报告题目: |
Opportunities of graphenes as photocatalysts for solar fuels production |
报告人: |
Prof. Hermenegildo Garcia |
|
Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia
Spain
|
报告时间: |
2016-06-24 16:00 |
报告地点: |
化学工程系工物馆324(A)会议室 |
主办单位: |
化学工程系 |
简介: |
简介:
Opportunities of graphenes as photocatalysts for solar fuels production.
Hermenegildo Garcia
Instituto de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, 460922 Valencia, Spain
Graphene as one carbon atom thick layer of sp2 carbons in hexagonal arrangement is almost transparent in the spectral UV-visible range and is a zero-band gap semiconductor with high electron mobility. However, in contrast to ideal, defectless, single layer layer graphene, the presence of defects in graphene as well as stacking as few or multilayer assemblies changes completely the properties of these materials, converting it into semiconductor exhibiting photocatalytic properties. The initial use of graphenes in photocatalysis was as additive of semiconductors to enhance their photocatalytic activity. Latter, it was realized that graphene oxide can behave itself as a semiconductor with UV photoresponse. A natural evolution has been to develop visible light photoresponsive graphene semiconductors.
In this presentation, a new procedure for defective graphene films preparation with semiconducting properties for overall water splitting in the absence of sacrificial electron donor or for CO2 reduction will be shown. The process is based on the use of suitable natural polymers that can form films of nanometric thickness essentially defect-free with subnanometric roughness. Pyrolysis of these films can render few-layers graphene and even single layer graphene, depending on the concentration and speed of the spin coating employed in film preparation. If the natural biopolymer contains N or sulfur in its composition, then, the resulting graphene can be doped, with a doping content that essentially depends on the pyrolysis conditions.
While graphene is a conductive material, the presence of dopant elements converts then into semiconductor and, as consequence, they undergo charge separation when they are illuminated with light of wavelength shorter than the band gap. These semiconducting doped graphenes can be used for photocatalytic hydrogen generation from water in the absence of any metal.[1, 2] However, the presence of metals acting as co-catalysts increases the efficiency of the materials for hydrogen generation.
In this presentation, data will be presented showing that it is possible to prepare oriented metal nanoparticles on few-layers graphene and that the resulting material has a record efficiency for the overall water splitting in the absence of sacrificial electron donors.[3-5] In addition, these materials can also be useful to promote the Sabatier methanation of CO2, the photocatalytic activity being dependent on the temperature of the system.
References.
[1] M. Latorre-Sanchez, A. Primo, H. Garcia, Angewandte Chemie-International Edition 52 (2013) 11813-11816.
[2] C. Lavorato, A. Primo, R. Molinari, H. Garcia, Chemistry-a European Journal 20 (2014) 187-194.
[3] D. Mateo, I. Esteve-Adell, J. Albero, J.F.S. Royo, A. Primo, H. Garcia, Nat Commun 7 (2016) article 11819.
[4] A. Primo, I. Esteve-Adell, J.F. Blandez, A. Dhakshinamoorthy, M. Alvaro, N. Candu, S.M. Coman, V.I. Parvulescu, H. Garcia, Nature Communications 6 (2015).
[5] A. Primo, I. Esteve-Adell, S.N. Coman, N. Candu, V.I. Parvulescu, H. Garcia, Angewandte Chemie-International Edition 55 (2016) 607-612.
|
|
