Hanyun Cheng

Bio: Hanyun Cheng is an academic researcher from Fudan University. The author has contributed to research in topics: Sulfate & Diffuse reflectance infrared fourier transform. The author has an hindex of 11, co-authored 32 publications receiving 1802 citations. Previous affiliations of Hanyun Cheng include Tsinghua University.

Significantly enhanced photocatalytic performance of ZnO via graphene hybridization and the mechanism study

Abstract: Graphene hybridized with ZnO could produce an efficient photocatalyst. The ZnO nanoparticles were firstly coated with an appropriate amount of graphene oxide, the graphene oxide was then in situ reduced to form the ZnO/graphene composite. Graphene hybridized ZnO photocatalyst showed enhanced photocatalytic activity for the degradation of organic dye. The degree of photocatalytic activity enhancement strongly depended on the coverage of graphene on the surface of ZnO nanoparticles. The sample of 2 wt% graphene hybridized ZnO showed the highest photocatalytic activity, which was about 4 times as that of pristine ZnO. The enhancement of photocatalytic activity was attributed to the high migration efficiency of photo-induced electrons and the inhibited charge carriers recombination due to the electronic interaction between ZnO and graphene. The electronic interaction was systematically studied and confirmed by the photoelectrochemical measurements.

Synthesis of Porous Bi2WO6 Thin Films as Efficient Visible-Light-Active Photocatalysts

Abstract: Bi(2)WO(6) ordered porous film with open pores, an example of a photocatalytically active ternary metal oxide under visible-light irradiation, is prepared using a simple and reproducible route. The ordered porous Bi(2)WO(6) films exhibited much higher photocatalytic activity and photocurrent coversion efficiency than nonporous Bi(2)WO(6) films under visible-light irradiation (lambda > 420 nm).

Photocorrosion Suppression of ZnO Nanoparticles via Hybridization with Graphite-like Carbon and Enhanced Photocatalytic Activity

Abstract: A method to suppress the photocorrosion of ZnO nanoparticles was developed by surface hybridization of ZnO with graphite-like carbon layers. The presence of carbon on the surface of the ZnO could significantly suppress the coalescence and crystal growth of ZnO nanoparticles during high-temperature treatment. The nanosized structure of ZnO was well preserved even after high-temperature calcination. The photocatalytic activity of ZnO was enhanced by hybridization with carbon layers attributed to the improved adsorption ability and crystallinity. The as-prepared samples exhibited high activity even after 720 h of photocatalysis reaction, while the pure ZnO nanoparticle was almost deactivated in 100 h due to serious photocorrosion. The as-prepared samples also showed much better activity under extreme pH conditions than that of pure ZnO. The mechanism of photocorrosion suppression and higher stability was then systematically investigated based on the crystal structure and the photocatalysis degradation process.

Surface-Enhanced Raman Spectroscopy Facilitates the Detection of Microplastics <1 μm in the Environment.

Abstract: Micro- and nanoplastics are considered one of the top pollutants that threaten the environment, aquatic life, and mammalian (including human) health. Unfortunately, the development of uncomplicated but reliable analytical methods that are sensitive to individual microplastic particles, with sizes smaller than 1 μm, remains incomplete. Here, we demonstrate the detection and identification of (single) micro- and nanoplastics by using surface-enhanced Raman spectroscopy (SERS) with Klarite substrates. Klarite is an exceptional SERS substrate; it is shaped as a dense grid of inverted pyramidal cavities made of gold. Numerical simulations demonstrate that these cavities (or pits) strongly focus incident light into intense hotspots. We show that Klarite has the potential to facilitate the detection and identification of synthesized and atmospheric/aquatic microplastic (single) particles, with sizes down to 360 nm. We find enhancement factors of up to 2 orders of magnitude for polystyrene analytes. In addition, we detect and identify microplastics with sizes down to 450 nm on Klarite, with samples extracted from ambient, airborne particles. Moreover, we demonstrate Raman mapping as a fast detection technique for submicron microplastic particles. The results show that SERS with Klarite is a facile technique that has the potential to detect and systematically measure nanoplastics in the environment. This research is an important step toward detecting nanoscale plastic particles that may cause toxic effects to mammalian and aquatic life when present in high concentrations.

Graphene-based semiconductor photocatalysts

Abstract: Graphene, a single layer of graphite, possesses a unique two-dimensional structure, high conductivity, superior electron mobility and extremely high specific surface area, and can be produced on a large scale at low cost. Thus, it has been regarded as an important component for making various functional composite materials. Especially, graphene-based semiconductor photocatalysts have attracted extensive attention because of their usefulness in environmental and energy applications. This critical review summarizes the recent progress in the design and fabrication of graphene-based semiconductor photocatalysts via various strategies including in situ growth, solution mixing, hydrothermal and/or solvothermal methods. Furthermore, the photocatalytic properties of the resulting graphene-based composite systems are also discussed in relation to the environmental and energy applications such as photocatalytic degradation of pollutants, photocatalytic hydrogen generation and photocatalytic disinfection. This critical review ends with a summary and some perspectives on the challenges and new directions in this emerging area of research (158 references).

Environmental applications of graphene-based nanomaterials.

Abstract: Graphene-based materials are gaining heightened attention as novel materials for environmental applications The unique physicochemical properties of graphene, notably its exceptionally high surface area, electron mobility, thermal conductivity, and mechanical strength, can lead to novel or improved technologies to address the pressing global environmental challenges This critical review assesses the recent developments in the use of graphene-based materials as sorbent or photocatalytic materials for environmental decontamination, as building blocks for next generation water treatment and desalination membranes, and as electrode materials for contaminant monitoring or removal The most promising areas of research are highlighted, with a discussion of the main challenges that we need to overcome in order to fully realize the exceptional properties of graphene in environmental applications

Significantly enhanced photocatalytic performance of ZnO via graphene hybridization and the mechanism study

Abstract: Graphene hybridized with ZnO could produce an efficient photocatalyst. The ZnO nanoparticles were firstly coated with an appropriate amount of graphene oxide, the graphene oxide was then in situ reduced to form the ZnO/graphene composite. Graphene hybridized ZnO photocatalyst showed enhanced photocatalytic activity for the degradation of organic dye. The degree of photocatalytic activity enhancement strongly depended on the coverage of graphene on the surface of ZnO nanoparticles. The sample of 2 wt% graphene hybridized ZnO showed the highest photocatalytic activity, which was about 4 times as that of pristine ZnO. The enhancement of photocatalytic activity was attributed to the high migration efficiency of photo-induced electrons and the inhibited charge carriers recombination due to the electronic interaction between ZnO and graphene. The electronic interaction was systematically studied and confirmed by the photoelectrochemical measurements.

Enhancement of photocurrent and photocatalytic activity of ZnO hybridized with graphite-like C3N4

Abstract: A ZnO photocatalyst was hybridized with graphite-like C3N4via a monolayer-dispersed method. After hybridization with C3N4, the photocurrent of ZnO was enhanced by 5 times under UV irradiation and a photocurrent under visible light irradiation was observed. The photocatalytic activity of C3N4/ZnO under UV irradiation was increased by 3.5 times, the visible light photocatalytic activity was generated and the photocorrosion of ZnO was suppressed completely after ZnO was hybridized with C3N4. The enhancement in performance and photocorrosion inhibition under UV irradiation was induced by the high separation efficiency of photoinduced holes from ZnO to the HOMO of C3N4. Under visible light irradiation, the electron excited from the HOMO to the LUMO of C3N4 could directly inject into the CB of ZnO, making C3N4/ZnO present visible light photocatalytic activity. The optimum synergetic effect of C3N4/ZnO was found at a weight ratio of 3%, which corresponded to a monolayer dispersion of C3N4 on the surface of ZnO.