Promoting Hydrogen Generation Research Articles

Boosting the Production of Hydrogen from an Overall Urea Splitting Reaction Using a Tri-Functional Scandium-Cobalt Electrocatalyst.

The creation of highly efficient and economical electrocatalysts is essential to the massive electrolysis of water to produce clean energy. The ability to use urea reaction of oxidation (UOR) in place of the oxygen/hydrogen evolution process (OER/HER) during water splitting is a significant step toward the production of high-purity hydrogen with less energy usage. Empirical evidence suggests that the UOR process consists of two stages. First, the metal sites undergo an electrochemical pre-oxidation reaction, and then the urea molecules on the high-valence metal sites are chemically oxidized. Here, the use of scandium-doped CoTe supported on carbon nanotubes called Sc@CoTe/CNT is reported and CoTe/CNT as a composite to efficiently promote hydrogen generation from highly durable and active electrocatalysts for the OER/UOR/HER in urea and alkali solutions. Electrochemical impedance spectroscopy indicates that the UOR facilitates charge transfer across the interface. Furthermore, the Sc@CoTe/CNT nanocatalyst has high performance in KOH and KOH-containing urea solutions as demonstrated by the HER, OER, and UOR (215mV, 1.59, and 1.31V, respectively, at 10mA cm-2 in 1m KOH) and CoTe/CNT shows 195 mV, 1.61 and 1.3V, respectively. Consequently, the total urea splitting system achieves 1.29V, whereas the overall water splitting device obtaines 1.49V of Sc@CoTe/CNT and CoTe/CNT shows 1.54, 1.48 V, respectively. This work presents a viable method of combining HER with UOR for maximally effective hydrogen production.

Synergistic catalytic performance of Co–Fe/CQD nanocatalyst for rapid hydrogen generation through NaBH4 hydrolysis

In this study, a bimetallic Co–Fe nanocatalyst supported on carbon quantum dots (CQDs) is introduced as an effective catalyst for promoting hydrogen generation upon hydrolysis of sodium borohydride. Hydrothermal synthesis routes were used to produce CQDs support. All samples were subjected to analysis using XRD, UV–Vis, Raman, FTIR, FESEM, EDX, and nitrogen adsorption-desorption techniques. Benefiting from the higher surface area (51 m2gr), pore volume (0.200 mLgr), and good dispersion of Co–Fe nanoparticles over the CQDs support, the CoFe/CQD spherical nanocatalysts with 5 wt.% iron content exhibited the highest catalytic activity of 20200 mL/min.gcat within only 1 min of reaction. The kinetics studies revealed a low activation energy of 48 kJ/mol over this optimum catalyst. In addition, it was found that the catalytic performance of this catalyst was decreased after 4 runs of recycling experiments. Catalyst degradation and leaching of the active phase were likely responsible for the decline in catalyst performance.

Construction of graphdiyne-based photocatalysts with strong built-in electric field by loading bimetallic oxides to promote the photocatalytic hydrogen evolution activity

The novel carbon material graphdiyne (GDY) is a two-dimensional planar structure material formed by the hybridization of sp and sp2, which has abundant carbon–carbon bonds and stable semiconductor properties. In this work, CoTiO3 was coupled with a carbon material GDY to successfully construct an S-scheme GDY/CoTiO3 heterojunction. This form of heterojunction can effectively promote the separation of charge carriers and shorten the electron transfer pathn. The loading of CoTiO3 effectively enhances the charge transfer rate of GDY and increases the number of photo-generated electrons involved in the hydrogen production reaction, thereby promoting hydrogen generation. The tests results demonstrate that GDY/CoTiO3-25 achieves a hydrogen production of 123.95 μmol under visible light irradiation, which is 13 times higher compared to GDY. This work provides insights into improving the photocatalytic performance of the novel carbon material GDY.

One-step synthesis of 2D/2D gC3N4/MoS2 composites for effective photocatalytic hydrogen evolution

Two-dimensional (2D) heterostructures have proven their efficiency in separating charges. Herein, a gC3N4/MoS2 (CN/MoS2) photocatalyst, in the form of 2D/2D van der Waals heterojunction with a type-II band alignment, was synthesized using a novel one-step method. The resulting in-situ formed heterojunction interface enhances electron transfer from gC3N4 to MoS2. The CN/MoS2 photocatalyst exhibits exceptional activity in generating hydrogen from water under simulated solar light. Its hydrogen production rate was 1285 μmol/h/g, which was approximately 3 times higher compared to gC3N4. This superiority is due to a significant increase in photogenerated carrier density and efficient charge separation facilitated by the type-II heterojunction. This study demonstrates a straightforward one-step approach for synthesizing 2D/2D composite photocatalysts, highlighting the effective synergy between different 2D materials in promoting hydrogen generation.

A case study on hydrogen refueling station techno-economic viability

The anticipated escalation in the utilization of renewable energy sources is projected to make a significant contribution to the attainment of long-term sustainability objectives and the promotion of resilient economic expansion. Australia is taking positive steps to increase its climate and clean energy ambitious targets through investment in the clean energy infrastructure and increased funding at federal and state levels. A systematic approach is required to propel the progress of environmentally friendly hydrogen production and to achieve these objectives, a techno-economic optimization analysis for hydrogen generation to use the findings to improve the efficiency of recharging fuel cell vehicles is performed. The results of the evaluation and optimization showed that the energy system which integrates wind-based sources with photovoltaic sources, presents the most advantageous metrics. The lowest values for the selected energy system include the Net Present Cost of $614,957, the Levelized Cost of Energy of $0.4347/kWh, and the Levelized Cost of Hydrogen of $0. 375/kg. More so, the cost of energy is expected to decrease further as the lifetime of the electrolyzer lifetime increases as supported by sensitivity analysis. The study showed that setting up a refueling station in the city of Geelong has the potential to serve as a viable solution for decreasing reliance on fossil fuels and achieving decarbonization within Geelong's transportation sector. This study is anticipated to enable stakeholders to promote hydrogen generation in Australia.

Two-dimensional siloxene as an advanced support of platinum for superior hydrogen evolution and methanol oxidation electrocatalysis

To improve the utilization efficiency of versatile platinum (Pt) in electrochemical energy conversion, precisely choosing support materials is a significantly promising strategy. Herein, we demonstrate the competitive advantages of novel two-dimensional Siloxene as the advanced support of Pt toward enhancing bifunctional electrocatalysis for hydrogen evolution (HER) and methanol oxidation (MOR) based on unusual metal–support interactions. The Pt NPs/Siloxene electrocatalyst by supporting Pt nanoparticles on Siloxene sheets is successfully synthesized via simple wet-chemical method. Compared to commercial Pt/C (20 wt%), Pt NPs/Siloxene with ultra-low Pt content (1.3 wt%) exhibits superior electrocatalytic activity with good stability toward HER and MOR in acidic media. For HER, a small overpotential of 24 mV is required to drive 10 mA cm−2 current with a low Tafel slope (24.6 mV dec−1). Meanwhile, preeminent Pt mass activity of 1957 mA mg−1 for MOR is achieved, which is 12.6 times higher than that of Pt/C. Theoretical calculations indicate that the binding energies are optimized to facilitate desorption or adsorption of related adsorbates during HER and MOR electrocatalysis, and thus enhancing Pt utilization efficiency. Specially, this support engineering can trigger hydrogen spillover from Pt to Siloxene to promote hydrogen generation, attributed to a unique hydrogen spillover-based HER pathway with favorable proton adsorption on Pt sites and efficient hydrogen desorption from Siloxene.

Interfacial ensemble effect of copper nanoparticles and nickel metal-organic framework on promoting hydrogen generation

Ammonia borane is a promising chemical hydrogen storage material to the hydrogen economy in the future. However, efficient and inexpensive catalyst for realizing this process remains challenging. Herein, the interfaces of copper nanoparticles (NPs) and nickel metal-organic framework (MOF) with different Cu/Ni ratios (Cu@Nix-MOF) have been constructed by Cu NPs in situ growth in Ni-MOF via a facile one-step solvothermal method. The Cu@Nix-MOF composites show much higher catalytic activity than their monometal counterparts and the optimized Cu@Ni6-MOF catalyst achieves a turnover frequency of 69.1 min−1 for ammonia borane hydrolysis, superior to most reported Ni-based catalysts. Density functional theory simulation and in situ Raman spectroscopy analysis propose that this remarkable enhanced activity of Ni-based catalysts is induced by a synergetic effect of Cu–Ni2+ dual active sites at their interfaces. This study shows that the strategy of dual active sites hold great promise to achieve efficient non-noble metal catalysts toward heterogeneous catalysis.

Efficient Hydrogen Generation and Total Nitrogen Removal for Urine Treatment in a Neutral Solution Based on a Self-Driving Nano Photoelectrocatalytic System.

Urine is the main source of nitrogen pollution, while urea is a hydrogen-enriched carrier that has been ignored. Decomposition of urea to H2 and N2 is of great significance. Unfortunately, direct urea oxidation suffers from sluggish kinetics, and needs strong alkaline condition. Herein, we developed a self-driving nano photoelectrocatalytic (PEC) system to efficiently produce hydrogen and remove total nitrogen (TN) for urine treatment under neutral pH conditions. TiO2/WO3 nanosheets were used as photoanode to generate chlorine radicals (Cl•) to convert urea-nitrogen to N2, which can promote hydrogen generation, due to the kinetic advantage of Cl−/Cl• cyclic catalysis. Copper nanowire electrodes (Cu NWs/CF) were employed as the cathode to produce hydrogen and simultaneously eliminate the over-oxidized nitrate-nitrogen. The self-driving was achieved based on a self-bias photoanode, consisting of confronted TiO2/WO3 nanosheets and a rear Si photovoltaic cell (Si PVC). The experiment results showed that hydrogen generation with Cl• is 2.03 times higher than in urine treatment without Cl•, generating hydrogen at 66.71 μmol h−1. At the same time, this system achieved a decomposition rate of 98.33% for urea in 2 h, with a reaction rate constant of 0.0359 min−1. The removal rate of total nitrogen and total organic carbon (TOC) reached 75.3% and 48.4% in 2 h, respectively. This study proposes an efficient and potential urine treatment and energy recovery method in neutral solution.

Enhancing Effect of Fe2+ Doping of Ni/NiO Nanocomposite Films on Catalytic Hydrogen Generation.

Highly active and stable non-noble metal catalysts are expected to play a critical role in future hydrogen storage and conversion applications. The design of active sites with composite oxides provides a new approach for developing high-performance catalysts. In this study, an Fe-doped Ni/NiO nanocomposite film was constructed on an ionic liquid/water interface to promote hydrogen generation. The optimized Ni/FeNiOx-25 catalyst showed excellent catalytic activity toward ammonia borane hydrolysis, with a turnover frequency of 72.3 min-1. The enhancing effect of Fe2+ doping on Ni/NiO films was confirmed by the improved intrinsic activity and theoretical simulations. Fe ion doping stabilized NiO and prevented NiO from becoming Ni. The interfacial Ni-Fe2+ dual active sites on the FeNiOx and Ni interfaces participated in the targeted adsorption and effective activation of water and NH3BH3 molecules, respectively. The sufficiently exposed plane surface of the nanofilms provided abundant active sites for catalytic reactions. This significant advance will inspire development in the ambient liquid hydrogen storage field.

Promoting hydrogen generation via co-hydrolysis of Al and MgH2 catalyzed by Mo and B2O3

The hydrolysis of MgH2 and Al can generate a large amount of hydrogen, but is hindered by its poor kinetics. The generated compact by-product layer is regarded as the main reason for this deficiency. In this work, a comparatively cost efficient Al12Mg17 alloy is fully hydrogenated to generate a mixture of MgH2 and Al. The mixtures are then refined effectively via ball milling with Mo (1.5 wt%) and B2O3 (3.5 wt%) as grinding agents. After 2 h of milling, the MgH2 and Al mixture with the grinding agents shows excellent hydrolysis properties, with the generation of 1420.2 mL/g in 50 min at room temperature in a 1 M AlCl3 solution and a reduction in the activation energy to 9.4 kJ/mol. The effective refinement of Al and MgH2, the generation of H3BO3 from B2O3 hydrolysis and the formation of an incompact MgAl2O4 by-product contribute to the kinetic properties in the hydrolysis of MgH2 and Al.

A Zeolite‐confined Pd/Acid Sites for High Efficiency of B−H Cleavage

AbstractConfining noble nanometal in zeolite framework is a promising way to improve its efficiency and durability for catalytic reactions. Herein, the synergistic effect of Pd nanoparticles and intrinsic acid sites in zeolite on promoting hydrogen generation performance is demonstrated. Pd nanoparticles are embedded into macroporous ZSM‐5 (designed as Pd@ZSM‐5) via a steam‐thermal strategy. The confined Pd and acid sites in Pd@ZSM‐5 synergistically promote the activation of ammonia borane (AB) and water molecules, resulting in the enhanced H2 generation rates for AB hydrolysis. The interaction of Pd and acid sites in zeolite is further confirmed by solid‐state NMR techniques and the key aspect is the confinement effect of zeolite. Furthermore, Pd@ZSM‐5 shows high activity and durability in tandem hydrogenation of nitrobenzene.

Highly dispersed Ru/Co catalyst with enhanced activity for catalyzing NaBH4 hydrolysis in alkaline solutions

Ru and Co are highly dispersed on the surface of TiO2 nanoparticles with an easy coprecipitation method to fabricate a novel Ru-based catalyst (Ru/Co-TiO2). The fabricated Ru/Co-TiO2 catalyst exhibits superior catalytic performance for promoting NaBH4 hydrolysis in alkaline medium, showing an impressive hydrogen generation rate per gram Ru as high as 172 L min−1 gRu-1, which is better than most of recently reported Ru-based catalysts. In addition, the fabricated Ru/Co-TiO2 catalyst also shows excellent durability in cycle use, with only 2.9% activity loss after being used for 5 cycles. These advantages make the developed Ru/Co-TiO2 catalyst a potential choice for promoting hydrogen generation from NaBH4 hydrolysis.

Protonated Poly(ethylene imine)-Coated Silica Nanoparticles for Promoting Hydrogen Generation by Hydrolysis of Sodium Borohydride.

Invited for this month's cover is the group of Dr. Hua Dong from Chengdu University of Technology, China. The cover picture shows a nonmetal catalyst (SiO2 @H+ PEI) that promotes hydrogen production by hydrolysis of NaBH4 . This newly developed catalyst, which is fabricated by covalently modifying SiO2 nanoparticles with protonated poly(ethylene imime), provides a promising choice for the cheap and efficient catalysis of NaBH4 hydrolysis. Read the full text of the article at 10.1002/cplu.201900609.

アルミ付き廃棄物を用いた水素発生における反応液の開発

This R&D aims to collect and separate aluminum-containing waste materials (general waists and industry waists), and recover highly-pure aluminum by the efficient dry distillation process. By using the cartridge system (containing the aluminum and reactant), hydrogen energy is generated for variety of applications. This system contributes the improvement of aluminum material flow and provides low-carbon solutions. In this paper, relation between concentration of NaOH and hydrogen generation rate was researched. It was found that 4% NaOH was optimum for hydrogen generation rate. Moreover the effect of inorganic salts on hydrogen generation was researched. As for the result, it was clarified that reaction liquid with FeSO4 could promote hydrogen generation.

Protonated Poly(ethylene imine)-Coated Silica Nanoparticles for Promoting Hydrogen Generation from the Hydrolysis of Sodium Borohydride.

Nonmetal catalysts are attracting a great deal of attention because of their advantages including high activity, low cost, and environmental friendliness. In this work, a nonmetal catalyst for NaBH4 hydrolysis was fabricated through covalent modification of silica nanoparticles with protonated poly(ethylene imine). The successful formation of the catalyst was verified by transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The fabricated catalyst shows excellent activity in catalyzing NaBH4 hydrolysis reactions. The hydrolysis of 15 mg NaBH4 catalyzed by 50 mg catalyst could provide a hydrogen generation rate as high as 117.53 mL min-1 at 20 °C. Although the catalytic activity decreased after use, it could be restored easily by regenerating in acetic acid solution.

Synergetic Effect of Ultrasmall Metal Clusters and Zeolites Promoting Hydrogen Generation.

Taking advantage of the synergetic effect of confined ultrasmall metal clusters and zeolite frameworks is an efficient strategy for improving the catalytic performance of metal nanocatalysts. Herein, it is demonstrated that the synergetic effect of ultrasmall ruthenium (Ru) clusters and intrinsic Brønsted acidity of zeolite frameworks can significantly promote the hydrogen generation of ammonia borane (AB) hydrolysis. Ultrasmall Ru clusters are embedded onto the silicoaluminophosphate SAPO‐34 (CHA) and various aluminosilicate zeolites (MFI, *BEA, and FAU) with tunable acidities by a facile incipient wetness impregnation method. Evidenced by high‐resolution scanning transmission electron microscopy, the sub‐nanometric Ru clusters are uniformly distributed throughout the zeolite crystals. The X‐ray absorption spectroscopy measurements reveal the existence of Ru‐H species between Ru clusters and adjacent Brønsted acid sites of zeolites, which could synergistically activate AB and water molecules, significantly enhancing the hydrogen evolution rate of AB hydrolysis. Notably, the Ru/SAPO‐34‐0.8Si (Si/Al = 0.8) and Ru/FAU (Si/Al = 30) catalysts with strong acidities afford high turnover frequency values up to 490 and 627 min−1, respectively. These values are more than a 13‐fold enhancement than that of the commercial Ru/C catalyst, and among the top level over other heterogeneous catalysts tested under similar conditions.

Hydrogen generation and simultaneous removal of Cr(VI) by hydrolysis of NaBH4 using Fe-Al-Si composite as accelerator

The present study reports a novel method for hydrogen generation and simultaneous removal of Cr(VI) from synthetic wastewater using NaBH4 as the reducing agent and Fe-Al-Si composite as accelerator. The results showed that the hydrogen generation yields of NaBH4 occurred at low pH, high temperature and stirring speed. The presence of Cr(VI) was found to inhibit hydrogen generation at the initial pH 3.0, especially at low temperature conditions. Increasing temperature resulted in the increase of hydrogen generation, whereas a higher reduction rate of Cr(VI) was obtained at low temperature. Therefore, to alleviate the contradiction between hydrogen generation and Cr(VI) removal with respect to temperature, we introduced reduction accelerator by preparing Fe-Al-Si composite using wasted fly ash as raw materials. The resultant hydrogen generation yield could be enhanced from 32.04 to 80.70%, and total Cr removal was increased from 46.72 to 98.96% at 30 °C. First, H+ produced by hydrolysis of Fe-Al-Si composite improves the hydrolysis ability of NaBH4, thus promoting its ability to reduce Cr(VI) and to produce hydrogen by itself. The Cr(VI) reduction and hydrogen generation process are competitive for H+, which is particularly evident at insufficient H+. Second, at low doses, Fe3+ exhibited a lower ability to promote hydrogen generation and simultaneous Cr(VI) removal than Al3+. One of the reasons for the low promotion ability of Fe3+ in the whole pH range was the formation of Fe0 at pH less than 3.0, and the other was the weaker hydrolysis ability of Fe3+ itself at pH greater than 3.0.

Hierarchically structured rugae-like RuP3–CoP arrays as robust catalysts synergistically promoting hydrogen generation

Designing a highly active and stable catalyst for NaBH4 hydrolysis is a key step towards overcoming the challenges of hydrogen storage.

Promoting hydrogen generation from the hydrolysis of Mg-Graphite composites by plasma-assisted milling

The effect of dielectric barrier discharge plasma-assisted milling (P-milling) on the hydrogen generation properties of Mg-graphite composites is investigated in this work. The results show that P-milling of Mg and 20 wt.% expanded graphite (EG) can significantly enhance the hydrolysis properties of Mg, and the obtained composite may generate 614.3 mL g−1 H2 with a hydrolysis conversion rate of 83.5% in 25 min. P-milling shows the optimal effect on the hydrolysis of Mg-graphite composites by comparing the varied milling process. The apparent activation energy of hydrolysis in deionized water of the Mg-EG composite obtained by P-milling is determined to be 67.6 kJ mol−1. The hydrolysis mechanism of this Mg-EG composite is also discussed. Scaled hydrogen supply test of 10 g of the Mg-EG composite by P-milling is demonstrated on a hydrogen generator and it shows a maximum hydrogen flow rate of 12.3 L min−1 with a conversion rate of 93.9%. The findings here present that the P-milled Mg-EG composite with high hydrogen density and low cost can be a promising hydrogen generation material.

Novel Ni–Co–B hollow nanospheres promote hydrogen generation from the hydrolysis of sodium borohydride

Ni–Co–B hollow nanospheres were synthesized by the galvanic replacement reaction using a Co–B amorphous alloy and a NiCl2 solution as the template and additional reagent, respectively. The Ni–Co–B hollow nanospheres that were synthesized in 60 min (Ni–Co–B-60) showed the best catalytic activity at 303 K, with a hydrogen production rate of 6400 mLhydrogenmin−1gcatalyst−1 and activation energy of 33.1 kJ/mol for the NaBH4 hydrolysis reaction. The high catalytic activity was attributed to the high surface area of the hollow structure and the electronic effect. The transfer of an electron from B to Co resulted in higher electron density at Co sites. It was also found that Ni was dispersed on the Co–B alloy surface as result of the galvanic replacement reaction. This, in turn, facilitated an efficient hydrolysis reaction to enhance the hydrogen production rate. The parameters that influenced the hydrolysis of NaBH4 over Ni–Co–B hollow nanospheres (e.g., NaOH concentration, reaction temperature, and catalyst loading) were investigated. The reusability test results show that the catalyst is active, even after the fifth run. Thus, the Ni–Co–B hollow nanospheres are a practical material for the generation of hydrogen from chemical hydrides.