Yuechang Wei

Bio: Yuechang Wei is an academic researcher from China University of Petroleum. The author has contributed to research in topics: Catalysis & Soot. The author has an hindex of 45, co-authored 187 publications receiving 5865 citations.

Facile in situ synthesis of graphitic carbon nitride (g-C3N4)-N-TiO2 heterojunction as an efficient photocatalyst for the selective photoreduction of CO2 to CO

Abstract: A series of composites of graphitic carbon nitride and in situ nitrogen-doped titanium dioxide (g-C3N4-N-TiO2) were prepared by a simple pyrolysis process of urea and Ti(OH)4. The obtained products were characterized by means of X-ray diffraction, FT-IR transmission spectroscopy, electron microscopy, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, etc. Compared with g-C3N4 and commercial P25, the as-prepared photocatalysts exhibit enhanced photocatalytic performance for photoreduction of CO2 in the presence of water vapor at room temperature. It was found that the mass ratios of urea to Ti(OH)4 in precursors play a role in formation of the composites, and the high ratios of urea to Ti(OH)4 result in the composites of g-C3N4 and N-doped TiO2, while low ratios only result in N-doped TiO2. An interesting selectivity of photocatalytic products displayed that N-doped TiO2 samples were related to CH4 and CO generation, while g-C3N4 and N-TiO2 composites were related to CO generation, and the product selectivity may originate from the formed g-C3N4. The highest amount of CO (14.73 μmol) was obtained on the optimized photocatalyst under 12 h light irradiation, which is four times of that over commercial P25. Based on these results, a possible mechanism for the enhanced photocatalytic performance was proposed.

Selective catalytic reduction of NO with NH3 over HZSM-5-supported Fe–Cu nanocomposite catalysts: The Fe–Cu bimetallic effect

Abstract: A series of Fe x –Cu 4 /ZSM-5 catalysts with fixed Cu content and variable Fe loading amounts were synthesized by an improved incipient-wetness-impregnation method, and their catalytic performances were tested for selective catalytic reduction (SCR) of NO with ammonia as reductant. The catalysts were characterized by means of XRD, BET, SEM, TEM, FT-IR, UV–vis DRS, UV-Raman, NH 3 -TPD, Py-IR, H 2 -TPR and XPS. The results indicated that the high activities of Fe x –Cu 4 /ZSM-5 could be attributed to the formation of Fe–Cu nanocomposites with high dispersion. The interaction between the iron and copper species in the Fe–Cu nanocomposites leads to the change of electronic properties, the stronger redox ability and more acid sites over catalyst surface for Fe x –Cu 4 /ZSM-5 comparing with Cu 4 /ZSM-5. Thus, the addition of iron to Cu 4 /ZSM-5 catalyst improved its catalytic performance, and Fe 4 –Cu 4 /ZSM-5 catalyst exhibited the high NO conversion (>90%) among the wide temperature range (200–475 °C).

Efficient Z-scheme photocatalysts of ultrathin g-C3N4-wrapped Au/TiO2-nanocrystals for enhanced visible-light-driven conversion of CO2 with H2O

Abstract: Z-scheme-type photocatalysts with two photochemical systems of graphic-C3N4 (g-C3N4) and anatase TiO2 (A-TiO2) nanocrystals combined with Au nanoparticles (NPs) [(Au/A-TiO2)@g-C3N4] were successfully fabricated. The surface heterojunction between coexposed {001} and {101} facets in A-TiO2 nanocrystals improves separation efficiency of photoelectrons and holes. Supported Au NPs gather and transfer the stimulated electrons originated from A-TiO2 to g-C3N4. Wrapped g-C3N4 nanosheets can not only trap the photoelectrons, but also its surface π bond can improve adsorption capabilities for CO2. (Au/A-TiO2)@g-C3N4 catalysts with enriched surface photoelectrons and CO2 exhibit high photocatalytic activity for visible-light-driven conversion of CO2, i.e., the formation rates of CH4 and CO over (Au/A-TiO2)@C3N4-5 catalyst are 37.4 and 21.7 μmol g−1 h−1, respectively. The selectivity for CO2 reduction is higher than 99%, and the selectivity of CH4 product increases from 1.4% to 63.3%. The innovation of Z-scheme-type photocatalysts is expected to provide new inspiration for artificial simulation photosynthesis.

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Polymeric Photocatalysts Based on Graphitic Carbon Nitride

Abstract: Semiconductor-based photocatalysis is considered to be an attractive way for solving the worldwide energy shortage and environmental pollution issues. Since the pioneering work in 2009 on graphitic carbon nitride (g-C3N4) for visible-light photocatalytic water splitting, g-C3N4 -based photocatalysis has become a very hot research topic. This review summarizes the recent progress regarding the design and preparation of g-C3N4 -based photocatalysts, including the fabrication and nanostructure design of pristine g-C3N4 , bandgap engineering through atomic-level doping and molecular-level modification, and the preparation of g-C3N4 -based semiconductor composites. Also, the photo-catalytic applications of g-C3N4 -based photocatalysts in the fields of water splitting, CO2 reduction, pollutant degradation, organic syntheses, and bacterial disinfection are reviewed, with emphasis on photocatalysis promoted by carbon materials, non-noble-metal cocatalysts, and Z-scheme heterojunctions. Finally, the concluding remarks are presented and some perspectives regarding the future development of g-C3N4 -based photocatalysts are highlighted.

Polymeric Graphitic Carbon Nitride as a Heterogeneous Organocatalyst: From Photochemistry to Multipurpose Catalysis to Sustainable Chemistry

Abstract: Polymeric graphitic carbon nitride materials (for simplicity: g-C(3)N(4)) have attracted much attention in recent years because of their similarity to graphene. They are composed of C, N, and some minor H content only. In contrast to graphenes, g-C(3)N(4) is a medium-bandgap semiconductor and in that role an effective photocatalyst and chemical catalyst for a broad variety of reactions. In this Review, we describe the "polymer chemistry" of this structure, how band positions and bandgap can be varied by doping and copolymerization, and how the organic solid can be textured to make it an effective heterogenous catalyst. g-C(3)N(4) and its modifications have a high thermal and chemical stability and can catalyze a number of "dream reactions", such as photochemical splitting of water, mild and selective oxidation reactions, and--as a coactive catalytic support--superactive hydrogenation reactions. As carbon nitride is metal-free as such, it also tolerates functional groups and is therefore suited for multipurpose applications in biomass conversion and sustainable chemistry.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

Abstract: Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.