Microcontact-Printing-Assisted Access of Graphitic Carbon Nitride Films with Favorable Textures toward Photoelectrochemical Application
Microcontact-Printing-Assisted Access of Graphitic Carbon Nitride Films with Favorable Textures toward Photoelectrochemical Application
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DOI：
10.1002/adma.201404543
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发表时间：
2015-01-27
影响因子：
29.4
通讯作者：
Antonietti, Markus
中科院分区：
文献类型：
--
作者：
Liu, Jian;Wang, Hongqiang;Antonietti, Markus
Toward such applications, a strategy for fabricating CN films should be developed. Generally, a successful photoelectrochemical device requires not only a high surface area, but also an optimization of the morphology and quality of the film, including the contact with the conductive substrate, the film thickness, and the size of the light harvesting microstructures.[12] However, within the scope of previous PEC characterizations, the morphology control of carbon nitride films is deficient, as the pre-synthesized graphitic carbon nitride powder has to be postprocessed onto conductive substrates.[8, 13, 14] The obtained pure CN-based films were usually reported to possess PEC properties with photocurrents up to a few µA cm–2, which was attributed to deleterious grain boundary effects and the poor contact with the substrate.[15] Considering the large efforts put into CN-based heterogeneous photocatalysis, unfortunately, up to now few efforts on direct growth of nanostructured graphitic carbon nitride films on desired substrates, especially on conductive substrates for PEC energy conversion, have been realized. Here, we report the first direct access of graphitic carbon nitride films on desired substrates by anodic aluminum oxide (AAO) membrane assisted growth, which is very well-known as a versatile template for fabricating various nanostructures.[16] Different from previous reports, each channel of AAO is employed here as the picoliter “ink” container of cyanamide (CA) for in situ printing CN films onto the sandwiching substrates. The film can be easily formed on desired substrates, such as glass slide (CN@ Gla) and fluorine-doped tin oxide glass (CN@ FTO). Following the “ink” infiltration into the AAO stamp, the AAO was placed in between two substrates (glass or FTO), as illustrated in Scheme 1. During a standard synthetic procedure toward graphitic carbon nitride, the sandwiched AAO starts to release CA ink and print in situ thermally condensed graphitic carbon nitride films onto the sandwiching substrates. The film thicknesses can be simply modulated by the ink concentrations in the starting aqueous solution. The film partially inherits the AAO periodic feature as the film surfaces present periodic microcluster patterns. The synthetic procedure is thus likely a combination of the “Chemical Vapor Deposition” and “Microcontact Printing” techniques, widely employed in growing carbon materials and various patterns, respectively.[17] It's worth pointing that no apparent differences in the film quality were observed for the upper and lower substrates. It's assumed that tri-s-triazine building blocks generated from the condensation of CA ink are diffused randomly and evenly upwards and downwards onto the substrates to form the finalCooperative photoelectrochemical (PEC) conversion of solar energy into chemical fuels is considered as one of the most promising solutions to the sustainable energy needs of mankind, considering the intermittent and spatial fluctuations in the availability of sunlight on earth.[1] Inspired by photochemical water splitting in natural photosynthesis, significant scientific efforts are aimed toward the development of solar fuel devices to split water into H 2 and O 2.[2] The key to the success of the solar fuel powered future lies on the design and development of the affordable semiconductors with high light absorbance and catalytic activity.[3, 4] The development of synthetic visible-light-driven semiconductor catalysts that functionally mimic the elegant water reduction chemistry of hydrogenase enzymes has attracted widespread interest and also created a lot of systems.[3, 5] Organic water oxidation catalysts based on earth-abundant elements are …
