Hydrogen Production Properties Research Articles

Twin Boundaries-Induced Centrosymmetric Breaking of Hollow CaTiO3 Nanocuboids for Piezocatalytic Hydrogen Evolution.

Piezocatalysis, a transformative mechanochemical energy conversion technique, has received considerable attention over the past decade for its role in processes such as hydrogen evolution from water. Despite notable progress in the field, challenges remain, particularly in the areas of limited piezocatalysis efficiency and limited availability of materials requiring a non-centrosymmetric structure. Here, a pioneering contribution is presented by elucidating the piezocatalytic properties of hollow CaTiO3 nanocuboids, a centrosymmetric material with a nominally nonpolar state. Remarkably, CaTiO3 nanocuboids exhibit an impressive hydrogen production rate of 3.44mmolg-1h-1 under ultrasonic vibrations, surpassing the performance of the well-established piezocatalyst BaTiO3 (2.23mmolg-1h-1). In contrast, commercial CaTiO3 nanoparticles do not exhibit piezocatalytic performance. The exceptional performance of hollow CaTiO3 nanocuboids is attributed to the abundance presence of twin boundaries on the {110} facet within its crystal structure, which can impart significant polarization strength to CaTiO3. Extending the investigation to other centrosymmetric materials, such as SrZrO3 and BaZrO3, the experimental results also demonstrate their commendable properties for piezocatalytic hydrogen production from water. This research underscores the significant potential of centrosymmetric materials in piezocatalysis.

Influence of the Interaction of Nickel and Copper with Ceria on Ethanol Steam Reforming over Ni-Cu-CeO2 Catalysts

Catalysts of nickel-ceria, nickel-copper-ceria, and copper-ceria were explored with respect to their properties for hydrogen production through ethanol steam reforming (ESR). They were prepared by coprecipitation of the components within inverse microemulsions to achieve intimate contact between them, and the catalysts were characterized by N2 adsorption measurements, XRD, Raman spectroscopy, TPR, and XPS. The catalysts were tested for the ESR reaction, and they were regenerated with oxygen when significant deactivation took place, as occurred for the copper-containing systems. In contrast, the nickel–ceria catalyst exhibits a high activity and stability despite the formation of an important amount of carbon deposits during the course of the ESR test. The presence of nickel sites, which strongly interact with the ceria support, and which are affected by the presence of copper, and the limitation of copper for C-C bond breaking are invoked to explain the results obtained on the whole.

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.

Electrostatic Self-Assembly of CdS Quantum Dots with Co9S8 Hollow Nanotubes for Enhanced Visible Light Photocatalytic H2 Production.

CdS quantum dots (CdS QDs) are regarded as a promising photocatalyst due to their remarkable response to visible light and suitable placement of conduction bands and valence bands. However, the problem of photocorrosion severely restricts their application. Herein, the CdS QDs-Co9S8 hollow nanotube composite photocatalyst has been successfully prepared by loading Co9S8 nanotubes onto CdS QDs through an electrostatic self-assembly method. The experimental results show that the introduction of Co9S8 cocatalyst can form a stable structure with CdS QDs, and can effectively avoid the photocorrosion of CdS QDs. Compared with blank CdS QDs, the CdS QDs-Co9S8 composite exhibits obviously better photocatalytic hydrogen evolution performance. In particular, CdS QDs loaded with 30% Co9S8 (CdS QDs-30%Co9S8) demonstrate the best photocatalytic performance, and the H2 production rate reaches 9642.7 μmol·g-1·h-1, which is 60.3 times that of the blank CdS QDs. A series of characterizations confirm that the growth of CdS QDs on Co9S8 nanotubes effectively facilitates the separation and migration of photogenerated carriers, thereby improving the photocatalytic hydrogen production properties of the composite. We expect that this work will facilitate the rational design of CdS-based photocatalysts, thereby enabling the development of more low-cost, high-efficiency and high-stability composites for photocatalysis.

Layered deposited MoS2 nanosheets on acorn leaf like CdS as an efficient anti-photocorrosion photocatalyst for hydrogen production

Photocatalytic hydrogen production through water splitting is an appealing technology to alleviate the escalating fossil fuel energy crisis. The advancement of visible-light-driven hydrogen production systems is a crucial aspect of hydrogen research. In this study, we successfully synthesized a unique acorn leaf-like CdS/MoS2 material via a hydrothermal method, with layered deposited MoS2 nanosheets, for driving hydrogen generation under illumination. By systematically varying the sodium molybdate concentration, We looked into how the MoS2 affected the optical properties and photocatalytic performance of the acorn-leaf-like CdS/MoS2.Under illumination, the photocatalytic hydrogen production performance of the acorn leaf-like CdS/MoS2 reached 70.05 mmol·g−1·h−1 (at a catalyst dosage of 10 mg), which is approximately 330 times higher than the unmodified CdS original material. It was determined that the apparent quantum yield at 450 nm was 2.104 %, corresponding to a solar-to-hydrogen conversion efficiency of 9.383 %. Mechanistic investigations revealed that MoS2 nanosheets function as co-catalysts and electron acceptors, effectively promoting electron transfer and the separation of photogenerated charge carriers from CdS, thereby consequently enhancing the kinetics of surface hydrogen evolution. This work offers valuable insights into the development of efficient photocatalysts with anti-photocorrosion properties for sustainable hydrogen production.

Synergistic enhancement of surface-doped Mn and Cu-mediated hierarchical reconstruction in Co–Ni–Cu–Mn electrocatalyst for hydrogen production in proton exchange membrane water electrolyzer

Multicomponent electrocatalysts offer inherent advantages because of the synergistic effects among their constituents at the atomic scale, rendering them suitable for enhancing the catalytic activity of the hydrogen evolution reaction (HER). In this study, self-supported Co–Ni–Cu–Mn electrocatalysts are deposited on porous carbon paper via one-step electrodeposition. These electrocatalysts exhibit remarkable synergistic enhancements, resulting in both improved acidic HER activity and overall durability. This synergy arises from the development of hierarchical structures triggered by Cu and Mn-doped surface. During HER, Cu leaches from the catalyst surface, while simultaneously, surface-doped Mn synergistically prevents activity degradation and facilitates surface reconstruction. The combination of these interactions helps to achieve a low overpotential of 100 mV at 10 mA cm−2. The Co–Ni–Cu–Mn electrocatalyst is applied as a high-efficient cathode gas diffusion electrode for proton exchange membrane water electrolyzer (PEMWE). The PEMWE single-cell equipped with Pt-free cathode achieves an outstanding performance of 2.57 A cm−2 at 2.0 Vcell, with exceptional stability for 60 h under high current density of 2.0 A cm−2. The successful implementation of the quaternary electrocatalyst highlights its potential for tailoring catalytic properties for hydrogen production, effectively bridging the gap between fundamental understanding and practical realization for cost-efficient PEMWE.

The activation of water by AlmGanXp [(X = In, Sn), (m + n + p ≤ 4)] clusters

Using density functional theory to study the activity of the first O–H in water activated by Ga–In and Ga–Sn clusters, and using displacement energy to explore the solubility of aluminum in Ga–In and Ga–Sn, the experimental phenomena of reaction rate and crack size were theoretically explained. Then the theoretical results were validated by the following well-designed experiments. We hope this study could provide theoretical support and guidance for the development of aluminum alloys with better hydrogen production properties in the future.

Hydrogen generation by hydrolysis of ultrafine microstructure Mg[sbnd]10Ni alloy wire

This work presents a MgNi alloy wire prepared by a combination of extrusion and multi-pass hot drawing for fast hydrogen generation from aqueous NaCl solution. The results showed that the hydrogen generation rates of the wire were significantly improved compared to the as-cast alloy. The hydrolysis of the MgNi alloy wire produced 820 ml g−1 hydrogen in 16 min and the maximum hydrogen generation rates reached 67.86 ml g−1 min−1 in 3.5 % NaCl solution and at 25 °C. The improved hydrogen production properties can be attributed to the increase in specific surface area and the ultrafine microstructure with highly dispersed submicron Mg2Ni particles of the MgNi alloy wire.

Exotic Electronic Properties of 2D Nanosheets Isolated from Liquid Phase Exfoliated Phyllosilicate Minerals.

Spectrally inactive, electrically insulating, and chemically inert are adjectives broadly used to describe phyllosilicate minerals like mica and chlorite. Here, the above is disproved by demonstrating aqueous suspensions of liquid exfoliated nanosheets from five bulk mica types and chlorite schist. Nanosheet quality is confirmed via transmission electron and X-ray photoelectron spectroscopies, as well as electron diffraction. Through Raman spectroscopy, a previously unreported size- and layer-dependent spectral fingerprint is observed. When analyzing the high-yield suspensions (≈1mgmL-1 ) through UV-vis spectroscopy, all phyllosilicates present bandgap (Eg ) narrowing from ≈7eV in the bulk to ≈4eV for monolayers. Unusually, the bandgap is inversely proportional to the areal size (A) of the nanosheets, measured via atomic force microscopy. Due to an unrecorded quantum confinement effect, nanosheet electronic properties scale toward semiconducting behavior (bandgap ≈3eV) as nanosheet area increases. Furthermore, modeling X-ray diffraction spectra shows that the root cause of the initial bandgap narrowing is lattice relaxation. Finally, with their broad range of isomorphically substituted ions, phyllosilicate nanosheets show remarkable catalytic properties for hydrogen production.

Severe Plastic Deformation for Advanced Electrocatalysts for Electrocatalytic Hydrogen Production

Developing electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of water splitting is very important for electrocatalytic hydrogen production. Very recently, emerging study have demonstrated that materials show some superior HER and OER performances of water splitting after processed by severe plastic deformation (SPD). In this work, recent advances on electrochemical hydrogen production performances of materials by SPD are summarized. Some basic principles of electrocatalytic water splitting are briefly described, and then the development of SPD technology and recent advances on SPDed materials with enhanced hydrogen production properties are comprehensively reviewed. Moreover, future direction on SPDed materials for hydrogen production is also prospected.

Novel visible-light-driven direct Z-scheme WO3/Mn-ZIF-67 heterojunctions with facilitation photocatalytic activity

In order to alleviate the problem of water resource pollution, the exploration of visible-light driven excellent photocatalysts is an important issue for worldwide sustainable green energy systems. In this work, a novel binary hybrid nanocomposite WO3/Mn-ZIF-67 heterojunction photocatalyst was prepared through simple template method. It was based on the particular structure and performance of metal-organic framework (MOFs), and the structure of the heterojunction photocatalyst was expressed by SEM, TEM, FT-IR, DRS, XPS, PXRD and EIS. The novel WO3/Mn-ZIF-67 heterostructure showed more efficient photocatalytic properties for Tetracycline (TC) decomposition and hydrogen production than that of WO3 monomer and Mn-ZIF-67 monomer under simulated light, respectively. Owing to the active radical catch and ESR experiments, a rational solid-state Z-model electron migration theory was rendered. Z-model mechanism can neatly be obligated to the raised degradative capacity of the photocatalytic reaction. The wonderful high-efficiency photocatalytic decomposability of heterojunction was mainly due to: (i) the WO3 structure improved dramatically the light absorption efficiency of the photocatalyst. (ii) the doped Mn enhanced the photoelectric properties of ZIF-67. (iii) contact with the close interface between WO3 and Mn-ZIF-67 produced efficient charge separation and migration.

Dual-Doping Strategy for Enhancing Hydrogen Evolution on Molybdenum Carbide Catalysts

Hydrogen evolution reaction (HER) is a topic of great interest due to its efficient hydrogen production properties, which can address the increasing demand for clean and sustainable energy sources. On the other hand, molybdenum carbide (MoC) has been widely studied due to its noble metal-like surface electronic properties. In the HER process, it is crucial to regulate the Mo−H bonding energy effectively and increase the electron transfer rate on the MoC catalyst surface in a rational manner. In this study, we introduce highly electronegative nitrogen and non-noble transition metal atoms (Cu or Co) into the molybdenum carbide crystal lattice (N−M−MoC, M: Cu, or Co), which leads to a dual—doping effect. This effect results in the rearrangement of the electronic configuration on the catalyst surface and the enrichment of electrons around Mo atom, leading to an optimization in the Mo−H bonding energy. Moreover, the unique two-dimensional nano-sheet structure of the N−M−MoC materials further promotes the electron transfer and exposure of active sites. Benefiting from the above, the HER performance of the N−M−MoC is significantly improved. Among them, N−Cu−MoC exhibits the lowest overpotential (η10 = 158 mV) and highest stability (about 30 h) in alkaline solutions.

A Universal Synthesis Strategy for Lanthanide Sulfide Nanocrystals with Efficient Photocatalytic Hydrogen Production.

As an important lanthanide (Ln)-based functional materials, the Ln chalcogenides possess unique properties and various applications. However, the controllable synthesis of Ln chalcogenide nanocrystals still faces great challenges because of the rather poor affinity between Ln and chalcogenide ions (S, Se, Te) as well as strong preference of combination with existed oxygen. Herein, a facile but general heterogeneous nucleation synthetic strategy is established toward a series of colloidal ternary Cu Ln sulfides nanocrystals using the Ln dithiocarbamates and CuIas precursors. To extend this synthetic protocol, similar strategy is used to prepare six kinds of high quality CuLnS2 nanocrystals, while the bulk ones are only obtained by the traditional solid-state reaction at rigorous condition. Importantly, high-entropy nanocrystals CuLnS2 and CuEux Ln2-x S3 which contain six Lnelements (Nd, Sm, Gd, Tb, Dy) are readily obtained by the co-decomposed process attributed to their similar diffusion speed. As a proof-of-concept application, CuEu2 S3 nanocrystals showed efficient photocatalytic hydrogen production properties.

Construction of CoS/NiS@CuS with dandelion flower-like heterostructures as efficient catalysts for overall urea splitting

The exploration of efficient and inexpensive electrocatalysts is of great importance for sustainable hydrogen production by water splitting. In this paper, we reported a simple preparation method for in situ growth of NiCoOOH@CuO on nickel foam by a two-step hydrothermal method to generate CoS/NiS@CuS with a dandelion-like heterostructure after a one-step sulfidation. The CoS/NiS@CuS electrode has excellent electrochemical properties for urea oxidation reactions, oxygen evolution reactions and urea electrolysis. Electrochemical performance was tested in alkaline solution, the overpotential of CoS/NiS@CuS is only 190 mV for the oxygen evolution reaction, the potential of CoS/NiS@CuS is only 1.35 V for urea oxidation, and the overpotential of CoS/NiS@CuS is only 110 mV at 10 mA cm−2 for the hydrogen evolution reaction, which are one of the best activities reported so far. Density functional theory calculations show that CoS2 exhibits the minimum Gibbs free energy of hydrogen, which plays an important role in promoting the reaction rate. The presence of CoS2 increases the electrical conductivity of the material, and synergistic effect of NiS and CuS makes the material exhibit superior hydrogen production properties. Our work proves that transition-metal sulfides have great potential in the direction of urea splitting, which provides new ideas and directions for subsequent exploration in the direction of transition-metal sulfides.

Heterostructured 2D/2D ZnIn2S4/g-C3N4 nanohybrids for photocatalytic degradation of antibiotic sulfamethoxazole and photoelectrochemical properties

In recent years, antibiotic drugs have been extensively used owing to increased industrial growth, and this has created issues related to drinking water and a green environment. Different techniques have been used to resolve these issues, among which heterogeneous photocatalysis has been widely explored for the elimination of toxic compounds from wastewater resources. In this study, ZnIn2S4, g-C3N4, and ZnIn2S4/g-C3N4 hybrid heterostructured composites are synthesized via hydrothermal method and used these (i) for the removal of antibiotic sulfamethoxazole pollutant and (ii) photoelectrochemical water oxidation. The nanomaterials were characterized using X-ray diffraction, Scanning electron microscopy, transmission electron microscopy, and UV–vis spectroscopy. The developed hybrid heterostructured composites were able to degrade sulfamethoxazole pollutants as well as offer improved photoelectrochemical properties compared to pristine samples. The catalytic performance of the materials developed under visible light irradiation was greatly improved for the degradation of the antibiotic drug up to 89.4% in 2 h. Moreover, the hybrid heterostructured photoelectrode showed a better photocurrent density (8.68 mA/cm2) and exhibited ∼19.2 and 29.9 times greater photocurrent density than the pristine photoelectrodes. Such a considerably increased catalytic activity was attributed to the active separation of charge carriers and transmission. The study offers an innovative approach to develop effective catalysts, and for the degradation of sulfamethoxazole as well as the PEC properties for hydrogen production.

1D/1D W18O49/Cd0.9Zn0.1S S-scheme heterojunction with spatial charge separation for high-yield photocatalytic H2 evolution

Semiconductor photocatalytic water splitting is a green way to convert solar energy into chemical energy, but the recombination of electron and hole pairs and the low utilization of sunlight restrict the development of photocatalytic technology. By comparing the morphologies and hydrogen production properties of different proportions of solid solutions (CdxZn1-xS), one-dimensional (1D) Cd0.9Zn0.1S nanorods (NRs) with the best photocatalytic properties are obtained. In addition, 1D W18O49 nanowires are assembled on the surface of 1D Cd0.9Zn0.1S NRs to construct a novel 1D/1D step-scheme (S-scheme) W18O49/Cd0.9Zn0.1S heterojunction photocatalyst. The W18O49/Cd0.9Zn0.1S heterojunction expands the optical absorption capacity of Cd0.9Zn0.1S NRs to provide more energy for the photoexcitation of electrons. The optimal hydrogen production rate of W18O49/Cd0.9Zn0.1S NRs with W18O49 content of 9 wt% is as high as 66.3 mmol·h−1·g−1, which is 5.7 times and 1.6 times higher than that of Cd0.9Zn0.1S NRs and 1 wt% Pt/Cd0.9Zn0.1S NRs. The apparent quantum efficiency (AQE) of 9 wt% W18O49/Cd0.9Zn0.1S reaches 56.0 % and 25.9 % under light wavelength irradiation at 370 and 456 nm, respectively. After the 20 h cycle stability test, the activity of photocatalytic hydrogen evolution does not decrease, due that the severe photo-corrosion of Cd0.9Zn0.1S NRs is efficiently inhibited. This work not only provides a simple and controllable synthesis method for the preparation of heterojunction structure, but also opens up a new way to improve the hydrogen evolution activity and stability of sulfur compounds.

Applications of surface modification trititanate nanotubes as PEC and hydrogen production device material

Herein, we report that self-assembled surface modification of 4-hydroxy thiophenol and gold nanoparticles imparted trititanate nanotubes (TiNTs) with stable, highly efficient hydrogen production and Photoelectrochemical (PEC) properties. After gold nanoparticles decoration, the modified TiNTs exhibited the photocurrent density of 232 [Formula: see text]A/cm2 at 0 V versus Ag/AgCl, with onset potentials ([Formula: see text]) of −0.4 V versus Ag/AgCl. Our process uses 4-hydroxy thiophenol to achieve control over the bond between gold particles and TiNTs, and improves the distribution uniformity of gold nanoparticles on the surface of TiNTs, which leads to above 90% Faradaic efficiency during 3 h water splitting reaction for hydrogen production.

An efficient and multifunctional S-scheme heterojunction photocatalyst constructed by tungsten oxide and graphitic carbon nitride: Design and mechanism study

The design of multifunctional photocatalyst with strong redox performance is the key to achieve sustainable utilization of solar energy. In this study, an elegant S-scheme heterojunction photocatalyst was constructed between metal-free graphitic carbon nitride (g-C3N4) and noble-metal-free tungsten oxide (W18O49). As-established S-scheme heterojunction photocatalyst enabled multifunctional photocatalysis behavior, including hydrogen production, degradation (Rhodamine B) and bactericidal (Escherichia coli) properties, which represented extraordinary sustainability. Finite-difference time-domain (FDTD) simulations manifested that the integration of double-layer hollow g-C3N4 nanotubes with W18O49 nanowires could expand the light harvesting ability. Demonstrated by density functional theory (DFT) calculations and electron spin resonance (ESR) measurements, the S-scheme heterojunction not only promoted the separation of carriers, but also improved the redox ability of the catalyst. This work provides a theoretical basis for enhancing the photocatalytic performances and broadening the application field of photocatalysis.

Effect of Fe on the Hydrogen Production Properties of Al-Bi-Sn Composite Powders.

Fe additives may play an important role in the preparation of aluminum-based hydrolysis hydrogen powder, with high hydrogen yield, low cost, and good oxidation resistance. Therefore, it is necessary to ascertain the effect of Fe on the hydrogen production performance of Al-Bi-Sn composite powders. According to the calculated vertical cross-section of the Al-10Bi-7Sn-(0~6)Fe (wt.%) quasi-binary system, Al-10Bi-7Sn-xFe (x = 0, 0.5, 1.5, 3) wt.% composite powders for hydrogen production were prepared by the gas-atomization method. The results showed that the Al-10Bi-7Sn-1.5Fe (wt.%) powder exhibited an extremely fast hydrogen generation rate at 50 °C, which reached 1105 mL·g−1 in 27 min in distilled water, 1086 mL·g−1 in 15 min in 0.1 mol·L−1 NaCl solution, and 1086 mL·g−1 in 15 min in 0.1 mol·L−1 CaCl2 solution. In addition, the antioxidant properties of these powders were also investigated. The results showed that the hydrogen production performance of the Al-10Bi-7Sn-1.5Fe (wt.%) powder could retain 91% of its hydrogen production activity, even though the powder was exposed to 25 °C and 60 RH% for 72 h. The addition of Fe not only promoted the hydrogen generation rate of the Al-Bi-Sn composite powders, but also improved their oxidation resistance. The Al-10Bi-7Sn-1.5Fe (wt.%) composite powder shows great potential for mobile hydrogen source scenarios with rapid hydrogen production.

Study on the hydrogen production properties and electron transfer mechanism of CdS/WO3 composite photocatalyst

In this paper, CdS nanoparticles with uniform grain sizes of 40–80 nm were prepared using oleic acid and oleylamine as surfactants by a hydrothermal method. Then, to promote the separation of charge carriers, CdS nanoparticles were loaded on WO3 nanorods to obtained CdS/WO3 heterojunction photocatalyst by a self-assemble method. The structure of CdS/WO3 was studied by XRD, SEM, TEM, XPS and zeta potential. In addition, the photocatalytic performance of CdS/WO3 was researched by UV–Vis, PL spectra and H2 evolution tests under visible light. The results showed that constructing heterojunction improved the separation of charge carriers and the hydrogen evolution rate of CdS/WO3 (mass ratio = 1:3) was up to 35.48 μmol/g/h, which is the best and 68.39% higher than pure CdS. What's more, it was determined that the electronic migration mechanism in CdS/WO3 is the Z-scheme by analyzing the results of H2 evolution tests and EPR.