Universität zu Köln

Afzali, Niloufar, Tangestaninejad, Shahram, Keshavarzi, Reza, Mirkhani, Valiollah, Nematollahi, Javad, Moghadam, Majid, Mohammadpoor-Baltork, Iraj, Reimer, Max, Olthof, Selina, Klein, Axel ORCID: 0000-0003-0093-9619 and Gimenez, Sixto ORCID: 0000-0002-4522-3174 (2020). Hierarchical Ti-Based MOF with Embedded RuO2 Nanoparticles: a Highly Efficient Photoelectrode for Visible Light Water Oxidation. ACS Sustain. Chem. Eng., 8 (50). S. 18366 - 18377. WASHINGTON: AMER CHEMICAL SOC. ISSN 2168-0485

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Abstract

The Ti-based metal-organic framework (MOF) MIL-125-NH2 is one of the promising materials for solar water splitting because it contains a sensitizer and a catalytic center in a single structure. MIL-125-NH2 as many other MOFs has a microporous structure with pore diameters less than 2 nm. Compared with common MOFs, hierarchical mesoporous materials exhibit very large specific surface areas that facilitate diffusion of active species, accelerate subsequent surface reactions, and increase the bubble release rate by providing larger free spaces. Thus, the development of a facile method to create hierarchical porous MOFs with larger pore sizes remains a chemical challenge. Furthermore, MOF-type semiconducting materials usually have low activities in oxygen evolution reaction, and the presence of a suitable cocatalyst is needed to reduce the large O-2 overpotential. This study attempted to generate a hierarchical MIL-125-NH 2 MOF material with embedded RuO2 nanopartides as a highly efficient cocatalyst in a simple one-step process for use in efficient solar water oxidation. Different amounts of RuCl3 center dot H2O precursor salt were used simultaneously for creating hierarchical porosity in MIL-125-NH2 and for producing the assumed RuO2 cocatalyst. For comparison, a hydrochloric acid treatment was applied to generate hierarchical porosity in the MOF in the absence of ruthenium. The samples were characterized using high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller adsorption, powder X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. HRTEM gave evidence that in the ruthenium oxide-containing MIL-125-NH2 samples, tetragonal RuO2 nanoparticles are present. The materials were applied as photoelectrodes, and photoelectrochemical (PEC) water oxidation performance under visible light illumination was studied. The PEC water oxidation performance of the MIL-125-NH2 layer could be strikingly improved with a photocurrent density of about 10 times more than that of the pure MOF at 1.23 V versus reversible hydrogen electrode in artificial seawater, as a result of the hierarchical MOF structure and the presence of RuO2 as a cocatalyst. Furthermore, density functional theory calculations were performed to shed light on the electronic properties and the role of the RuO2 in the assumed hole transport.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Afzali, Niloufar UNSPECIFIED UNSPECIFIED UNSPECIFIED Tangestaninejad, Shahram UNSPECIFIED UNSPECIFIED UNSPECIFIED Keshavarzi, Reza UNSPECIFIED UNSPECIFIED UNSPECIFIED Mirkhani, Valiollah UNSPECIFIED UNSPECIFIED UNSPECIFIED Nematollahi, Javad UNSPECIFIED UNSPECIFIED UNSPECIFIED Moghadam, Majid UNSPECIFIED UNSPECIFIED UNSPECIFIED Mohammadpoor-Baltork, Iraj UNSPECIFIED UNSPECIFIED UNSPECIFIED Reimer, Max UNSPECIFIED UNSPECIFIED UNSPECIFIED Olthof, Selina UNSPECIFIED UNSPECIFIED UNSPECIFIED Klein, Axel UNSPECIFIED orcid.org/0000-0003-0093-9619 UNSPECIFIED Gimenez, Sixto UNSPECIFIED orcid.org/0000-0002-4522-3174 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-307612
DOI:	10.1021/acssuschemeng.0c04682
Journal or Publication Title:	ACS Sustain. Chem. Eng.
Volume:	8
Number:	50
Page Range:	S. 18366 - 18377
Date:	2020
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	2168-0485
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language METAL-ORGANIC FRAMEWORKS; COMPUTATIONAL DESIGN; HYDROGEN; COCATALYSTS; ELECTROCATALYSTS; PHOTOCATALYSIS; CONSTRUCTION; DEGRADATION; NH2-MIL-125; SURFACTANT Multiple languages Chemistry, Multidisciplinary; Green & Sustainable Science & Technology; Engineering, Chemical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/30761