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The solar photocatalytic degradation of pulp and paper mill wastewater has been reported by several scientists. However, this is the first time we are reporting for solar photocatalytic hydrogen production from pulp and paper mill wastewater and simultaneous degradation of pollutants. In this work, CuO based photocatalysts and novel square type photocatalytic reactor of 5 L capacity were used. The result shows that the prepared photocatalysts are solar active, efficient in hydrogen recovery and pollutant degradation from the pulp and paper wastewater. The effects of catalyst loading, sacrificial agent, pollutant removal efficiency and stability check were investigated. At 0.25 g/L of CuO/Fe 2 O 3 , 0.2 M of sacrificial agent (Na 2 SO 3 2−) and hydrogen yield of 1000 mL from 1000 mL of wastewater was achieved. The removal efficiency of TSS, TDS, BOD, COD, turbidity and TOC are around 70, 50, 60, 65, 70 and 45% respectively. Reusability study revealed that CuO/Fe 2 O 3 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. [Display omitted] • Visible light active CuO mixed with novel metal oxides were employed. • Hydrogen recovery from black liquor, paper mill wastewater were 1000 mL/h/L and 850 mL/h/L. • Efficiency of degradation of pulp & paper wastewater chemicals were around 50–70%. • AcHieved high recovery of hydrogen from pulp & paper wastewater. [ABSTRACT FROM AUTHOR]

1 Amorphous carbon was facilely obtained via the treatment of waste papers with sulfuric acid. 2 The combination of amorphous carbon with graphitic carbon nitride leads to an increased photo-catalytic H 2 generation. 3 The enhancement in H 2 generation is resultant from the efficient separation of electrons and holes owing to the excellent electrical conductivity of amorphous carbon. Up-cycling of waste papers to value-added carbon products has significant environmental and economic benefits in real life. This work aims to recycle the waste papers to construct amorphous carbon modified graphitic carbon nitride composite photocatalysts for efficient photocatalytic hydrogen generation from water under visible light. Amorphous carbon (labeled as a-C) was yielded from the office waste papers by simple sulphuric-acid treatment and then combined with graphitic carbon nitride (g-CN) to form the g-CN/a-C composite photocatalysts by the thermolysis of a-C and melamine mixture. The addition of a-C enlarges the surface area of g-CN from 11.52 m2 g−1 of pristine g-CN to 28.12 m2 g−1 of g-CN/a-C-100. In addition, the a-C incorporation can significantly separate the electrons from the photoexcited g-CN owing to the excellent conductivity of a-C. As a result, an increased photocatalytic H 2 generation was realized under visible light exposure. The g-CN/a-C-100 sample with optimized a-C contents offers the highest photocatalytic H 2 generation rate of up to 17.1 μ mol h−1, which is ∼12 times higher than that of pristine g-CN under the same condition. The present study manifests the great potential of the recycling of office waste papers for increased photocatalytic H 2 generation. Graphical Abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

In this study, practical application for the industrial-scale hydrogen evolution reaction (HER) process is established using sustainable Cu 2 CoSnS 4 embedded in paper-working electrodes. The Cu 2 CoSnS 4 is produced using a solvent-free solid-phase approach. The effect of a wide pH range of electrolytes on working electrodes for hydrogen evolution reactions is also investigated. The Cu 2 CoSnS 4 embedded paper-working electrodes exhibit goodelectrocatalytic activity for hydrogen evolution reaction with low overpotential values of 233, 310, and 261 mV vs RHE at 10 mA/cm 2 in 0.5 M H 2 SO 4 ,1 M KOH, and 1 M PBS, respectively. These designed electrodes exhibit high double-layer capacitance and electrochemical surface area for a wide pH range. In acidic, alkaline and neutral environments, the catalyst-embedded paper electrodes explicit high turnover frequencies of 2.15 s−1, 2.75 s−1, and 2.11 s−1, respectively. The temperature-dependent hydrogen evolution reaction is studied to calculate the activation energy of the cathodic electrode. Utilising chrono-amperometry for about 118 h in an acidic media, which shows that electrodes have a high degree of stability. In comparison to other previously reported work on catalyst-embedded electrodes, the Cu 2 CoSnS 4 embedded paper-working electrodes offer excellentpotential for HER activity across a wide pH range and are suitable for industrial application. • Cu 2 CoSnS 4 embedded paper working electrodes are developed for hydrogen generation. • The electrodes exhibit universal pH hydrogen evolution reaction. • Electrodes shows excellent stability upto 40hr for continuous hydrogen generation. • The electrode displays good stability at current density more than 200 mA/cm2. [ABSTRACT FROM AUTHOR]

Solar-driven water splitting by inorganic semiconductor photocatalysts is considered a promising method to produce hydrogen fuel. Loading inorganic semiconductor on cellulose fiber to construct photocatalytic paper contributes to the dispersion and recycling of photocatalyst. In addition, the photocatalytic paper floating on water can build a solid–gas biphase photocatalytic interface (photothermal-generated steam/photocatalytic paper/hydrogen), replacing the traditional liquid–solid–gas triphase photocatalytic interface (liquid water/photocatalyst/hydrogen) for improving photocatalytic kinetics. Here, we design and synthesize a photocatalytic composite paper with zinc sulfide (ZnS) anchored onto cellulose fibers (CF) with the help of polydopamine (PDA). PDA achieves high load and uniform distribution of ZnS on cellulose fibers, and forms the ZnS/PDA heterojunction to increase photogenerated charge separation efficiency and photocatalytic stability. Solid–gas biphase photocatalytic interface constructed by the CF/PDA/ZnS composite paper minimizes the interface barriers of hydrogen transport and water molecular adsorption for improving hydrogen evolution rate. The CF/PDA/ZnS composite paper shows a high hydrogen production rate up to 18706.8 μmol h−1 g−1. Stable loading of ZnS/PDA heterojunction in composite paper contributes to the photocatalytic stability. In the third photocatalytic cycle, the hydrogen evolution rate of CF/PDA/ZnS composite paper remains 96.4%. This work inspires that anchoring of inorganic semiconductor on cellulose fibers with the help of PDA can be a promising strategy for designing efficient photocatalytic paper for solar hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluation of dark fermentative hydrogen production using paper mill effluent (PME) • Investigation of the impact of different HRTs on the biofilm reactor performance. • H 2 production rate was enhanced to 6.21 L H 2 d−1 L−1 by decreasing HRT to 2 h. • Max. yield of H 2 was 0.96 mmol H 2 g−1 COD at 8 h HRT. • Production of VFAs as valuable by-products as well as COD removal. This study assessed the feasibility of continuous hydrogen production in an anaerobic packed bed biofilm reactor (APBR) using paper mill effluent (PME) without any pretreatment or modification. To form a microbial biofilm on supports, the reactor was seeded with a thermal pretreated anaerobic sludge. After the start-up stage, under mesophilic conditions and pH control, the system performance in the case of hydrogen production as biofuel and VFAs as valuable by-products as well as COD removal was investigated at different hydraulic retention times (HRTs) (24, 16, 12, 8, 4, 2 and 1.2 h). The highest hydrogen concentration in the produced gas was 41.5 % obtained at HRT 4 h. The highest hydrogen production rate and yield were 6.21 L H 2 d−1 L−1 at HRT 2 h and 0.96 mmol H 2 g−1 COD at HRT 8 h, respectively. With decreasing the HRT from 24 to 1.2 h, the OLR was increased from 27.35 to 547 g COD L−1 d−1 that positively affect the hydrogen production rate for all HRTs except for the shortest HRT. Furthermore, COD removal efficiency was reduced from 25.2 to 6 %. Low value of COD removal efficiency is because of conversion of organic inlet to valuable metabolites such as VFAs in the effluent. [ABSTRACT FROM AUTHOR]

Cost-effective, simple and flexible hydrogen gas sensors operating at room temperature were demonstrated based on DC magnetron sputtered palladium thin films. The main idea is to use commercial microfiber filtration paper as a cheap, fibrous and flexible substrate for palladium. With this objective, Pd thin films with 21, 38 and 54 nm thicknesses were deposited and characterized by grazing incident X-ray diffraction (GIXRD) and scanning electron microscope (SEM). The gas sensing behavior was tested by hydrogen gas in the concentration rang of 0.5–10%. GIXRD showed a PdX/Pd phase and SEM revealed existing of many structural nanocracks. An activation process was needed where sensors were heated up to 110 °C in the presence of 10% H 2. Then a desirable hydrogen sensitivity with good stability based on hydrogen induced lattice expansion (HILE) effect in which conductance increases was observed. However, for low Pd thicknesses (21 and 38 nm) and at below 4% H 2 , an inverse effect was observed in which the conductance decreased instead of increasing. For all samples the response time is incremental in the range of 0.5–4% and declining for 4–10%. Moreover, the deposited Pd sensors operate well when they are bent inward or outward. The governed physical mechanism was expressed and discussed. • Pd thin films were deposited on microfiber filtration paper by DC sputtering method. • Their hydrogen sensing properties were examined for different Pd thicknesses. • Sensing mechanisms including invers and direct current responses were observed. • The stability of sensing response of fabricated sensors was examined. • The response to bending in presence and absence of gas was investigated. [ABSTRACT FROM AUTHOR]

In this work, a paper-based hydrogen fuel cell is developed without the need for hydrogen storage. Instead, an embedded aluminum foil inside the paper is utilized for in-situ hydrogen generation. The electrodes and current collectors are also deposited on the paper, leading to a lightweight, compact and flexible hydrogen fuel cell with an OCV reaching 0.93 V and a peak power density of 4 mW cm−2. Benefited from the impeded hydroxyl ion diffusion, the hydrogen generation rate is well controlled, leading to a high faradaic efficiency of 72%. In addition, the cell can be operated under different bending angles with negligible power loss. Furthermore, it can be conveniently stacked in the same piece of paper for higher voltage and power outputs. Such a novel fuel cell design is especially suitable for powering various flexible devices with small rated power. • A paper-based hydrogen fuel cell is developed with an OCV of 0.93 V. • The peak power density is 4 mW cm−2 and the maximum current density is 8 mA cm−2. • Faradaic efficiency and energy efficiency are as high as 72% and 18%, respectively. • 75–87.5% of the cell performance remains when bended by angles from 45° to 135°. • A 4-cell stack is developed with an OCV of 3.8 V and a stacking efficiency of 90.6%. [ABSTRACT FROM AUTHOR]

Biohythane, the promising gaseous biofuel, can be produced by the recirculated two-phase anaerobic digestion (R-TPAD). The effect of hydraulic retention time (HRT) as 30, 20 and 10 days on biohythane production via R-TPAD (recirculation ratio = 0.4) was investigated with co-digestion of food waste and paper waste. The results showed that HRTs of 30 and 20 days maintained stable performance for R-TPAD but HRT of 10 days led to the final decrease in biogas production. The failure in the end was attributed to the wash-out of microbes. The removal efficiencies for COD and carbohydrates were decreased by short HRTs while for VS it remained relatively stable at about 75.7 ± 4.0%. All through the operation, acidogenic phase and methanogenic phase were separated stably and butyrate pathway was the dominant pathway for hydrogen fermentation in the first stage. The microbial community in the first stage reached the highest diversity when total HRT was 20 days, where the hydrogen production rate was the highest. The genera Lactobacillus and Caproiciproducens kept dominating the dark fermentation in the acidogenic phase, and Ruminococcus and Methanosarcina were decreasing in the methanogenic phase. The biohythane yields were 411 mL/g-VS fed , 332 mL/g-VS fed and 253 mL/g-VS fed , respectively, where the H 2 contents were 18.4%, 14.7% and 8.8%, respectively. [Display omitted] • The R-TPAD system (R = 0.4) was operated for biohythane production. • R-TPAD operated under HRTs of 30 and 20 maintained stable performance. • Organic removals and biohythane yields were lowered by short HRTs. • Different microbial communities were identified by co-occurrence network. • Biohythane yields affected by different parameters were discussed. [ABSTRACT FROM AUTHOR]

Paper industries are water-intensive industries that produce large amount of wastewater containing dyes, toxicity and high nutrient content. These industries require sustainable technology for their waste disposal and MEC could be one of them. However, effective MEC operation at neutral pH and ambient temperature requires economical and efficient cathodes that are capable to treat indusial wastewater along with recovery of energy/biohydrogen. Co-deposits of Nickel, Nickel–Cobalt and Nickel–Cobalt–Phosphorous on the surface of SS and Cu base metals distinctly were used as cathodes in MEC for the concurrent treatment of real paper industry wastewater and biohydrogen production. MECs were utilized in batch mode at neutral pH, applied voltage of 0.6 V and 30 ± 2 °C temperature with paper industry wastewater and activated sludge as microbial sources. The fabricated Nickel–Cobalt–Phosphorous gives the higher hydrogen production rate of 0.16 ± 0.002 m3(H 2) m−3d−1 and 0.14 ± 0.002 m3(H 2) m −3d −1 respectively, with ~33–42 % treatment efficiency for a 500 ml wastewater in 7-day batch cycle in both the cases; while it is lowest in the case of the control cathodes (SS1 (0.07 ± 0.002 m3(H 2) m−3d−1) & Cu1 (0.06 ± 0.004 m3(H 2) m−3d−1)). It was also found that fabricated cathodes have the capability to treat industrial wastewater at ambient conditions efficiently with higher energy recovery. Prepared cathodes show enhanced hydrogen production and treatment efficiency as well as are competitive to some reported literature. [Display omitted] • The fabricated cathodes exhibited higher electrochemical catalytic activity in real paper industry wastewater. • MECs were used concurrently for energy recovery and treatment of real paper industry wastewater. • Reaction inside MECs can be enhanced by depositing Ni–Co–P based particle on electrode surface. • Ni-Co-P co-deposits attained the maximum H 2 production rate of 0.16-0.06 ±0.002 m3(H 2) m-3d-1 with ~42 % COD reduction. • Higher biohydrogen production, cathodic efficiency and energy recovery were obtained with co –deposited cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Paper mill sludge is a carbohydrate rich substrate for bioenergy production. • Floc dissociation can enhance bacterial disintegration of biomass. • Floc removal was optimized at 0.05 g/g SS of calcium peroxide at 70 °C. • Thermal calcium peroxide-bacterial pretreatment exhibits 18.6% solubilization. • Increase in solubilization aids in efficient generation of hydrogen of 94.1 mL/gCOD. This study envisioned attaining the percipience of effective biohydrogen production from paper mill waste-activated sludge through low-temperature calcium peroxide-mediated bacterial pretreatment (TCP-BP). Floc dissociation with limited cell destruction was attained at a calcium peroxide dosage of 0.05 g/g suspended solids (SS) at 70 °C temperature. This TCP-BP method improves bacterial fragmentation, and very high SS solubilization was achieved at 42 h, with the solubilization and solid reduction of 18.6% and 14.1%, respectively. BP-only pretreatment shows lower solubilization efficiency of 9.4% than TCP-BP pretreatment due to the presence of flocs, which inhibit the enzymatic action during bacterial fragmentation. A biohydrogen test shows a high biohydrogen potential of 94.1 mL H 2 /gCOD for the TCP-BP sample, which is higher than that of the BP-only and control samples. According to the findings, low-temperature calcium peroxide-mediated bacterial fragmentation is validated to be an efficient process for sludge degradation and biohydrogen production. [ABSTRACT FROM AUTHOR]

The authors of the title paper (Appl Phys A 126:394, 2020) report to have grown a new nonlinear optical potassium hydrogen oxalate (KHO) single crystal, which exhibits second harmonic generation response. In this comment, it is shown that these claims are erroneous since KHO is a well-known solid which crystallizes in the centrosymmetric P21/c space group. [ABSTRACT FROM AUTHOR]

“Mass transfer in catalyst supports”and “reactive sites”are two critical factors for supported thin film catalysts. Based on such considerations, paper composed of cellulose fibers (CFs) is chosen as a competent nano-catalyst carrier because its broad porous structure is conducive to mass transfer. Then a facile aquatic synergistic synthesis is developed to decorate polypyrrole (PPy) encapsulated palladium nano-composites onto the CF paper structures. The pyrrole monomers (Py) reduce Pd 2+ to Pd nanoparticles in aqueous solution, and meanwhile the Pd 2+ initiates the polymerization of Py to PPy. In the as-prepared composite paper catalysts, the broad pores constructed by the microfibers facilitate the reactant diffusion and the Pd/PPy nanoparticles supported on the fibers provide more reactive sites for catalysis. As a result, the catalytic activity for hydrolysis of ammonia borane is improved. The H 2 turnover frequency is 21.1 mol H 2 mol Pd −1 min −1 , surpassed most other Pd based film catalysts. Importantly, excellent stability and reproducibility are also realized by the immobilization of Pd NPs by PPy layers onto fibers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A paper-based photoanode is developed for photoelectrochemical water splitting. • MoSe 2 nanosheet anchored CdS-ZnO array functional paper is prepared. • Tandem Z-scheme configuration with double IEFs and photothermal effect are integrated. • The flexible photoanode achieves admirable solar water splitting performance. Rational design of photoelectrode architectures is deemed as an effective solution to enhance efficiency of photoelectrochemical water splitting for conquering increasingly prominent environmental problems. Herein, a programmable flexible photoanode with built-in tandem Z-scheme configuration fabricated by in-situ growth of MoSe 2 -CdS-ZnO array with ultrathin nanosheet-interlaced-nanorod structure on the Au paper electrode, is firstly reported. By taking advantages of the interwoven nanonetwork structure, high conductivity as well as larger porosity of the as-fabricated Au paper electrode, a stable light-harvesting paper chip with fast transfer/separate mediators of the charge/carriers is thus integrated. By virtue of double internal electric fields (IEFs) and photothermal effect, the developed MoSe 2 -CdS-ZnO photoanode exhibits incident-photon-to-current efficiency of 52 % under 460 nm of light irradiation, and the current density reaches 2.4 mA cm−2 at 0.3 V versus normal hydrogen electrode, which is comparable with respect to current state-of-the-art "type-II-scheme", "surface-scheme", and cocatalyst-free photocatalysts (0.03–2.4 mA cm−2). Consequently, the paper-based photoanode achieves admirable photoelectrocatalytic hydrogen generation property (39.7 μmol cm−2 h-1). The synergistic effect of tailorable tandem Z-scheme configuration with double IEFs and delineating of 3D cross-linked network structure of the proposed photoanode in this work may open an avenue for constructing high-performance photoelectrochemical water splitting devices. [ABSTRACT FROM AUTHOR]

To improve the hydrogen detection performance, a flexible palladium-based hydrogen sensor was designed and fabricated on normal photocopy paper. The paper substrate offers advantages such as light weight, low cost, flexibility and unique surface texture. A conventional vacuum evaporation technique was utilized for 60 nm palladium deposition on the paper and glass substrates. The unique surface texture of the paper effectively increased the surface area to volume ratio for the sensing element, which achieved a higher gas response with faster speed than the glass-based sensor. In addition, we investigated the temperature impacts on sensing performance of the paper-based hydrogen sensor at room temperature and 50 °C. Furthermore, the flexibility test results of the paper-based hydrogen sensor showed that the sensing performances were impervious to mechanical bending of 5.7°. [ABSTRACT FROM AUTHOR]

The synergistic effects derived from optimizing the chemical and structural features of electrocatalysts permit them to attain remarkable activity and stability. Herein, 1D/2D cobalt‐based nanohybrid (CoNH) electrodes are developed; the structural design consists of Co3O4 electrospun nanoribbons (NRs) deposited onto a carbon fiber paper substrate where Co3O4 nanosheets are subsequently grown via an electrodeposition step and UV/ozone treatment. The content of noncovalently functionalized carbon nanotubes within the Co3O4 NRs is first tuned to enhance their charge transfer properties and mechanical stability. The electrocatalytic activity of the electrodes is further improved by a phosphorus modification of the 1D NRs, resulting in the formation of NaCoPO4. The optimized 1D/2D CoNH electrode, i.e., ED‐0.09 wt% fCNTs/P‐CoNHs, displays a similar performance to that of platinum in 0.25 m Na2S/0.35 m Na2SO3 (Tafel slope ≈102 mV dec−1 for the former and ≈96 mV dec−1 for the latter) and outstanding stability for up to 48 h. The versatility and high activity of this electrode is also demonstrated according to tests in a conventional water splitting system (cell voltage 1.55V, to produce 10 mA cm−2) and a solar‐driven electrolyzer (1 m KOH). [ABSTRACT FROM AUTHOR]

This paper presents the results of a severe accident parametric sensitivity study performed on a model of a generic integral pressurized water reactor (iPWR). The analyzed sequence is a loss of coolant accident (LOCA)-type scenario, postulating that safety systems are not available. In this work, a MELCOR 2.2 input deck of a generic iPWR was developed based on publicly available data. The iPWR used in this work is a generic iPWR with a thermal power of about 160 MWth, characterized by a compact steam generator and a submerged containment configuration. A hypothetical scenario considered in this work was an unmitigated small break LOCA leading to a severe accident with partial core degradation, due to the postulated assumptions. In the presented paper, 16 sensitivity cases were calculated and analyzed, focusing mainly on heat transfer, decay heat, and core degradation parameters. The selected parameters and their combination caused partial core degradation and showed significant differences in investigated variables such as core degradation and hydrogen generation, as well as examined CPU time consumption. This a preparatory work performed in the framework of the Horizon Euratom SASPAM-SA project, which aims to investigate the applicability and transfer of the operating large light-water reactor knowledge and know-how to the iPWR, taking into account European licensing analysis needs for the severe accident and emergency planning zone. [ABSTRACT FROM AUTHOR]

Summary: Pristine WSe2 based electrocatalyst shows poor reaction kinetics in electrochemical hydrogen evolution reaction due to a lack of active atomic sites and an inert basal plane. Herein, we report an active system of non‐metallic plasmonic WSe2/WO3−x, supported by highly conductive and eco‐friendly Ag/cellulose paper electrodes. An air thermal annealing technique is used to enrich the p‐WO3−x dopants in WSe2, which is significant for substantially improving electrocatalytic behaviour as well as photo responsive performance in the near‐infrared (NIR) region. The WSe2/WO3−x dramatically decreases the overpotential of HER from −330 to −150 mV (at 10 mA/cm2) owing to homo doping and generation of Se‐vacancies. Surface plasmons resonances of p‐WO3−x give the contributions to injection of photogenerated electrons and overpotential as low as −120 mV can be achieved under the illumination of NIR light. These results represent significant advances in light‐enhanced electrocatalysis and would provide potential applications for commercial hydrogen generation. Novelty Statement: Novel WSe2/WO3−X hybrid nanosheets‐based electrocatalysts exhibit the light‐enhanced hydrogen evolution reaction. WO3−X enriched WSe2 nanosheets exhibit rapid electrochemical charge transport due to p‐homodoping and Se‐vacancies. Overall, the 3D‐porous structure of cellulose paper and 2D‐ WSe2/WO3−X leads the promising optimisation. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on use of BaTaO 2 N as a photocathode (duly nanocomposited), and of CuO QDs as a source for nanocomposite formation. • Inexpensive carbon paper was used as an effective electrode substrate instead of an FTO plate. • Nanocomposite photocatalyst, BTN-CuO QD showed a photocurrent density of 3.1 mA cm−2 at 0 V vs RHE (∼83 % improvement from BTN CuO case). • BTN-CuO QD nanocomposites show a reduction in charge transfer resistance when compared to BTN-CuO samples. • The reported oxynitride-oxide nanocomposite is shown to be much more viable than the BTN CuO phase for water splitting (for HER). Barium tantalum oxynitride (BaTaO 2 N) has been demonstrated to be an attractive catalyst for photo-electrochemical water splitting, especially oxygen evolution reactions. However, the hydrogen production rates and charge transfer resistances of BTN leave much to be desired from a practical standpoint. In fact, it has never been reported for photocathode applications. On the other hand, CuO has been reported for hydrogen evolution reactions. Given this, here nanocomposites of BaTaO 2 N and copper oxide quantum dots (CuO QDs), where the latter are digestively ripened, are reported for photoelectrochemical water splitting on a carbon paper substrate. To assess the role of ultra-small quantum dots, composites of commercially available CuO nanoparticles with BaTaO 2 N were also tested. BaTaO 2 N and CuO QD nanocomposites performed well and showed a high photocurrent density of 3.1 mA cm−2 at 0 V vs RHE. This was also accompanied by reduced charge transfer resistance (225.4 Ω) due to the high interfacial surface area provided by nanoscopic CuO on BaTaO 2 N. [ABSTRACT FROM AUTHOR]

As new sources of energy and advanced technologies are used, there is a continuous evolution in energy supply, demand, and distribution. Advanced nuclear reactors and clean hydrogen have the opportunity to scale together and diversify the hydrogen production market away from fossil fuel-based production. Nevertheless, the technical uncertainties surrounding nuclear hydrogen processes necessitate thorough research and a solid development effort. This paper aims to position pink hydrogen for nuclear hydrogen production at the forefront of sustainable energy-related solutions by offering a comprehensive review of recent advancements in nuclear hydrogen production, covering both research endeavors and industrial applications. It delves into various pink hydrogen generation methodologies, elucidating their respective merits and challenges. Furthermore, this paper analyzes the evolving landscape of pink hydrogen in terms of its levelized cost by comparatively assessing different production pathways. By synthesizing insights from academic research and industrial practices, this paper provides valuable perspectives for stakeholders involved in shaping the future of nuclear hydrogen production. [ABSTRACT FROM AUTHOR]

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with graphene Co x Zn 1 - x S rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity of Co x Zn 1 - x S rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene and Co x Zn 1 - x S rGO NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. The Co 0.04 Zn 0.96 S rGO NSs sample had the highest photocatalytic activity, measured at 7648.9 μ mol h - 1 . A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons, Co x Zn 1 - x S rGO NSs increased the photocatalytic hydrogen generation activity. [ABSTRACT FROM AUTHOR]

Most renewable energy sources are intermittent and seasonal, making energy storage and consumption problematic. Hydrogen gas can save and convey chemical energy, making it a promising sustainable energy source. Electrochemical water electrolysis technology's sustainable and efficient hydrogen gas production attracts global attention. Higher hydrogen production rates enhance hydrogen volumetric energy capacity by storing intermittent hydrogen gas in high-pressure tanks. Pressurized storage tanks are cost-effective and efficient. Hydrogen gas may be stored economically and efficiently in pressurized tanks, making electrochemical water electrolysis a sustainable energy source. This paper introduced hydrogen as an alternative to natural gas, detailed water electrolysis technologies for hydrogen production, and highlighted how they can manufacture hydrogen efficiently and cost-effectively. The theoretical volume of gaseous hydrogen and oxygen that could be produced by electrolyzing water under typical temperature and pressure (STP) circumstances, assuming a 100% efficiency rate of the process. Since there are always two moles of hydrogen produced by electrolysis and one mole of gas occupies the same volume, the volume of hydrogen developed from water is twice that of oxygen. The volume of liberated oxygen is 0.21 (L/min), and the volume of liberated hydrogen is 0.42 (L/min) with a current density of 30 A, for instance, the tracer's diffusion coefficient for all conceivable flow rates. A maximum value of 90 liters per hour was determined to be the threshold at which the diffusion coefficient increased with increasing flow rate. It would appear that the diffusion coefficient remains unchanged at flow rates greater than 90 liters per hour. [ABSTRACT FROM AUTHOR]

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The global issue of climate change caused by humans and its inextricable linkage to our present and future energy demand presents the biggest challenge facing our globe. Hydrogen has been introduced as a new renewable energy resource. It is envisaged to be a crucial vector in the vast low-carbon transition to mitigate climate change, minimize oil reliance, reinforce energy security, solve the intermittency of renewable energy resources, and ameliorate energy performance in the transportation sector by using it in energy storage, energy generation, and transport sectors. Many technologies have been developed to generate hydrogen. The current paper presents a review of the current and developing technologies to produce hydrogen from fossil fuels and alternative resources like water and biomass. The results showed that reformation and gasification are the most mature and used technologies. However, the weaknesses of these technologies include high energy consumption and high carbon emissions. Thermochemical water splitting, biohydrogen, and photo-electrolysis are long-term and clean technologies, but they require more technical development and cost reduction to implement reformation technologies efficiently and on a large scale. A combination of water electrolysis with renewable energy resources is an ecofriendly method. Since hydrogen is viewed as a considerable game-changer for future fuels, this paper also highlights the challenges facing hydrogen generation. Moreover, an economic analysis of the technologies used to generate hydrogen is carried out in this study. [ABSTRACT FROM AUTHOR]

The design and development of efficient nitride photocatalysts have attracted much attention. Herein, two-dimensional mesoporous Ta 3 N 5 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 Ta 3 N 5 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 Ta 3 N 5 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 Ta 2 O 5 and partial nitridation of Ta 2 O 5 (N–Ta 2 O 5), 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. Two-dimensional mesoporous Ta 3 N 5 is synthesized by a simple sol-gel process with filter paper as a biological template and vacuum nitriding reaction, leading to an efficient photocatalytic performance. [Display omitted] • Two-dimensional mesoporous Ta 3 N 5 was prepared by a biological template. • The prepared Ta 3 N 5 shows a wide light response range up to the near infrared region. • The special two-dimensional structure shortens the charge transfer distance. • The Ta 3 N 5 photocatalyst shows a superior hydrogen production performance. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) of coal is a promising clean coal technology, which discards the traditional coal combustion and oxidation reaction to release carbon dioxide and other pollutants and replaces coal with a gasification reduction reaction in supercritical water to finally convert coal into a hydrogen-rich gas product with no net carbon dioxide emissions and no pollutant emissions, and thus has received much attention in recent years. However, the experimental conditions of coal to the hydrogen reactor are harsh, costly, and not easy to visualize and analyze, so numerical calculation and simulation analysis are important for the design, optimization, and industrial scaling-up of the reactor. In order to study the effect of the temperature field on the hydrogen production rate of the coal supercritical water gasification hydrogen production reactor, a numerical simulation calculation model is developed for this reactor in this paper. Comparing the experimental data in the literature, the maximum relative error of the gasification product yield per kg of coal between the two is less than 5%, which verifies the accuracy of the model built and the numerical method adopted in this paper. On this basis, the effects of supercritical water temperature and coal slurry temperature on the reactor's gasification products and reaction rate were investigated in depth. The results show that increasing the supercritical water temperature is beneficial to improve the reactor hydrogen production efficiency, while the high coal slurry temperature is not conducive to adequate reaction, thus reducing the hydrogen production efficiency. For the laboratory coal supercritical water gasification to hydrogen reactor studied in this paper, the ideal temperature of supercritical water is 850~900 K, and the ideal temperature of coal slurry is 400–450 K. The conclusions of this paper can provide some reference for subsequent industrial scale-up studies of the reactor. [ABSTRACT FROM AUTHOR]

Hydrogen has received widespread attention as a new clean energy in order to reduce the carbon emissions of fuel vehicles. This paper studies a tubular microreactor based on methanol steam reforming. Methanol and steam are mixed in proportion and the chemical reaction takes place in a porous catalytic bed. For heating purposes, hot gas from the burner penetrates the reactor bed through heating tubes. Energy is supplied through the heating tubes to drive the endothermic reaction system. The microreactor is enclosed in an insulated jacket. In this paper, parameters such as methanol conversion and hydrogen concentration are evaluated by considering microreactor materials, heating gas temperature and flow direction, heating tube distribution, pressure drop and reaction channel length. First of all, choosing a microreactor material with a smaller thermal conductivity can avoid excessive heat loss, and improve heat transfer performance. Increasing the heating gas temperature leads to an increase in the temperature of the reaction zone, thereby increasing the CH3OH conversion rate and H2 mass fraction. Changing the flow direction of the heating gas affects the reaction rate, but has little effect on the reaction result. Through the research on the distribution of the heating tubes, the results show that the hydrogen production rate is higher when the contact area between the heating tubes and the reaction zone is larger. Secondly, through the comparison of the data under different pressure drops, the best parameter P = 5 0 pa is obtained, and the CH3OH conversion rate is 80.6% at this time. Finally, increasing the length of the reaction channel can make the reaction more complete. For example, when the reaction channel length L = 0. 3 9 m, the CH3OH conversion rate is as high as 83.7%. [ABSTRACT FROM AUTHOR]

As an example of principally different type of catalytic support in the paper by Suboch and Podyacheva [[11]], bamboo-like nitrogen-doped carbon nanotubes (N-CNTs) were used to synthesize supported palladium catalysts (0.2-2 wt.%) for hydrogen production via gas phase formic acid decomposition. Similarly, high activity and stability were demonstrated in the formic acid decomposition by a single-atom Ni catalyst supported on N-doped porous carbon with active Ni-N SB 4 sb sites [[2]]. To solve problems related to global warming, environmental pollution, and green energy fields, a lot of research is now devoted to the catalysis of biofuels and biogas transformation into syngas and hydrogen. [Extracted from the article]

Nowadays, hydrogen is gaining attention as one of the green energy alternatives within transition to a zero-emission economy. Increasing demand for hydrogen and its production has prompted the development of low-carbon strategies and technologies for hydrogen generation from hydrocarbons. This paper provides a thorough analysis of traditional and innovative methods for hydrogen production from fossil feedstock, reviewing the critical aspects and recent advancements in the field. The paper emphasizes the potential of in situ hydrogen generation as the most promising method, taking into account CO2 emission concerns. Additionally, this study explores the use of software packages for modeling hydrogen production, outlining their advantages and disadvantages and proposing the most favorable software for in situ hydrogen generation from hydrocarbons. Subsequent analysis sheds light on the effectiveness, economic viability, environmental impact, and future perspectives of various hydrogen production technologies. • Overview of hydrogen production technologies: conventional and innovative methods. • Key issues and best practices of the latest experimental and numerical studies. • Comparative analysis of various hydrogen production technologies and approaches. • Subsurface hydrogen generation has a great development potential. • There are methods for clean hydrogen production from hydrocarbon feedstock. [ABSTRACT FROM AUTHOR]

The utilization of coal for hydrogen generation presents a multifaceted approach employing processes like coal gasification, pyrolysis, or high-temperature steam reforming. These methodologies entail reacting coal with steam or oxygen under elevated temperatures, yielding a gas mixture comprising hydrogen, carbon monoxide, and various byproducts. This paper delves into the exploration of hydrogen generation from coal, highlighting techniques such as gasification, pyrolysis, and other emerging methods. Notably, hydrogen discoveries within coal basins have garnered significant attention due to their implications for energy production and environmental sustainability. Certain coal basins harbor deposits rich in hydrogen, surpassing conventional coal reserves in their hydrogen content. These hydrogen-rich coals, including select sub-bituminous and lignite varieties, offer promising avenues for hydrogen production and utilization. However, the utilization of coal for hydrogen generation is not without its challenges. Technical hurdles, such as process efficiency and environmental concerns, demand rigorous investigation and innovative solutions. This paper addresses the challenges faced in coal-based hydrogen generation while elucidating the potential future prospects. It explores avenues for enhancing process efficiency, mitigating environmental impacts, and integrating coal-based hydrogen generation into broader energy strategies. Moreover, it underscores the importance of interdisciplinary research and collaboration in unlocking the full potential of coal for sustainable hydrogen production. [ABSTRACT FROM AUTHOR]

Copper-based catalysts are widely used in methanol steam reforming to produce hydrogen. In this paper, the supportive effect of the crystal phase of ZrO2 on Cu-based catalysts in methanol steam reforming is discussed. Monoclinic(m-), Tetragonal(t-) and mixed ZrO2 phases were prepared, and structure–activity relationships were investigated with XRD, H2-TPR, BET, HR-TEM and XPS. It was found that the catalyst with a 81.4% monoclinic ZrO2 crystal phase exhibited the highest methanol conversion (88.5%) and the highest hydrogen production rate (104.6 μmol/gcat·s) at 275 °C as it displayed the best reducing properties and more oxygen vacancies on the catalyst surface. Oxygen vacancies can produce more Cu1+ + Cu0, which is the active species for methanol steam reforming on the catalyst surface, and therefore affect catalytic activity. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds. [ABSTRACT FROM AUTHOR]

Owing to the massive expansion and intermittent nature of renewable power, green hydrogen production, storage, and transportation technologies with improved economic returns need to be developed. Moreover, the slowness of the dehydrogenation reaction is a primary barrier to the commercialization of liquid organic hydrogen carrier (LOHC) technology. The present study focused on increasing the speed of dehydrogenation, resulting in the proposal of a triple-loop dehydrogenation system comprising reaction, heating, and chilling loops. The reactor has a rotating cage containing a packed bed of catalyst pellets, which is designed to enhance both heat and mass transfer by helping to detach precipitated hydrogen bubbles from the catalyst surface. In addition, the centrifugal force aids in isolating the gas phase from the LOHC liquid. A dehydrogenation experiment was conducted using the reaction and chilling loops, which revealed that the average hydrogen production rate during the first hour was 52.6 LPM (liter per minute) from 26.3 L of perhydro-dibenzyl-toluene with 1.5 kg of 0.5 wt% Pt/Al2O3 catalyst. This was approximately 48% more than the value predicted with the reaction kinetics measured with a small-scale plug flow dehydrogenation reactor with less than 1.0 g of 5.0 wt% Pt/Al2O3 catalyst. The concept, construction methods, and results of the preliminary gas infiltration, flow visualization, and reactor pumping experiments are also described in this paper. [ABSTRACT FROM AUTHOR]

Offshore wind-hydrogen systems operate in harsh marine environments for extended periods, posing risks of low accessibility and high failure rates. This paper proposes a data-driven fault detection framework for offshore wind-hydrogen systems, aiming to promptly detect potential faults based on the system's physical parameters. The research establishes a comprehensive model based on the operating principles of offshore wind-hydrogen systems. The study uses fault injection techniques to simulate common partial faults in offshore wind-hydrogen systems and collects relevant physical parameters (such as wind turbine power generation, energy storage battery charging/discharging current, and electrolyzer hydrogen production rate). A fault detection model was constructed using a combination of Convolutional Neural Networks (CNN) and Bidirectional Long Short-Term Memory (BiLSTM) to enable precise detection of potential faults in the system. The established model provides theoretical support for designing, optimizing, and operating offshore wind-hydrogen systems, reducing reliance on actual experiments and lowering project risks and costs. Introducing artificial faults can evaluate the system's performance in different fault scenarios. This paper proposes a CNN-BiLSTM fault detection method that achieves automatic feature extraction and high-precision classification of time-series fault data, confirming the practicality and feasibility of offshore wind-hydrogen systems. This investigation realizes the integration of the offshore wind-hydrogen system model and deep learning, as well as a fully automated learning process from data to fault detection. By calculating and comparing results, it is verified that the framework has a high accuracy of 96.9%. This innovative research offers new methods and perspectives for enhancing the reliability and efficiency of fault detection in offshore wind-hydrogen systems. • A comprehensive multi-system simulation model for offshore wind-hydrogen systems is established. • Fault injection is employed to acquire data samples for offshore wind-hydrogen systems. • Utilizing the CNN-BiLSTM method, a high-accuracy deep learning fault detection model is crafted. • A simulation model-based data-driven deep learning framework for fault detection is devised in this study. [ABSTRACT FROM AUTHOR]

With the current trends of wind energy already playing a major part in the Scottish energy supply, the capacity of wind farms is predicted to grow exponentially and reach further depths offshore. However, a key challenge that presents itself is the integration of large producing assets into the current UK grid. One potential solution to this is green hydrogen production, which is being heavily researched in industry, with many concepts being investigated for large-scale purposes. However, the operations and maintenance (O&M) costs and availability of green hydrogen systems need to be quantified to ensure economical and technical viability, which is sparse in the available literature. The study presented in this paper investigated the availability and O&M costs of coupled wind–hydrogen systems by attempting to quantify the failure rates, repair times, repair costs and number of technicians required for key green hydrogen components. This study also utilised an O&M model created by the University of Strathclyde, which uses Monte Carlo Markov chain simulations to produce the O&M outputs. A number of assumptions were made throughout the study in relation to the O&M model inputs, and the baseline availability for the coupled wind–hydrogen system was 85.24%. Whilst the wind turbine still contributed a major part to the downtime seen in the simulations, the combined hydrogen system also contributed a significant amount, a total of 37%, which could have been due to the technology readiness levels of some the components included in the hydrogen system. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is a potential solution to meet energy needs with green and inexhaustible solar energy. However, designing efficient and stable photocatalysts is a challenging task due to the limited ability to effectively separate electrons and holes. In this paper, by using a straightforward ethanol dispersion technique, we were able to combine ultrathin layered Cu-TCPP MOFs with g-C3N4 nanosheets, resulting in the creation of an extremely effective nano-composite photocatalyst with exceptional UV-vis activity. CT/CN heterojunctions displayed remarkable photocatalytic efficacy for the production of H2, with 3CT/CN showcasing a five-fold enhancement in photoactivity as compared to the unadorned g-C3N4. Based on the results of photoluminescence spectroscopy, electrochemical impedance spectroscopy, and electrochemical reduction, the considerably improved charge transfer and separation, together with the possible catalytic capability of uniformly distributed metal nodes in Cu-TCPP, are believed to be the underlying reason for the observed exceptional photoactivity. After thorough analysis, a potential process for charge transfer and segregation between g-C3N4 and Cu-TCPP has been suggested. [ABSTRACT FROM AUTHOR]

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In this paper, the reported MOF ([Co(bimip)(H2O)0.5]·0.5H2O) was employed in photocatalytic CO2 reduction, antibacterial, and dye adsorption experiments. The photocatalytic activity of the MOF for CO2 reduction was systematically investigated. The high average CO generation rate of 3421.59 μmol·g−1·h−1 after 12 h confirms the efficient photocatalytic CO2 reduction ability of the MOF. At the same time, the MOF can completely inhibit the growth of S. aureus and C. albicans within 24 h when its concentration reaches 400 μg/mL and 500 μg/mL, respectively. The MOF has an adsorption capacity for CR. The adsorption rate was 83.42% at 60 min, and the adsorption capacity of the MOF for CR reached 500.00 mg·g−1. [ABSTRACT FROM AUTHOR]

Hydrogen is a relatively new source of sustainable energy resources; presently, its usage ranges from direct energy generation in mixed-cycle thermal power plants to its usage in the internal combustion engine. If the generation of hydrogen is coupled with renewable energy resources, the use of hydrocarbons can be substantially reduced in both energy generation and transportation. In this paper, we conducted a national-level assessment to identify the hydrogen generation capacity of Pakistan. The methodology used in this study is a combination of spatial multi-criteria analysis and density-based clustering in a geographical information systems environment. Based on the analysis, the national clusters capable of producing green hydrogen were identified. The results shows that the hydrogen generation capacity for Pakistan is approximately 7 million tons per year using solar photovoltaic energy. The Surab-Gwadar alignment, N-25 national highway, and Quetta-to-D-I-Khan alignment offer potential hydrogen generation sites with water resources. Most of the identified sites for the production of hydrogen in the country were found to be near the national electricity transmission networks. The Best-Worst Method was further employed to provide policymakers with a road map for prioritizing the development of these capacities based on their proximity to the national networks, their terrain suitability, and their generation capacities. • This paper assesses the suitable sites for solar-based green hydrogen production in Pakistan. • The methodology used involves a combination of spatial multicriteria analysis, clustering, and the best-worst method. • Pakistan's theoretical annual hydrogen generation capacity is around 7 million tons annually. • The Surab-Gwadar alignment presents promising hydrogen generation opportunities. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of hydrogen generation from hydrocarbon gases using Steam Methane Reforming (SMR) with byproduct CO2 injected into and stored in a partially depleted oil reservoir. It focuses on the reservoir aspects of the problem using numerical simulation of the processes. To this aim, a numerical model of a real oil reservoir was constructed and calibrated based on its 30-year production history. An algorithm was developed to quantify the CO2 amount from the SMR process as well as from the produced fluids, and optionally, from external sources. Multiple simulation forecasts were performed for oil and gas production from the reservoir, hydrogen generation, and concomitant injection of the byproduct CO2 back to the same reservoir. EOR from miscible oil displacement was found to occur in the reservoir. Various scenarios of the forecasts confirmed the effectiveness of the adopted strategy for the same source of hydrocarbons and CO2 sink. Detailed simulation results are discussed, and both the advantages and drawbacks of the proposed approach for blue hydrogen generation are concluded. In particular, the question of reservoir fluid balance was emphasized, and its consequences were presented. The presented technology, using CO2 from hydrogen production and other sources to increase oil production, also has a significant impact on the protection of the natural environment via the elimination of CO2 emission to the atmosphere with concomitant production of H2. [ABSTRACT FROM AUTHOR]

Microbial electrolysis cells (MECs) are emerging sustainable power generation technologies that can be used for biohydrogen production and wastewater treatment. The prospect for hydrogen gas as a vehicle fuel suitable for the environment is enormous. MEC serves as a reactor for producing biohydrogen by mixing MFC with electrolysis. MECs are the most sustainable, clean, and effective ways to produce biohydrogen. Effective aspects impacting H 2 production, including microbial culture, electrodes, membrane, and substrate, have been explored for greater comprehension of creating MEC technology-based hydrogen generation. The present issues with effective scale-up include the costly production expenses of microbial electrolysis cells, their significant internal resistance, methanogenesis, and membrane/cathode biofouling. This review examines the various operational parameters in optimization studies that influence overall hydrogen generation. This paper also presents strategies to overcome the constraints listed above by creating effective architecture, including several reactor designs, biological, and physical properties, and the use of various operational conditions for improved hydrogen production. This study summarizes recent developments and several other operating factors (organic loading, ionic strength, hydraulic retention time, applied voltage, etc.) that affect hydrogen production in an MEC system. The paper outlines the present technical difficulties and offers practical future ideas for addressing the constraints. [Display omitted] • MEC has great efficiency in hydrogen recovery and concurrent waste conversion. • Microbial culture, electrodes, membrane, and substrate affect H 2 production in MEC. • Scale-up constraints: high costs, internal resistance, methanogenesis, and biofouling. • Modifying strain, nanoparticles, and reactor design can help in overcoming this. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced by water electrolysis with renewable energy, plays a crucial role in the revolution towards energy sustainability, and it is considered a key source of clean energy and efficient storage. Its ability to address the intermittency of renewable sources and its potential to decarbonize sectors that are difficult to electrify make it a strategic component in climate change mitigation. By using a method based on a bibliometric review of scientific publications, this paper represents a significant contribution to the emerging field of research on green hydrogen and provides a detailed review of electrolyzer technologies, identifying key areas for future research and technology development. The results reflect the immaturity of a technology which advances with different technical advancements, waiting to find the optimal technical solution that allows for its massive implementation as a source of green hydrogen generation. According to the results found in this article, alkaline (ALK) and proton exchange membrane (PEM) electrolyzers seem to be the ones that interest the scientific community the most. Similarly, in terms of regional analysis, Europe is clearly committed to green hydrogen, in view of the analysis of its scientific results on materials and electrolyzer capacity forecasts for 2030. [ABSTRACT FROM AUTHOR]

The activation capacity of molecular oxygen is an important indicator to evaluate the photocatalytic efficiency of photocatalysts. In this paper, WS2 nanosheet was deposited on hyper-crosslinked CTF-1-G (obtained by molecular expansion from covalent triazine framework CTF-1) to form a C-GW heterojunction, which promoted the photodegradation of pollutants and the activation of molecular oxygen. This novel C-GW heterojunction exhibited excellent degradation property for organic pollutants (tetracycline (TC), rhodamine B (RhB)) and activating molecular oxygen under visible light irradiation. Among them, C-GW15 could degrade 98% of 20 ppm TC in 60 min and 99% of 30 ppm RhB in 30 min, and it had the highest hydrogen generation rate and hydrogen production amount in 4 hours, which were 8.74 mmol h−1 g−1 and 34.94 mmol g−1, respectively. Meanwhile, C-GW15 had the strongest 3,3′,5,5′-tetramethylbenzidine oxidation capacity and could generate 1.83 μmol of ˙O2− in 60 min and the production of H2O2 was 20.8 μmol L−1 in 40 min. The results of this study clearly indicated that the combination of WS2 and CTF-1-G can enhance the visible light absorption capacity and photogenerated carrier separation efficiency, thus promoting the photocatalytic performance. Finally, a Z-type photocatalytic mechanism was proposed based on radical capture, molecular oxygen activation experiments and electron spin resonance analysis. These findings will extend the fundamental understanding of the Z-type photocatalytic mechanism and provide new opportunities for the rational design of CTF heterojunctions for the treatment of environmental pollution and clean energy conversion. [ABSTRACT FROM AUTHOR]

In recent times, renewable energy systems (RESs) such as Photovoltaic (PV) and wind turbine (WT) are being employed to produce hydrogen. This paper aims to compare the efficiency and performance of PV and WT as sources of RESs to power polymer electrolyte membrane electrolyzer (PEMEL) under different conditions. The study assessed the input/output power of PV and WT, the efficiency of the MPPT controller, the calculation of the green hydrogen production rate, and the efficiency of each system separately. The study analyzed variable irradiance from 600 to 1000 W/m2 for a PV system and a fixed temperature of 25°C, while for the WT system, it considered variable wind speed from 10 to 14 m/s and zero fixed pitch angle. The study demonstrated that the applied controllers were effective, fast, low computational, and highly accurate. The obtained results showed that WT produces twice the PEMEL capacity, while the PV system is designed to be equal to the PEMEL capacity. The study serves as a reference for designing PV or WT to feed an electrolyzer. The MATLAB program validated the proposed configurations with their control schemes. [ABSTRACT FROM AUTHOR]

Nowadays, one of the most important areas in refining the energy sector in the developed countries is the transition to environmentally friendly technologies, and hydrogen energy production is the most promising of them. In this rapidly advancing area, significant progress in creating new technologies for hydrogen fuel generation, transportation, storage, and consumption has been recently observed, while a fast-growing number of research papers and implemented commercial projects related to hydrogen makes it necessary to give their general review. In particular, the combination of the latest achievements in this area is of particular interest with a view to analyzing the possibility of creating hydrogen fuel supply chains. This paper presents an analytical review of existing methods of hydrogen production, storage, and transportation, including their key economic and energy-related characteristics, and proposes an approach to the creation, analysis, and optimization of hydrogen supply chains. A mathematical model has been developed to determine the cost of hydrogen, taking into account the supply chain, including production, transport and storage. Based on the results of modeling in the given scenario conditions for 2030, 2040 and 2050, promising hydrogen supply chains have been established. Under the various scenario conditions, hydrogen production by 2050 is most preferable by the method of steam conversion of methane with a cost of 8.85 USD/kg H2. However, due to the environmental effect, electrolysis also remains a promising technology with a cost of hydrogen produced of 17.84 USD/kg. [ABSTRACT FROM AUTHOR]

This paper presents a systematic and comprehensive mathematical model for alkaline water electrolyzer cells, which can be used for simulation and analysis. The model accounts for factors such as gas evolution reactions, dissolution of gases in the electrolyte, bubble formation, and charge transport. It is based on a numerical two-phase model using the Euler-Euler approach, which has been validated against experimental data for various current densities. The study compares the impact of varying potassium hydroxide (KOH) concentration, separator porosity, and electrolyte flow rates on two-phase flow and bubble coverage. Therefore, the electrolyte in the cell consists of a solution of potassium hydroxide in water. The formation of gas bubbles at the electrodes decreases the electrolyte's ionic conductivity. Additionally, the presence of these bubbles on the electrode surfaces reduces the available surface area for electrochemical reactions, leading to an increase in the overpotential at a given current density. Furthermore, this paper demonstrates how a neural network and ensembled tree model can predict hydrogen production rates in an alkaline water electrolysis process. The trained neural network accurately predicted the hydrogen production rates, indicating the potential of using neural networks for optimization and control of alkaline water electrolysis processes. The model has an average R-squared value of 0.98, indicating a good fit to the data. A new method of describing bubble transfer, "bubble diffusion," is introduced to improve performance and reduce costs. The model is solved using COMSOL Multi physics 6.0. The machine learning models in this study were built, trained, and tested using MATLAB software R2020a. [ABSTRACT FROM AUTHOR]

The simultaneous production of hydrogen and biomass-based chemicals from biomass-derived feedstock aqueous solutions via photocatalysis is appealing because no additional sacrificial agent is needed. However, limited success has been achieved. This paper reports efficient nori-shaped carbon nitride-based photocatalysts with potassium/oxygen co-doping and cyano group introduction for efficient conversion of biomass-derived monosaccharides to produce lactic acid and hydrogen simultaneously. The obtained photocatalyst has an adjustable bandgap, fast migration/separation rate of photo-generated carriers and displays excellent photocatalytic performance with respect to xylose conversion (∼95.0%), lactic acid selectivity (90.5%) and hydrogen generation (∼33 380 μmol g−1 h−1) in the presence of visible light. The h+, ˙OH, ˙O2− and 1O2 drive xylose conversion and lactic acid production. For biomass-derived pentoses and hexoses, the reaction system also exhibits excellent photocatalytic activity of lactic acid selectivity and hydrogen generation; the reported photocatalyst has excellent reusability. This paper provides a new perspective for hydrogen generation and biorefineries via a photocatalyst. [ABSTRACT FROM AUTHOR]

Purpose: Elaboration of an indicator to include the dynamic aspect of citations in bibliometric indexes. Design/methodology/approach: A new bibliometric methodology—the f2-index—is applied at the career level and at the level of the recent 5 years to analyze the dynamic aspect of bibliometrics. The method is applied, as an illustration, to the field of corporate governance. Findings: The compound F2-index as an extension of the f2-index recognizes past achievements but also values new research work with potential. The method is extended to the h-index and the h2-index. An activity index is defined as the ratio between the recent h'-index to the career h-index. Research limitations: The compound F2 and H-indexes are PAC, probably approximately correct, and depend on the selection and database. Practical implications: The F2- and H compound indexes allow identifying the rising stars of a field from a dynamic perspective. The activity ratio highlights the contribution of younger researchers. Originality/value: The new methodology demonstrates the underestimated dynamic capacity of bibliometric research. [ABSTRACT FROM AUTHOR]

In this paper, NiCo2S4 was coated on the surface of WS2 of a 1T/2H mixed phase by a two-step hydrothermal method to form an in situ core–shell structure. The unique S-scheme heterojunction of the NiCo2S4@WS2 core–shell composite photocatalyst improved the easy recombination of carriers caused by the narrow band gap of NiCo2S4 and WS2, and improved the photocatalytic hydrogen production performance. The loading ratio of NiCo2S4@WS2, the addition of Eosin Y, and the pH value of TEOA were optimized. Under the optimal conditions, the hydrogen production rate reached 5.814 mmol g−1 h−1, which is about 8.55 times and 3.35 times the hydrogen evolution rates of NiCo2S4 and WS2, respectively. The composite catalyst exhibits excellent charge separation efficiency in photoelectrochemistry, PL and BET tests, carrier transport rate and large specific surface area that can provide more active sites, which are the main factors for the improvement of the hydrogen evolution performance. This paper demonstrates new design strategies to drive efficient photocatalytic hydrogen production by building in situ core–shell structures and optimizing the carrier transport paths, which will yield new insights. [ABSTRACT FROM AUTHOR]

It reviews the papers reporting on the use of rhodium nanocatalysts in hydrogen generation from the hydrolysis of ammonia borane in the following groups: (i) water soluble rhodium complexes, (ii) colloidal nanoparticles of rhodium, (iii) rhodium(0) nanoparticles supported on carbonaceous materials such as activated carbon, graphene, carbon nanotubes, (iv) the use of oxide supports for rhodium(0) nanoparticles, (v) the use of magnetic powders as support for rhodium(0) nanoparticles to make them magnetically recoverable. In each group, the reported results are evaluated by considering the increase in the catalytic activity (specifically measured in turnover frequency), the stability and durability, the lifetime (that is, how long the nanocatalyst can be used in releasing hydrogen gas from the hydrolysis of ammonia borane at appreciable rate), reusability (that is, how many times the catalyst can be isolated and reused for the same hydrolysis reaction generating hydrogen at acceptable rate). Overall, the work reported in each of the papers is evaluated in terms of contribution to the catalytic efficiency of rhodium nanocatalysts in hydrogen generation from the hydrolysis of ammonia borane at room temperature. At the end, conclusions and suggestions are given how to increase the overall catalytic efficacy of the precious rhodium nanocatalysts in hydrolytic dehydrogenation of ammonia borane. [Display omitted] • Using colloidal nanoparticles is an efficient way of increasing catalytic activity of rhodium catalysts. • Supporting the rhodium nanoparticles on materials with large surface area increases their stability. • Selecting a suitable oxide support can increase the catalytic efficiency of rhodium nanocatalysts. • Reusability of rhodium nanoparticles can be increased by using magnetic support. [ABSTRACT FROM AUTHOR]

The number of Fuel Cell Electric Vehicles (FCEVs) in circulation has undergone a significant increase in recent years. This trend is foreseen to be stronger in the near future. In correlation with the FCEVs market increase, the hydrogen delivery infrastructure must be developed. With this aim, many countries have announced ambitious projects. For example, Spain has the objective of increasing the number of Hydrogen Refuelling Stations (HRS) with public access from three units in operation currently to about 150 by 2030. HRSs are complex systems with high variability in terms of layout design, size of components, operational strategy, hydrogen generation method or hydrogen generation location. This paper is focused on on-site HRS with electrolysis-based hydrogen production, which provides interesting advantages when renewable energy is utilized compared to off-site hydrogen production despite their complexity. To optimize HRS design and operation, a simulation model must be implemented. This paper describes a generic on-site HRS with electrolysis-based hydrogen production, a cascaded multi-tank storage system with multiple compressors, renewable energy sources, and multiple types of dispensing formats. A modelling approach of the layout is presented and tested with real-based parameters of an HRS currently under development, which is capable of producing 11.34 kg/h of green H 2 with irradiation at 1000 W/m2. For the operation, an operational strategy is proposed. The modelled system is tested through several simulations. A sensitivity analysis of the effects of hydrogen demand and day-ahead hydrogen production objective on emissions, demand satisfaction and variable costs is performed. Simulation results show how the operational strategy has achieved service up to 310 FCEVs refuelling events of heavy duty and light duty FCEVs, bringing the total H 2 sold up to almost 7200 H2kg in one month of winter. Additionally, considering variable costs of the energy from the utility grid, the model shows a profit in the range of 21–50 k€ for a daily demand of 60 H2kg/day and 100 H2kg/day, respectively. In terms of emissions, a year simulation with 60 H2kg/day of demand shows specific emissions in the production of H 2 in Spain of 6.26 kgCO2eq/H2kg, which represents a greenhouse gas emission intensity of 52.26 gCO2eq/H2MJ. • Modelling approach of hydrogen refuelling station with on-site hydrogen production. • Operational strategy with day-ahead scheduled grid-connected hydrogen production. • Finite-state machine online control of a multi-tank and multi-compressor plant. • Sensitivity analysis of hydrogen demand magnitude and frequency. • A trade-off between demand satisfaction, profits and emissions. [ABSTRACT FROM AUTHOR]