Abstract In the past 10 years, ZnO as a semiconductor has attracted considerable attention due to its unique properties, such as high electron mobility, wide and direct band gap and large exciton binding energy. ZnO has been considered a promising material for optoelectronic device applications, and the fabrications of high quality p-type ZnO and p–n junction are the key steps to realize these applications. However, the reliable p-type doping of the material remains a major challenge because of the self-compensation from native donor defects (V O and Zn i ) and/or hydrogen incorporation. Considerable efforts have been made to obtain p-type ZnO by doping different elements with various techniques. Remarkable progresses have been achieved, both theoretically and experimentally. In this paper, we discuss p-type ZnO materials: theory, growth, properties and devices, comprehensively. We first discuss the native defects in ZnO. Among the native defects in ZnO, V Zn and O i act as acceptors. We then present the theory of p-type doping in ZnO, and summarize the growth techniques for p-type ZnO and the properties of p-type ZnO materials. Theoretically, the principles of selection of p-type dopant, codoping method and X Zn –2V Zn acceptor model are introduced. Experimentally, besides the intrinsic p-type ZnO grown at O-rich ambient, p-type ZnO (MgZnO) materials have been prepared by various techniques using Group-I, IV and V elements. We pay a special attention to the band gap of p-type ZnO by band-gap engineering and room temperature ferromagnetism observed in p-type ZnO. Finally, we summarize the devices based on p-type ZnO materials.

RaoP-Type ZnO Materials: Theory, Growth, Properties, and Devices

Facile construction of porous intramolecular g-C3N4-based donor-acceptor conjugated copolymers as highly efficient photocatalysts for superior H2 evolution

Atomically 2D thin-layered structures, such as graphene nanosheets, graphitic carbon nitride nanosheets (g-C3N4), hexagonal boron nitride, and transition metal dichalcogenides are emerging as fascinating materials for a good array of domains owing to their rare physicochemical characteristics. In particular, graphitic carbon nitride has turned into a hot subject in the scientific community due to numerous qualities such as simple preparation, electrochemical properties, high adsorption capacity, good photochemical properties, thermal stability, and acid-alkali chemical resistance, etc. Basically, g-C3N4 is considered as a polymeric material consisting of N and C atoms forming a tri-s-triazine network connected by planar amino groups. In comparison with most C-based materials, g-C3N4 possesses electron-rich characteristics, basic moieties, and hydrogen-bonding groups owing to the presence of hydrogen and nitrogen atoms; therefore, it is taken into account as an interesting nominee to further complement carbon in applications of functional materials. Nevertheless, g-C3N4 has some intrinsic limitations and drawbacks mainly related to a relatively poor specific surface area, rapid charge recombination, a limited light absorption range, and a poor dispersibility in both aqueous and organic mediums. To overcome these shortcomings, numerous chemical modification approaches have been conducted with the aim of expanding the range of application of g-C3N4 and enhancing its properties. In the current review, the comprehensive survey is conducted on g-C3N4 chemical functionalization strategies including covalent and noncovalent approaches. Covalent approaches consist of establishing covalent linkage between the g-C3N4 structure and the chemical modifier such as oxidation/carboxylation, amidation, polymer grafting, etc., whereas the noncovalent approaches mainly consist of physical bonding and intermolecular interaction such as van der Waals interactions, electrostatic interactions, π-π interactions, and so on. Furthermore, the preparation, characterization, and diverse applications of functionalized g-C3N4 in various domains are described and recapped. We believe that this work will inspire scientists and readers to conduct research with the aim of exploring other functionalization strategies for this material in numerous applications.

Emerging Chemical Functionalization of g-C3N4: Covalent/Noncovalent Modifications and Applications.

Colloidal nanocrystals are nanometer-sized, solution-grown inorganic particles stabilized by a layer of surfactants attached to their surface. The inorganic cores exhibit useful properties controlled by composition as well as size and shape, while the surfactant coating ensures that these structures are easy to fabricate and process. It is this combination of features that makes colloidal nanocrystals attractive and promising building blocks for advanced materials and devices. But their full potential can only be exploited if we achieve exquisite control over their composition, size, shape, crystal structure and surface properties. Here we review what is known about nanocrystal growth and outline strategies for controlling it.

Colloidal nanocrystal synthesis and the organic-inorganic interface

2D Graphitic Carbon Nitride for Energy Conversion and Storage

Amorphous TiO2 nanostructures: synthesis, fundamental properties and photocatalytic applications

Exposed high-index facets with a high density of low-coordinated atoms (including edges, steps and kinks) can provide more high-active sites for chemical reactions. Therefore, great progress has made in the facet-dependent application of various high-index faceted micro-/nanostructures in the past decades. Previous review papers have mainly highlighted the advances in high-index faceted noble metal nanocrystals. However, to date, there is no specialized review paper on high-index faceted metal oxides and their facet-dependent applications. Thus, in this review, the existing high-index faceted metal oxide micro-/nanostructures, including Cu2O, TiO2, Fe2O3, ZnO, SnO2 and BiVO4, are reviewed based on their characterization, synthesis engineering and facet-dependent applications in the fields of catalysis, sensors, lithium-ion batteries and carbon monoxide oxidation. Also, several challenges and perspectives are presented. Hopefully, this review article will be a useful guideline and resource for researchers currently concentrating on high-index faceted metal oxides to design and synthesize novel micro-/nanostructures for overcoming the practical environment-, biology- and energy-related problems.

High-index faceted metal oxide micro-/nanostructures: a review on their characterization, synthesis and applications

Facile constructing of isotype g-C3N4(bulk)/g-C3N4(nanosheet) heterojunctions through thermal polymerization of single-source glucose-modified melamine: An efficient charge separation system for photocatalytic hydrogen production

As a significant n-type semiconductor, MoOx (2 ≤ x ≤ 3) micro-/nanostructures with well-tuned shapes, sizes, crystalline phases, and compositions have attracted great attention in the past few decades due to remarkable performances in numerous fields of photodevices, energy storage and conversion, gas sensing and catalysts. Additionally, the cheapness, nontoxicity, and ecofriendly nature as well as semiconducting properties also endow them with competitive advantages for their practical applications. However, a comprehensive review on morphological MoOx micro-/nanostructures is still lacking so far. Hence, it is necessary to thoroughly summarize the recent advances made in function-oriented MoOx-based architectures. In this review, we have highlighted the progress in diversified MoOx micro-/nanostructures, including the general synthetic strategies for the synthesis of zero-, one-, two-, and three-dimensional MoOx micro-/nanostructures and the modification (such as doping and hybridization) of MoOx-based ...

Synthesis, Functional Modifications, and Diversified Applications of Molybdenum Oxides Micro-/Nanocrystals: A Review

The application of templating and etching agents for the synthesis of mesoporous graphitic carbon nitride (mpg-C3N4) is not environmentally friendly, motivating attempts to develop a green and efficient strategy to construct mpg-C3N4 with improved photocatalytic performance. Herein, for the first time, we demonstrate a general carbonated beverage-assisted hydrothermally-reformed commercial melamine (MA) strategy for the synthesis of mpg-C3N4 nanosheets. Although the dosage of carbonated beverage (including Coca-Cola, Pepsi-Cola, Sprite and Fanta) is very small for the modification of MA precursors, the improvement in the photocatalytic activity of the mpg-C3N4 products is very remarkable. With the unique structural advantages for aligned energy bands and charge carrier migration, and numerous photocatalytic sites, the visible-light-driven photocatalytic hydrogen evolution rate (HER) of mpg-C3N4 nanosheets synthesized from a Coca-Cola-reformed MA precursor is 15.1 times higher than that of bulk g-C3N4, achieving an apparent quantum yield of 7.7% at 420 nm. Similarly, mpg-C3N4 nanosheets synthesized from Pepsi-Cola-, Sprite- and Fanta-reformed MA precursors also exhibit enhanced photocatalytic HERs.

Mesoporous graphitic carbon nitride (g-C3N4) nanosheets synthesized from carbonated beverage-reformed commercial melamine for enhanced photocatalytic hydrogen evolution

Jie Cui

Papers

Amorphous TiO2 nanostructures: synthesis, fundamental properties and photocatalytic applications

High-index faceted metal oxide micro-/nanostructures: a review on their characterization, synthesis and applications

Facile constructing of isotype g-C3N4(bulk)/g-C3N4(nanosheet) heterojunctions through thermal polymerization of single-source glucose-modified melamine: An efficient charge separation system for photocatalytic hydrogen production

Synthesis, Functional Modifications, and Diversified Applications of Molybdenum Oxides Micro-/Nanocrystals: A Review

Mesoporous graphitic carbon nitride (g-C3N4) nanosheets synthesized from carbonated beverage-reformed commercial melamine for enhanced photocatalytic hydrogen evolution