfer pathway is established through the interfacial engineering between CoAl-LDH and Cv-CN forming the heterojunction at the interface of CoAl-LDH and Cv-CN. The heterojunction structure formed by interfacial engineering between CoAl-LDH and Cv-CN enables effective photocatalytic removal of antibiotics and hydrogen production providing new insights into the treatment of aqueous environments and clean energy production.

Visible light photocatalytic performance of Co/Ag bimetallic coordination polymer catalysts designed from hard and soft acid-base theory

Heterometallic coordination polymers have promising applications in photocatalysis, and the design and selection of suitable organic ligands and coordination metals is the key to improve the catalytic activity of polymer photocatalysts. Herein, a novel Co/Ag bimetallic coordination photocatalyst, designed based on the hard and soft acid-base (HSAB) theory, has been successfully prepared by a stepwise method with Ag-S coordination as the main component and Co-N/Co-S as the complementary component. The obtained Co/Ag photocatalyst demonstrates excellent performance in the photocatalytic degradation (visible light) of halogenated phenolic pollutants. Degradation of 10 ppm of 4-chlorophenol could reach 100 % in 4 h, and 70 % degradation of 4-fluorophenol, which is even more difficult to degrade, could also be achieved. In addition, hydrogen production experiments conducted under visible light irradiation showed that the hydrogen production could reach 36.95 μmol h−1 g−1 for 6 h, which strongly demonstrated the excellent reduction ability of Co/Ag photocatalysts. The photocatalyst exhibits enhanced photocatalytic activity which is ascribed to the formation of Ag-S and Co-N/Co-S coordination, which greatly increases the charge density and facilitates charge transfer. Thus, the photogenerated electrons can induce both the conversion of O2 to •O2- for oxidation reactions, as well as the direct attack of the C-Cl bond for reduction reactions. This study demonstrates the successful design of the synergistic Co/Ag bimetallic coordination photocatalysts based on the HSAB theory, thereby offering a promising research avenue for the fabrication of heterometallic coordination photocatalysts.

Hydrogen inhibition performance of blueberry anthocyanin as a green-potent inhibitor in wet Al alloy dust collector systems

To solve the fire and explosion risks caused by hydrogen generation of Al alloy dust in wet dust collector systems, an attempt is made to use blueberry anthocyanin (B-ACN), as a non-toxic and environmentally friendly inhibitor for hydrogen generation of Al alloy dust. Hydrogen inhibition effect and mechanism are evaluated through hydrogen production experiments, hydrolysis kinetic models, surface characterization analysis, and adsorption model. The results show that B-ACN exhibited a potent hydrogen inhibition efficiency of 97.36% at 4.50 g/L concentration, and maintained a hydrogen inhibition stability higher than 94.21% under temperature disturbance. In addition, theoretical calculations and surface characterization were performed to investigate the inhibition mechanism of B-ACN. SEM-EDS and XRD confirmed that the surface of the hydrolysis products of Al alloy dust in B-ACN solution is smooth and complete, with almost no generation of hydroxides. FTIR indicated that B-ACN adsorbs on the dust surface through the O atom. XPS and adsorption model suggested that the surface adsorption of B-ACN on the Al alloy dust involves both physical and chemical processes and follows the Langmuir adsorption model. Therefore, a dense and complete B-ACN protective film formed on the surface of Al alloy as a physical barrier, blocking the reaction between Al3+ and water molecules. This research provides a cost-effective, sustainable natural plant extract inhibitor to solve the risk of hydrogen generation and explosion, thereby achieving inherently safer industrial production and environmental protection.

Preparation of carbon/Fe-doped g-C3N4 and study on its photocatalytic hydrogen production performance

With the large consumption of non-renewable energy, energy shortage has become a major challenge to human society. Among many new energy production technologies, photocatalytic hydrogen production from water can be realized by using abundant solar energy as the driving force, and the conditions of hydrogen production are mild, green and pollution-free, it is considered one of the effective technologies to solve the current energy shortage crisis. The core of photocatalytic hydrogen production is photocatalyst, therefore, the study of efficient, stable and cheap photocatalysts has become a hot spot. Two-dimensional layered g-C3N4 has become an important photocatalytic material in recent years because of its suitable band gap, its response in the visible light band and its chemical and thermal stability. Due to the high rate of photogenerated electron-hole recombination and the slow rate of photoreaction of g-C3N4, the addition of [Fe2(HMOPIP)6]·8H2O·10OH to regulate g-C3N4 forming carbon/Fe-doped g-C3N4, it can reduces the recombination efficiency of photogenerated electron-hole and improves photocatalytic activity. Through hydrogen production experiment, we can see that, compared with g-C3N4, the carbon/Fe-doped g-C3N4 has better electron-hole separation ability and photocatalytic hydrogen production performance, with the hydrogen production rate of the carbon/Fe-doped g-C3N4 being approximately 5.92-fold higher than g-C3N4.

Impact of catalyst carrier with TPMS structures on hydrogen production by methanol reforming

As the core part of a microreactor, the reaction carrier provides reaction site and energy supply for hydrogen production. Among various types of reaction carriers, porous reaction carriers with complex flow path structures can effectively improve hydrogen production performance, and thus are widely applied in fuel cells. To optimize the structure of catalyst carriers and improve the efficiency of hydrogen production of methanol reforming, we designed four TPMS porous carrier structures, namely structures D, G, P and IWP, and analyzed the effect of carrier structure and parameters on hydrogen production reaction in theory. After that, we manufactured TPMS carriers with varied structures and parameters using 3D printing, and designed and carried out loading tests, flow velocity simulation experiments and pressure drop calculation to study the influence of the structure morphology on load intensity, heat and mass transfer and other performance indexes with catalyst load. Finally, we carried out hydrogen production experiments in microreactors with different TPMS structures, from which we obtained an pattern influence of hydrogen production conversion rate and hydrogen velocity etc. At different velocities and temperatures. The experimental results indicate that structure type and parameters of TPMS node and porosity have a great effect on the performance of hydrogen production. Specifically, structure D performs the best and structure P performs the worst in hydrogen production. When the velocity is 1.7 ml/h and the temperature is 250 °C, the maximum difference of the hydrogen conversion rate between D and P structure can reach to 22 %, and that of the hydrogen velocity can reach to 0.02 mol/h.

Boosting the photocatalytic hydrogen production activity of marigold-like Zn2In2S5 by using noble-metal-free Ni2P as cocatalyst

To enhance the activity of photocatalysts, it is crucial to use non-noble metal as a cocatalyst instead of noble metal in the arena of photocatalysis. In this study, to boost the photocatalytic hydrogen activity of pristine Zn2In2S5, XNi2P/ZIS5 composite photocatalysts were prepared using noble-metal-free Ni2P as cocatalyst. Before photocatalytic hydrogen production experiments, the physicochemical properties of the synthesized materials were systematically characterized by advanced characterization methods. The experiment results demonstrate that the load of Ni2P cocatalyst can noticeably enhances the photocatalytic performance of Zn2In2S5 and the photocatalytic hydrogen generation activities are observably influenced by the mass ratio of Ni2P to Zn2In2S5. Among XNi2P/ZIS5, the 10Ni2P/ZIS5 sample presents the optimal hydrogen production rate of 17.74 mmol g−1 h−1, which is 7.58 times as high as that of pristine Zn2In2S5. The increased photocatalytic hydrogen evolution activity could be attributed to the introduction of noble-metal-free cocatalyst Ni2P, which serves as an electronic collector and reduction sites remarkably facilitates the separation and migration of photoexcited electrons of Zn2In2S5. Meanwhile, the rate of reactions is significantly accelerated.

Deep learning prediction of photocatalytic water splitting for hydrogen production under natural light based on experiments

Harnessing hydrogen through photocatalytic water splitting represents a pivotal stride towards carbon neutrality. Evaluating ongoing experiments under natural light conditions is critical for scaling this technology. Given the inherent instability of natural light, devising precise hydrogen production forecasts has emerged as a core focus to streamline project timelines and financial governance. This research introduces a robust system for continuous photocatalytic water splitting, leveraging natural light for hydrogen production. Analysis and prognostication of hydrogen generation are conducted using experimental data from 21 distinct groups. Critical factors, including radiation intensity, reaction temperature, reactant concentration, solar concentrator specifics, and hydrogen production rate (HPR), undergo thorough correlation scrutiny. Employing a deep-learning framework, gated recurrent units (GRU) neural network is utilized for nuanced feature apprehension, enhancing hydrogen output forecasting precision. The results illustrate that the mean daily solar-to-hydrogen (STH) energy conversion efficiency across the 21 groups is approximately 0.25 %. Radiation intensity prevails as a significant influencer, with reaction temperature also playing a substantial role. Solar concentrator utilization proves beneficial for augmenting HPR. Nevertheless, the unevenness of solar concentrator presents adverse effects, necessitating consideration during system conceptualization. The optimized prediction model's outcomes align closely with experimental observations, and with a test loss of 2.61 × 10−3 and 682 epochs, the model's predictive superiority is affirmed. The continuous hydrogen production experiments leveraging natural light provide the feasible reference for the large-scale application of this technology. The correlation analysis of critical factors provides the optimization direction for practical engineering design. The hydrogen production prediction model aims to provide scientific basis for the decision-making of this technology.

Direct ink writing of hierarchical porous SiC ceramics as catalyst support for hydrogen production

Due to the tunable porosity at multiple scales, hierarchical porous ceramics feature large specific surface area and excellent heat and mass transfer performance, which can effectively improve the catalytic reaction performance. This paper presents a method to fabricate SiC scaffolds with regular and hierarchical pore structures by direct ink writing (DIW) combined with sacrificial template technology, which can be used as methanol steam reforming (MSR) microreactor catalyst supports. Through printing along a defined path, primary pores with a regular pore structure were created. After sintering, the sacrificial template was removed and secondary pores appeared. Four different types of hierarchical porous SiC scaffolds were successfully prepared and the pore structure, total porosity, linear shrinkage and compressive strength of these scaffolds were investigated. The catalyst coating was then loaded onto the scaffold, and the microstructure characterization showed that the pore structure would not be damaged and blocked. Finally, the hydrogen production experiments were carried out on the MSR microreactor, and the results showed that the support with larger and denser secondary pores had the best fluid flow and hydrogen production characteristics. At the temperature of 280 °C and the gas hourly space velocity (GHSV) of 30000 ml g−1 h−1, the methanol conversion and hydrogen production of the best support can reach 90.95 % and 44.96 ml/min, respectively.

A Simple Approach for Regenerating Electrolyzed Hydrogen Production Using Non-De-Ionized Water Sources

This research focuses on using natural renewable water resources, filters, and performance recovery systems to reduce the cost of generating pure hydrogen for Proton Exchange Membrane Fuel Cells (PEMFCs). This study uses de-ionized (DI) water, tap water, and river water from upstream as the water source. Water from these sources passes through 1 μm PP filters, activated carbon, and reverse osmosis for filtering. The filtered water then undergoes hydrogen production experiments for a duration of 6000 min. Performance recovery experiments follow directly after hydrogen production experiments. The hydrogen production experiments show the following: DI water yielded a hydrogen production rate of 27.13 mL/min; unfiltered tap water produced 15.41 mL/min; unfiltered upstream river water resulted in 10.03 mL/min; filtered tap water yielded 19.24 mL/min; and filtered upstream river water generated 18.54 mL/min. Performance recovery experiments conducted by passing DI water into PEMFCs for 15 min show that the hydrogen generation rate of tap water increased to 25.73 mL/min, and the rate of hydrogen generation of upstream river water increased to 22.58 mL/min. In terms of cost-effectiveness, under the same volume of hydrogen production (approximately 600 kg/year), using only DI water costs 1.8-times more than the cost of using filtered tap water in experiments.

Engineering of Solar Energy Harvesting Tb3+-Ion-Doped CdS Quantum Dot Glasses for Photodissociation of Hydrogen Sulfide.

The photocatalytic properties of CdS quantum dots (Q-dots) and Tb3+-doped CdS Q-dots dispersed in a borosilicate glass matrix were investigated for the photodissociation of hydrogen sulfide (H2S) into hydrogen (H2) gas and elemental sulfur (S). The Q-dot-containing glass samples were fabricated using the conventional melt-quench method and isothermal annealing between 550 and 600 °C for 6 h for controlling the growth of CdS and Tb3+-ion-doped CdS Q-dots. The structure, electronic band gap, and spectroscopic properties of the Q-dots formed in the glass matrix after annealing were analyzed using Raman and UV-visible spectroscopies, X-ray powder diffraction, and transmission electron microscopy. With increasing annealing temperature, the average size range of the Q-dots increased, corresponding to the decrease of electronic band gap from 3.32 to 2.24 eV. For developing the model for photocatalytic energy exchange, the excited state lifetime and photoluminescence emission were investigated by exciting the CdS and Tb3+-doped CdS quantum states with a 450 nm source. The results from the photoluminescence and lifetime demonstrated that the Tb3+-CdS photodissociation energy exchange is more efficient from the excited Q-dot states compared to the CdS Q-dot glasses. Under natural sunlight, the hydrogen production experiment was conducted, and an increase of 26.2% in hydrogen evolution rate was observed from 0.02 wt % Tb3+-doped CdS (3867 μmol/h/0.5 g) heat-treated at 550 °C when compared to CdS Q-dot glass with a similar heat treatment temperature (3064 μmol/h/0.5 g). Furthermore, the photodegradation stability of 0.02 wt % Tb3+-CdS was analyzed by reusing the catalyst glass powders four times with little evidence of degradation.

Solid-state synthesis of ZnS/ZnO nanocomposites and their decoration with NiS cocatalyst for photocatalytic hydrogen production

Herein was demonstrated the facile solid-state synthesis of ZnS/ZnO nanocomposites using planetary ball milling followed by subsequent thermal treatment. X-ray diffraction analysis has shown that the ZnS/ZnO products are nanocrystalline with an estimated crystallite size of less than 60 nm. A transmission electron microscope has demonstrated the presence of spherical heterostructures and core-shell structured ZnS/ZnO nanocomposites with the size being 40–80 nm in diameter. Fourier transform infrared spectroscopy analysis confirmed the presence of Zn–O and Zn–S bonds. The formation of a thin boundary between the ZnS and ZnO phases, where the sulfur oxidation state varies from −2 to +6, was determined by X-ray photoelectron spectroscopy. Degradation of methylene blue and Orange II organic dyes was used to assess the photocatalytic activity of ZnS/ZnO nanocomposites, and the nanocomposites of ZnS/ZnO, with a mass ratio of ∼1:1, demonstrated the highest visible light photocatalytic activity. For photocatalytic hydrogen production experiments, the surface of ZnS/ZnO nanocomposites was in situ decorated with NiS nanoparticles, where the mass content of NiS was 1.5%. The presence of NiS cocatalyst promotes the separation and transfer of photogenerated charges, thereby increasing the photocatalytic activity of ZnS/ZnO nanocomposites during hydrogen generation. The apparent quantum efficiency of photocatalytic hydrogen generation using ZnS/ZnO-3h-NiS photocatalyst was equal to 1.13%. This contribution shows the possibility to prepare nano-structured photocatalysts via mechanochemistry.

Impact of the bromination of carbazole-based D-π-A organic dyes on their optical and electrochemical properties and visible-light-driven hydrogen evolution.

Brominated dyes, 2C-n (n = 1-5), 3C-4 and 4C-4, were prepared through bromination of three carbazole-based D-π-A dyes, 2C, 3C and 4C with N-bromosuccinimide (NBS). The detailed structures of the brominated dyes were confirmed by 1H NMR spectroscopy and mass spectrometry (MS). The introduction of the Br atom on the 1,8-positon of carbazole moieties led to blueshifted UV-vis and photoluminescence (PL) spectra, increased initial oxidation potentials and enlarged dihedral angles, indicating bromination enhanced non-planarity of the dye molecules. In the hydrogen production experiments, with the increase of the Br content in brominated dyes, the photocatalytic activity increased continuously (except 2C-1). The dye-sensitized Pt/TiO2, 2C-4@T, 3C-4@T and 4C-4@T, exhibited high hydrogen production efficiencies of 655.4, 877.9 and 905.6 μmol h-1 g-1, respectively, which were 4-6-fold higher than those of 2C@T, 3C@T and 4C@T. The enhanced performance of photocatalytic hydrogen evolution was attributed to decreased dye aggregation resulting from the highly non-planar molecular structures of the brominated dyes.

The development of ternary-based TiO2-SnS2/GO-RGO composite material for photocatalytic H2 production under Solar light irradiation

Production of alternative fuels, such as hydrogen, by harvesting abundant Solar energy is under continuous scientific development and improvement. Accordingly, in this work TiO2-based composite materials with different wt% of SnS2 and GO-RGO were synthetized employing in-situ solvothermal method, and their activity for H2 evolution under Solar irradiation was investigated. Through the synthesis, GO was considerably reduced forming RGO. Prior testing the activity, a comprehensive characterization to elucidate structural, morphological and semiconducting properties of as-prepared materials was performed. Photocatalytic hydrogen production experiments were conducted in with sacrificial agent (TEOA). Photocatalytic tests have shown that a smaller mass ratio of SnS2 (5 wt%), and a minimal mass ratio of GO-RGO (0.01 wt%), provided the highest hydrogen generation rate of 61.5 μmol/(hgcatal) among tested materials. Hence, the higher GO-RGO material incorporation into the composite presumably blocked the photocatalytic active surface preventing intrusion of Solar irradiation necessary for the activation of material.

Preparation of High Geometric Filling Factor Perovskite Module and Feasibility Study on Electrocatalytic Hydrogen Production

In recent years, perovskite solar cells have achieved high efficiency in small areas, but the industrialization of perovskite solar cells is still hampered by the efficiency loss of cells during area scaling. Series modules are currently the most widely used and effective modular process for perovskite solar cells, a process that requires the patterning of the layer stack in individual cells. This interconnection scheme consists of three lines, P1–P3, which are ablated using a pulsed laser beam. In this work, we developed an efficient perovskite module with a high geometric fill factor (GFF) based on a two-step spin-coating method by optimizing the laser ablation step. We constructed the entire device structure by means of a picosecond green pulsed laser, meanwhile, the dead area is greatly reduced by optimizing the parameters and process, and finally achieving an ultra-high GFF of over 99%. In addition, we investigated the effect of poor P2 and P3 ablation on the perovskite solar modules and compared the performance of the module before and after ablation optimization. We finally obtained a maximum photoelectric conversion efficiency of 22.79% with an aperture area of 12.6 cm2. Concurrently, we conducted electrocatalytic hydrogen production experiments on the prepared perovskite solar modules, and the experimental results have also shown excellent performance and good prospects.

Integration of the PEMFC with a hydrogen production device adopting sodium borohydride and metal cobalt catalyst

Hydrolysis technology that releases hydrogen from chemical hydrogen storage materials is a method to produce hydrogen. Hydrogen storage has excellent development potential and is also one of the sources of large amounts of hydrogen. A sodium borohydride hydrogen production experiment was carried out based on steam hydrolysis technology. The system reaction tank is divided into a water-carrying bed and a catalyst bed. A mixed aqueous solution with a concentration of 1 wt% sodium hydroxide (NaOH) + 10 wt% sodium borohydride (NaBH4) was used for the hydrogen production reaction test. These experiments determined the appropriate aqueous solution and water vapor combination, and optimal parameters for hydrogen production. The hydrogen production catalyst powder, blend ratio, different steel ball ratios, and ball milling time at the steam hydrogen production end will all affect the powder's fineness and hydrogen production stability. Under catalyst temperature control, the by-products solidify at a specific temperature, which affects the gas passage and causes blockage. Increasing the hydrogen production in an aqueous solution requires a Co2+/Al2O3 catalyst, or a temperature control method to catalyze hydrogen production to obtain stable hydrogen production suitable for emergencies without hydrogen storage containers. This experiment built a hydrogen production system combined with a fuel cell for power generation testing. The test process and results indicate whether the aqueous solution and steam technology can be an effective solution when the hydrolysis hydrogen production technology is matched.

Reductively-induced carbon vacancies facilitate visible light-driven hydrogen evolution enhancement of g-C3N4

Graphite nitrogen carbide (g-C3N4, GCN) has attracted extensive attention. Herein, the g-C3N4 precursor was obtained through a conventional pyrolysis condensation path employing melamine as raw material. The g-C3N4 with abundant C vacancies was prepared with sodium borohydride (NaBH4) as reductant in different concentrations. Under visible light irradiation, the 3NBCN catalyst treated with 3 mol L−1 NaBH4 solution reveals outstanding photocatalytic hydrogen production activity, reaching 1764.9 μmol g−1 h−1, which is 7.56 folds higher than that of the reference GCN (206.3 μmol g−1 h−1). The 3NBCN also exhibits remarkable stability in the photocatalytic cyclic hydrogen production experiment. As a control experiment, Cr(VI) reduction further attests that g-C3N4 reduced by NaBH4 has an increased photocatalytic performance. The reduction rate of Cr(VI) over 3NBCN is 3.38 folds higher than that over the reference GCN. Multiple characterization results and density functional theory (DFT) calculations prove that the boosted photocatalytic activity benefits from the successful introduction of C defects, which promotes that photoexcited charges separate and transfer considerably faster and more efficiently. Considering all our results, a hypothesis for the mechanism of enhancement in photocatalytic performance is presented.

Preparation of direct Z-scheme Bi2WO6/TiO2 heterojunction by one-step solvothermal method and enhancement mechanism of photocatalytic H2 production

Direct Z-scheme Bi2WO6/TiO2 heterojunction photocatalyst was prepared by one-step solvothermal method. The catalyst was characterized by XRD, TEM, XPS, UV–Vis DRS, photoluminescence spectroscopy and photoelectrochemical studies. The photocatalytic hydrogen production experiments show that Bi2WO6 did not generate H2 and the H2-production rate of TiO2 is only 0.1 mmol⋅g−1h−1. The hydrogen production rate of the Bi2WO6/TiO2 heterojunction photocatalyst reaches 12.9 mmol⋅g−1h−1, which is 129 times that of TiO2. Compared with TiO2, the enhanced H2-production activity of the heterojunction catalyst can be attributed to the wider light absorption range and the efficient separation and migration of carriers at the close contact interface between Bi2WO6 and TiO2. Based on the work functions of Bi2WO6, TiO2 and their heterojunctions, combined with the results of electron paramagnetic resonance spectroscopy and Mott-Schottky measurements, the photocatalytic H2 production mechanism of Z-scheme heterojunction Bi2WO6/TiO2 was proposed. This work provides an easy and simple way to design a binary Z-scheme photocatalyst with efficient catalytic H2-production activity without electron mediators.

Palladium based bimetallic nanocatalysts: Synthesis, characterization and hydrogen fuel production

In this study, Palladium dopped Copper oxide nanoparticles (CuO@Pd NPs) were synthesized by an environmentally friendly green synthesis method for hydrogen production experiments. Characterizations of synthesized nanoparticles; UV–vis Spectroscopy to characterize the optical properties, Scanning Electron Microscopy (SEM) to determine the morphology and particle size of the particles, Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of organic groups, and X-ray Diffraction Spectroscopy (XRD) for the crystal lattice type analysis were used. As a result of the UV–vis Spectroscopy characterization of the synthesized nanoparticles, an absorption peak compatible with metals visible at 422 nm was observed. According to the XRD analysis results, the crystal size observed in the cubic phase was calculated as approximately 4.426 nm. According to the results of the SEM analysis the average particle size of the cubic nanoparticles was seen as 26.2 nm. The catalytic properties of CuO@Pd NPs were determined by the sodium borohydride hydrolysis reaction. As a result of catalyst, substrate, temperature, and reusability experiments, some activation parameters required for a catalytic reaction of nanoparticles were calculated. The activation energy of CuO@Pd NPs was calculated as 37.39 kJ/mol, enthalpy change as 34.84 kJ/mol, and entropy change as −189.8 J/mol.K. TOF, which is an indicator of hydrogen efficiency, was calculated as 1513.4 h−1. Reusability experiments were carried out in 4 cycles and the catalytic activity of CuO@Pd NPs was measured as 70 %. In light of these results, it was seen that nanoparticles provide optimal conditions for a catalytic reaction.

Design of gas-liquid two-phase separation device with application in solar hydrogen production system

Currently, solar thermochemical energy conversion technology has attracted more and more attention because of the increasing global need for clean fuel and chemical energy demand. The thermochemical hydrogen production technology uses solar radiation with concentrated high-density as a high-temperature heat source to produce hydrogen by decomposing water through two-step cycle redox reactions. It is an environment-friendly technology based on artificial photosynthesis utilizing water vapor as the reaction gas. However, limited by the separation efficiency, current gas-liquid separation devices cannot output stable high-purity water vapor and sophisticate the experimental processes. In this research, intensive numerical investigations were carried out on the widely-used corrugated plate steam separators. The structural parameters are designed by the multi-objective optimization method combining the artificial neural network and the genetic algorithm. Nine optimized structures are designed by adding hydrophobic hooks, streamlined, and reducing the plate distance optimization methods. The results give engineering application conditions of different optimized separators. The streamlined single-hook corrugated plate separator with rounded corners exhibited the best separation efficiency under the heat state condition, which is 97.27%. It can also completely separate droplets over 28.5 μm. The applicability of the cyclone steam separators indicated that it is more suitable for pretreatment. The benchmark experimental system was built for the measurement of the separation efficiency resulting in only a 0.73% error. The designed steam separator was successfully applied to the solar thermochemical hydrogen production experiment, which ensures its practicability and pertinence in the process of solar fuel synthesis.