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Xinguo Ma

Other affiliations: Hubei University of Technology
Bio: Xinguo Ma is an academic researcher from Tsinghua University. The author has contributed to research in topics: Materials science & Band gap. The author has an hindex of 7, co-authored 8 publications receiving 1216 citations. Previous affiliations of Xinguo Ma include Hubei University of Technology.

Papers
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TL;DR: In this article, an effective structural doping approach has been described to modify the photoelectrochemical properties of g-C3N4 by doping with nonmetal (sulfur or phosphorus) impurities.
Abstract: An effective structural doping approach has been described to modify the photoelectrochemical properties of g-C3N4 by doping with nonmetal (sulfur or phosphorus) impurities. Here, the substitutional and interstitial doped models of g-C3N4 systems were constructed with different doped sites, and then their dopant formation energies and electronic properties were performed to study the stability and visible-light photoactivity using first-principles density functional theory, respectively. Our results have identified that an S atom preferentially substitutes for the edge N atom of g-C3N4; however, a P atom preferentially situates the interstitial sites of in-planar of g-C3N4. Furthermore, it is demonstrated that the doping with nonmetal impurities reduces the energy gap to enhance the visible-light absorption of g-C3N4. The increased dispersion of the contour distribution of the HOMO and LUMO brought by doping facilitates the enhancement of the carrier mobility, while the noncoplanar HOMO and LUMO favor the...

568 citations

Journal ArticleDOI
Xinguo Ma1, Bin Lu1, Di Li1, Rui Shi1, Chenshi Pan1, Yongfa Zhu1 
TL;DR: In this article, a density functional theory incorporating the LDA + U formalism has been used to investigate the origin of photocatalytic activation of Ag3PO4, which provides an improved band gap and the position of the valence band if both Up and Ud are used.
Abstract: First-principles density functional theory incorporating the LDA + U formalism has been used to investigate the origin of photocatalytic activation of Ag3PO4. The approach provides an improved band gap and the position of the valence band if both Up and Ud are used. Through examining the energy band structure and density of states, we can understand why Ag3PO4 is a promising photocatalyst for oxidizing water as well as degrading organic contaminants. The results show that Ag3PO4 has a large dispersion of conduction band and the inductive effect of PO43−, which help the separation of electron−hole pairs. It is demonstrated theoretically that Ag vacancies in Ag3PO4 with high concentration have a significant effect on the separation of electron−hole pairs and optical absorbance in the visible-light region. These findings present a reasonable explanation of recent experimental results.

253 citations

Journal ArticleDOI
Yanhui Lv1, Chengsi Pan1, Xinguo Ma1, Ruilong Zong1, Xiaojuan Bai1, Yongfa Zhu1 
TL;DR: In this article, a ZnO photocatalyst with surface oxygen vacancies was obtained via vacuum deoxidation method, where the concentration of surface oxygen vacancy could be controlled by tuning the temperature and time in vacuum, which governs the production of visible activity and the enhanced level of photocatalytic activity.
Abstract: ZnO photocatalyst with surface oxygen vacancies was obtained via vacuum deoxidation method. The concentration of surface oxygen vacancies could be controlled by tuning the temperature and time in vacuum, which governs the production of visible activity and the enhanced level of photocatalytic activity. The optimum UV photocatalytic activity and photocurrent of vacuum ZnO are almost 1.7 and 2.4 times as high as that of pure ZnO, respectively. Interestingly, the dramatic visible photocatalytic activity and distinct photocurrent both are generated due to the introducing of oxygen vacancies on ZnO surface. The enhancement in performance is attributed to the high separation efficiency of photogeneration electron–hole pairs due to the broadening of the valance band (VB) induced by surface oxygen-vacancies states. The production of visible photoactivity is demonstrated to be the narrow of energy band gap resulting from the rising of VB.

181 citations

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TL;DR: In this paper, the electronic structures of ZnO were calculated using density functional theory, in which the electronic interactions are described within the GGA+U (GGA = generalized gradient approximation) formalism, where on-site Coulomb corrections are applied on the Zn 3d orbitals (Ud) and O 2p orbitals(Up).
Abstract: The electronic structures of ZnO were calculated using density functional theory, in which the electronic interactions are described within the GGA+U (GGA = generalized gradient approximation) formalism, where on-site Coulomb corrections are applied on the Zn 3d orbitals (Ud) and O 2p orbitals (Up). The relaxed GGA+U calculation can correct completely the band gap, the position of Zn 3d states, the transition levels of O vacancy in band gap, and so on, which is different from other GGA+U (equivalent LDA+U) calculations partially correcting the energy band structure for fixed lattice constants. By comparing with experimental data, the pair of Ud = 10 and Up = 7 eV was identified as an optimum choice for the energy band structure of W-ZnO. Then, the proper pair of Ud and Up parameters was taken to predict the energy band structure of ZB- and RS- ZnO, of which the former is in good agreement with experimental values, and the latter is in dispute, relating to the decrease of the octahedral symmetry. Subsequen...

146 citations

Journal ArticleDOI
Chengsi Pan1, Di Li1, Xinguo Ma1, Yi Chen2, Yongfa Zhu1 
TL;DR: In this paper, three kinds of crystal phase BiPO4 (HBIP, nMBIP and mMBIP) were selectively synthesized by a hydrothermal method and showed higher activity for degradation of MB solution under UV irradiation than HBIP, mMBIP and HBIP.

133 citations


Cited by
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TL;DR: It is anticipated that this review can stimulate a new research doorway to facilitate the next generation of g-C3N4-based photocatalysts with ameliorated performances by harnessing the outstanding structural, electronic, and optical properties for the development of a sustainable future without environmental detriment.
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...

5,054 citations

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TL;DR: This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials, and highlights crucial issues that should be addressed in future research activities.
Abstract: Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

3,265 citations

Journal ArticleDOI
TL;DR: 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 coc atalysts, and Z-scheme heterojunctions.
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.

2,868 citations

Journal ArticleDOI
TL;DR: In this paper, the fundamental mechanism of heterogeneous photocatalysis, advantages, challenges and the design considerations of g-C3N4-based photocatalysts are summarized, including their crystal structural, surface phisicochemical, stability, optical, adsorption, electrochemical, photoelectrochemical and electronic properties.

2,132 citations

Journal ArticleDOI
Xiaoyang Pan1, Min-Quan Yang1, Xianzhi Fu1, Nan Zhang1, Yi-Jun Xu1 
TL;DR: This tutorial minireview gives a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties ofTiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO 2.
Abstract: Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.

1,661 citations