Query: Graphitic C3N4 based noble-metal-free photocatalyst systems: a review

Candidate papers:

abstract: Many reviews are written on this interesting visible light active polymeric semiconductor material, the graphitic carbon nitride (g C3N4) Yet the ever expanding volume of the ongoing research on this materials has inspired us to compile this review, especially on its nanoscale architectures of noble metal free photocatalyst systems. From the viewpoint of sustainable development, an economical photocatalyst which is made up of abundant elements e. g. C and N has a good prospect for large scale applications. Stability of the photocatalyst material under the experimental conditions is essential for its repeated usage, however, many semiconductors sought for visible light driven reaction, particularly sulfides and nitrides are in a compromising situation. However, g C3N4 has high chemical and photo stability besides its high activity under visible light irradiation. Furthermore, solely semiconductor materials have the intrinsic problem of recombination of photogenerated electron hole pairs. To overcome this problem, loading of the semiconductor with a co catalyst, usually a noble metal is a common practice for transfer of electron and thus avoiding the recombination. Development of a noble metal free photocatalyst systems is essentially important for sustainable applications. Hence, the construction of a hybrid composite structure is interesting in the separation of photogenerated charge carriers. Besides diminishing the rate of recombination, the heterostructures are constructed for harnessing a wider spectrum of sunlight. In contrast to bulk semiconductors, their nanoscale counterpart offers a larger number of active sites along with interesting electrical and optical properties. Importantly, construction of extensive junctions between nanomaterials greatly enhance the separation of charges and consequently improve their photocatalytic efficiency. Usually, the stability of materials is compromised with the reduction of size to nano level, however, g C3N4 and its nanomaterials demonstrate exceptional recycling in photocatalytic testing. One of the most important interests in controlling nanoparticle size, shape and composition is to develop noble metal free photocatalyst systems. Here in this review, we have compiled research on all the various applications of noble metal free nanoscale photocatalyst systems based on g C3N4. By the end, we conclude the research topic and put forward future perspectives for further developments in designing practicable photocatalyst systems.
author_names: Dilshad Masih

Yuanyu Ma

Sohrab Rohani
title: Graphitic C3N4 based noble metal free photocatalyst systems: A review
year: 2017

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 construction and characteristics of each classification of the heterojunction system will be critically reviewed, namely metal g C3N4, semiconductor g C3N4, isotype g C3N4/g C3N4, graphitic carbon g C3N4, conducting polymer g C3N4, sensitizer g C3N4, and multicomponent heterojunctions. The band structures, electronic properties, optical absorption, and interfacial charge transfer of g C3N4 based heterostructured nanohybrids will also be theoretically discussed based on the first principles density functional theory (DFT) calculations to provide insightful outlooks on the charge carrier dynamics. Apart from that, the advancement of the versatile photoredox applications toward artificial photosynthesis (water splitting and photofixation of CO2) environmental decontamination, and bacteria disinfection will be presented in detail. Last but not least, this comprehensive review will conclude with a summary and some invigorating perspectives on the challenges and future directions at the forefront of this research platform. 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.
author_names: Wee-Jun Ong

Lling-Lling Tan

Yun Hau Ng

Siek-Ting Yong

Siang-Piao Chai
title: Graphitic Carbon Nitride (g C3N4) Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?
venue: Chemical reviews
year: 2016

abstract: The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.
author_names: Xinchen Wang

Kazuhiko Maeda

Arne Thomas

Kazuhiro Takanabe

Gang Xin

Johan M Carlsson

Kazunari Domen

Markus Antonietti
title: A metal free polymeric photocatalyst for hydrogen production from water under visible light.
venue: Nature materials
year: 2009

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.
author_names: Shaowen Cao

Jingxiang Low

Jiaguo Yu

Mietek Jaroniec
title: Polymeric photocatalysts based on graphitic carbon nitride.
venue: Advanced materials
year: 2015

abstract: Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource derived electricity and direct solar to hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal free hydrogen evolution catalysts to make the water splitting process more energy efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER) We review several important kinds of heterogeneous non precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition catalytic activity relationship. We also summarize some important examples showing that non Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar to hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.
author_names: Xiaoxin Zou

Yuanchen Zhang
title: Noble metal free hydrogen evolution catalysts for water splitting.
venue: Chemical Society reviews
year: 2015

abstract: Graphitic carbon nitride, g C3N4, can be made by polymerization of cyanamide, dicyandiamide or melamine. Depending on reaction conditions, different materials with different degrees of condensation, properties and reactivities are obtained. The firstly formed polymeric C3N4 structure, melon, with pendant amino groups, is a highly ordered polymer. Further reaction leads to more condensed and less defective C3N4 species, based on tri s triazine (C6N7) units as elementary building blocks. High resolution transmission electron microscopy proves the extended two dimensional character of the condensation motif. Due to the polymerization type synthesis from a liquid precursor, a variety of material nanostructures such as nanoparticles or mesoporous powders can be accessed. Those nanostructures also allow fine tuning of properties, the ability for intercalation, as well as the possibility to give surface rich materials for heterogeneous reactions. Due to the special semiconductor properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene, trimerization reactions, and also the activation of carbon dioxide. Model calculations are presented to explain this unusual case of heterogeneous, metal free catalysis. Carbon nitride can also act as a heterogeneous reactant, and a new family of metal nitride nanostructures can be accessed from the corresponding oxides.
author_names: Arne Thomas

Anna Fischer

Frederic Goettmann

Markus Antonietti

Jens Muller

Robert Schlogl

Johan M Carlsson
title: Graphitic carbon nitride materials: variation of structure and morphology and their use as metal free catalysts
year: 2008

abstract: Abstract As one of the most appealing and attractive technologies, heterogeneous photocatalysis has been utilized to directly harvest, convert and store renewable solar energy for producing sustainable and green solar fuels and a broad range of environmental applications. Due to their unique physicochemical, optical and electrical properties, a wide variety of g C 3 N 4 based photocatalysts have been designed to drive various reduction and oxidation reactions under light irradiation with suitable wavelengths. In this review, we have systematically summarized the photocatalytic fundamentals of g C 3 N 4 based photocatalysts, including fundamental mechanism of heterogeneous photocatalysis, advantages, challenges and the design considerations of g C 3 N 4 based photocatalysts. The versatile properties of g C 3 N 4 based photocatalysts are highlighted, including their crystal structural, surface phisicochemical, stability, optical, adsorption, electrochemical, photoelectrochemical and electronic properties. Various design strategies are also thoroughly reviewed, including band gap engineering, defect control, dimensionality tuning, pore texture tailoring, surface sensitization, heterojunction construction, co catalyst and nanocarbon loading. Many important applications are also addressed, such as photocatalytic water splitting (H 2 evolution and overall water splitting) degradation of pollutants, carbon dioxide reduction, selective organic transformations and disinfection. Through reviewing the important state of the art advances on this topic, it may provide new opportunities for designing and constructing highly effective g C 3 N 4 based photocatalysts for various applications in photocatalysis and other related fields, such as solar cell, photoelectrocatalysis, electrocatalysis, lithium battery, supercapacitor, fuel cell and separation and purification.
author_names: Jiuqing Wen

Jun Xie

Xiaobo Chen

Xin Li
title: A review on g C3N4 based photocatalysts
year: 2017

abstract: Graphitic carbon nitride (g C3N4) based photocatalysts have attracted dramatically increasing interest in the area of visible light induced photocatalytic hydrogen generation due to the unique electronic band structure and high thermal and chemical stability of g C3N4. This Perspective summarizes the recent significant advances on designing high performance g C3N4 based photocatalysts for hydrogen generation under visible light irradiation. The rational strategies such as nanostructure design, band gap engineering, dye sensitization, and heterojunction construction are described. Finally, this Perspective highlights the ongoing challenges and opportunities for the future development of g C3N4 based photocatalysts in the exciting research area.
author_names: Shaowen Cao

Jiaguo Yu
title: g C3N4 Based Photocatalysts for Hydrogen Generation.
venue: The journal of physical chemistry letters
year: 2014

abstract: To address the challenge in sustainable global development, considerable effort has been made to produce fuels from renewable resources with photocatalysts and photoelectrochemical cells (PECs) by harvesting solar energy. The solar energy conversion efficiency of photocatalysts and PECs is strongly dependent on the light absorption, charge separation, charge migration, charge recombination processes and (electro)catalytic activity in photoactive semiconductors. This perspective article describes the barrier, progress and future direction of research on the correlation of the chemical constituent, size, dimensionality, architecture, crystal structure, microstructure and electronic band structure of photocatalysts (or photoelectrodes) with five vital processes including light absorption, charge separation, migration and recombination as well as surface redox reactions. This article deals with both single materials and composites such as co catalysts on photoelectrodes/photocatalysts, dye sensitized or plasmon enhanced photocatalysts, semiconductor semiconductor heterostructures, semiconductor carbon hybrids as wells as Z scheme and tandem cells. This article also highlights the application of representative photocatalysts and PECs in solar water splitting.
author_names: Jiangtian Li

Nianqiang Wu
title: Semiconductor based photocatalysts and photoelectrochemical cells for solar fuel generation: a review
year: 2015

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)
author_names: Quanjun Xiang

Jiaguo Yu

Mietek Jaroniec
title: Graphene based semiconductor photocatalysts.
venue: Chemical Society reviews
year: 2012