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Highly active and stable multi-walled carbon nanotubes-graphene-TiO2 nanohybrid: An efficient non-noble metal photocatalyst for water splitting
Catalysis Today ( IF 5.3 ) Pub Date : 2017-10-27 , DOI: 10.1016/j.cattod.2017.10.023
Sankeerthana Bellamkonda , Nithya Thangavel , Hafeez Yusuf Hafeez , B. Neppolian , G. Ranga Rao

Novel multiwalled carbon nanotubes-graphene-TiO2 (CNT-GR-TiO2) composite materials without noble metal co-catalysts are designed for photocatalytic decomposition of water using solar light. The CNT-GR-TiO2 nanocomposite shows the highest H2 production rate of 29 mmol h−1g−1 under the full spectrum of solar light irradiation. The rate of H2 production is 8-fold higher than the commercial TiO2 (Degussa P25) and the estimated solar energy conversion efficiency is 14.6%. Spectroscopic and photocatalytic studies reveal that graphene acts as an electron reservoir through which interfacial charge transfer occurs for water splitting. The UV–vis-DRS study shows that the absorption peak maximum for anatase TiO2 occurs at ∼315 nm, which is shifted to ∼355 nm and 380 nm for GR-TiO2 and CNT-GR-TiO2 composites, respectively. The EPR spectra of GR-TiO2 and CNT-GR-TiO2 composites indicate that graphene and multiwalled carbon nanotubes in the composites promote the generation of Ti3+ and oxygen vacancies and in turn reduce the band gap of anatase TiO2 from 3.32 eV to 2.79 eV. This is corroborated by XPS and photoluminescence analyses of the samples. The role of CNTs is to prevent the restacking of graphene nanosheets and provide additional electron transport channels thereby suppressing the recombination rate of electron-hole pairs in the CNT-GR-TiO2 composite. The combination of all these factors results in increasing the hydrogen production rate from 19 mmol h−1 g−1 (anatase TiO2) to 22 mmol h−1 g−1 (GR-TiO2) to 29 mmol h−1 g−1 (CNT-GR-TiO2).



中文翻译:

高活性和稳定的多壁碳纳米管-石墨烯-TiO 2纳米杂化物:一种高效的非贵金属光分解水催化剂

设计了无贵金属助催化剂的新型多壁碳纳米管-石墨烯-TiO 2(CNT-GR-TiO 2)复合材料,用于利用太阳光对水进行光催化分解。CNT-GR-TiO 2纳米复合材料在太阳光照射的全光谱下显示出最高的H 2产生速率,为29 mmol h -1 g -1。H 2的生产速率比市售的TiO 2高8倍(Degussa P25),预计太阳能转换效率为14.6%。光谱和光催化研究表明,石墨烯充当电子储库,通过该电子储库发生界面电荷转移以分解水。UV-vis-DRS研究表明,锐钛矿型TiO 2的最大吸收峰出现在315 nm处,而GR-TiO 2和CNT-GR-TiO 2复合材料的吸收峰分别移至355 nm和380 nm 。GR-TiO 2和CNT-GR-TiO 2复合材料的EPR光谱表明,复合材料中的石墨烯和多壁碳纳米管促进了Ti 3+和氧空位的产生,进而减小了锐钛矿型TiO 2的带隙。从3.32 eV到2.79 eV。XPS和样品的光致发光分析证实了这一点。CNT的作用是防止石墨烯纳米片的重新堆叠,并提供其他电子传输通道,从而抑制CNT-GR-TiO 2复合材料中电子-空穴对的复合速率。所有这些因素的结果,从19毫摩尔ħ增加氢生产速率的组合-1 克-1(锐钛矿型的TiO 2),以22毫摩尔ħ -1 克-1(GR-TIO 2),以29毫摩尔ħ -1 克- 1(CNT-GR-TiO 2)。

更新日期:2017-10-27
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