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Although it suffers from a heavy dependence on the noble platinum catalyst, the electrochemical hydrogen evolution reaction (HER) is one of the most promising methods for the production of hydrogen. After numerous efforts, it is found that MoS2-based heterostructure may replace platinum as the electrochemical HER catalyst. In this work, the nanocrystalline NiSe2/MoS2 heterostructures were successfully prepared on the carbon fiber paper (CFP) substrate through electrochemical deposition and hydrothermal process. According to a series of electrochemical HER tests and a comparison with other MoS2-based heterostructure catalysts, the CFP/NiSe2/MoS2 catalyst with an overpotential η10 of 143 mV and a Tafel slope of 45 mV dec−1 exhibited an excellent electrochemical HER catalytic performance and durability. In addition, CFP/NiSe2/MoS2 catalyst was treated by plasma to further improve the catalytic performance of the catalyst. [ABSTRACT FROM AUTHOR]

The main objective of this study was to develop a system for the production of "renewable" hydrogen. Paper sludge is a solid industrial waste yielding mainly cellulose, which can be used, after hydrolysis, as a feedstock in anaerobic fermentation by (hyper)thermophilic organisms, such as Thermotoga elfii and Caldicellulosiruptor saccharolyticus. Tests on different medium compositions showed that both bacteria were able to produce hydrogen from paper sludge hydrolysate, but the amount of produced hydrogen and the requirement for other components differed. Hydrogen production by T. elfii strongly depended on the presence of yeast extract and salts. By contrast, C. saccharolyticus was less dependent on medium components but seemed to be inhibited by a component present in the sludge hydrolysate. Utilization of xylose was preferred over glucose by C. saccharolyticus. [ABSTRACT FROM AUTHOR]

Highlights: [•] Flexible and porous paper-like Ni/MgO catalysts were successfully fabricated. [•] Ni/MgO catalysts were dispersed on the inorganic fiber networks of paper composites. [•] Catalytic steam reforming of methane proceeded efficiently to produce hydrogen. [•] Paper catalysts exhibited much higher performance than conventional solid catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The present study focused on the mesophilic anaerobic bio-hydrogen production from PPS (pulp & paper sludge) and FW (food waste), and the subsequent anaerobic digestion of the effluent for the methane production under thermophilic conditions by a two-stage process. The maximum hydrogen yield of 64.48 mL g−1 VSfed and methane yield of 432.3 mL g−1 VSfed were obtained when PPS and FW were applied with 1: 1 VS ratio as the feedstock. No VFA were cumulated in the reactor during the period of hydrogen - methane fermentation, as well as no NH3–N and Na+ inhibition were found in the process. 71%–87% removal efficiencies of SCOD were attained for hydrogen and methane co-production. pH 4.8–6.4 and alkalinity 794–3316 mg CaCO3 L−1 for H2 fermentation, as well as pH 6.5–8.8 and alkalinity 4165–4679 mg CaCO3 L−1 for CH4 fermentation, were achieved without any adjustment. This work showed that anaerobic co-digestion of PPS and FW for hydrogen-methane co-production was a stable, reliable and effective way for energy recovery and bio-solid waste stabilization by the two-stage mesophilic–thermophilic process. [Copyright &y& Elsevier]

The development of dual-function catalysts with high activity and durability is essential in overall water splitting applications. In this work, FeCoNiPtRu HEA was rapidly synthesized on carbon support by carbothermal shock process. The synergistic interaction among metal elements enhanced the catalytic activity. The catalyst demonstrated overpotentials of 104 mV for HER and 331 mV for OER at 10 mA cm−2. In addition, FeCoNiPtRu HEA was aimed on carbon paper and the nanoparticles were encapsulated by a carbon layer with a stability of up to 100 h. Finally, as a dual-function catalyst, when applied as both the cathode and anode in overall water splitting (OWS), FeCoNiPtRu demonstrated a voltage of 1.69 V at 10 mA cm−2. This work demonstrates the significant potential of high-entropy alloy catalysts in hydrogen production through overall water splitting. • FeCoNiPtRu bifunctional catalyst was synthesized on carbon paper using the carbothermal shock method. • The synergistic effect of the high-entropy alloy improved and optimized the electrochemical performance of the catalyst. • The stability and oxidation resistance of the catalyst were promoted by aiming the high-entropy alloy on the carbon paper. • It represented excellent catalytic activity in the overall water splitting (η 10 =1.69 V). [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Green Chemistry," published by The Royal Society of Chemistry. It highlights the articles and research papers included in the issue, covering topics such as sustainable water treatment, lignocellulose pretreatment, and biomass valorization. The journal aims to promote cutting-edge research for a greener and more sustainable future. [Extracted from the article]

Abstract: The effect of lime mud from paper-making process (LMP) addition on the H2 fermentation of food waste (FW) was investigated. It was found that a slight addition of LMP (1.0–4.0 g in 200 g FW) significantly enhanced the H2 fermentation performance, not only increasing the total amount of H2 produced but also accelerating the whole reaction, shortening the lag period, and increasing the H2 production rate. Fermentation stability and microbial germination were also facilitated by LMP addition. This was attributed to the existence of Ca, Fe, Mn and alkaline substances such as CaCO3 and NaOH. The batch process treating a mixture of FW and LMP was showed that the highest hydrogen production of 137.6 mL H2/g VS was achieved at final pH 5.0, adding 3 g LMP (in 200 g FW) to the fermentation process, which lag-phase time was about 2.5 h. [Copyright &y& Elsevier]

Microfluidic electrolyzers have been fabricated using graphite coated paper electrodes to electrolyze sea water into oxygen (O 2) and hydrogen (H 2) when integrated with a photovoltaic (PV) cell. The 'open' electrolyzer (OME) consists of a microchannel confined by a pair of graphite electrodes, which is drawn with the help of pencil tips. A sea water microdroplet has been dispensed at the junction of the electrodes while the PV cell is integrated to the electrodes to supply current. The microscale width of channel generates a high intensity electric field even at a lower potential, which facilitates the microdroplets to electrolyze into H 2 and O 2 near the cathode and anode. The rate of production of the gases increased with field intensity. In the 'close' electrolyzer (CME), the paper decorated with graphite electrodes is covered with a substrate embedded with polymeric microchannels. The microcapillaries are placed closer to the anode and cathode for in situ separation of H 2 and O 2. The economic, flexible, and metal-free micro-electrolyzer facilitates the water-splitting at a much lower applied voltage at an efficiency of 1–2%. Use of multiple separation channels in CME for production and separation of H 2 and O 2 shows the potential for micro-very-large-scale-integration (μ-VLSI). Paper based microfluidic reactor for production and separation of H 2 an O 2 gases. [Display omitted] • Development of a paper-based electrodes coated with graphite or RGO. • Electrolysis of sea water on the paper based microelectrolyzer. • Development of paper microelectrolyzer integrated with graphite/RGO electrode for electrolysis. • Integration of the solar panel to generate high intensity electric field for water splitting. • Synthesis and separation of hydrogen and oxygen in the OME and CME. [ABSTRACT FROM AUTHOR]

Photosystem I/dithiol molecular wire/nanoparticle bioconjugates have been shown to photocatalytically generate dihydrogen at linear rates when continuously illuminated. In an effort to maximize H2production, the pH and ionic concentration of the solution, the mobility of the electron donor, the length and degree of saturation of the molecular wire, and the intensity of the light were systematically investigated. Optimal conditions included a solution buffered at pH 6.0, cross-linked plastocyanin, rebuilt spinach PS I, and the use of 1,4-benzenedithiol to connect PS I to the Pt nanoparticle. Illumination of this optimized Photosystem I/dithiol molecular wire/nanoparticle bioconjugate at a light intensity of 70 μE m−2s−1generated a measured one time H2production rate of 312 μmol H2mg Chl−1h−1. [ABSTRACT FROM AUTHOR]

SOEC (Solid Oxide Electrolysis Cell) require high temperature steam, but generating steam with electricity is very energy intensive. Concentrated solar power can be a good substitute for electricity to generate high temperature steam. In this paper, the thermal performance of a solar steam generator is researched. The steam generator improves the heat transfer capacity by installing porous ceramic material inside and using spray cooling technique. Due to the limited heat transfer capacity of previous steam generators, other types of steam generators can only produce steam with a temperature below 700°C. The steam generator in this paper has a high thermal efficiency depending on the nozzle characteristics. Therefore, the steam generator has obvious advantages in terms of generating high-temperature steam. The experimental results show that the instantaneous thermal efficiency of the steam generator with a new nozzle can reach a maximum of 58% when the solar irradiation power is 2.26 kW and the inlet water flow rate is 1.23 kg/h. At this time, the steam generator can produce high temperature water vapour at a maximum temperature of 715.4°C. The optimized solar steam generator was also coupled with the SOEC system, and hydrogen production was successfully achieved by experimental means. The solar SOEC system has great potential for hydrogen production. [ABSTRACT FROM AUTHOR]

A highly crystalline ordered Cu-TiO2 nanostructure was synthesized using a simple paper template method using cupric nitrate and titanium isopropoxide as precursors. The structural study by XRD confirmed the formation of highly crystalline anatase phase of Cu-TiO2. The broad diffraction peaks of Cu-TiO2 exhibit the nanocrystalline nature of the product. The optical study by UV-DRS indicated the red shift in absorption wavelength with an increase in Cu doping, i.e., towards the visible region. The FE-SEM and FE-TEM study validated the formation of spherical shaped nanoparticles of Cu-TiO2 having sizes in the range of 20–30 nm. Considering the absorption in the visible region, the photocatalytic study was performed for water splitting and rhodamine-B (RhB) dye degradation under natural sunlight. The 2% Cu-doped TiO2 showed the highest photocatalytic hydrogen evolution, i.e., 1400 µmol·g−1·h−1 from water, among the prepared compositions. The photocatalytic performance of Cu-TiO2 conferred complete degradation of RhB dye within 40 min. The higher activity in both cases was attributed to the formation of highly crystalline ordered nanostructure of Cu-doped TiO2. This synthesis approach has potential to prepare other highly crystalline ordered nanostructured semiconductors for different applications. [ABSTRACT FROM AUTHOR]

• A bifunctional catalyst is synthesized by one-step thermal exfoliation. • The best catalyst shows overpotential of 254 mV at 10 mA/cm2 in alkaline seawater. • It exhibits excellent selectivity towards OER over hypochlorite formation. • The seawater electrolyzer shows a stability of 210 h at 20 mA/cm2. • A zero-gap electrolyzer is fabricated and performance is demonstrated. Developing bifunctional, non-precious catalysts for seawater electrolysis is pivotal yet remains challenging due to sluggish oxygen and hydrogen evolution reactions (OER and HER) and chlorine corrosion. Herein, Ni-NiFe 2 O 4 /rGO (NFO1/erGO) obtained by a one-step exfoliation is reported as a bifunctional catalyst for seawater electrolysis. The NFO1/erGO (85.3 % NiFe 2 O 4 , 14.7 % Ni) exhibits outstanding OER and HER activities in seawater. The NFO1/erGO/Carbon paper(CP)||NFO1/erGO/CP electrolyzer demonstrates low overall seawater splitting voltages of 1.74 V and 1.98 V to achieve 10 mA/cm2 and 100 mA/cm2, respectively. Electronic charge modulation across the metal centres, enhanced conductivity, optimum binding strength of reaction intermediates, and corrosion resistance ensure excellent stability and electrocatalytic activity. Interestingly, NFO1/erGO maintains its original phase even after seawater electrolysis, suggesting its exceptional structural durability. Finally, a membrane-less zero-gap seawater electrolyzer is fabricated, demonstrating an H 2 production rate of 0.36 L/h. These observations boost the practical realization of seawater electrolyzers based on non-precious catalysts. [ABSTRACT FROM AUTHOR]

The article states that Scientists for Future, an organization that consists of German-speaking scientists who focus on climate change issues, has published a policy paper warning that the use of hydrogen may not be advisable for several reasons. It mentions that directly applying electricity is recommended for replacing natural gas and crude oil in many cases due to the high cost and inefficiency of green hydrogen production.

Cu nanoparticles (CuNPs) were successfully synthesized in situon ZnO whiskers as a selective scaffold, which were supported in a microstructured paper matrix composed of inorganic fibers; as-prepared paper composites were easy to handle in practical use and demonstrated excellent catalytic performance in the methanol reforming process for effective hydrogen production. [ABSTRACT FROM AUTHOR]

The effect of the crystalline phase of TiO2(anatase, rutile and brookite) on its photocatalytic activity in hydrogen production from methanol–water vapours has been investigated by testing a series of both home-made and commercial TiO2photocatalysts, either bare or surface-modified by deposition of a fixed amount, i.e.1 wt%, of platinum as co-catalyst. For all of the TiO2samples the rate of hydrogen production increased by one order of magnitude upon Pt deposition, because of the ability of Pt to enhance the separation of photoproduced electron–hole pairs. Under irradiation in the 350–450 nm wavelength range, brookite and anatase showed similar photoactivities, both superior to that of rutile. By contrast, rutile, possessing a narrower band gap, was active also under visible light (λ> 400 nm), whereas no hydrogen evolution was observed with anatase and brookite under such conditions. Surface area proved to be a key parameter, strongly influencing photoactivity. However, as the particle size became ultra-small, the semiconductor absorption edge was blue-shifted because of size quantisation effects, with a consequent decrease in hydrogen production rate due to the smaller portion of incident photons absorbed by the photocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: Plating bath concentrations of Pt(IV) and Ir(III) have been optimized as well as the total catalytic loading of bimetallic Pt–Ir alloy for the electro-oxidation of ammonia in alkaline media at standard conditions. This was accomplished using cyclic voltammetry, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and statistical optimization tools. Concentrations of Pt(IV) and Ir(III) of the plating bath strongly influence electrode surface atomic compositions of the Pt–Ir alloy directly affecting the electro-oxidation behavior of ammonia. Several anode materials were studied using cyclic voltammetry, which demonstrated that Pt–Ir was the most active catalyst for the electro-oxidation of ammonia. Criteria for optimization were minimizing the climatic oxidation overpotential for ammonia and maximizing the exchange current density. Optimized bath composition was found to be 8.844±0.001gL−1 Pt(IV) and 4.112±0.001gL−1 Ir(III) based on electrochemical techniques. Physical characterization of the electrodes by SEM indicates that the plating bath concentrations of Pt and Ir influence the growth and deposition behavior of the alloy. [Copyright &y& Elsevier]

Titanium dioxide was modified with Pt–polypyrrole nanocomposites through the in situsimultaneous reduction of Pt(iv) and the oxidative polymerization of pyrrole monomers at ambient temperature. The modified powders were characterized using X-ray photoelectron spectroscopy (XPS), dark-field scanning transmission electron microscopy (DF-STEM), infrared spectroscopy (IR) and by the determination of the BET surface area by nitrogen adsorption. Photocatalytic hydrogen production tests were performed employing 75 ml aqueous solution containing 2250 μmol methanol as the sacrificial electron donor. The obtained results show that 0.5 and 1.0 wt% Pt and polypyrrole, respectively, are the optimum ratios for high photocatalytic H2production rates. The amount of H2evolved during 5 h of UV-vis illumination of the suspension of Pt–polypyrrole modified TiO2powder is three times higher than that obtained with Pt-loaded TiO2prepared by a photochemical deposition method. The photonic efficiencies of the H2production employing 75 ml aqueous solution containing 370 mmol methanol were calculated to be 10.6 ± 0.5 and 4.5 ± 0.2% for TiO2modified with Pt–polypyrrole nanocomposites and for Pt-loaded TiO2prepared by a photochemical deposition method, respectively. A synergistic effect between Pt nanoparticles and polypyrrole leading to a better separation of the charge carriers is proposed to explain the enhanced reactivity of the newly synthesized photocatalyst. [ABSTRACT FROM AUTHOR]

Titania nanocrystalline films have been deposited on glass slides and loaded with Pt nanoparticles by adsorption from aqueous solutions of sodium tetrachloroplatinate followed by UVA radiation or heat treatment. These metal/semiconductor combined photocatalysts have been used for photooxidation of aqueous ethanol and production of hydrogen. The efficiency of the photocatalytic process was associated with the metal load on the titania films and the size of the metal nanoparticles. Characterization of the combined photocatalyst has been made by X-ray photoelectron spectroscopy and transmission electron microscopy. [ABSTRACT FROM AUTHOR]

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In this paper, a NiAl-LDH with the characteristic structure of a hydrotalc-like compound was applied as a carrier in a two-step hydrothermal process, and a MnCdS/In2S3/NiAl-LDH composite material was successfully prepared by loading MnCdS and In2S3 on the flower spherical-like surface of NiAl-LDH. The combination of NiAl-LDH with In2S3 and MnCdS made the band gap smaller and the light absorption range larger, thus increasing the utilization rate of light. 50% MnCdS/In2S3/NiAl-LDH composites had the best photoinduced charge separation and highest surface enrichment of photogenerated electrons. In the degradation experiment of crystal violet (CV), 50% MnCdS/In2S3/NiAl-LDH composites showed superior photocatalytic degradation efficiency (>98.5%) under full spectrum light. Furthermore, the applicability and universality of photocatalysts were studied by observing the degradation of CV by MnCdS/In2S3/NiAl-LDH composites under different conditions. In addition, the composites showed excellent hydrogen production capacity in the photolysis of water, in which hydrogen production within 8 hours was about 7661.51 μmol g−1. By combining the results of active species capture experiments, density functional theory (DFT) calculations and photoelectrochemical experiments, the possible mechanism of double S-scheme heterojunction photocatalysis among NiAl-LDH, In2S3 and MnCdS was inferred, which is one of the main reasons for the enhancement of photocatalytic activity. [ABSTRACT FROM AUTHOR]

This paper navigates the critical role of hydrogen in catalyzing a sustainable energy transformation. This review delves into hydrogen production methodologies, spotlighting green and blue hydrogen as pivotal for future energy systems because of their potential to significantly reduce greenhouse gas emissions. Through a comprehensive literature review and a bibliometric analysis, this study underscores the importance of technological advancements, policy support, and market incentives in promoting hydrogen as a key energy vector. It also explores the necessity of expanding renewable energy sources and international cooperation to secure a sustainable, low-carbon future. The analysis highlights the importance of scalable and cost-effective hydrogen production methods, such as solar-thermochemical and photo-electrochemical processes, and addresses the challenges posed by resource availability and geopolitical factors in establishing a hydrogen economy. This paper serves as a guide for policy and innovation toward achieving global sustainability goals, illustrating the essential role of hydrogen in the energy transition. [ABSTRACT FROM AUTHOR]

A holistic approach to decision-making in modern energy systems is vital due to their increase in complexity and interconnectedness. However, decision makers often rely on narrowly-focused strategies, such as economic assessments, for energy system strategy selection. The approach in this paper helps considers various factors such as economic viability, technological feasibility, environmental impact, and social acceptance. By integrating these diverse elements, decision makers can identify more economically feasible, sustainable, and resilient energy strategies. While existing focused approaches are valuable since they provide clear metrics of a potential solution (e.g., an economic measure of profitability), they do not offer the much needed system-as-a-whole understanding. This lack of understanding often leads to selecting suboptimal or unfeasible solutions, which is often discovered much later in the process when a change may not be possible. This paper presents a novel evaluation framework to support holistic decision-making in energy systems. The framework is based on a systems thinking approach, applied through systems engineering principles and model-based systems engineering tools, coupled with a multicriteria decision analysis approach. The systems engineering approach guides the development of feasible solutions for novel energy systems, and the multicriteria decision analysis is used for a systematic evaluation of available strategies and objective selection of the best solution. The proposed framework enables holistic, multidisciplinary, and objective evaluations of solutions and strategies for energy systems, clearly demonstrates the pros and cons of available options, and supports knowledge collection and retention to be used for a different scenario or context. The framework is demonstrated in case study evaluation solutions for a novel energy system of clean hydrogen generation. [ABSTRACT FROM AUTHOR]

With the rapid development of hydrogen production by water electrolysis, the coupling between the electricity-hydrogen system has become closer, providing an effective way to consume surplus new energy generation. As a form of centralized management of distributed energy resources, virtual power plants can aggregate the integrated energy production and consumption segments in a certain region and participate in electricity market transactions as a single entity to enhance overall revenue. Based on this, this paper proposes an optimal scheduling model of an electricity-hydrogen coupling virtual power plant (EHC-VPP) considering hydrogen load response, relying on hydrogen to ammonia as a flexibly adjustable load-side resource in the EHC-VPP to enable the VPP to participate in the day-ahead energy market to maximize benefits. In addition, this paper also considers the impact of the carbon emission penalty to practice the green development concept of energy saving and emission reduction. To validate the economy of the proposed optimization scheduling method in this paper, the optimization scheduling results under three different operation scenarios are compared and analyzed. The results show that considering the hydrogen load response and fully exploiting the flexibility resources of the EHC-VPP can further reduce the system operating cost and improve the overall operating efficiency. [ABSTRACT FROM AUTHOR]

Why Hydrogen. Nowadays, the energy industry and research laboratories are heavily working on developing ideas and methods to reduce and/or eliminate the carbon dioxide emission to control the problem of global warming. The solution relies on finding alternative green energy resources to reduce the world's dependence on conventional fossil hydrocarbon energy. Green hydrogen gas from water stands on the top of the alternative resources since it does not produce carbon dioxide when burned and in return does not add to global warming. Since seawater is the largest resource on earth, this makes the hydrogen production from seawater the most economically attractive solution. It is very important to avoid using fresh water as a source of hydrogen energy due to the dependence of all living creatures, humans, animals, plants, etc., on such very limited resources. In this paper, the applications of the proposed novel solution of green hydrogen production directly from seawater relies on solving one of the major problems, electrode corrosion. Generating Hydrogen. The direct method to produce green hydrogen from seawater is the electrolysis technique. This technique requires a direct current power supply for the positive and the negative electrodes. The outcome of the electrolysis is decomposing the saltwater to its positively charged hydrogen and sodium ions at the negative electrode and its negatively charged oxygen and chlorine ions at the positive electrode. The Real Challenge. Traditionally in the electrolysis analysis of water, both electrodes are made of metals. At the positive electrode, both the oxygen and the chlorine cause a high rate of corrosion to that electrode. This results in the interruption of the electrolysis process, bad water condition due to the corrosion deposits, and cost burden due to the need to periodically replace the corroded electrodes and/or use high-cost corrosion-resistant alloys. The Novel Solution. A low-cost but powerful solution to the corrosion problem is introduced, tested, and experimentally proved. The novelty of the solution relies on replacing the classic special high-cost metallic positive electrode with a nonmetallic, no-cost, one. The nonmetallic electrode is made of surface rock portions that have high porosity and pore volume and high permeability and pore connectivity and is saturated with saline water. Surface rocks with the above properties exhibit very low resistivity and hence conduct electricity like metallic electrodes. The voltage and the current conducted by such electrode are controlled by the electrode geometry, connectivity, and physical properties. Results and Discussions. Multiple experiments using the proposed nonmetallic high-porosity and high-permeability positive electrode are conducted and presented in this paper. The experimental work is based on testing multiple rock electrodes with different rock properties, sizes, and connectivity in comparison to the metallic ones. The comparison showed that the novel solution solved the corrosion challenges of the metallic electrodes with excellent efficiency. [ABSTRACT FROM AUTHOR]

In this study, we hypothesized that anaerobic biodegradation of cellulose is influenced by cellulose type and concentration, temperature, and their interactions. Cellulose biodegradation by an anaerobic consortium was tested in thermophilic batch experiments that combined cellulase action, hydrolysis, and fermentation. Initially, the main constituents in the inocula were Thermoanaerobacter , Clostridium , and Acetivibrio spp. Four types of cellulose and a range of concentrations were used as feedstock with pathways involving hydrolysis and glycolysis to produce H 2 , CO 2 , acetate, and ethanol. Long fibrous cellulose, two types of microcrystalline cellulose, and filter paper squares were tested at several concentrations between 2 and 20 g/l as substrates. The yields ranged between 0.1 and 2.9 mmol H 2 and 0.7–2.6 mmol ethanol per g cellulose. The rates ranged between 0.01 and 0.2 mmol H 2 , 0.03–0.2 mmol CO 2 , and 0.01–0.05 mmol ethanol per g cellulose·h. Statistical analyses indicated that the rates and yields of metabolite production were influenced by two-way interactions between the temperature, type, and concentration of cellulose. The results suggest that two-way interactions between experimental variables may impact the outcomes in cellulose bioconversion studies. • Fermentative biodegradation of four cellulose types was tested at 50, 55 and 60 °C. • The cellulose types comprised long and short fibers and filter paper squares. • Thermoanaerobacter , Clostridium , and Acetivibrio were dominant in the consortium. • Yields and rates were measured for H 2 , CO 2 , ethanol and acetate formation. • Temperature and cellulose type and concentration were two-way interactive variables. [ABSTRACT FROM AUTHOR]

Abstract: The present study aimed to investigate the biotransformation of different kinds of wastepaper to hydrogen by the fibrotylic bacterium Ruminococcus albus. Five different types i.e. paper tissue, office paper, illustrated magazine paper, paperboard and newspaper, were selected as representatives of the most common types of wastepaper found in municipal solid wastes. The percentage of total carbohydrates measured as glucose equivalents, ranged from 50% to 100% (w/w), whereas the bioconversion by R. albus ranged from 18% to 100% of their initial weigh. The only metabolic products detected in all cases were acetate, ethanol, formate, hydrogen and carbon dioxide. The hydrogen yields ranged from 46 to 280L H2/kg paper, indicating that wastepaper could be a promising candidate for second generation biohydrogen production. Subsequently, hydrolysis was investigated for paper tissue and paperboard. It was shown that in both cases the degradation process could be satisfactory described by zero order kinetics and it was identified to be the rate limiting step for the whole process, controlling biomass growth and metabolites generation rate. [Copyright &y& Elsevier]

Supercritical water gasification is a clean technology for biomass conversion and utilization. In supercritical water gasification systems, H2O is often used as the transport medium. Decreases in the reaction temperature at the gasification area and in the heating rate of biomass may limit the gasification rate and efficiency. In this paper, CO2 is used as the transport medium due to its relatively low critical point and specific heat capacity. Moreover, a corn stalk gasification system with different transport media is established in this paper, and the influences of various operating parameters, such as temperature, pressure and feedstock concentration, are investigated. The results show that the gas yield in the CO2-transport system decreases by no more than 5 wt %. In addition, thermodynamic analysis reveals that a system with CO2 as transport medium consumes approximately 25% less electricity than a system with H2O as the transport medium. In addition, the reaction heat absorption decreases. The results show the superiority of CO2 to H2O as a transport medium. [ABSTRACT FROM AUTHOR]

• The loading of CNT into acid-treated carbon papers enhances the 2e-transfer process. • The Faradaic efficiency for H 2 O 2 production using CNT/a-CP cathodes is ˜100. • The Faradaic efficiency for As(III) oxidation using h-TNR photoanodes is >80%. • The h-TNR and CNT/a-CP pair drives the As(III) oxidation and H 2 O 2 production. We present an off-grid, standalone electrocatalytic H 2 O 2 production reaction (HPR) using carbon nanotubes (CNT) wired to hydrogen-treated TiO 2 nanorod (h-TNR) arrays catalyzing the oxidation of As(III) to As(V) under simulated solar light (AM 1.5; 100 mW cm−2). Loading CNT onto acid-treated carbon paper (a-CP) significantly enhances the catalytic 2-electron transfer to O 2 , leading to a Faradaic efficiency (FE) of ∼100% for the HPR. To drive the HPR, the 2-electron oxidation of toxic As(III) to less toxic As(V) that accompanies the production of the proton/electron couples is achieved at an FE of >80% using the h-TNR arrays. The high FEs of the anodic and cathodic reactions are maintained over 10 h when a direct-current voltage of 0.7 V is applied to the h-TNR photoanode and CNT/a-CP cathode pair. The coupling of a mono-Si photovoltaic array that is one-tenth the size of h-TNR photoanode to the pair of h-TNR and CNT/a-CP successfully drives the standalone operation of both reactions at the high FEs (>90%). The surface characterization of the as-synthesized materials and the reaction mechanism are discussed in detail. [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]

China has a huge potential for biomass utilization. Converting low-grade biomass into high-quality hydrogen and natural gas is of great significance in promoting the utilization of biomass resources and the achievement of carbon reduction goals. Based on the data of biomass collection, transportation, power generation, hydrogen production and gas production stages in China, this paper constructs a multi-chain hybrid whole-life process evaluation model for "electricity to gas" and comprehensively compares the energy consumption, carbon emission and cost of the two chains of "hydrogen production from biomass power generation" and "methane production from biomass power generation". We comprehensively compare the energy consumption, carbon emissions and costs of biomass-to-hydrogen and biomass-to-methane technologies. Biomass natural gas is found to have significant advantages in terms of energy consumption, carbon emissions and economics compared to biomass hydrogen production. In order to promote the development of the biomass "electricity to gas" industry in China, this paper proposes that PEM electrolysis tanks can be used for hydrogen production, and the distance from the biomass feedstock collection to the hydrogen production chemical park should be optimized to reduce the whole-life-cycle cost. Biomass natural gas can buy time for the development of China's hydrogen industry and infrastructure construction. [ABSTRACT FROM AUTHOR]

In light of growing concerns regarding greenhouse gas emissions and the increasingly severe impacts of climate change, the global situation demands immediate action to transition towards sustainable energy solutions. In this sense, hydrogen could play a fundamental role in the energy transition, offering a potential clean and versatile energy carrier. This paper reviews the recent results of Life Cycle Assessment studies of different hydrogen production pathways, which are trying to define the routes that can guarantee the least environmental burdens. Steam methane reforming was considered as the benchmark for Global Warming Potential, with an average emission of 11 kgCO2eq/kgH2. Hydrogen produced from water electrolysis powered by renewable energy (green H2) or nuclear energy (pink H2) showed the average lowest impacts, with mean values of 2.02 kgCO2eq/kgH2 and 0.41 kgCO2eq/kgH2, respectively. The use of grid electricity to power the electrolyzer (yellow H2) raised the mean carbon footprint up to 17.2 kgCO2eq/kgH2, with a peak of 41.4 kgCO2eq/kgH2 in the case of countries with low renewable energy production. Waste pyrolysis and/or gasification presented average emissions three times higher than steam methane reforming, while the recourse to residual biomass and biowaste significantly lowered greenhouse gas emissions. The acidification potential presents comparable results for all the technologies studied, except for biomass gasification which showed significantly higher and more scattered values. Regarding the abiotic depletion potential (mineral), the main issue is the lack of an established recycling strategy, especially for electrolysis technologies that hamper the inclusion of the End of Life stage in LCA computation. Whenever data were available, hotspots for each hydrogen production process were identified. [ABSTRACT FROM AUTHOR]

The green transition in the sustainable production and processing of polymers poses multifaceted challenges that demand integral comprehensive solutions. Specific problems of presences of toxic trace elements are often missed and this prevents shifting towards eco-friendly alternatives. Therefore, substantial research and the development of novel approaches is needed to discover and implement innovative, sustainable production materials and methods. This paper is focused on the most vital problems of the green transition from the aspect of establishing universally accepted criteria for the characterization and classification of eco-friendly polymers, which is essential to ensuring transparency and trust among consumers. Additionally, the recycling infrastructure needs substantial improvement to manage the end-of-life stage of polymer products effectively. Moreover, the lack of standardized regulations and certifications for sustainable polymers adds to the complexity of this problem. In this paper we propose solutions from the aspect of standardization protocols for the characterization of polymers foreseen as materials that should be used in Zero Energy Innovations in Hydrogen Storage. The role model standards originate from eco-labeling procedures for materials that come into direct or prolonged contact with human skin, and that are monitored by different methods and testing procedures. In conclusion, the challenges of transitioning to green practices in polymer production and processing demands a concerted effort from experts in the field which need to emphasize the problems of the analysis of toxic ultra trace and trace impurities in samples that will be used in hydrogen storage, as trace impurities may cause terrific obstacles due to their decreasing the safety of materials. Overcoming these obstacles requires the development and application of current state-of-the-art methodologies for monitoring the quality of polymers during their recycling, processing, and using, as well as the development of other technological innovations, financial initiatives, and a collective commitment to fostering a sustainable and environmentally responsible future for the polymer industry and innovations in the field of zero energy applications. [ABSTRACT FROM AUTHOR]

The technique of producing hydrogen by utilizing green and renewable energy sources is called green hydrogen production. Therefore, by implementing this technique, hydrogen will become a sustainable and clean energy source by lowering greenhouse gas emissions and reducing our reliance on fossil fuels. The key benefit of producing green hydrogen by utilizing green energy is that no harmful pollutants or greenhouse gases are directly released throughout the process. Hence, to guarantee all of the environmental advantages, it is crucial to consider the entire hydrogen supply chain, involving storage, transportation and end users. Hydrogen is a promising clean energy source and targets plan pathways towards decarbonization and net-zero emissions by 2050. This paper has highlighted the techniques for generating green hydrogen that are needed for a clean environment and sustainable energy solutions. Moreover, it summarizes an overview, outlook and energy transient of green hydrogen production. Consequently, its perspective provides new insights and research directions in order to accelerate the development and identify the potential of green hydrogen production. [ABSTRACT FROM AUTHOR]

As the global energy landscape transitions towards a more sustainable future, hydrogen has emerged as a promising energy carrier due to its potential to decarbonize various sectors. However, the economic competitiveness of hydrogen production by water electrolysis strongly depends on renewable energy source (RES) availability. Thus, it is necessary to overcome the challenges related to the intermittent nature of RESs. This paper presents a comprehensive techno-economic analysis of complementing green hydrogen production with grid electricity. An evaluation model for the levelized cost of hydrogen (LCOH) is proposed, considering both CO2 emissions and the influence of RES fluctuations on electrolyzers. A minimum load restriction is required to avoid crossover gas. Moreover, a new operation strategy is developed for hydrogen production plants to determine optimal bidding in the grid electricity market to minimize the LCOH. We evaluate the feasibility of the proposed approach with a case study based on data from the Kyushu area in Japan. The results show that the proposed method can reduce the LCOH by 11% to 33%, and increase hydrogen productivity by 86% to 140%, without significantly increasing CO2 emission levels. [ABSTRACT FROM AUTHOR]