Photocatalyst For Hydrogen Evolution Research Articles

Ultrasonically anchored MoO3-g-C3N4 photocatalyst for enhanced solar driven hydrogen generation and environmental remediation

An ultrasonic fabrication of MoO3-g-C3N4 photocatalyst for substantially better photocatalytic recital is presented. XRD and FTIR confirmed the orthorhombic phase of MoO3-g-C3N4. The SEM manifests the oblate-like structure of g-C3N4 and nano rod-like morphology for MoO3 and MoO3-g-C3N4, respectively. The photocatalytic properties are evaluated by photoelectrochemical (PEC) and photodegradation measurements under visible light. The linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) comprehend MoO3-g-C3N4 as a hydrogen evolution photocatalyst. The photocurrent density of MoO3-g-C3N4 is recorded beyond 7.5 mA/cm2, which is approximately 5–6 folds greater than pure MoO3 and g-C3N4. In addition, the visible light exposure showed MoO3-g-C3N4 photocatalyst could decompose methylene blue (MB) dye up to 93%. The efficient separation and transfer of charges allocated to MoO3-g-C3N4 follow Z-scheme and pseudo-first-order kinetic reaction. The creation of heterojunctions among g-C3N4 and MoO3 suppresses the unfavorable electron-hole pairs recombination process and therefore recesses charge transfer resistance, hence augmenting photocatalytic performance.

One-Step MOF-Templated Strategy to Fabrication of Ce-Doped ZnIn2 S4 Tetrakaidecahedron Hollow Nanocages as an Efficient Photocatalyst for Hydrogen Evolution.

Achieving structure optimizing and component regulation simultaneously in the ZnIn2S4‐based photocatalytic system is an enormous challenge in improving its hydrogen evolution performance. 3D hollow‐structured photocatalysts have been intensively studied due to their obvious advantages in solar energy conversion reactions. The synthesis of 3D hollow‐structured ZnIn2S4, however, is limited by the lack of suitable template or synthesis methods, thereby restricting the wide application of ZnIn2S4 in the field of photocatalysis. Herein, Ce‐doped ZnIn2S4 photocatalysts with hollow nanocages are obtained via one‐step hydrothermal method with an ordered large‐pore tetrakaidecahedron cerium‐based metal–organic frameworks (Ce‐MOFs) as template and Ce ion source. The doping of Ce and the formation of ZnIn2S4 tetrakaidecahedron hollow nanocages with ultrathin nanosheet subunits are simultaneously induced by the Ce‐MOFs, making this groundbreaking work. The Ce‐doped ZnIn2S4 with a nonspherical 3D hollow nanostructure inherit the tetrakaidecahedron shape of the Ce‐MOF templates, and the shell is composed of ultrathin nanosheet subunits. Both theoretical and experimental results indicate that the doping of Ce and the formation of hollow nanocages increase light capture and the separation of photogenerated charge carriers.

Ethanol Solvothermal Treatment on Graphitic Carbon Nitride Materials for Enhancing Photocatalytic Hydrogen Evolution Performance.

Recently, Pt-loaded graphic carbon nitride (g-C3N4) materials have attracted great attention as a photocatalyst for hydrogen evolution from water. The simple surface modification of g-C3N4 by hydrothermal methods improves photocatalytic performance. In this study, ethanol is used as a solvothermal solvent to modify the surface properties of g-C3N4 for the first time. The g-C3N4 is thermally treated in ethanol at different temperatures (T = 140 °C, 160 °C, 180 °C, and 220 °C), and the Pt co-catalyst is subsequently deposited on the g-C3N4 via a photodeposition method. Elemental analysis and XPS O 1s data confirm that the ethanol solvothermal treatment increased the contents of the oxygen-containing functional groups on the g-C3N4 and were proportional to the treatment temperatures. However, the XPS Pt 4f data show that the Pt2+/Pt0 value for the Pt/g-C3N4 treated at ethanol solvothermal temperature of 160 °C (Pt/CN-160) is the highest at 7.03, implying the highest hydrogen production rate of Pt/CN-160 is at 492.3 μmol g−1 h−1 because the PtO phase is favorable for the water adsorption and hydrogen desorption in the hydrogen evolution process. In addition, the electrochemical impedance spectroscopy data and the photoluminescence spectra emission peak intensify reflect that the Pt/CN-160 had a more efficient charge separation process that also enhanced the photocatalytic activity.

S-scheme heterojunction of CuBi2O4 supported Na doped P25 for enhanced photocatalytic H2 evolution

Rational design and construction of Step-scheme (S-scheme) photocatalyst have attracted considerable attention in the photocatalytic field. In this study, a series of Step-scheme (S-scheme) CuBi2O4/Na doped P25 photocatalysts (CBO/Na–P25) were synthesized through a facile hydrothermal method. CBO/Na–P25 photocatalyst without co-catalyst exhibited good photocatalytic performance for hydrogen evolution, and the H2 yield rate of the 7.5%CBO/Na–P25 sample achieved 2695.73 μmol/gcat/h after 4 h of illumination, which was more than 37.8, 13.7 and above 100 times those of pure P25, Na–P25 and CuBi2O4. The calculated apparent band gap of P25 decreased by Na doping and the construction of CuBi2O4/Na–P25 heterojunction contributed to efficient interfacial charge separation. Meanwhile, the S-scheme carrier transfer mechanism for the CuBi2O4/Na–P25 heterojunction photocatalyst was verified by the experimental results under different light wavelengths. This work demonstrated that the P25 based S-scheme heterojunction is a promising photocatalyst for hydrogen evolution.

Electroluminescence and photocatalytic hydrogen evolution of S,N co-doped graphene oxide quantum dots

S,N-GOQDs with stable electroluminescence, photoluminescence, and photocatalytic properties have been developed. They can be used as emitters for LED devices and as photocatalysts for hydrogen evolution in photo-electro-chemical energy conversion.

Ni12 tetracubane cores with slow relaxation of magnetization and efficient charge utilization for photocatalytic hydrogen evolution.

We report two Ni12 multicubane topologies enclosed in the polyanions [Ni12(OH)9(WO4)3(PO4)(B-α-PW9O34)3]21-{Ni12W30} and [Ni12(OH)9(HPO4)3(PO4)(B-α-PW9O34)(A-α-PW9O34)2]21-{Ni12W27} that magnetically behave as Ni12 units clearly distinguishing them from typical Ni4 cubanes as shown by magnetic studies together with high field and frequency electron paramagnetic resonance (HFEPR). Beyond the unprecedented static properties, {Ni12W30} shows the unusual coexistence of slow relaxation of the magnetization and a diamagnetic ground state (S = 0), providing the unique opportunity of studying the essentially elusive magnetic relaxation behavior in excited states. The cubane-topology dependent activity of {Ni12W30} and {Ni12W27} as homogeneous HER photocatalysts unveils the structural key features significant for the design of photocatalysts with efficient charge utilization exemplified by high quantum yields (QY) of 10.42% and 8.36% for {Ni12W30} and {Ni12W27}, respectively.

An investigation on PANI/NENP-1 composite as a novel photocatalyst for photocatalytic dye wastewater degradation and photocatalytic hydrogen evolution

Integrating nitrogen-enriched nanoporous polytriazine COF on polyaniline nanofiber tube photocatalysts forms a unique interfacial structure for the efficient photocatalytic degradation of dye wastewater and hydrogen evolution under solar light.

Using sound to synthesize covalent organic frameworks in water

Covalent organic frameworks (COFs) are typically synthesized using solvothermal conditions (>120 °C, >72 hours) in harmful organic solvents. Here we report a strategy to rapidly (<60 minutes) synthesize imine-linked COFs in aqueous acetic acid using sonochemistry and thus avoid most of the disadvantages of solvothermal methods. Using the sonochemical method, we synthesized to our knowledge previously unreported COFs. The crystallinity and porosity of these COFs is comparable to or better than those of the same materials made by established solvothermal routes. The sonochemical method even works in sustainable solvents, such as food-grade vinegar. The generality of the method is shown in the preparation of a 2D COF with pendant functionalization and of a COF with 3D connectivity. Finally, a COF synthesized sonochemically acts as an excellent photocatalyst for the sacrificial hydrogen evolution from water, showing a more sustained catalytic performance compared with that of its solvothermal analogue. The speed, ease and generality of this sonochemical method together with improved material quality makes the use of sound an enabling methodology for the rapid discovery of functional COFs. A sonochemical route rapidly synthesizes covalent organic frameworks (COFs) in aqueous solutions of acetic acid. This method has operational advantages compared with conventional solvothermal routes and yields COFs of higher crystallinity and porosity, and hence improved materials properties.

Fast charge transfer kinetics in an inorganic–organic S-scheme heterojunction photocatalyst for cooperative hydrogen evolution and furfuryl alcohol upgrading

Inorganic Znln2S4 nanosheets were grown in situ on organic Tp-Tta COF nanoplates to construct an inorganic–organic S-scheme photocatalyst for synergetic hydrogen precipitation and furfuryl alcohol upgrading oxidation.

Construction of Core-Shelled Hollow Cupc/Zn0.5cd0.5s Photocatalyst for Stable Hydrogen Evolution Under Visible-Light Irradiation

Construction of Core-Shelled Hollow Cupc/Zn0.5cd0.5s Photocatalyst for Stable Hydrogen Evolution Under Visible-Light Irradiation

Rational catalyst design for spatial separation of charge carriers in a multi-component photocatalyst for effective hydrogen evolution

This manuscript comprehensively reviews the effect of spatial separation of charge carriers and novel strategies to achieve spatially separated active sites for enhancing photocatalytic hydrogen evolution over different photocatalyst systems.

Ultrathin ZIS nanosheets encapsulated in metal–organic-framework-derived CNCo-Fe3O4 as an efficient functional photocatalyst for hydrogen evolution

The reported CNCo-Fe3O4/ZIS heterojunction catalysts exhibit excellent photocatalytic water splitting and long-term stability under visible-light irradiation, indicating their great potential in improvement of the greenhouse effect.

Reversing electron transfer in a covalent triazine framework for efficient photocatalytic hydrogen evolution.

Covalent triazine-based frameworks (CTFs) have emerged as some of the most important materials for photocatalytic water splitting. However, development of CTF-based photocatalytic systems with non-platinum cocatalysts for highly efficient hydrogen evolution still remains a challenge. Herein, we demonstrated, for the first time, a one-step phosphidation strategy for simultaneously achieving phosphorus atom bonding with the benzene rings of CTFs and the anchoring of well-defined dicobalt phosphide (Co2P) nanocrystals (∼7 nm). The hydrogen evolution activities of CTFs were significantly enhanced under simulated solar-light (7.6 mmol h−1 g−1), more than 20 times higher than that of the CTF/Co2P composite. Both comparative experiments and in situ X-ray photoelectron spectroscopy reveal that the strong interfacial P–C bonding and the anchoring of the Co2P cocatalyst reverse the charge transfer direction from triazine to benzene rings, promote charge separation, and accelerate hydrogen evolution. Thus, the rational anchoring of transition-metal phosphides on conjugated polymers should be a promising approach for developing highly efficient photocatalysts for hydrogen evolution.

Double-Shelled Ceo2 Coupled Cdzns Nanoparticles as an Efficient Heterojunction Visible Light Photocatalyst for Hydrogen Evolution

Double-Shelled Ceo2 Coupled Cdzns Nanoparticles as an Efficient Heterojunction Visible Light Photocatalyst for Hydrogen Evolution

Hybrid Heterostructure of Transition Metal Dichalcogenides as Potential Photocatalyst for Hydrogen Evolution

Hybrid Heterostructure of Transition Metal Dichalcogenides as Potential Photocatalyst for Hydrogen Evolution

Violet phosphorus: an effective metal-free elemental photocatalyst for hydrogen evolution

Violet phosphorus, a non-metallic elemental layered structure, has not been reported as a photocatalyst due to the lack of its resources. An excellent photocatalytic H2 evolution rate of 675 ± 109 μmol h-1 g-1 with high stability has been achieved by the violet phosphorus simply dispersed in deionized water with addition of 1.0 wt% of co-catalyst Pt, which is much higher than that obtained from black phosphorus. The H2 evolution rate was observed to reach values as high as 553 μmol h-1 g-1 with addition of 0.5 wt% co-catalyst Pt.

Deciphering the photophysical kinetics, electronic configurations and structural conformations of iridium-cobalt hydrogen evolution photocatalysts.

Picosecond optical and X-ray absorption spectroscopies with time-dependent density functional theory revealed the reaction pathways, electronic and structural conformations of Ir-Co hydrogen evolution photocatalysts. The dyad bearing 2-phenylpyridine ancillary ligands produced more photoreduced Co(II) than its 2-phenylisoquinoline analogue. These findings are important for designs of earth-abundant photosensitizers for photocatalytic applications.

Ultra-thin graphene/g-C3N4 nanosheets with in-plane heterojunction for enhanced visible-light photocatalytic hydrogen evolution performance

ABSTRACT Ultra-thin graphene/g-C3N4 nanosheets (CN/G) with in-plane heterojunction were prepared by facial two-step thermal condensation of urea and glucose under mild conditions to improve photocatalytic hydrogen evolution under visible-light irradiation. The characterisation indicated that graphene was connected to the end of g-C3N4. The thermal exfoliation process can transform the bulk structure of g-C3N4 into ultra-thin nanosheets. Consequently, photocatalytic activity for hydrogen evolution rate of CN/G-0.1 was 704 µmol g–1 h–1, about 14 times higher than that of pure g-C3N4 under visible light irradiation (λ > 420 nm). CN/G-0.1 also exhibited high stability from the cycling tests for 18 h and superior photocatalytic properties at 500 nm. In-plane graphene modification can significantly enhance visible-light absorption and promote photogenerated electron-hole pair separation. On the other hand, ultra-thin nanosheets can increase specific surface area (153.8 m2 g–1) and provide abundant active sites. This study provides a suitable method to prepare g-C3N4 based on highly efficient photocatalysts for metal-free photocatalytic hydrogen evolution.

3D interconnected g-C3N4 hybridized with 2D Ti3C2 MXene nanosheets for enhancing visible light photocatalytic hydrogen evolution and dye contaminant elimination

The g-C3N4 has received extensive attention for its unique properties. However, g-C3N4 still suffers from the intrinsic limitations, which limit its large-scale applications. Hence, it is an urgent requirement to find a high-performance g-C3N4 photocatalyst possesses both a high separation rate of charge carriers and a strong light response. In this work, we have designed a 3D/2D g-C3N4/Ti3C2 (CNTC) heterojunction with a 3D interconnected porous structure as high efficiency photocatalyst for the photocatalytic hydrogen evolution (Pt as co-catalyst) and contaminant degradation. Benefiting from the 3D interconnected morphology and the incorporation of Ti3C2 nanosheets, the CNTC hybrids exhibit a high specific surface area (85.08 m2 g−1) and highly efficient charge migration, thus leading to excellent catalytic performance for the hydrogen generation and organic dye elimination. In addition, the mechanism of improved photocatalytic performance was analysed by characterization measurements, active species analysis and density functional theory calculations.

Cu/CdS/MnOx Nanostructure-Based Photocatalyst for Photocatalytic Hydrogen Evolution

Cu/CdS/MnO_<i>x</i> Nanostructure-Based Photocatalyst for Photocatalytic Hydrogen Evolution