This work reports on the fabrication of Fe2O3/Pt/Au nanocomposite immobilized on g-C3N4 surface with highly enhanced visible light photocatalytic activity toward efficient and stable hydrogen production. The results showed that the designed nanosystem photocatalysts were successfully fabricated, with intimate interfacial contact between g-C3N4 and Fe2O3 and uniform distribution of Pt and Au on the surface of g-C3N4 which can significantly improve the photocatalytic activity compared to its constituents. Localized surface plasmon resonance of Au, Z-scheme heterojunction interaction of two semiconductors, Schottky barriers and active sites of Pt can effectively promote hydrogen production. The photocatalytic mechanism of the produced system is suggested. The H2-evolution rate of 4.6 μmol h−1 mg−1 was achieved and the synthesized samples exhibited good photocatalytic stability in recycling H2 evolution. This work provides a new way to design effective photocatalysts for splitting water under solar light, which can simultaneously extend light absorption range for better electron-hole generation, reduce carrier recombination and increase H+ absorption for efficient H2 production.
The development of efficient photocatalysts that can work both under visible light and in darkness remains an important research target for environmental applications. A large number of photocatalysts have been reported, but they still suffer from low activity that originates from fundamental efficiency bottlenecks: i.e., weak photon absorption and poor electron–hole pair separation when operating under irradiation, and poor electron storage capacity when operating in darkness. Herein, we report the first synthesis of hollow double-shell H:Pt–WO3/TiO2–Au nanospheres with high specific surface area, large TiO2/WO3 interfacial contact and strong visible light absorption. Because of these features, this type of nanocomposite shows high charge separation and electron storage capacity, and exhibits efficient degradation of organic pollutants both under visible light (λ ≥ 420 nm) and in darkness. In addition, CO2 generation from formaldehyde gave a high quantum efficiency of 77.6%.
Nickel deposited S-doped carbon nitride (Ni–S:g-C3N4/Ni-SCN) nanosheets have been synthesized using calcination followed by a sulfidation process. X-ray photoelectron spectra revealed that the doped S atoms are successfully introduced into the 301 lattices of the host g-C3N4. XPS spectra indicated that the deposited Ni species are chemically bonded onto the host SCN nanosheets through sulfur bonds. The sunlight-driven photocatalytic hydrogen production efficiency of the synthesized Ni-SCN nanosheets is found to be 3628 μmol g–1 h–1, which is around 1.5 folds higher than that of Pt-SCN that synthesized in the present study. The observed efficiency is attributed to the chemical bonding of Ni through S that largely favored the photocatalytic process in terms of charge-separation as well as self-catalytic reactions. The apparent quantum efficiency of the photocatalyst at 420 nm is estimated to be 17.2%, which is relatively one of the higher values reported in the literature. The photocatalytic recyclability results showed consistent hydrogen evolution efficiency over 4 cycles (8 h) that revealed the excellent stability of the photocatalyst. This work has demonstrated that the chemical bonding of cocatalyst onto the host photocatalyst is relatively an effective strategy as compared to the conventional deposition of cocatalyst by means of electrostatic or van der Waals forces.
Herein, we report a novel air-assisted carbon sphere combustion process to produce phase-tunable anatase-rutile (A/R) C/Pt-TiO2 photocatalysts for hydrogen generation and organic pollutant degradation under solar light irradiation. In the formed carbon/amorphous TiO2 core/shell structure, the carbon-core was acted as a fuel to prepare the mixed phase A/R TiO2 nanostructures. The A/R ratio of the TiO2 nanoparticles was tuned by varying the purged air flow during the combustion process. The obtained materials exhibited several unique properties not achievable using conventional methods, including anatase/rutile homojunction, co-existence of C and Pt/PtO and very high surface area, significantly improved charge separation and transfer characteristics towards excellent photocatalytic properties. Eventually, the photocatalytic activities of the obtained materials were found to be more than 23 and 17 folds higher than commercial TiO2-P25 for hydrogen generation and organic pollutant degradation, respectively.
Abstract This study aimed at providing a route towards the production of a novel exopolysaccharide (EPS) from fermented bamboo shoot-isolated Lactobacillus fermentum. A lactic acid bacteria strain, with high EPS production ability, was isolated from fermented bamboo shoots. This strain, R-49757, was identified in the BCCM/LMG Bacteria Collection, Ghent University, Belgium by the phenylalanyl-tRNA synthetase gene sequencing method, and it was named Lb. fermentum MC3. The molecular mass of the EPS measured via gel permeation chromatography was found to be 9.85 × 104 Da. Moreover, the monosaccharide composition in the EPS was analyzed by gas chromatography–mass spectrometry. Consequently, the EPS was discovered to be a heteropolysaccharide with the appearance of two main sugars—D-glucose and D-mannose—in the backbone. The results of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance spectroscopy analyses prove the repeating unit of this polysaccharide to be [→6)-β-D-Glcp-(1→3)-β-D-Manp-(1→6)-β-D-Glcp-(1→]n, which appears to be a new EPS. The obtained results open up an avenue for the production of novel EPSs for biomedical applications.
Abstract Photocatalysts comprising 2D carbon nitride-based systems have emerged as a fervently researched topic for addressing the problems of fuel depletion and the environment. However, the photocatalytic activities of pristine g-C3N4 are still mediocre and suffer from issues pertaining to the restrictions in light absorption, charge separation, and carrier-induced surface reactions; however, efforts have been made in the past decades to boost the efficiencies. This review endeavors to present a roadmap to prepare high-performance g-C3N4 photocatalysts by expounding the cutting-edge research on g-C3N4 materials either as a single component or g-C3N4-based composites including current challenges and perspectives on this topical theme. We believe that this review will provide a broader picture and recommendations for the preparation of superior g-C3N4 photocatalysts towards a greener, cleaner, and resilient future.
Abstract Two-dimensional MXenes have gained tremendous interest as frontier materials for a wide variety of applications and play a pivotal role in the development of future energy, electronic and optoelectronic devices as they exhibit high catalytic activity in diverse electrocatalytic and photocatalytic devices. The fabrication and application of MXenes as catalysts have become more progressive in recent years and more than 30 different varieties have been experimentally discovered and utilized. In this review, we rationally summarized and discussed the most recent advances in the synthesis and specific applications of MXenes as electrocatalysts and photocatalyst for hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) including strategies for boosting their catalytic activity for target products. Finally, we highlight the lingering challenges and direction for the future development of MXenes as catalysts for HER and CO2RR.
Converting solar energy into fuel via photo-assisted water splitting to generate H2 or drive CO2 photoreduction is an attractive scientific and technological goal to address the increasing global demand for energy and to reduce the impact of energy production on climate change. Solar-driven hydrogenation of CO2 into value-added chemical products is one of the most promising strategies for reducing CO2 and is anticipated to be a sustainable energy source shortly. In this study, we focus on the utilization of different sustainable H2 sources for the photoreduction of CO2 to value-added organic products. Various photocatalysts, photoreactor configurations, and reaction parameters for the photoreduction of CO2 are discussed. For future research endeavors, a general approach for the photoreduction of CO2 to mimic natural photosynthesis, in which the H2 source is provided directly during the photocatalytic water splitting, is proposed and verified to generate value-added organic products successfully.
