High H2 Research Articles

Enhancing photocatalytic performance of covalent organic frameworks via ionic polarization

Covalent organic frameworks have emerged as a thriving family in the realm of photocatalysis recently, yet with concerns about their high exciton dissociation energy and sluggish charge transfer. Herein, a strategy to enhance the built-in electric field of series β-keto-enamine-based covalent organic frameworks by ionic polarization method is proposed. The ionic polarization is achieved through a distinctive post-synthetic quaternization reaction which can endow the covalent organic frameworks with separated charge centers comprising cationic skeleton and iodide counter-anions. The stronger built-in electric field generated between their cationic framework and iodide anions promotes charge transfer and exciton dissociation efficiency. Moreover, the introduced iodide anions not only serve as reaction centers with lowered H* formation energy barrier, but also act as electron extractant suppressing the recombination of electron-hole pairs. Therefore, the photocatalytic performance of the covalent organic frameworks shows notable improvement, among which the CH3I-TpPa-1 can deliver an high H2 production rate up to 9.21 mmol g−1 h−1 without any co-catalysts, representing a 42-fold increase compared to TpPa-1, being comparable to or possibly exceeding the current covalent organic framework photocatalysts with the addition of Pt co-catalysts.

Single-atom Barium Promoter Enormously Enhanced Non-noble Metal Catalyst for Ammonia Decomposition.

As a well-established topic, single-atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single-atom form, the intrinsic roles of single-atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co-Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co-Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat-1·min-1 at very low temperature (500 °C, GHSV = 840,000 mL·g-1·h-1) and Co-Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non-noble catalysts, and reaches or even exceeds numerous reported Ru-based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co-O-Ba-Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N-H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Single‐atom Barium Promoter Enormously Enhanced Non‐noble Metal Catalyst for Ammonia Decomposition

As a well‐established topic, single‐atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single‐atom form, the intrinsic roles of single‐atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co‐Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co‐Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat−1·min−1 at very low temperature (500 °C, GHSV = 840,000 mL·g−1·h−1) and Co‐Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non‐noble catalysts, and reaches or even exceeds numerous reported Ru‐based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co‐O‐Ba‐Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N‐H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Photothermal Induced Dual-Interface: Accelerating Sustainable Hydrogen Evolution from Formic Acid.

Formic acid (FA), a liquid hydrogen storage carrier, can release hydrogen via photothermal catalysis, providing a clean and sustainable solution toward a carbon-neutral energy cycle. Despite recent advances in the design of efficient catalysts, the development of advanced systems with high H2 yield, stability, and durability remains challenging due to the inefficient photothermal conversion and mass transfer in the traditional liquid-solid bulk system, as well as the trade-off between hydrogen storage density and dehydrogenation rate. Here, we address these challenges by creating a photothermal-induced dual-interface characterized by high spectral absorption and low heat loss, a facile supply of FA, and vaporization of FA to minimize the energy barrier of the reaction. As a result, a record hydrogen evolution rate (200.9 mmol g-1 h-1) is achieved in a high concentration (26 M) of FA, which is about 15 times higher than the liquid-solid bulk system. In addition, it can be operated continuously for more than 192 h without additive addition and energy consumption, providing a strategy for accelerating interfacial mass transfer to improve catalytic activity, and also presents a reference for sustainable hydrogen production.

Regeneration of bulk and silica-supported gallium oxide catalysts applied in the dehydrogenation of methanol to formaldehyde and hydrogen by reaction-oxygen regeneration cycles and oxygen pulses in the feed

The oxygen-free dehydrogenation of methanol to formaldehyde and hydrogen is a potential alternative to the established industrial oxidative dehydrogenation yielding aqueous formaldehyde solutions. Advantages are the production of anhydrous formaldehyde and of hydrogen as a valuable coupled product. However, fast deactivation of the catalyst occurs under the high-temperature reaction conditions mainly due to coking, which can be overcome by applying oxygen at a temperature high enough to allow fast oxidation of the carbon deposits but low enough to prevent the loss of Ga. From an engineering point of view, a stable reaction temperature in the catalyst bed and a high H2 yield have to be maintained, requiring that the catalyst enables methanol dehydrogenation, but not the oxidation of hydrogen to water. Thus, two modes of regeneration of GaOx-based catalysts were investigated using reaction − oxygen regeneration cycles and oxygen pulses in the feed. When using bulk Ga2O3 as catalyst and applying optimized reaction-regeneration cycles, a formaldehyde yield of 51 % and a hydrogen yield of 45 % at a stable methanol conversion of 65 % were achieved, whereas undiluted O2 pulsed into the feed every 30 s resulted in a continuous formaldehyde yield of 40 % and a hydrogen yield of 35 % at a stable methanol conversion of 59 % with water yields below 2 % and 4 %, respectively. The effects of the two operation modes on stability and product distribution are discussed in terms of the carbon removal rate from the surface, refilling of oxygen vacancies and parasitic reactions in the presence of oxygen. Specifically, the consumption of O2 did not lead to excessive water formation but preferentially effected the oxidation of the carbon deposits to CO and CO2.

Construction of Highly Porous and Robust Hydrogen-Bonded Organic Framework for High-Capacity Clean Energy Gas Storage.

Development of highly porous and robust hydrogen-bonded organic frameworks (HOFs) for high-pressure methane and hydrogen storage remains a grand challenge due to the fragile nature of hydrogen bonds. Herein, we report a strategy of constructing the double-walled framework to target highly porous and robust HOF (ZJU-HOF-5a) for extraordinary CH4 and H2 storage. ZJU-HOF-5a features a minimized twofold interpenetration with double-walled structure, in which multiple supramolecular interactions are existed between the interpenetrated walls. This structural configuration can notably enhance the framework robustness while maintaining its high porosity, affording one of the highest gravimetric and volumetric surface areas of 3102 m2 g-1 and 1976 m2 cm-3 among the reported HOFs so far. ZJU-HOF-5a thus exhibits an extremely high volumetric H2 uptake of 43.6 g L-1 at 77 K/100 bar and working capacity of 41.3 g L-1 under combined swing conditions (77 K/100 bar→160 K/5 bar), and also impressive methane storage performance with a 5-100 bar working capacity of 187 (or 159) cm3 (STP) cm-3 at 270 K (or 296 K), outperforming most of the reported porous organic materials. Single-crystal X-ray diffraction studies on CH4-loaded ZJU-HOF-5a reveal that abundant supramolecular binding sites combined with ultrahigh porosities account for its high CH4 storage capacities. Combined with high stability, super-hydrophobicity, and easy recovery, ZJU-HOF-5a is placed among the most promising materials for H2 and CH4 storage applications.

Genomic Prediction and Genome-Wide Association Studies for Productivity, Conformation and Heat Tolerance Traits in Tropical Smallholder Dairy Cows.

Genomic selection (GS) and genome-wide association studies (GWAS) have not been investigated in Vietnamese dairy cattle, even for basic milk production traits, largely due to the scarcity of individual phenotype recording in smallholder dairy farms (SDFs). This study aimed to estimate heritability (h2) and test the applicability of GS and GWAS for milk production, body conformation and novel heat tolerance traits using single test day phenotypic data. Thirty-two SDFs located in either the north (a lowland vs. a highland) or the south (a lowland vs. a highland) of Vietnam were each visited for an afternoon and the next morning to collect phenotype data of all lactating cows (n = 345). Tail hair from each cow was sampled for subsequent genotyping with a 50K SNP chip at that same visit. Milk production traits (single-test day) were milk yield (MILK, kg/cow/day), energy corrected milk yield adjusted for body weight (ECMbw, kg/100 kg BW/day), fat (mFA, %), protein (mPR, %) and dry matter (mDM, %). Conformation traits were body weight (BW, kg) and body condition score (BCS, 1 = thin to 5 = obese). Heat tolerance traits were panting score (PS, 0 = normal to 4.5 = extremely heat-stressed) and infrared temperatures (IRTs, °C) at 11 areas on the external body surface of the cow (inner vulval lip, outer vulval surface, inner tail base surface, ocular area, muzzle, armpit area, paralumbar fossa area, fore udder, rear udder, forehoof and hind hoof), assessed by an Infrared Camera. Univariate linear mixed models and a 10-fold cross-validation approach were applied for GS. Univariate single SNP mixed linear models were applied for the GWAS. Estimated h2 (using the genotype information to build relationships among animals) were moderate (0.20-0.37) for ECMbw, mFA, mPR, mRE, BW, BCS and IRT at rear udder; low (0.08-0.19) for PS and other IRTs; and very low (≤ 0.07) for MILK, ECM and mDM. Accuracy of genomic estimated breeding values (GEBVs) was low (≤ 0.12) for MILK, ECM, mDM and IRT at hind hoof; and moderate to high (0.32-0.46) for all other traits. The most significant regions on chromosomes (BTA) associated with milk production traits were 0.47-1.18 Mb on BTA14. Moderate to high h2 and moderate accuracies of GEBVs for mFA, mPR, ECMbw, BCS, BW, PS and IRTs at rear udder and outer vulval surface suggested that GS using single test day phenotypic data could be applied for these traits. However, a greater sample size is required to decrease the bias of GEBVs by GS and increase the power of detecting significant quantitative trait loci (QTLs) by GWAS.

Photocatalytic Semi-Hydrogenation of Acetylene to Polymer-Grade Ethylene with Molecular and Metal-Organic Framework Cobaloximes.

The semi-hydrogenation of acetylene in ethylene-rich gas streams is a high-priority industrial chemical reaction for producing polymer-grade ethylene. Traditional thermocatalytic routes for acetylene reduction to ethylene, despite progress, still require high temperatures and high H2 consumption, possess relatively low selectivity, and use a noble metal catalyst. Light-powered strategies are starting to emerge, given that they have the potential to use directly the abundant and sustainable solar irradiation, but are ineffective. Here an efficient, >99.9% selective, visible-light powered, catalytic conversion of acetylene to ethylene is reported. The catalyst is a homogeneous molecular cobaloxime that operates in tandem with a photosensitizer at room temperature and bypasses the use of non-environmentally friendly and flammable H2 gas feed. The reaction proceeds through a cobalt-hydride intermediate with ≈100% conversion of acetylene under competitive (ethylene co-feed) conditions after only 50 min, and with no evolution of H2 or over-hydrogenation to ethane. The cobaloxime is further incorporated as a linker in a metal-organic framework; the result is a heterogeneous catalyst for the conversion of acetylene under competitive (ethylene co-feed) conditions that can be recycled up to six times and remains catalytically active for 48 h, before significant loss of performance is observed.

Comprehensive experimental assessment of biomass steam gasification with different types: correlation and multiple linear regression analysis with feedstock characteristics

In order to reveal the correlation between gasification behavior and products with feedstock characteristics, the steam gasification of 13 biomasses was investigated using a thermogravimetric analyzer and a fixed-bed reactor. Meanwhile, a multiple linear regression was used to construct correlation models. The results showed that cellulose content and crystallinity had the greatest influence on pyrolysis reactivity, which was reflected that the cellulose content was strongly positively correlated with the pyrolysis reactivity (Pmax = 0.77), while the lignin content and cellulose crystallinity were opposite. H/C, O/C ratios and SiO2 content had the greatest influence on gasification stage. O/C were strongly negatively correlated with gasification reactivity (Pmax = −0.81). But correlations of K and Ca contents were much less than that of Si. Husk has the best gasification performance than straw and woody with highest H2 and total gas yield of 28.26 and 68.93 mmol·g−1. H2 concentration and yield were significantly affected by the cellulose crystallinity and the fixed carbon content with positively correlation (P = 0.69–0.85). CH4 and CnHm were also influenced by them, but the trend was opposite to that of H2. Cellulose content, followed by SiO2 content mainly affected CO and CO2 and negatively correlated with CO while positively with CO2.

Construction of COF/COF Organic S-Scheme Heterostructure for Enhanced Overall Water Splitting.

Covalent organic frameworks (COFs) as a new type of photocatalysts have shown unique advantages in visible-light-driven hydrogen evolution, while the reported overall water-splitting systems are still very rare among various COF-based photocatalysts. Herein, two COFs are integrated to construct a type of organic S-scheme heterojunction for improved overall water splitting. In this system, TpBpy-COF and COF-316 serve as H2- and O2-evolving components, respectively, which are combined through π-π interaction between conjugated aromatic rings. By introducing ultra-small Pt nanoparticles (NPs) into the pores of the TpBpy-COF nanosheets (NS), the resultant COF-316/Pt@TpBpy-COF NS heterostructure achieves extremely high H2 and O2 evolution rates of 220.4 and 110.2µmolg-1h-1, respectively, under visible light irradiation (λ ≥ 420nm). The results of transient absorption spectra (TAS) and photoelectronic measurements indicate that the organic heterojunction interface notably facilitates the separation and transfer of photogenerated electron-hole pairs. Further, theoretical calculations and in situ experiments confirm the spontaneous formation of the COF/COF heterojunction interface and the active sites for overall water splitting.

7310 System-level Analysis in Polycystic Ovary Syndrome on a Panel of Genetically Diverse Strains of Mice

Abstract Disclosure: L.M. Velez: None. C. Johnson: None. I. Tamburrini: None. M. Zhou: None. C. Viesi: None. N. Ujagar: None. D. Ashbrook: None. M. Nelson: None. A. Senior: None. D. James: None. R. Williams: None. D. Nicholas: None. M. Seldin: None. Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women, with a prevalence of ∼4-20% in women of reproductive age. The diagnosis of the syndrome generally occurs when the patient consults for fertility issues and is only based on a reproductive criterion, which includes (1) hyperandrogenism, (2) oligo-anovulation, and (3) polycystic ovary morphology. However, the overlap of PCOS with cardiometabolic diseases is significant. To put in numbers; up to 75% of PCOS women present some degree of insulin insensitivity, 38-88% present obesity or overweight, 20-50% develop type 2 diabetes by age 40, and PCOS women are at increased risk of cardiovascular disease. Despite these facts, shared reproductive/metabolic mechanisms are largely underexplored. Moreover, studies addressing the genetic architecture of PCOS are missing. Here, we induced a PCOS-like condition in 25 recombinant and classical inbred female strains and matched placebo controls over 6 weeks. Comprehensive in vivo and terminal reproductive/metabolic analyses were performed, as well as ovary and adipose RNA-Seq. These strains varied in PCOS response in a number of key metabolic and reproductive traits, including circulating hormone levels, glucose metabolism, and cardiac function. We applied a linear mixed-effects model to estimate heritability, and genetic (h2), PCOS, and gene-by-PCOS interactions. High h2 was observed for lean and fat mass, glucose, and AUC, whereas PCOS effects were high for the BW change, testosterone, and AUC. Substantial gene-by-PCOS interactions were found for reproductive hormones. Undirected network construction and centrality estimates showed that the reproductive hormones LH and LH/FSH ratio were the strongest central traits connecting metabolic phenotypes. We also showed select strains represent subtypes of human PCOS-metabolism interaction with varied susceptibilities to disease in a PCOS setting. Ovarian RNA-seq analysis of PCOS DEGs showed strong enrichments with human disease settings such as hyperandrogenism, inflammation, and pregnancy hypertension. Similar analyses in GWAT RNA-seq showed enrichments in weight gain, liposarcoma, inflammation, and reproductive diseases were at the top, with adipose genes connecting these diseases and potentially involved with PCOS. In conclusion, we established a PCOS model to study relevant mechanisms intersecting reproduction with metabolism in the context of genetic variation. Presentation: 6/2/2024

Effect of Ni/Co ratio on Ce-Sc-ZrO2 catalysts for selective H2 production via methane partial oxidation

Partial oxidation of methane (POM) is a promising route for hydrogen production, and achieving a high H2 yield with an H2/CO ratio >3 is highly appealing. Optimization of Ni/Co ratios over Ce-Sc-ZrO2 (CSZ) is investigated for POM reaction and characterized by X-ray diffraction, Raman spectroscopy, temperature-programmed reduction/oxidation/desorption, and transmission electron microscopy. The active site derived from the reduction of “strongly interacted NiO” is responsible for the dissociation of C–H (of CH4), resulting high activity towards POM. 5Ni/CSZ has the highest amount of such active sites and attains the highest activity. 5Co/CSZ catalyst has cobalt-based active sites, and there is an inert carbon deposit during the reaction, causing the least activity. 3.75 wt% Ni and 1.25 wt% Co combination over CSZ support surges the highest density of basicity, oxide vacancy, and adequate amount of active sites derived from “strongly interacted NiO”. The active sites with enhanced metal-support interaction are further grown under exposure to oxidizing gas (O2) and reducing gas (H2) during the POM reaction. The highest density of basicity and oxide vacancy involves more CO2 and H2O in the sequential oxidation of CH4 under indirect pathways. The exclusive involvement of indirect pathways of POM and inhibition of hydrogen consuming reaction (like reverse water gas shift reaction) over 3.75Ni1.25Co/CSZ results into 48 % H2 yield and 3.26 H2/CO ratio up to 24 h time on stream at 600 °C. The H2 yield doubles to ∼97 %, and the H2/CO ratio comes close to 2 over 3.75Ni1.25Co/CSZ catalyst at 900 °C.

Efficient production of hydrogen through bioaugmentation of the organic fraction of municipal solid waste by the newly isolated Clostridium sartagoforme SA1

Bio-hydrogen from organic waste holds promise as renewable energy. However, its large-scale production is limited by technical challenges, with low H2 yields and the absence of robust microbial strains being the major ones.To address these limitations, H2-producing microbes have been isolated from a full-scale anaerobic digestor treating complex organic waste. Clostridium sartagoforme SA1 was selected because of high H2 yields from glucose, soluble starch, and carboxymethylcellulose. The strain was then tested for H2 production from the Organic Fraction of Municipal Solid Waste (OFMSW), rich in starch and cellulose, with productions up to 55 mLH2 g/VS. Additionally, C. sartagoforme SA1 confirmed high H2 performances even in the presence of OFMSW’s indigenous microflora, increasing the H2 yield by 38 % and highlighting its robustness in a highly competitive environment. This is the first report describing the efficient adoption of a C. sartagoforme strain for bioaugmentation of non-sterile OFMSW towards high H2 yields.

Analysis of the synergetic effect of process parameters of hydrogenated amorphous carbon deposition in plasma-enhanced chemical vapor deposition using machine learning

The synergetic effects of process parameters on hydrogenated amorphous carbon (a-C:H) films properties were quantitatively analyzed in plasma-enhanced chemical vapor deposition. Predictive models, created from experimental datasets and machine learning, indicate a synergetic effect between the H2 ratio and ion energy impacting on the substrate. At a H2 ratio of 75 %, etch rates of 200 nm/min were predicted, regardless of radio frequency (RF) bias. These rates decreased to 120–140 nm/min at lower H2 ratios, primarily depending on RF bias. Quadrupole mass spectrometry and Raman scattering were used to investigate the underlying mechanisms. High H2 ratios led to a greater presence of low-mass hydrogen-rich molecules in the plasma. The C2H3 radical intensity at a 75 % H2 ratio was 15 times greater than that at 0 % at an RF bias of 50 W, and similar trends were observed for other low-mass neutrals. The synergetic effects of H2 ratio and RF bias decreased the film's hydrogen content. Machine learning and those diagnostics revealed that ion bombardment induces dehydrogenation of a-C:H, influenced by hydrogen-rich species. This study demonstrates that machine learning can uncover complex plasma processes and optimize material synthesis.

The effect of co-modification of ultrathin g-C3N4 nanosheets with Ag and S on photocatalytic hydrogen production

The technology of photocatalytic water splitting holds immense potential for hydrogen (H2) generation. However, its development is hindered by a lack of active sites and low efficiency of photogenerated carriers. In this study, Ag-S-CN ultrathin nanosheets were successfully fabricated by co-modification of graphitic carbon nitride (CN) with silver (Ag) and sulfur (S). S doping within the CN layers broadened light absorption and provided additional reaction sites, while the incorporation of Ag into the CN interlayers enhanced the migration rate of photogenerated carriers between adjacent layers via Ag-S bonds. Consequently, the 0.05 Ag-S-CN photocatalyst achieved a high H2 yield of 0.93 mmol g-1 h-1 without requiring any additional cocatalyst, which is approximately 23.25 and 10.33 times higher than that of CN and S-CN, respectively. This work presents an effective strategy for developing highly efficient photocatalysts.

Oriented Titanium-MOF Membrane for Hydrogen Purification.

Precise hydrogen sorting from purge gas (H2/N2) and coke gas (H2/CH4), commonly carried out by cryogenic distillation, still suffers from low separation efficiency, high energy consumption, and considerable capital cost. Though still in its infancy, membrane technology offers a potential to achieve more efficient hydrogen purification. In this study, an optimum separation of hydrogen towards both methane and nitrogen via a kinetically-driven mechanism is realized through preferred orientation control of a MOF membrane. Relying on the 0.3 nm-sized window aligned vertical to the substrate, b-oriented Ti-MOF membrane exhibits ultra-high hydrogen selectivity, surpassing the upper bound limit of separating H2/N2 and H2/CH4 gas pairs attained so far by inorganic membranes. This spectacular selectivity is combined with a high H2 permeability owing to the synergistic effect of the 1 nm-sized MOF channel.

Oriented Titanium‐MOF Membrane for Hydrogen Purification

Precise hydrogen sorting from purge gas (H2/N2) and coke gas (H2/CH4), commonly carried out by cryogenic distillation, still suffers from low separation efficiency, high energy consumption, and considerable capital cost. Though still in its infancy, membrane technology offers a potential to achieve more efficient hydrogen purification. In this study, an optimum separation of hydrogen towards both methane and nitrogen via a kinetically‐driven mechanism is realized through preferred orientation control of a MOF membrane. Relying on the 0.3 nm‐sized window aligned vertical to the substrate, b‐oriented Ti‐MOF membrane exhibits ultra‐high hydrogen selectivity, surpassing the upper bound limit of separating H2/N2 and H2/CH4 gas pairs attained so far by inorganic membranes. This spectacular selectivity is combined with a high H2 permeability owing to the synergistic effect of the 1 nm‐sized MOF channel.

Highly Durable Chemoresistive Micropatterned PdAu Hydrogen Sensors: Performance and Mechanism.

Hydrogen (H2) is a promising alternative energy source for Net-zero, but the risk of explosion requires accurate and rapid detection systems. As the use of H2 energy expands, sensors require high performance in a variety of properties. Palladium (Pd) is an attractive material for H2 detection due to its high H2 affinity and catalytic properties. However, poor stability caused by volume changes and reliability due to environmental sensitivity remain obstacles. This study proposes a micropatterned thin film of PdAu with optimized composition (Pd0.62Au0.38) as a chemoresistive sensor to overcome these issues. At room temperature, the sensor has a wide detection range of 0.0002% to 5% and a fast response time of 9.5 s. Significantly, the sensor exhibits excellent durability for repeated operation (>35 h) in 5% H2 and resistance to humidity and carbon monoxide. We also report a negative resistivity change in PdAu, which is opposite to that of Pd. Density functional theory (DFT) calculations were performed to investigate the resistance change. DFT analysis revealed that H2 penetrates specific interstitial sites, causing partial lattice compression. The lattice compression causes a decrease in electrical resistance. This work is expected to contribute to the development of high-performance H2 sensors using Pd-based alloys.

Novel CoFe2O4 / LaAlO3 nanocomposites: An impressive photocatalyst with p-n hetero-junction for improved H2 generation under visible exposure

The present work is devoted to the synthesis of perovskite LaAlO3 by Sol-Gel approach and its application for the photo-evolution of H2 in conjunction with cobalt ferrite CoFe2O4 prepared by nitrate route. The thermal analysis (TG/DSC) showed that the formation is completed at 600 °C. The X-ray diffraction (XRD) pattern is characteristic of a single phase, crystallizing in a rhombohedral symmetry with a crystallite size of 36 nm. The SEM micrographs revealed a homogeneous structure with an agglomeration of shaped grains (40–80 nm). The forbidden band (3.39 eV), calculated from diffuse reflectance data, is assigned to the ligand charge transfer O2−: 2p → Al3+: 3s orbital. As prepared, LaAlO3 is an n-type semiconductor as demonstrated from the capacitance - potential (C−2 - E) graph with an electron density of 9.4 × 1014 cm−3 due to oxygen under-stoichiometry. Attention was directed to photo-electrochemistry in connection with water reduction into hydrogen. With a negative conduction band potential (−0.11 VSCE), H2 generation can be synergized over the hetero-system by visible light. The photocatalytic capability of CoFe2O4 25%/LaAlO3 revealed a high H2 generation of 963 μmol g−1 in the alkaline electrolyte (NaOH, 0.1 M) with a catalyst dose of 1 mg mL−1, which is 1.3 times more than CoFe2O4 under similar conditions. Photoactivity is significantly improved by 60%, up to 2400 μmol g−1 in the presence of oxalate C2O42− as a hole scavenger in the hetero-junction, two hydrogen release tests were successfully recorded. The higher H2 production in the hetero-junction system is attributed to the lower recombination rate of electron/hole (e−/h+) in the material, due to the large band bending at the solid interfacial.

Ultraselective carbon hollow fiber membrane for H2 extraction from blended natural gas

Blending hydrogen into natural gas (H2NG) pipelines is a feasible solution for low-cost hydrogen delivery while purifying H2 at end-use remains challenging due to its high pressure and low H2 concentration. Herein, biomass-derived carbon hollow fiber membranes (CHFMs) with ultrahigh H2/CH4 separation factor of 4149.0 under a simulated H2NG (10 mol% H2/90 mol% CH4) at 30 bar were reported, and the separation performance maintained within 150 h in a dynamic durability test. Furthermore, the CHFMs showed good stability under fluctuating temperature feeds (up to 100 °C). To evaluate the feasibility of the CHFMs for H2 extraction from H2NG, a three-stage membrane system was designed based on the mixed gas separation performances. It suggested that 99.99 mol% H2 can be achieved with a 90 % recovery, and the specific H2 purification cost was 0.245 $/Nm3 for a 1.8 × 105 Nm3/h production scale, which provides the possibility of hydrogen extraction from H2NG pipelines.