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Progress and Challenges of Semiconducting Materials for Solar Photocatalysis
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Tariq Altalhi, Optical Properties and Applications of Semiconductors, 2023
Mridula Guin, Tanaya Kundu, Vinay K. Verma, Nakshatra Bahadur Singh
Carbon nitride, C3N4, is an attractive polymeric material having hardness more than diamonds (Cao et al. 2015). It can exist in different phases, e.g. α-, β-, cubic, quasi-cubic and graphitic phase. Graphitic carbon nitride, g-C3N4, have graphite like layered structure is a purely non-metallic polymeric semiconductor (Fina et al. 2015). It has several unique properties, e.g. narrow band gap (2.7–2.8 eV), excellent thermal and chemical stability, fast electron-hole transporting ability. These features impart photocatalytic properties to g-C3N4. According to the band gap, g-C3N4 absorbs strongly around 400–450 nm in the visible range. Nowadays it is gaining much popularity as a photocatalyst because of its easily controllable structure. The properties can be tailored according to the role it plays. g-C3N4 has found extensive application as a photocatalyst in H2 production, CO2 reduction, photo hydrolysis, photodegradation of pollutants, disinfectants, production of capacitor material etc. (Cui et al. 2015, Liu et al. 2018, Lv et al. 2018, Maeda et al. 2014Zhu et al. 2014,).
Photocatalyst
Published in Amit Soni, Dharmendra Tripathi, Jagrati Sahariya, Kamal Nayan Sharma, Energy Conversion and Green Energy Storage, 2023
Carbon nitride is considered as the most popular, stable, low-cost, metal-free photocatalyst under visible light, but due to its high charge carrier recombination, various successful attempts have been made to enhance the photocatalytic efficiency by anion doping, cation doping, anion–cation co-doping, formation of heterostructure, or loading of co-catalyst to form Schottky barrier and heterojunctions as reviewed in this chapter. Effects of various functionalization methods on band edges, optical properties, overall charge distribution on the surface of g-C3N4 and effect on overpotential have also been discussed in terms of HER, OER and CO2RR. For better understanding of optical properties, studies based on excitonic effects are highly required in this field. For better understanding of reaction mechanism, nudged elastic band method is also highly required for functionalized g-C3N4 especially to determine the role of charge carrier transfer on adsorption of an intermediate molecule and to have some elaborative insights to reduce the barrier height of rate-determining reaction.
Nanostructured Photocatalytic Materials for Water Purification
Published in Maulin P. Shah, Sweta Parimita Bera, Günay Yıldız Töre, Advanced Oxidation Processes for Wastewater Treatment, 2022
Jennyffer Martinez Quimbayo, Satu Ojala, Samuli Urpelainen, Mika Huuhtanen, Wei Cao, Marko Huttula, Riitta L. Keiski
Apart from metal compounds, nonmetal semiconductors are also potential candidates for photocatalytic water treatment. Graphitic carbon nitride (g-C3N4) is an n-type semiconductor composed of earth-abundant elements. This is the most stable form of carbon nitride in ambient conditions, and its light absorption properties as well as redox potential can be modified according to the requirements. The availability of different surface sites and tunable porosity make it interesting for several catalytic applications. It has been shown that g-C3N4 materials are also active in bacterial disinfection and degradation of pollutants. For example, tylosin (antibiotic) was degraded in 30 min under simulated solar light using novel crystal structure-modified g-C3N4 (Xu, 2019; Vilé, 2020).
Organocatalysis with carbon nitrides
Published in Science and Technology of Advanced Materials, 2023
Sujanya Maria Ruban, Kavitha Ramadass, Gurwinder Singh, Siddulu Naidu Talapaneni, Gunda Kamalakar, Chandrakanth Rajanna Gadipelly, Lakshmi Kantham Mannepalli, Yoshihiro Sugi, Ajayan Vinu
Carbon nitride materials gathered massive attraction owing to their excellent catalytic, electronic, and electrical properties. Based on their structures, carbon nitrides are classified into five different forms which include graphitic carbon nitride (g-C3N4), α-C3N4, β- C3N4, cubic C3N4 and pseudocubic C3N4. The synthesis of these carbon nitrides except g-C3N4 requires high pressure and high temperature which limit the progression of bulk production of these materials. However, g-C3N4, whose structure closely resembles graphene, can be prepared by using chemical or molecular precursors and require only mild synthesis conditions [37–40]. Interestingly, g-C3N4 possesses the properties of a medium-band gap semiconductor having a graphite-like structure with the CN framework attached with amine functionalities which mainly contributes to the catalysis of chemical reactions [41]. However, g-C3N4 has low electronic conductivity and less specific surface area; therefore, cannot be used in electro-chemical hydrolysis reactions (1.4–2.8 eV) but it has been widely used in photocatalytic applications owing to its unique band structure. In addition, the electro and thermal catalytic application of these materials are also quite rare [42,43].
Synthesis and comparison of two different morphologies of graphitic carbon nitride as adsorbent for preconcentration of heavy metal ions by effervescent salt-assisted dispersive micro solid phase extraction method
Published in Journal of Dispersion Science and Technology, 2022
Samira Khalesi, Bahareh Fahimirad, Maryam Rajabi, Omirserik Baigenzhenov, Ahmad Hosseini-Bandegharaei
Graphitic carbon nitride (g-C3N4) is a new 2D material rich in nitrogen that, due to its special properties, in recent years has been considered in the fields of catalysis, biomedical imaging, and sensing application.[7,8] G-C3N4 has also been used as an adsorbent in solid phase extraction methods.[9–11] Unfortunately, bulk g-C3N4 has several shortcomings, including possibility of re-aggregation of the nanosheets and very low surface area. Hence, seeking a way to improve g-C3N4 performance as an adsorbent is necessary. So far, different morphologies have been synthesized from carbon nitride graphite,[6,12,13] and all these morphologies have shown better performance than bulk graphite in various applications.
Development of photocatalytic chip seal for nitric oxide removal on the surface of pavement using g-C3N4/TiO2 composite
Published in Road Materials and Pavement Design, 2021
Xuejuan Cao, Mei Deng, Boming Tang, Yongjie Ding, Xiaoyu Yang
Graphitic carbon nitride (g-C3N4) is a novel visible light photocatalyst with a narrow band gap (2.73 eV), favourable chemical and thermal stability (Zhang, Zhang, & Dai, 2017). The g-C3N4 has a higher visible light utilisation rate so that it was used by researchers to modify TiO2 for constructing heterojunctions (Giannakopoulou, Papailias, Todorova, Boukos, & Trapalis, 2017). Yan, Zhao et al. (2011, 2012) used melamine and titanium tetrachloride (TiCl4) as precursors to prepare g-C3N4 and TiO2, and then mixed the two monomers to obtain the TiO2-g-C3N4 hybrid on a muffle furnace with high temperature. The results showed that the photocatalytic efficiency of the composite is significantly enhanced compared with the two monomer materials.