There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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...

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

There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

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.

Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

Composite Photocatalysts Nan Zhang,†,‡ Min-Quan Yang,†,‡ Siqi Liu,†,‡ Yugang Sun,* and Yi-Jun Xu*,†,‡ †State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350002, P.R. China ‡College of Chemistry, New Campus, Fuzhou University, Fuzhou 350108, P.R. China Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States

Waltzing with the Versatile Platform of Graphene to Synthesize Composite Photocatalysts.

Graphene (GR) has become a sparkling rising star on the horizon of material science. Due to its unique planar structure, excellent transparency, superior electron conductivity and mobility, high specific surface area, and high chemical stability, GR is regarded as an ideal high performance candidate to prepare GR-based nanocomposites for energy storage and conversion. During the past few years, GR-based photocatalysts have been attracting ever-increasing research attention. In this tutorial review, the applications of GR-based nanocomposites in photocatalysis, including nonselective processes for degradation of pollutants, selective transformations for organic synthesis and water splitting to clean hydrogen energy, are summarized systematically. In particular, in addition to discussing opportunities offered by GR, we will also describe the existing challenges for future exploitation and development of GR-based nanocomposites, which we hope would significantly advance us to rationally and efficiently harness the outstanding structural and electronic properties of GR to design smarter and more efficient GR-based photocatalysts instead of joining the graphene “gold rush”.

Recent progress on graphene-based photocatalysts: current status and future perspectives

We report the assembly of nanosized ZnS particles on the 2D platform of a graphene oxide (GO) sheet by a facile two-step wet chemistry process, during which the reduced graphene oxide (RGO, also called GR) and the intimate interfacial contact between ZnS nanoparticles and the GR sheet are achieved simultaneously. The ZnS–GR nanocomposites exhibit visible light photoactivity toward aerobic selective oxidation of alcohols and epoxidation of alkenes under ambient conditions. In terms of structure–photoactivity correlation analysis, we for the first time propose a new photocatalytic mechanism where the role of GR in the ZnS–GR nanocomposites acts as an organic dye-like macromolecular “photosensitizer” for ZnS instead of an electron reservoir. This novel photocatalytic mechanism is distinctly different from all previous research on GR–semiconductor photocatalysts, for which GR is claimed to behave as an electron reservoir to capture/shuttle the electrons photogenerated from the semiconductor. This new concept ...

Nan Zhang

Papers

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

Waltzing with the Versatile Platform of Graphene to Synthesize Composite Photocatalysts.

Recent progress on graphene-based photocatalysts: current status and future perspectives

Graphene Transforms Wide Band Gap ZnS to a Visible Light Photocatalyst. The New Role of Graphene as a Macromolecular Photosensitizer