Hydrogen Generation Performance Research Articles

Exploring multimetal interactions between FeNi3 alloy and Lu3Ga5O12 metal oxide for improved water splitting performance

The production of energy from fossil fuels generates greenhouse gases, leading to global warming and various environmental impacts. Extensive research into sustainable alternative fuels has identified hydrogen (H2) as a viable option. With net zero carbon emissions, hydrogen presents a promising solution for sustainable and renewable energy. This study employs a simple gel-matrix method to fabricate Ni-Fe alloy-based nanocomposites in alkaline media (1 M KOH). Achieving outstanding performance in hydrogen generation through the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with impressive turn-over frequencies (TOF) of 2.98 s−1 at 177 mV and 1.48 s−1 at 219 mV. Nanocomposite’s unique structure enhances electroactive surface area (347.5 cm2/gram), extending electrocatalytic active sites and durability to 60 h. It shows excellent performance, characterized by low Tafel slopes of 50 mV/dec and 37 mV/dec, and minimal overpotentials of 219 mV for the oxygen evolution reaction (OER) and 177 mV for the hydrogen evolution reaction (HER), reaching a current density of 10 mA cm−2. This study presents a method for synthesizing high-performance, sustainable metal-alloy/garnet hybrid electrocatalysts, offering a new frontier in design of next-generation materials for advanced energy conversion technologies.

TiO2 Films with Macroscopic Chiral Nematic-Like Structure Stabilized by Copper Promoting Light-Harvesting Capability for Hydrogen Generation.

Cellulose nanocrystals (CNCs) have inspired the synthesis of various advanced nanomaterials, opening opportunities for different applications. However, a simple and robust approach for transferring the long-range chiral nematic nanostructures into TiO2 photocatalyst is still fancy. Herein, a successful fabrication of freestanding TiO2 films maintaining their macroscopic chiral nematic structures after removing the CNCs biotemplate is reported. It is demonstrated that including copper acetate in the sol avoids the epitaxial growth of the lamellar-like structure of TiO2 and stabilizes the chiral nematic structure instead. The experimental results and optical simulation demonstrate an enhancement at the blue and red edges of the Fabry-Pérot reflectance peak located in the visible range. This enhancement arises from the light scattering effect induced by the formation of the chiral nematic structure. The nanostructured films showed 5.3 times higher performance in the photocatalytic hydrogen generation, compared to lamellar TiO2, and benefited from the presence of copper species for charge carriers' separation. This work is therefore anticipated to provide a simple approach for the design of chiral nematic photocatalysts and also offers insights into the electron transfer mechanisms on TiO2/CuxO with variable oxidation states for photocatalytic hydrogen generation.

Microstructure and improved hydrogen generation performance via hydrolysis of Mg–Ca alloys with TiC and Ni addition

Mg-xCa (x = 3, 7, 11, 14, wt.%) binary hypoeutectic alloys are successfully synthesized via solidification in the present work. The microstructure, phase compositions and hydrogen generation characteristics of as-cast Mg–Ca alloys and ball milled Mg–Ca composites with TiC and Ni addition have been investigated in this work for a new hydrogen supply source application. A lamellar structure with alternately distributed Mg and Mg2Ca is formed in the eutectic regions of as-cast Mg–Ca binary alloys. It is found that as-cast Mg–Ca binary alloys show extremely sluggish hydrolysis kinetics and low hydrogen yield in both tap water and simulated seawater. Mg2Ca phase preferentially reacts with water during hydrolysis process in simulated seawater. Many cracks arise with hydrolysis reaction, meanwhile, the cracks further assist in the hydrolysis of the internal matrix via assisting water solution transfer. After ball milling with TiC and Ni of Mg–Ca binary alloys, the hydrolysis performance is substantially modified. Mg–14Ca-3wt.%TiC-5wt.%Ni composite generates 836.6 mL g−1 of hydrogen within initial 95 min. The conversion rate of Mg–14Ca-3wt.%TiC-5wt.%Ni composite in simulated seawater is as high as 99.4%, indicating a thorough hydrolysis of Mg and Mg2Ca phases with the catalysis of TiC and Ni. This work shows that microstructure refinement, catalysis, Mg(OH)2 exfoliation and water solution transfer account for the complete hydrolysis.

Design a well-dispersed Ag-based/CoFe2O4–CNT catalyst for hydrogen production via NaBH4 hydrolysis

Green hydrogen is a crucial element in the hydrogen value chain, encompassing hydrogen production, transportation, storage, and application. The production of green hydrogen via NaBH4 hydrolysis (SBH) entails a high cost. However, the fast kinetics of this process with a catalyst compensate for the substantial cost, especially in specific applications, such as local or intermittent use. Silver is known for its excellent catalytic properties. Its high catalytic activity is a key factor in achieving efficient hydrogen generation from (SBH). In this study, a nanocomposite catalyst composed of silver nanoparticles (AgNPs), CoFe2O4, and carbon nanotubes (CNT) was investigated to demonstrate an effective catalyst design approach to achieve enhanced hydrogen generation performance. The H2 production rate in the presence of Ag-based/CoFe2O4–CNT was 320 mL min−1 g−1, and the apparent activation energy was 14.7 kJ mol−1, superior to that of Ag-based catalysts reported in the literature. Analyses of the observed outcomes revealed that the CNT was decorated with well-dispersed AgNPs and CoFe2O4 nanoparticles. The synergistic effects of AgNPs, CoFe2O4, and CNT were demonstrated by analyzing the kinetic behaviour of each component based on systematic comparisons. Furthermore, the paramagnetic property of CoFe2O4 enables harvesting of the catalyst using an external magnetic field, and it was verified that the reactivity of the collected catalyst was maintained throughout seven successive cycles. The outstanding catalytic performance of Ag/CoFe2O4–CNT should be attributed to the uniform dispersion of nanoparticles on the CNT surface. Furthermore, our key approach for developing efficient Ag-based carbon advanced catalysts for SBH in the future is to ensure their suitability for industrial applications.

Engineering of g-C3N4 for Photocatalytic Hydrogen Production: A Review.

Graphitic carbon nitride (g-C3N4)-based photocatalysts have garnered significant interest as a promising photocatalyst for hydrogen generation under visible light, to address energy and environmental challenges owing to their favorable electronic structure, affordability, and stability. In spite of that, issues such as high charge carrier recombination rates and low quantum efficiency impede its broader application. To overcome these limitations, structural and morphological modification of the g-C3N4-based photocatalysts is a novel frontline to improve the photocatalytic performance. Therefore, we briefly summarize the current preparation methods of g-C3N4. Importantly, this review highlights recent advancements in crafting high-performance g-C3N4-based photocatalysts, focusing on strategies like elemental doping, nanostructure design, bandgap engineering, and heterostructure construction. Notably, sophisticated doping techniques have propelled hydrogen production rates to a 104-fold increase. Ingenious nanostructure designs have expanded the surface area by a factor of 26, concurrently extending the fluorescence lifetime of charge carriers by 50%. Moreover, the strategic assembly of heterojunctions has not only elevated charge carrier separation efficiency but also preserved formidable redox properties, culminating in a dramatic hundredfold surge in hydrogen generation performance. This work provides a reliable and brief overview of the controlled modification engineering of g-C3N4-based photocatalyst systems, paving the way for more efficient hydrogen production.

Nanoporous Mg–Zn materials for efficient and controllable in-situ hydrogen generation

Mg is a research focus in the field of in-situ hydrogen generation due to its high activity, abundant reserves and mature circulation mode. However, the passivation issue of Mg bulks and the explosion risk of Mg powders hinder its practical application. In this work, we propose a novel nanoporous Mg-based material, whose nanoscale pores significantly reduce the passivation, and the self-supporting characteristic ensures its safe application. By co-depositing Mg–Zn and adjusting their ratios, three kinds of nanoporous Mg–Zn materials with different morphology and composition are obtained, that is, granular nanoporous (GNP) Mg–Zn, coral-like nanoporous (CNP) Mg–Zn and lotus root-like nanoporous (LNP) Mg–Zn materials. The GNP Mg–Zn material shows the best hydrogen generation performance among the three nanoporous Mg–Zn materials, and realizes an efficient and controllable hydrogen generation. The formation mechanism, the morphology evolution and the hydrogen generation mechanism of the nanoporous Mg–Zn materials are discussed in detail.

Rare earth oxide Y2O3 modified g-C3N4 for efficient photocatalytic hydrogen production: photocatalytic performance and electron transfer channels

This work used a one-step calcination process to prepare g-C3N4 composites with varying Y2O3 loading. XRD, TEM, and XPS verified the structure and morphology of the composite photocatalyst, and its photoelectrochemical and hydrogen production performance were studied. According to the experimental results, it is found that the composite structure between Y2O3 and g-C3N4 effectively suppresses the photoelectron–hole complex and enhances the photocatalytic hydrogen production properties of g-C3N4. Under the irradiation of a 300 W xenon lamp, YCN-3 had superior photocatalytic hydrogen generation performance, achieving a rate of 1079.61 μmol g−1 h−1, which was 2.3 times greater than that of g-C3N4 in its unmodified state. After three consecutive photocatalytic operations, satisfactory stability and reusability were obtained. Finally, the possibility of a mechanism for the photocatalytic charge transfer pathway is discussed, which provides an effective way for g-C3N4 photocatalytic hydrogen production.

Maneuvering magic-sized transition metal chalcogenides nanoclusters for Solar-to-Hydrogen conversion

Magic-sized nanoclusters (MSCs) have recently deemed as a novel and crucial sector of nanomaterials on account of their large absorption coefficient for light harvesting, peculiar quantum confinement effect, and abundant active. Nevertheless, precise control of photoinduced charge carriers over MSCs has so far not yet been reported because of the ultra-short carrier lifetime and intrinsic instability of MSCs, which renders the complexity of MSCs photosystems with photoredox mechanism remaining blank. Herein, we for the first time conceptually demonstrate the grafting of amino-containing organic molecular onto the L-cysteine (L-Cys) ligand of CdSe@L-Cys MSCs as charge transport mediator, and the amino functional group acts as an efficient electron-withdrawing trap, which markedly boosts the charge separation and prolongs the charge lifetime of CdSe@L-Cys MSCs, resulting in the significantly improved photocatalytic hydrogen generation performances under visible light irradiation along with favorable stability. Our work will provide sparking ideas for fine tuning of photoinduced charge separation and transfer over transition metal chalcogenides MSCs photosystems for solar-to-hydrogen energy conversion.

Beyond Conventional Catalysts: Monoelemental Tellurium as a Game Changer for Piezo-Driven Hydrogen Evolution.

The increasing demand for clean hydrogen production over fossil fuels necessitates the development of sustainable piezoelectrochemical methods that can overcome the limitations of conventional electrocatalytic and photocatalytic approaches. In this regard, existing piezocatalysts face challenges related to their low piezoelectricity or active site coverage for hydrogen evolution reaction (HER). Driven by global environmental concerns, there is a compelling push to engineer practical materials for highly efficient HER. Herein, monoelemental 2D tellurium (Te) is presented as a class of layered chalcogenide with a non-centrosymmetric crystal structure (P3121 space group). The refined Te nanosheets demonstrate an unprecedented highly efficient H2 production rate ≈9000µmolg-1h-1 under ultrasonic mechanical vibration due to built-in piezo-potential in the system. The remarkable piezocatalytic performance of Te nanosheets arises from a synergistic interplay between their semi-metallic nature, favorable free energy landscape, enhanced electrical conductivity and outstanding piezoelectricity. As a proof of concept, the theoretical approach based on Density Functional Theory (DFT) validates the findings due to the gradual exposure of active sites on the Te nanosheets leading to a self-optimized catalytic performance for hydrogen generation. Therefore, mechanically driven Te emerges as a promising piezocatalyst with the potential to revolutionize highly efficient and sustainable technology for futuristic applications.

Structure-performance relationship of SrTiO3/S@g-C3N4 nanocomposites for highly active hydrogen production via NaBH4 methanolysis

The catalytic performance of SrTiO3/S@g-C3N4 nanocomposite catalyst for hydrogen production from NaBH4 methanolysis was investigated. The X-ray diffraction (XRD), attenuated total reflectance (ATR) spectroscopy, and scanning electron microscopy (SEM) analyses revealed the structure of the nanocomposite catalyst. The XRD spectrum of SrTiO3/S@g-C3N4 showed the presence of both SrTiO3 and S@g-C3N4 phases. ATR spectroscopy analysis proved the interaction between SrTiO3 and g-C3N4 that facilitates electron-hole separation and charge transfer. The SEM images demonstrated that the SrTiO3/S@g-C3N4 sheets were broken up during growth. The surface area of SrTiO3/S@g-C3N4 was 195 m2/g, which is higher than that of pristine S@g-C3N4 (40 m2/g), while the BJH pore size of SrTiO3/S@g-C3N4 (1.6 nm) was lower than that of S@g-C3N4 (2.0 nm). The band gap of the nanocomposite catalyst was reduced from 2.71 to 2.67 eV after the incorporation of SrTiO3. The PL spectra showed a characteristic peak of S@g-C3N4 at 457 nm, which red-shifted with the addition of SrTiO3. The catalyst SrTiO3/S@g-C3N4 achieved a promising hydrogen production rate of 8537 mL/g.min and a reaction activation energy of 19.20 kJ/mol. These findings show promise for catalytic performance and high efficiency in hydrogen generation from NaBH4 methanolysis.

Rational design of Z-scheme CoS@NC/CdS heterojunction with N doped carbon (NC) as an electron mediator for enhanced photocatalytic H2 evolution

Rational construction of Z-scheme heterojunction photocatalysts have been regarded as a promising approach for enhanced hydrogen generation performance from splitting water. Herein, a Z-scheme heterojunction CoS@NC/CdS using N doped carbon (NC) as an electron mediator bridge was fabricated by coupling CdS with CoS@NC prepared via solid-state self-sulfuring a novel cationic cobalt (Co) based metal–organic framework (namely PZH-42) under argon atmosphere. Notably, the H2 production activity could be optimized by regulating the sulfurization temperature and the content of CoS@NC. The 20-CoS@NC−700/CdS with sulfurization temperature of 700 ℃ and the content for CoS@NC−700 of approximately 20 wt% exhibited the highest H2 generation activity of 20.56 mmol h−1 g−1 with an apparent quantum efficiency (AQE) of 23.98 %, which was 70 and 10-folds as high as that of CdS and CdS/CoS. Such improvement might be attributed to the four synergisms of rapidly separating the electrons and holes by the NC electron mediator bridge in Z-scheme system, retaining electrons at the higher position conduction band (CB) of Z-scheme heterojunction more than that of the type-II heterojunction, increasing the specific surface area and enhancing light absorption range and intensity. More significantly, this rare idea can not only provide a promising strategy for designing highly efficient Z-scheme heterojunction photocatalysts, but also expand the photocatalytic H2 production applications of Co-based metal–organic framework.

Impact of Anchoring Groups on the Photocatalytic Performance of Iridium(III) Complexes and Their Toxicological Analysis.

Three different iridium(III) complexes, labelled as Ir1-Ir3, each bearing a unique anchoring moiety (diethyl [2,2'-bipyridine]-4,4'-dicarboxylate, tetraethyl [2,2'-bipyridine]-4,4'-diylbis(phosphonate), or [2,2'-biquinoline]-4,4'-dicarboxylic acid), were synthesized to serve as photosensitizers. Their electrochemical and photophysical characteristics were systematically investigated. ERP measurements were employed to elucidate the impact of the anchoring groups on the photocatalytic hydrogen generation performance of the complexes. The novel iridium(III) complexes were integrated with platinized TiO2 (Pt-TiO2) nanoparticles and tested for their ability to catalyze hydrogen production under visible light. A H2 turnover number (TON) of up to 3670 was obtained upon irradiation for 120 h. The complexes with tetraethyl [2,2'-bipyridine]-4,4'-diylbis(phosphonate) anchoring groups were found to outperform those bearing other moieties, which may be one of the important steps in the development of high-efficiency iridium(III) photosensitizers for hydrogen generation by water splitting. Additionally, toxicological analyses found no significant difference in the toxicity to luminescent bacteria of any of the present iridium(III) complexes compared with that of TiO2, which implies that the complexes investigated in this study do not pose a high risk to the aquatic environment compared to TiO2.

Development of sustainable energy: Performance investigation of the combined utilisation of a seawater electrolyser and single slope solar desalination still

The primary objective of this work is to investigate experimentally the desalination performance of seawater, hydrogen, and oxygen gas generation through the use of two identical single-slope solar stills. Seawater collected from “Bay of Bengal” was used as the fluid and analysis was conducted at a constant water depth of 20 mm. The system was constructed using mild steel and stainless steel 316 L was used as electrodes. A set voltage and current of 12 V and 40 A was supplied to the electrodes through switched-mode power supply (SMPS). The study investigated the impact of solar radiation and induction of electrolysis system on the performance of solar stills. The results demonstrate a significant positive correlation between solar radiation and still temperature, with 877.1 W/m2 of maximum solar radiation intensity resulting in a still temperature of 53.9 °C. The temperature of the basin water increased by an average of 4.25% upon the addition of an electrolyser. It was noted that with the introduction of electrolyser there was increase in productivity by 48 % than the still without the electrolyser. When the solar radiation was at its peak the maximum amount of hydrogen and oxygen were produced which is 0.44 kg/L and 0.24 kg/L respectively. It was noted that when the system with electrolyser is operated at its peak there was increase in solar still and exergy efficiency by 30.5 % and 9.32 % than the system operated without electrolyser. The economic analysis revealed that the hybrid system which possessed electrolyser has very short pay back period of 1.5 days which is approximately 90 days less than the still without electrolyser. The study shows the use of hybrid system reduces the carbon emission significantly which contributes for its sustainable utilisation. The study highlights the interaction between solar radiation, electrolyser induction, and overall efficiency in the context of seawater desalination and shows the system's strong performance.

Two-dimensional molybdenum boride coordinating with ruthenium nanoparticles to boost hydrogen generation from hydrolytic dehydrogenation of ammonia borane

The coordination between carrier and active metal is critical to the catalytic efficiency of ammonia borane (AB) hydrolysis reaction. In the present study, we report a new type of catalytic support based on molybdenum boride (MBene) MoAl1-xB and demonstrate that the effective combination of MoAl1-xB with Ru nanoparticles can realize the significantly enhanced performance for hydrogen generation. Owing to the efficient activation and dissociation of reactants, the optimal Ru/MoAl1-xB catalyst achieves the large turnover frequency of 494 molH2 molRu-1 min−1, high hydrogen generation rate of 119817 mL min−1 gRu-1 and favorable apparent activation energy of 39.2 kJ mol−1 for the catalytic hydrolysis of AB under alkaline-free condition. The isotopic test suggests the cleavage of OH bond in H2O is the rate-determining step for hydrolysis reaction, while the fracture of B–H bond in AB is also well revealed by attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy. Significantly, the flexible on-demand hydrogen generation is achieved by using chemical switches for on–off AB hydrolysis. This study provides a new support platform based on two-dimensional MBene to exploit efficient catalysts to boost AB dehydrogenation.

High efficiency of energy recovery from formaldehyde wastewater over CoS2@MoS2 heterostructure: Enhanced electronic transfer and mechanism

Recently, the simultaneous recovery of hydrogen energy via purification of formaldehyde (FA) wastewater has been recognized as a promising and environmentally beneficial method. In this study, a novel bis-transition metal disulfide heterojunction material CoS2@MoS2 was prepared by a hydrothermal method for peroxymonosulfate (PMS) activation towards formaldehyde wastewater treatment and synchronous hydrogen evolution. Interestingly, CoS2@MoS2 exhibited high performance on formaldehyde-degrading and hydrogen evolution (k = 12.65 μmol/min), outperforming CoS2 (k = 4.13 μmol/min) and MoS2 (k = 3.28 μmol/min) by 3 and 4 times, respectively. Besides, the impacts of catalyst dosage, PMS dosage, NaOH dosage, FA concentration, and reaction temperature on the system's hydrogen generation performance were thoroughly examined. Moreover, anions (Cl−, NO3− and HCO3−) in aqueous solution were also examined for their impact on hydrogen evolution. Through radical quenching experiments, the superoxide radical (O2−) was identified to be the main reactive oxygen species (ROS), while sulfate radical (SO4−) played a minor role and hydroxyl radical (OH) effect can be ignored in the CoS2@MoS2/PMS system. The heterostructure of CoS2@MoS2 enhanced the conductivity, promoted the activated decomposition of PMS as tested by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and Tafel slope analysis. Additionally, after four cycles, the composite still presented good hydrogen evolution rate. This study furnishes a new method for constructing catalysts with highly efficient towards in-situ FA wastewater purification and clean energy development.

From Co-MOF to Co@carbon–comparison of needle-like catalysts in photo-driven hydrogen evolution

In response to the rising demand for catalytic hydrogen production, more attention is focused on noble-metal-free catalysts such as cobalt-based metal–organic frameworks (MOFs) and their derivatives. Due to the varying activity of cobalt forms in photocatalytic processes, the present study explores the performance of photo-driven hydrogen generation of cobalt nitrilotriacetate (Co-NTA) with metal ions and MOF-derived carbons containing Co/CoOx/CoNx. The needle-like morphology of the obtained Co-NTA template was preserved in carbon materials prepared through carbonization with and without furfuryl alcohol. Carbons featured nitrogen-containing graphitic structures and oxygen functional groups. They were also characterized by a more developed specific surface area and larger pore volume compared to their parent MOF. All materials evolved hydrogen under visible light in a photosensitized system. Owing to the high content of metallic cobalt on the surface of non-impregnated carbon, it produced three times more hydrogen (14.2 mmol g−1) than Co-NTA.

Bifunctional S-scheme Fe7S8/CuIn5S8 heterostructures with S-vacancies for boosted photocatalytic antibiotic degradation and hydrogen evolution

The reasonable designing, interfacial tuning and construction of S-scheme heterostructures offering high performance water pollutants treatment and energy production still remains challenging. Following the structure, band structure and interface function perspective, we prepared Fe7S8/CuIn5S8 heterostructures photocatalysts with sulfur vacancies for superior norfloxacin (NOR) degradation and hydrogen production under visible light. In particular, for optimal 30FS/CIS (30%Fe7S8/CuIn5S8), the H2 evolution was up to 35.6 mmol g−1 h−1 which was 11.5 times than pristine Fe7S8 with TEOA as sacrificial agent. The heterojunction could also show 98.7% degradation of NOR in 90 min under visible light. Interestingly, using NOR pollutant as sacrificial agent under synergistic conditions, 22.7 mmol g−1 h−1 H2 evolution and 98.9% degradation of NOR (in 45 min) was achieved. The significantly boosted photocatalytic pollutant degradation and hydrogen generation performance over Fe7S8/CuIn5S8 hybrids is ascribed to the efficient S-scheme charge transfer and active sites provided by sulfur vacancies (Vs). The deep electron transfer mechanism and the charge transfer efficiency were supported by in-situ XPS, UPS, electrochemical experiments and photoluminescence. Experimental results including scavenging tests and ESR findings provided the direct evidence of photogenerated holes and ●OH radicals for pollutant degradation and electrons in hydrogen generation. This work contributes to effective designing and developing high-activity visible light/solar light assisted heterojunction photocatalysts for realizing superior clean energy generation and pollutant degradation.

Catalysing a sustainable future: Harnessing solar energy with novel Co3O4@VO2 nanocomposites for enhanced photocatalytic hydrogen generation and dye degradation

This study focuses on the hydrothermal synthesis and characterization of Concentration dependent Co3O4@VO2 nanocomposites with varying molar ratios of Co3O4 to VO2 (2:1, 1:1, and 1:2) for efficient hydrogen generation and dye degradation. The structural and morphological characteristics of the prepared nanocomposites were analysed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Crystallographic analysis using XRD confirmed the formation of crystalline Co3O4 with a monoclinic structure, while the presence of VO2 was identified by characteristic peaks in the XPS. Microscopic analysis using SEM and TEM revealed well-dispersed nanocomposites with nanoscale dimensions. Photocatalytic activities were evaluated for hydrogen evolution and dye degradation, with the nanocomposite featuring a 2:1 ratio of Co3O4 to VO2 (CV-21) demonstrating significantly enhanced performance. CV-21 exhibited a lower onset potential and higher current density for hydrogen evolution (2270μmol/h/g), indicating improved photocatalytic activity. Additionally, it displayed rapid and superior dye degradation (93% within 10 min) under sunlight compared to Victoria blue B (VBB) dye. The Co3O4@VO2 nanocomposites, particularly CV-21, demonstrate enhanced photocatalytic performance for hydrogen generation and dye degradation compared to pristine VO2 and Co3O4. This improvement possibly due to synergistic effects between Co3O4 and VO2, optimized structural characteristics, and improved interfacial properties in the nanocomposite structure. These findings highlight the promising potential of Co3O4@VO2 nanocomposites, particularly CV-21, for environmental remediation applications.

Hydrogen generation by hydrolysis of Sc–Sn alloy over a wide temperature range as low as 0 °C

A series of Sc–Sn alloys are prepared by the arc-melting method and their hydrogen generation performance of hydrolysis in pure water is investigated. It was found that only Sc element reacts with water in Sc–Sn alloy, while Sn element is retained as an elemental metal. The reaction temperature of Sc with water can be reduced below 0 °C after Sc and Sn are alloyed. The Sc3Sn2 alloy has the best hydrogen generation performance. Its hydrogen conversion rate is up to 90% at 0 °C for 100 min as well as when the water temperature dropped from 60 °C to 0 °C, the average conversion rate in the first 30 min only dropped from 19.95 mL/min∙g to 14.31 mL/min∙g. The hydrogen generation performance of Sc–Sn alloys depends on the reaction activity after Sc and Sn alloying, the effect of micro galvanic cells and the solidification microstructure in the alloy ingot.

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.