Enhanced Hydrogen Production Research Articles

Review on Catalytic Biomass Gasification for Hydrogen Production as a Sustainable Energy Form and Social, Technological, Economic, Environmental, and Political Analysis of Catalysts.

Sustainable energy production is a worldwide concern due to the adverse effects and limited availability of fossil fuels, requiring the development of suitable environmentally friendly alternatives. Hydrogen is considered a sustainable future energy source owing to its unique properties as a clean and nontoxic fuel with high energy yield and abundance. Hydrogen can be produced through renewable and nonrenewable sources where the production method and feedstock used are indicators of whether they are carbon-neutral or not. Biomass is one of the renewable hydrogen sources that is also available in large quantities and can be used in different conversion methods to produce fuel, heat, chemicals, etc. Biomass gasification is a promising technology to generate carbon-neutral hydrogen. However, tar production during this process is the biggest obstacle limiting hydrogen production and commercialization of biomass gasification technology. This review focuses on hydrogen production through catalytic biomass gasification. The effect of different catalysts to enhance hydrogen production is reviewed, and social, technological, economic, environmental, and political (STEEP) analysis of catalysts is carried out to demonstrate challenges in the field and the development of catalysts.

H2O2 Exfoliation of TiO2 for Enhanced Hydrogen Production from Photocatalytic Reforming of Methanol

Hydrogen is considered a future energy carrier for clean and sustainable technology. Photocatalytic reforming of methanol produced hydrogen using water and energy from sunlight. This study reported enhanced activity of TiO2 without metal co-catalyst for hydrogen production following H2O2 exfoliation. TiO2 was transformed into peroxo-titania species on the outer layer of the particles, resulting in surface exfoliation. The exfoliation reduced TiO2 crystallite sizes enhanced the surface hydroxyl group and reduced the band gap to 3.0 eV. Hydrogen production from methanol-water mixtures on the TiO2 after four consecutive exfoliations was measured at 300 µmol, significantly higher than the fresh TiO2 (50 µmol). H2O2 exfoliated TiO2 reduced the pathway for charge migration to the surface. A high concentration of surface hydroxyl group trapped the charge carriers for efficient hydrogen production. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhancement of bioelectricity and hydrogen production from xylose by a nanofiber polyaniline modified anode with yeast microbial fuel cell

In this study, modification of carbon felt (CF) electrode using polymerized nanofiber polyaniline (PANI) was developed for increasing the conductivity of anodic electrode toward efficient adherence of exoelectrogenic yeast cells of Cystobasidium slooffiae JSUX1 and further enhancing both bioelectricity and hydrogen production from xylose in MFCs. The morphology analysis with SEM images verified the formed nanofiber structure of PANI on the surface of the PANI/CF electrode. Nanofiber PANI with a higher surface area could improve the conductivity of the PANI/CF anode for a durable attachment of yeast C. slooffiae JSUX1 to form a dense biofilm and boost a high-performance in MFCs. The maximum derived power output of MFCs with PANI/CF (119.35 ± 3.27 mW/m2) was about 2.2 times higher than that of MFCs with the bare CF (50.41 ± 6.9 mW/m2) and the maximum hydrogen yield reached 25.83 mL by using xylose as the sole carbon source. The obtained results of PANI/CF modified electrodes compared to the bare CF anode suggested that the extracellular electron transfer (EET) and energy production by yeast cell C. slooffiae JSUX1 have an excellent capability to be improved by PANI polymers in MFCs.

Electrochemical Activation of Silicon: Enhancing Hydrogen Production from FeNi Electrocatalysts

A two-sided electrode composed of FexNi100–xOy and Si was implemented to produce hydrogen. The hydrogen evolution reaction is facilitated by the FexNi100–xOy electrocatalyst. The high pH of the alkaline electrolyte and the reducing potential of the electrode result in the activation of the Si side, allowing spontaneous production of H2. Results demonstrate that the FexNi100–xOy composition and the electrolyte composition influence the performance of the FexNi100–xOy/Si system. The activation and subsequent production of H2 by the Si was demonstrated to be favored in 0.1 M KOH and NaOH electrolytes over LiOH, and this result was consistent when the electrochemical cell was operated under applied voltage and at open circuit voltage. At the same time, results showed that the Fe80Ni20/Si composition maintained a current of −10 mA at a lower potential (∼50 mV) compared to the Fe20Ni80/Si composition. Overall, the results of this study demonstrate that the two-sided FexNi100–xOy/Si electrode can be used to boost the production of hydrogen, leading to a maximum of 140% H2 efficiency, which includes both Faradaic H2 production and non-Faradaic H2 evolution through Si corrosion.

Acceleration of lactate-utilizing pathway for enhancing biohydrogen production by magnetite supplementation in Clostridium butyricum

A conductive metal compound can be used as a catalyst for enhancing hydrogen production by dark fermentation. This study aimed to identify mechanisms of enhanced hydrogen production by magnetite supplementation. Experiments were performed with lactate and/or magnetite supplementation to confirm that the lactate-utilizing pathway is the key cause of enhanced hydrogen production. Also, ribonucleic acid sample was collected for monitoring gene regulation under each condition. Hydrogen production was significantly enhanced by approximately 25.6% and 58.9%, respectively, via magnetite alone and with lactate. Moreover, the expression of genes involved in hydrogen production, including pyruvate ferredoxin oxidoreductase, hydrogenase, and ferredoxin, via magnetite alone and with lactate was upregulated by 0.26, 0.71, and 3.50 and 1.06, 2.14, and 1.94 times, respectively.

Comparison of magnetite/reduced graphene oxide nanocomposites and magnetite nanoparticles on enhancing hydrogen production in dark fermentation

Magnetite/reduced graphene oxide nanocomposites (Fe3O4-rGO NCs) and magnetite nanoparticles (Fe3O4 NPs) were added to enhance biohydrogen (bioH2) production in dark fermentation. Concentration of supplements from 10 to 100 mg/L was appropriate to enhance bioH2 production, and inhibition appeared once concentration exceeded 100 mg/L. The best bioH2 yield was 198.30 mL/g glucose at 100 mg/L Fe3O4 NPs and 225.60 mL/g glucose at 100 mg/L Fe3O4-rGO NCs, which was 42.97% and 62.65% higher than that in the blank group, respectively. Both Fe3O4 NPs and Fe3O4-rGO NCs could intensify butyrate-type fermentation and change the hydrogen-producing microorganism cells morphology, but the enhancement effect of Fe3O4-rGO NCs was superior. Microbial community structure analysis showed that Clostridium-sensu-stricto-1 became more dominant ultimately by Fe3O4-rGO NCs.

Enhanced hydrogen production using a tandem biomass pyrolysis and plasma reforming process

Converting biomass into energy and fuels is considered a promising strategy for replacing the exhaustible fossil fuels. In this study, we report on a tandem process that combines cellulose pyrolysis and plasma-assisted reforming for H2 production. The hybrid pyrolysis/plasma reforming process was carried out in a two-stage reaction system incorporating a coaxial dielectric barrier discharge (DBD) plasma reactor. The effects of discharge power, steam, reforming temperature, and catalyst on the reaction performance were investigated. The results show that low temperatures are preferred in the non-catalytic plasma reforming process, whereas high temperatures are desired to achieve a high H2 yield and a high H2 selectivity in the plasma-catalytic reforming system. The synergistic effect of plasma catalysis was dominant in the plasma-catalytic reforming process at 250 °C. In contrast, the catalyst, rather than the plasma, played a dominant role in the plasma-catalytic reforming at higher temperatures (550 °C). Using Ni-Co/Al2O3 at a reforming temperature of 550 °C, a high H2 yield of 26.6 mmol/g was attainted, which was more than 8 times and about 100% greater than that obtained using plasma alone and catalyst alone, respectively. This work highlights the potential of non-thermal plasmas in low-temperature biomass conversion.

Utilization of renewable hybrid energy for refueling station in Al-Kharj, Saudi Arabia

Hydrogen is one of the energy carriers that can be produced using different techniques. Combining multiple energy sources can enhance hydrogen production and meet other electrical demands. The hybrid arrangement allows the produced hydrogen to be stored and used when the electrical energy sources are not adequate. In this study, utilizing the meteorological data was investigated using HOMER (Hybrid Optimization of Multiple Energy Resources) software for the optimal solution. The results demonstrated that the “best-optimized system has 270 kW of photovoltaic (PV), 1 unit of 300 kW of wind turbine (WT), 500 kW of electrolyzer, 100 kg/L of the hydrogen tank, 70 units of 1 kWh lithium-ion battery, and 472 kW of the converter. The selected hybrid energy system has the lowest Levelized cost of energy (LCOE), Levelized cost of hydrogen (LCOH), and net present cost (NPC) of $/kg 0.6208, $/kg 9.34, and $ 484,360.00 respectively which judged the system to be the best choice for the proposed hydrogen project in AI-Kharj. This investigation will help stakeholders and policymakers optimize hybrid energy systems that economically meet the hydrogen production and refueling station demands of the AI-Kharj community.

Nanoengineering of Catalysts for Enhanced Hydrogen Production

Hydrogen (H2) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H2 production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H2 production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H2 production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H2 production, identifying the promising applications of controlled nanomaterials.

Ultrathin 3D radial tandem-junction photocathode with a high onset potential of 1.15 V for solar hydrogen production

Combining a progressive tandem junction design with a unique Si nanowire (SiNW) framework paves the way for the development of high-onset-potential photocathodes and enhancement of solar hydrogen production. Herein, a radial tandem junction (RTJ) thin film water-splitting photocathode has been demonstrated experimentally for the first time. The photocathode is directly fabricated on vapor-liquid-solid-grown SiNWs and consists of two radially stacked p - i - n junctions, featuring hydrogenated amorphous silicon (a-Si:H) as the outer absorber layer, which absorbs short wavelengths, and hydrogenated amorphous silicon germanium (a-SiGe:H) as the inner layer, which absorbs long wavelengths. The randomly distributed SiNW framework enables highly efficient light-trapping, which facilitates the use of very thin absorber layers of a-Si:H (~50 nm) and a-SiGe:H (~40 nm). In a neutral electrolyte (pH = 7), the three-dimensional (3D) RTJ photocathode delivers a high photocurrent onset of 1.15 V vs. the reversible hydrogen electrode (RHE), accompanied by a photocurrent of 2.98 mA/cm 2 at 0 V vs. RHE, and an overall applied-bias photon-to-current efficiency of 1.72%. These results emphasize the promising role of 3D radial tandem technology in developing a new generation of durable, low-cost, high-onset-potential photocathodes capable of large-scale implementation. A radial tandem junction thin-film photocathode with a V onset of 1.15 V vs. RHE has been demonstrated directly on VLS-grown SiNWs for the first time, using a-Si:H (~50 nm) as the outer absorber layer and a-SiGe:H (~40 nm) as the inner layer.

Enhanced hydrogen production from water hyacinth by a combination of ultrasonic-assisted alkaline pretreatment, dark fermentation, and microbial electrolysis cell

In this study, hydrogen (H2) production from water hyacinth (WH) was enhanced by the integration of the ultrasonic-assisted alkaline (UAA) pretreatment, dark fermentation (DF), and microbial electrolysis cell (MEC). The results showed that UAA pretreatment improved around 350% in H2 production in the DF stage and nearly 400% in the whole process compared to un-pretreated. The H2 yield in the DF stage reached the maximum value of 110.4 mL/g-VS at a WH concentration of 20 g-TS/L. However, high concentrations of co-produced soluble metabolite products (SMPs) and suspended solid in DF effluent adversely affected the efficiency of the MEC stage. Consequently, a WH concentration of 5 g-TS/L was optimal for the UAA-DF-MEC process that achieved the highest H2 yield of 565.8 mL/g-VS. It suggests that other auxiliary processes (e.g., dilution, centrifugation, effective methanogen inhibition, etc.) need to be developed to further improve the H2 production from WH via the UAA-DF-MEC process.

Construction of ternary Z-scheme covalent triazine framework@Au@TiO2 for enhanced visible-light-driven hydrogen evolution activity

One key challenge in photocatalytic hydrogen production is how to construct high-performance photocatalyst. Covalent triazine framework (CTF) based polymers as photocatalysts show great application potential because of their good photocatalytic activity, high chemical stability, tunable electronic and optical properties, and easy synthesis process. In this paper, we designed the ternary Z-scheme heterojunction Au@TiO2-X%TrTh based on CTF polymer TrTh, TiO2 and Au nanoparticle, which exhibit higher photocatalytic hydrogen production rate compared with the corresponding binary heterojunction Au@TiO2 and TiO2-12%TrTh. The results of photocatalytic hydrogen production show that the optimized Au@TiO2-12%TrTh has a remarkable hydrogen production rate of 4288.54 μmol g−1 h−1, which is about 312.3 times of Au@TiO2 and 9.1 times of the TiO2-12%TrTh. The enhanced hydrogen production activity of the ternary heterojunction comes from the local surface plasmonic resonance effect of Au nanoparticle, lower recombination efficiency of photogenerated electron-holes pairs and Z-scheme electron transfer pathway of Au@TiO2-12%TrTh. The work provides a new strategy for designing efficient and practical photocatalyst.

Phenyl-incorporated carbon nitride photocatalyst with extended visible-light-absorption for enhanced hydrogen production from water splitting

Developing and employing photocatalysts with extended visible-light-absorption has emerged as a fundamental issue for the enhanced capability of photocatalytic H2 evolution from water splitting. Herein, a wide-spectrum light-responsive phenyl-grafted carbon nitride photocatalyst was synthesized. It was found that benzonquanmine-derived g-C3N4 (BCN) exhibits significantly extended light absorption (∼670 nm) compared with conventional melamine-derived g-C3N4 (MCN). Correspondingly, the photocatalytic H2-evolution rate of BCN (2846 μmol h−1 g−1) is five times as that of MCN under visible-light irradiation. Particularly, an impressive H2-evolution rate of 58 μmol h−1 g−1 could be achieved on BCN even under light irradiation beyond 620 nm. The outstanding photocatalytic H2-evolution performance could be not only attributed to the enriched photons generated from the enhanced solar energy harvesting, but also to the distinctly inhibited rapid recombination of photogenerated electron-hole pairs resulting from the incorporation of phenyl groups. This work furnishes a new train of thought for the designing of carbon-nitride-based photocatalysts with enhanced capability of visible-light-utilization.

Enhanced Hydrogen Production at Optimum pH for the Recovery Cycle of β-FeOOH.

In the photo-Fenton reaction, highly reactive oxygen species are generated on UV irradiation of β-FeOOH, which contributes significantly to hydrogen production. The production process was performed by adjusting the pH of the solution. The effect of acid concentration on hydrogen production was analyzed in this study, and the difference in the amount of hydrogen gas produced in each sample with different pH values was determined. X-ray powder diffraction (XRD) measurements of the samples corresponding to the peaks of β-FeOOH were compared with the reference data, and crystallite sizes were calculated by the Scherrer equation using XRD patterns. The rod-like structure of the sample particles was revealed by scanning electron microscopy. A higher amount of hydrogen was produced at lower pH, and these results confirmed that pH plays an important role in hydrogen production.

Preparation of two-dimensional mesoporous Ta3N5 by utilizing a biological template for enhanced photocatalytic hydrogen production

The design and development of efficient nitride photocatalysts have attracted much attention. Herein, two-dimensional mesoporous Ta3N5 is successfully synthesized through a simple sol-gel process with filter paper as a biological template and a combination of vacuum nitriding reactions. The prepared Ta3N5 shows a wide light response range up to the near infrared (NIR) region due to the nitrogen vacancies generated from substitution of N3− for O2− ions during vacuum nitridation. Significantly, such a narrow bandgap (∼1.99 eV) still satisfies the redox potential of water splitting in thermodynamics. The experimental results show that the Ta3N5 photocatalyst exhibits an enhanced hydrogen production rate of 34.6 μmol h−1 g−1, which is 3.9 and 2.1 times higher than that of Ta2O5 and partial nitridation of Ta2O5 (N–Ta2O5), respectively. This enhanced photocatalytic performance could be attributed to the high specific surface area to provide reactive active sites, substitution of N3− for O2− ions to optimize the band structure, and special two-dimensional mesoporous structure to shorten the charge transfer distance. This work provides a new perspective for the preparation of two-dimensional nitride materials by a biological template method combining vacuum nitriding with enhanced photocatalytic performance.

Formation of 6H-Ba3Ce0.75Mn2.25O9 during Thermochemical Reduction of 12R-Ba4CeMn3O12: Identification of a Polytype in the Ba(Ce,Mn)O3 Family.

The resurgence of interest in a hydrogen economy and the development of hydrogen-related technologies has initiated numerous research and development efforts aimed at making the generation, storage, and transportation of hydrogen more efficient and affordable. Solar thermochemical hydrogen production (STCH) is a process that potentially exhibits numerous benefits such as high reaction efficiencies, tunable thermodynamics, and continued performance over extended cycling. Although CeO2 has been the de facto standard STCH material for many years, more recently 12R-Ba4CeMn3O12 (BCM) has demonstrated enhanced hydrogen production at intermediate H2/H2O conditions compared to CeO2, making it a contender for large-scale hydrogen production. However, the thermo-reduction stability of 12R-BCM dictates the oxygen partial pressure (pO2) and temperature conditions optimal for cycling. In this study, we identify the formation of a 6H-BCM polytype at high temperature and reducing conditions, experimentally and computationally, as a mechanism and pathway for 12R-BCM decomposition. 12R-BCM was synthesized with high purity and then controllably reduced using thermogravimetric analysis (TGA). Synchrotron X-ray diffraction (XRD) data is used to identify the formation of a 6H-Ba3Ce0.75Mn2.25O9 (6H-BCM) polytype that is formed at 1350 °C under strongly reducing pO2. Density functional theory (DFT) total energy and defect calculations show a window of thermodynamic stability for the 6H-polytype consistent with the XRD results. These data provide the first evidence of the 6H-BCM polytype and could provide a mechanistic explanation for the superior water-splitting behaviors of 12R-BCM.

Photocatalytic performance of alkali metal doped graphitic carbon nitrides and Pd-alkali metal doped graphitic carbon nitride composites

Although there are several reports about the beneficial performance of metal doped graphitic carbon nitrides (g-C3N4) in various photocatalytic reactions, the effect of different alkali metal dopants has not been studied systematically. Series of undoped, Li-, Na- and K-doped samples was synthetized and used for the preparation of novel type of photocatalysts, composed of palladium nanoparticles supported on alkali metals-doped graphitic carbon nitride. Palladium loading was achieved via citrate reduction of palladium precursor in the presence of the carbon nitride material. Several physicochemical characterization methods such as attenuated total reflection infrared-(ATR-IR), diffuse reflectance UV–visible spectroscopy, high-resolution transmission microscopy (HRTEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and thermogravimetric analysis (TGA) were used to get information about the morphology and composition of the novel composites. According to the optical characterization results, the band gap of g-C3N4 decreased upon Na- and K doping but increased after Li-doping. The palladium nanoparticles were distributed over the support and appeared in dispersed (undoped g-C3N4, Li-g-C3N4) or agglomerated (Na-g-C3N4, K-g-C3N4) form with individual particle size below 5 nm. The catalytic performance of these composite materials was tested in two processes: (i) photodegradation of methyl orange and (ii) hydrogen production from methanol. The Na- doping of graphitic carbon nitride was found to be a key issue to enhance hydrogen production. The carbon nitride matrix was found to be stable during the photocatalytic experiments, while the Pd component underwent certain changes during the photocatalytic reforming reaction of methanol. Our results indicated that the really acting metallic Pd cocatalyst was formed mainly in situ.

Investigation on the effect of temperature on photothermal glycerol reforming hydrogen production over Ag/TiO2 nanoflake catalyst

Photothermal reforming of biomass-derived hydrocarbons is an efficient approach to generate renewable hydrogen driven by solar. However, the current understanding of the general thermal effect on hydrogen production is limited since the photothermal and thermal radiation from solar is difficult to separate. Herein, an experimental study is carried out by synthesizing a series of photothermal catalysts composed of Ag nanoparticles supported on TiO2 nanoflake (TNF). The structure of the Ag/TNF was examined by XRD, XPS, and HRTEM, respectively. The local temperature rise of the Ag/TNF was detected during the photothermal reforming reaction of the aqueous bio-glycerol, and its influence on H2 yield was analyzed. By introducing different weight ratios of Ag nanoparticles on TNF, the equilibrium temperature was obviously increased due to the localized surface plasmon resonance (LSPR) effect and dynamic balance between LSPR and heat dissipation was found. It was observed that increasing the weight ratio of Ag particles could result in an increased temperature and lower hydrogen yields. In fact, such photothermal reforming hydrogen production was a synergistic effect between photogenerated-electrons and phonons. Therefore, precisely regulating the photothermal effect by controlling the metal nanoparticles loading to achieve proper thermal balance and high catalytic activity is one effective countermeasure to enhance hydrogen production.

Regulation of the NADH supply by nuoE deletion and pncB overexpression to enhance hydrogen production in Enterobacter aerogenes

In this study, seven mutants from E. aerogenes IAM1183 wildtype were constructed via different strategies including deletion of lactate dehydrogenase, disruption of NADH dehydrogenase gene nuoE , overexpression of pncB and a combination of both to regulate of the NADH supply to enhance hydrogen production. Compared with the parental strain, the hydrogen yields of the strains IAM1183-E, IAM1183-L and IAM1183-EL increased by 23.3, 81.7 and 97.9%, respectively. When the pncB gene was overexpressed, the hydrogen yield of IAM1183/P, IAM1183-E/P, IAM1183-L/P and IAM1183-EL/P increased by 39.0, 6.5, 5.9, and 5.1% compared with the respective original knockout strains. Among them, the total hydrogen yield of strain IAM1183-EL/P with highest production efficiency was 58% higher than IAM1183. Further metabolite analysis indicated that the knockout of nuoE and ldhA , combined with the overexpression of pncB , resulted in a redistribution of the metabolic fluxes in E. aerogenes , which led to an improvement of the hydrogen yield. • Disruption of nuoE or overexpression of pncB in E. aerogenes increased NADH/NAD + pool. • Deletion of ldhA of E. aerogenes enhanced the competitiveness of NADH dehydrogenase. • The knockout of nuoE and ldhA , combined with the overexpression of pncB improved H 2 yield. • Hydrogen yield of IAM1183-EL/P increased by 58% in 5-L fermenter.

High-yield H2 production from polypropylene through pyrolysis-catalytic reforming over activated carbon based nickel catalyst

With the aggravation of energy crisis and environmental pollution, green and renewable new alternative energy has become the focus of global attention. Hydrogen energy has become an important part of the global energy pattern in the future. Conversion of solid waste plastics into hydrogen energy by pyrolysis/gasification is a promising solution. This study aims to explore a method of high-yield in hydrogen by breaking down polypropylene, a cheap and efficient nickel catalyst is prepared and applied to the experimental study of hydrogen production by pyrolysis-catalytic reforming. The effects of catalytic temperature, Ni loading (%) and catalyst addition amount on hydrogen production of catalyst were investigated, the hydrogen production was increased by introducing water vapor. Under the optimized reaction parameters (catalytic temperature 900 °C, PP to catalyst ratio 1:0.75, Ni loading 15 wt%), the hydrogen yield is up to 40.24 mmol/gPP without water and 134.91 mmol/gPP with water, the addition of water significantly increased hydrogen production. this results have obvious advantages in hydrogen production compared with similar studies. Furthermore, the existence of various forms (snake-like, straight carbon nanotubes and carbon nanospheres) of carbon deposition found in this paper can provide new ideas for researchers working on graphite carbon. This study provides an effective new approaches for enhancing hydrogen production by pyrolysis/gasification of waste plastics.