Hydrogen Generation Reaction Research Articles

A New Integrated System for Carbon Capture and Clean Hydrogen Production for Sustainable Societal Utilization

Hydrogen production and carbon dioxide removal are considered two of the critical pieces to achieve ultimate sustainability target. This study proposes and investigates a new variation of potassium hydroxide thermochemical cycle in order to combine hydrogen production and carbon dioxide removal, synergistically. An alkali metal redox thermochemical cycle developed where the potassium hydroxide is considered by using a nonequilibrium reaction. Also, the multigeneration options are explored by using two stage steam Rankine cycle, multi-effect distillation desalination, Li-Br absorption chiller, which are integrated with potassium hydroxide thermochemical cycle for hydrogen production, carbon capture, power generation, water desalination, and cooling purposes. A comparative assessment under different scenarios is carried out. The energy and exergy efficiencies of the hydrogen production thermochemical cycle are 44.2% and 67.66% when the hydrogen generation reaction is carried out at 180°C and the separation reactor temperature set at 400°C. Among the multigeneration scenarios, a trigeneration option of hydrogen, power and water indicates the highest energy efficiency as 66.02%. For

The Dependence of NiMo/Cu Catalyst Composition on Its Catalytic Activity in Sodium Borohydride Hydrolysis Reactions.

The production of high-purity hydrogen from hydrogen storage materials with further direct use of generated hydrogen in fuel cells is still a relevant research field. For this purpose, nickel-molybdenum-plated copper catalysts (NiMo/Cu), comprising between 1 and 20 wt.% molybdenum, as catalytic materials for hydrogen generation, were prepared using a low-cost, straightforward electroless metal deposition method by using citrate plating baths containing Ni2+-Mo6+ ions as a metal source and morpholine borane as a reducing agent. The catalytic activity of the prepared NiMo/Cu catalysts toward alkaline sodium borohydride (NaBH4) hydrolysis increased with the increase in the content of molybdenum present in the catalysts. The hydrogen generation rate of 6.48 L min-1 gcat-1 was achieved by employing NiMo/Cu comprising 20 wt.% at a temperature of 343 K and a calculated activation energy of 60.49 kJ mol-1 with remarkable stability, retaining 94% of its initial catalytic activity for NaBH4 hydrolysis following the completion of the fifth cycle. The synergetic effect between nickel and molybdenum, in addition to the formation of solid-state solutions between metals, promoted the hydrogen generation reaction.

Effect of L-glutamic acid as hydrogen generation inhibitor on aluminum waste

Aluminum on reaction with water generates hydrogen, aluminum waste (AW) under moist condition causes hydrogen blast. To inhibit the evolution of hydrogen during the reaction of aluminum with water, environmentally friendly L-glutamic acid (GA)was utilized. The results of hydrogen generation experiment show that 0.3 g GA with 0.5 g AW and 0.5 g sodium borohydride (NH) has the ability to suppress the hydrogen generation reaction. The XRD, FTIR and SEM analysis indicate the presence of protective covering film of GA is formed on the surface of AW, blocking the reaction to occur between aluminum with water. This study addresses the lack of research on inhibitors for hydrogen fire blasts when removing wet aluminum dust.

Pulsed dynamic electrolysis enhanced PEMWE hydrogen production: Revealing the effects of pulsed electric fields on protons mass transport and hydrogen bubble escape

The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway, with renewable energy-powered proton exchange membrane water electrolysis (PEMWE) emerging as the preeminent pathway for hydrogen production. Despite remarkable advancements in this field, confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle. This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment. To address these challenges, we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system. Compared to constant voltage electrolysis (hydrogen production rate: 51.6 mL h−1, energy consumption: 5.37 kWh Nm−3 H2), this strategy (hydrogen production rate: 66 mL h−1, energy consumption: 3.83 kWh Nm−3 H2) increases the hydrogen production rate by approximately 27% and reduces the energy consumption by about 28%. Furthermore, we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic (PV) system designed for outdoor operation, successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V. The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism: pulsed dynamic electrolysis (PDE) dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface. As such, PDE-enhanced PEMWE represents a synergistic advancement, concurrently enhancing both the hydrogen generation reaction and associated transport processes. This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.

Bimetallic NiCo Metal-Organic Frameworks with High Stability and Performance Toward Electrocatalytic Oxidation of Urea in Seawater.

The urea oxidation reaction (UOR) is an alternative anodic reaction for hydrogen generation via water splitting. The significance of UOR lies in both H2 production and the decontamination of urea-containing wastewater. Commercial electrocatalysts in this field are generally based on noble metals and show several limitations. Bimetal-organic frameworks (BMOFs) can be excellent candidates for the replacement of noble-metal-based catalysts beacuse of their promising features, such as a tunable structure, high surface area, and abundant sites for electrocatalysis. In this study, a series of nickel-cobalt BMOFs (Nix-Coy-BMOFs: x and y refer to a molar fraction of Ni and Co) were synthesized and applied as electrocatalysts in UOR. In particular, a Ni0.15Co0.85-MOF material with a structure similar to that of its parent Co-MOF, revealed exceptional electrocatalytic performance, as evidenced by low values of overpotential (1.33 V vs RHE at 10 mA cm-2), TOF (0.47 s-1), and Tafel slope (125 mV dec-1). At a 40 mA cm-2 current density, Ni0.15Co0.85-MOF also showed excellent stability during the 72 h tests. This performance of NiCo-BMOF can be assigned to the synergistic effect between Co and Ni, abundant active sites, porosity, and a tunable structure, all of which result in an increased reaction rate due to the acceleration of charge and mass transfers. Thus, the present work introduces an efficient noble-metal-free UOR for energy generation from urea-based wastewater.

Cooperative coupling of microscopic enhanced electric field and macroscopic efficient bubble traffic for industrial hydrogen evolution

The alkaline hydrogen evolution reaction (HER) for industrial hydrogen generation is a promising way to achieve intermittent energy storage. However, challenges, such as the insufficient supply of adsorbed hydrogen atoms (*H) and slow bubble dynamics, hinder the development of industrial HER. Here, we report a cooperative strategy by leveraging both microscopic enhanced electric field and macroscopic efficient bubble traffic for industrial hydrogen evolution, demonstrated through the NiCoP nanotips on NiP nanorods (NiCoP-tip@NiP). Specifically, during the HER process, the nanotips can accumulate a large number of electrons, enhancing the electric field of the Stern layer. This enhanced electric field accelerates the dissociation of water, resulting in favorable *H for HER. Simultaneously, the confined space between the nanotips hinders the growth of bubbles generated at the tips. Newly formed bubbles will push out the existing bubbles, thus accelerating gas release. As a result, NiCoP-tip@NiP exhibits a low overpotential of 300 mV at 1000 mA cm−2 and maintains stable operation over 90 h at approximately 300 mA cm−2 during HER processes. This cooperative strategy provides profound insights for industrial hydrogen generation.

Electrocatalytic Upgrading of CO2 to Light Olefins in Protonic Ceramic Electrochemical Cells

Light olefins (ethylene, propylene, butylene) are primary building blocks for chemical manufacturing of large volume products including organic chemicals, plastics, and even sustainable aviation fuels. Currently, the dominant commercial process for olefin production is steam cracking of naphtha or ethane, which is highly energy intensive and accounts for a large fraction of global CO2 emissions. To decarbonize olefin production processes, electrochemical CO2-to-olefin conversion coupled with renewable or low-emission energy sources including electricity and heat offers an attractive alternative. Previously, extensive research efforts have been devoted to low temperature electrochemical CO2 reduction in aqueous media, i.e., occurring below 100 °C. This approach, however, still faces enormous scientific and technological challenges in improving CO2 utilization, energy efficiency, and product selectivity. In this work, we have developed a new electrochemical process for direct conversion of CO2 to ethylene at intermediate temperatures (350-500°C) in an electrochemical membrane reactor. This process is based on high-performance protonic ceramic electrochemical cells (PCECs) that integrate CO2 hydrogenation reaction to produce olefins in the cathode and concurrent hydrogen generation reaction in the anode to provide hydrogen for CO2 conversion. Highly active and selective catalysts for CO2-to-olefin conversion have been identified and integrated into the PCECs. Both the catalytic and electrochemical performances of the integrated reactor system are evaluated and optimized. In contrast to the use of molecular H2 in conventional thermal catalytic pathways, the active hydrogen in PCECs could be sourced from different feedstocks including H2O, light alkanes, and ammonia, etc. This work also provides valuable insights into the selection and design of efficient catalysts for electrochemical CO2 conversion at elevated temperatures.

Synergistic Ni-Ce-SSZ-13 catalysts for enhanced dry reforming of methane

The dry reforming of methane (DRM) serves as a pivotal reaction for hydrogen generation and the simultaneous conversion of methane and carbon dioxide, two major greenhouse gases, into syngas that can further be converted into high-value fuels and chemicals. However, catalyst deactivation imposes a major challenge that prohibits the market penetration of DRM. Here we reported a series of bifunctional Ni-Ce catalysts supported on SSZ-13 (Ni-Ce-SSZ-13) and discovered that a small amount of Ce could significantly enhance the activity, selectivity, and stability for DRM. Optimal ratio of Ni to Ce has been identified to yield peak catalytic performance. The optimal performance is correlated with the maximum Ce3+/Ce4+ ratio as revealed by XPS analysis, which implies an increased presence of oxygen vacancies in the catalysts. It played a crucial role in facilitating the oxidation of activated CH4 species at Ni sites, thereby enhancing DRM activity and diminishing the detrimental coke formation. It is also disclosed that integrating proper amount of Ce fosters its interactions with Ni, effectively preventing the agglomeration of Ni sites. This work presents great implications for the rational design and catalytic synergy of bi-/multi-functional zeolite catalysts for other technological applications.

Application of Palladium Mesoporous Carbon Composite Obtained from a Sustainable Source for Catalyzing Hydrogen Generation Reaction

Alternative fuel sources are necessary in today’s economic and environmental climate. Hydrogen fuel arises as an environmentally friendly and energy dense option; however, the volatility of hydrogen gas makes it dangerous to store and utilize. The evolution of hydrogen from hydrogen feedstock materials may prove to overcome this safety barrier, but a catalyst for this reaction is necessary to optimize production. In this work, a composite catalyst comprised of palladium nanoparticles embedded on mesoporous carbon materials (Pd-MCM) was synthesized and characterized by Transmission Electron Microscope (TEM), Powder X-Ray diffraction (P-XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscope (EDS). Various reaction conditions such as concentration of reactant, temperature, and pH were applied in measuring the catalytic activity of Pd-MCM. Results show the catalytic activity of the Pd-MCM composite catalysts increased with increasing concentrations of sodium borohydride, increasing temperature, and lower pH. The reaction involving the Pd-MCM composite had an activation energy of 27.9 kJ mol−1. Reusability trials showed the Pd-MCM composite remained stable for up to five consecutive trials.

Application of Platinum Nanoparticles Decorating Mesoporous Carbon Derived from Sustainable Source for Hydrogen Evolution Reaction

The perpetually fluctuating economic and environmental climate significantly increases the demand for alternative fuel sources. The utilization of hydrogen gas is a viable option for such a fuel source. Hydrogen is one of the most energy-dense known substances; however, it is unfortunately also highly volatile, especially in the diatomic gaseous state most commonly used to store it. The utilization of a hydrogen feedstock material such as sodium borohydride (NaBH4) may prove to mitigate this danger. When NaBH4 reacts with water, hydrogen stored within its chemical structure is released. However, the rate of hydrogen release is slow and thus necessitates a catalyst. Platinum nanoparticles were chosen to act as a catalyst for the reaction, and to prevent them from conglomerating, they were embedded in a backbone of mesoporous carbon material (MCM) derived from a sustainable corn starch source. The nanocomposite (Pt-MCM) was characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Pt-MCM underwent catalytic testing, revealing that the catalytic activity of the Pt-MCM composite catalysts increased with increasing quantities of sodium borohydride, lower pH levels, and higher temperatures. The activation energy of the catalyzed reaction was found to be 37.7 kJ mol−1. Reusability experiments showed an initial drop off in hydrogen production after the first trial but subsequent stability. This Pt-MCM catalyst’s competitive activation energy and sustainable MCM backbone derived from readily available corn starch make it a promising option for optimizing the hydrogen generation reaction of NaBH4.

Edge-Rich 3D Structuring of Metal Chalcogenide/Graphene with Vertical Nanosheets for Efficient Photocatalytic Hydrogen Production.

Constructing pertinent nanoarchitecture with abundant exposed active sites is a valid strategy for boosting photocatalytic hydrogen generation. However, the controllable approach of an ideal architecture comprising vertically standing transition metal chalcogenides (TMDs) nanosheets on a 3D graphene network remains challenging despite the potential for efficient photocatalytic hydrogen production. In this study, we fabricated edge-rich 3D structuring photocatalysts involving vertically grown TMDs nanosheets on a 3D porous graphene framework (referred to as 3D Gr). 2D TMDs (MoS2 and WS2)/3D Gr heterostructures were produced by location-specific photon-pen writing and metal-organic chemical vapor deposition for maximum edge site exposure enabling efficient photocatalytic reactivity. Vertically aligned 2D Mo(W)S2/3D Gr heterostructures exhibited distinctly boosted hydrogen production because of the 3D Gr caused by synergetic impacts associated with the large specific surface area and improved density of exposed active sites in vertically standing Mo(W)S2. The heterostructure involving graphene and TMDs corroborates an optimum charge transport pathway to rapidly separate the photogenerated electron-hole pairs, allowing more electrons to contribute to the photocatalytic hydrogen generation reaction. Consequently, the size-tailored heterostructure showed a superior hydrogen generation rate of 6.51 mmol g-1 h-1 for MoS2/3D graphene and 7.26 mmol g-1 h-1 for WS2/3D graphene, respectively, which were 3.59 and 3.76 times greater than that of MoS2 and WS2 samples. This study offers a promising path for the potential of 3D structuring of vertical TMDs/graphene heterostructure with edge-rich nanosheets for photocatalytic applications.

Highly efficient photocatalytic hydrogen generation of PtPdy nanoframe/2D-CdS: Shape-controlled preparation and property modulation

This work focuses on the structure design of Pt-based alloys, and their influences on 2D-CdS semiconductor photocatalyst in hydrogen (H2) generation reaction from water-splitting under visible light, using traditional experimental techniques and DFT calculations as Pd concave nanocube (Pd CNCs) as a template, PtPdx alloy with cuboctahedron core-shell structure (PtPdx NPs) and cuboctahedron nanoframe (PtPdy NFs) were successfully synthesized via wet chemical routes. The structure of Pt-based alloys was certified by XRD, HRTEM, XPS, and ICP. The Pt-based co-catalysts were photo-deposited on 2D-CdS in an aqueous solution of (NH4)2SO3 while the reaction for photo-generating of H2 occurred. The obtained photocatalysts show excellent activity towards hydrogen generation, i.e., in ascending order, Pd CNCs/2D-CdS (46.1 mmol/h/g) < PtPd1.8 NPs/2D-CdS (55.4 mmol/h/g) < PtPd0.2 NFs/2D-CdS (71.7 mmol/h/g, QE=61.46%, λ=420 nm). Photoelectrochemical tests, ESR, and work functions results indicate that PtPd0.2 NFs have excellent photoelectrochemical performance, the longest lifetime of electrons, and the highest work function, respectively. Moreover, DFT calculations unveil that PtPd0.2 has the largest surface energy and the lowest activation energy ΔGH* which results in the fast charge transfer rate at the PtPd0.2/2D-CdS interface. This work offers a novel thought into the structural design of Pt-based co-catalysts applied in photocatalytic hydrogen generation from water-splitting.

Topological insulator Bi2Te3 and graphene oxide synergistically enhance the photothermal effect and photocatalytic hydrogen evolution activity

Photothermal co-catalysis with the partial conversion of solar energy to thermal energy has the potential to overcome the current bottleneck of realizing efficient photocatalytic hydrogen production with zero artificial energy consumption. However, it is still challenging to design highly efficient photocatalysts that can make use of light and thermal energy synergistically. In this work, we successfully improved the photothermal effect and visible-light-catalyzed hydrogen evolution performance by constructing a novel heterojunction based on the topological insulator Bi2Te3 and graphene oxide (GO) synergistically modified with Zn0.67Cd0.33S. The photocatalytic hydrogen evolution rate of the 1.1 wt% Bi2Te3@0.05% GO@Zn0.67Cd0.33S heterojunctions reached 11.52 mmol/h/g (Apparent Quantum Yield of 21.7%), which was 12.9 times higher than that of pure Zn0.67Cd0.33S. Furthermore, the hydrogen production rate reached 71.79 mmol/h/g without cooling. The improved photocatalytic activity originated from the synergistic enhancement of visible-light absorption and the systematic enhancement of the photothermal effect by the Bi2Te3 and GO. In addition, the high electrical conductivity of Bi2Te3 and the high proton conductivity of GO not only increased the electron transfer rate but also synergistically mediated the acceleration of the hydrogen generation reaction. A strong built-in electric field is formed between Bi2Te3 and Zn0.67Cd0.33S, which greatly facilitates the efficient separation of photogenerated carriers. The obtained results illustrate a promising strategy for the development of efficient new photothermal catalysts.

Efficient hierarchical ZIF-based electro/photocatalyst toward hydrogen generation and evolution

In this study, a well-designed hierarchical BiFeO3/ZIF-67 (BFO-ZIF) composite was successfully synthesized to improve the performance of photocatalytic hydrogen generation in comparison to bare BiFeO3 and ZIF-67. Moreover, the behavior of the resultant electrocatalysts was also investigated in the hydrogen evolution reaction (HER). The synthesized electro-photocatalysts were characterized by various physical and photo/electrochemical analyses. The remarkable outcomes of the composite with 50 wt% of ZIF-67 in hydrogen generation correspond to the high specific surface area of the photocatalyst concurrently with the formation of active sites and new charge channels, leading to a modified charge transfer pathway and lower electron-hole recombination. The maximum H2 generation rate over the optimal BFO-ZIF composite (BFO-ZIF(50)) attained 1617 μmol g−1 h−1 during visible light exposure, surpassing the rates observed for pure BFO and ZIF-67. Furthermore, the BFO-ZIF(50) electrocatalyst, with the onset potential of −0.089 V, resulted in an overpotential of −0.19 V at a current density of 10 mA cm−2, while a Tafel slope of 81.6 mV dec−1 in 1.0 M KOH showed the highest activity. The elevated photocatalytic hydrogen generation and improved HER performance of the developed catalysts signify a synergistic effect resulting from the junction and the Z-scheme charge transfer mechanism between the ZIF-67 and BFO nanomaterials. This introduces the BFO-ZIF composite as an efficient photocatalyst and electrocatalyst for hydrogen generation and evolution reaction.

Carbon Based Supports for Metal Nanoparticles for Hydrogen Generation Reactions Review

Hydrogen represents a highly promising alternative to fossil fuels due to its exceptional attributes. As the most abundant element in the universe, it holds the potential to revolutionize the energy landscape. When combusted, it generates energy, and the byproduct of this process is simply water, making it an environmentally friendly choice. The adoption of hydrogen as a fuel source has faced constraints primarily related to hydrogen storage technology. Nevertheless, innovative solutions are emerging, such as hydrogen feedstock materials like sodium borohydride (NaBH4), which could offer effective storage capabilities. NaBH4 is particularly noteworthy for containing 10.8% hydrogen by weight and for its ability to release hydrogen gas when reacting with water. Although this release occurs at a relatively slow rate, the introduction of a catalyst could enhance the efficiency of hydrogen production. This comprehensive review endeavors to evaluate the catalytic efficacy of metal nanoparticles when paired with environmentally sustainable catalyst support materials derived from fused carbon microspheres and graphene-like materials. These support materials, sourced from renewable origins, will be intricately combined with a spectrum of metal nanoparticles, encompassing gold, silver, platinum, palladium, and copper nanoparticles. The overarching objective is to investigate how these synergistic combinations can catalyze the expedited release of hydrogen from sodium borohydride, thereby contributing to the streamlined and efficient production of this clean and abundant energy source.

In Situ Creation of Surface Defects on Pd@NiPd with Core-shell Hierarchical Structure Toward Boosting Electrocatalytic Activity.

A deep insight into surface structural evolution of the catalyst is a challenging issue to reveal the structure-activity relationship. In this contribution, based on a surface alloying strategy, the dual-functional Pd@NiPd catalyst with a unique core-shell hierarchical structure is developed through selective crystal growth, surface cocrystallization, directional self-assembly, and reduction process. The surface defects are created in situ on the outer NiPd alloy layer in the electrochemical redox processes, which endow the Pd@NiPd catalyst with excellent electrocatalytic activity of hydrogen generation reaction (HER) and oxygen generation reaction (OER) in alkaline media. The optimal Pd@NiPd-2 catalyst requires an overpotential of only 18 mV that is far lower than Pt/C benchmark (43 mV) at the current density of 10 mA cm-2 for the HER, and 210 mV that is far lower than RuO2 benchmark (430 mV) at 50 mA cm-2 for the OER. Density functional theory (DFT) calculations reveal that the outstanding electrocatalytic activity is originated from the creation of surface defect structure that induces a significant reduction in the adsorption and dissociation energy barriers of H2O molecules in the HER and a decrease in the conversion energy from O* to OOH* that resulted from the synergy of two adjacent Pd sites by forming O-bridge. This work affords a typical paradigm for exploiting efficient catalysts and investigating the dependence of electrocatalytic activity on the surface structural evolution.

Supported Manganese Organic Framework as Catalyst for Hydrogen Evolution Reaction

The dependence on fossil fuels has caused significant harmful impact on the environment. The combustion of fossil fuels increases the harmful greenhouse gases including carbon dioxide and methane. The pollution not only worsens the impact of global warming but also affects human health. Many renewable energy sources have been discovered to replace fossil energy, but it is a challenge to find a cheap and effective energy source. Hydrogen arises as a potential candidate due to its high energy density and abundance. However, hydrogen was difficult to store. Hydrogen was often stored in liquid form at high pressure and extremely low temperature conditions. Another method of effectively storing hydrogen is by using hydrogen feedstock materials such as sodium borohydride. Sodium borohydride can be stored at room temperature and has a high gravimetric hydrogen capacity of 10% by weight. However, the process of extracting hydrogen from the materials was slow so it required catalysts. Many precious metal catalysts such as gold and silver catalyst have been applied to improve hydrogen generation reaction, but those metal catalysts were expensive to create. Additionally, those metal catalysts were often agglomerate and impossible to reuse. In this study, we used a non-precious metal complex supported over carbon-based materials to catalyze the hydrogen evolution reaction. We discovered a novel method of synthesizing manganese terephthalate complex at room temperature. The metals complex was coupled with graphene (G) and multiwalled carbon nanotubes (MWCNT) to increase its durability and efficiency. Each material was characterized by Powdered X-ray diffraction (P-XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). During the reaction with sodium borohydride, we discovered that the manganese terephthalate complex converted to manganese boride and further improved the catalysis process. In the first trial, the reaction catalyzed by Mn complex coupled with MWCNT produced 25ml of hydrogen. At the fifth reuse trials, the amount of generated hydrogen (~44 ml) was nearly doubled. A similar phenomenon was observed in Mn complex coupled with graphene. This study introduces a novel method in synthesizing a stable, cheap and efficient catalyst for hydrogen evolution.

STUDY ON THE DISPOSAL OF WASTE FROM THE HYDROGEN GENERATION BY ALUMINUM OXIDATION IN ALKALINE SOLUTION

In face of the current high energy consumption and demand worldwide, a change to a sustainable energy matrix became one of the pillars for global sustainability. The use of renewable energy has been one of the most attractive subjects in recent years. Several public policies in this matter have been suggested and there are ongoing efforts toward their implementation. The United Nations (UN) proposed what is called the 2030 Agenda, which considers 17 Sustainable Development Goals (SDG) to be achieved by the year 2030. In support of the 2030 Agenda, research on the production of fuels from clean and sustainable sources is being conducted by the scientific community around the world. Fossil fuels are finite and also a major source of environmental pollutants, therefore the choice of using renewable sources of energy tends to be an increasingly growing and attractive alternative. Hydrogen is a fuel with a high heating value and is known as the most abundant gaseous element and simplest in chemical structure. The scientific community researching fuel cells has given much attention to the generation and storage of hydrogen. Besides the electrolytic hydrogen production and the reforming of fossil fuels (e.g., natural gas), hydrogen can be generated by metallic means, for example, by oxidation of aluminum in an alkaline solution. The use of recyclable metals, such as aluminum in this study, is an option for sustainable hydrogen generation processes. Nevertheless, like any chemical reaction, part of the products generated are waste, and some are even harmful to the environment, which makes the production of sustainable fuels unfeasible in case of not finding an appropriate technological industrial destination for such waste. The herein study comprises the investigation of the industrial and technological applications of the products of the hydrogen generation reaction from aluminum. Mastering the chemical reaction parameters of that reaction is paramount for the optimal design of a hydrogen generation system. The disposal of the waste is relevant since it makes the energy supply chain complete and sustainable.

Application of TiS2 as an Active Material for Aqueous Calcium-Ion Batteries: Electrochemical Calcium Intercalation into TiS2 from Aqueous Solutions

This study explores the potential of titanium disulfide (TiS2) as an active material for aqueous calcium-ion batteries (CIBs). We investigate the electrochemical redox reactions of calcium ions within TiS2 and assess its suitability for use in aqueous CIBs. Additionally, we examine the impact of varying electrolyte concentrations, ranging from 1.0 to 8.0 mol dm−3, on TiS2 electrode reactions. Our findings reveal that TiS2 exhibits distinct charge–discharge behaviors in various aqueous calcium-ion electrolytes. Notably, at higher electrolyte concentrations, TiS2 effectively suppresses the hydrogen generation reaction caused by water decomposition. In situ X-ray diffraction analysis confirms the intercalation of Ca2+ ions between the TiS2 layers during charging, which is a groundbreaking discovery, signifying TiS2’s applicability in aqueous CIBs. X-ray photoelectron spectroscopy analysis further supports the formation of a solid electrolyte interphase (SEI) on the TiS2 electrode surface, contributing to the suppression of electrolyte decomposition reactions. Furthermore, we investigate the influence of anions in the electrolyte on charge–discharge behavior. Our findings suggest that the choice of anion coordinated with Ca2+ ions affects the SEI formation and cycling performance. Understanding the role of anions in SEI formation is crucial for optimizing aqueous CIBs. In conclusion, this research underscores TiS2’s potential as an active material for aqueous calcium-ion batteries and emphasizes the importance of the electrolyte composition in influencing SEI formation and battery performance, contributing to sustainable and efficient energy storage technologies.

Interface engineering of bifunctional nickel hydroxide/ nickel phosphide heterostructure for efficient intermittent hydrazine-assisted water splitting

Hydrazine oxidation reaction (HzOR) has been proposed to replace the sluggish oxygen evolution reaction (OER) for energy-saving hydrogen generation. However, the rational design of bifunctional electrocatalysts that can simultaneously accelerate HER/HzOR kinetics and the source of the hydrazine chemical substrate are still challenging. Herein, interfacial heterogeneous nickel hydroxide/nickel phosphide microstructures are in-situ grown on nickel foam (Ni(OH)2/Ni2P/NF) via a combined electrodeposition-phosphorization-electrodeposition strategy. After Ni(OH)2 modification, a charge redistribution is triggered between Ni(OH)2 and Ni2P, reducing the charge-transfer resistance and optimizing the adsorption energy of reaction intermediates. Ni(OH)2/Ni2P/NF thus yields an impressive bifunctional electrocatalytic activity for HER and HzOR with potentials of −72 and −14 mV at 10 mA cm−2, respectively. When using Ni(OH)2/Ni2P/NF as both electrodes, decreased cell voltage of 0.357 V is required to drive a current density of 100 mA cm−2 in 0.5 M hydrazine-containing alkaline electrolyte. Furthermore, an intermittent hydrazine-assisted water electrolysis system is proposed to make the combination of hydrazine sewage purification and energy-saving hydrogen production realistic.