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Ombaka LM, McGettrick JD, Oseghe EO, Al-Madanat O, Rieck Genannt Best F, Msagati TAM, Davies ML, Bredow T, Bahnemann DW. Photocatalytic H 2 production and degradation of aqueous 2-chlorophenol over B/N-graphene-coated Cu 0/TiO 2: A DFT, experimental and mechanistic investigation. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 311:114822. [PMID: 35255324 DOI: 10.1016/j.jenvman.2022.114822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/17/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
Energy and environmental challenges are global concerns that scientists are interested in alleviating. It is on this premise that we prepared boron/nitrogen graphene-coated Cu0/TiO2 (B/N-graphene-coated Cu/TiO2) photocatalyst of varying B:N ratios with dual functionality of H2 production and 2-Chlorophenol (2-CP) degradation. In-situ coating of Cu0 with B/N-graphene is achieved via solvothermal synthesis and calcination under an inert atmosphere. All B/N-graphene-coated Cu/TiO2 exhibit higher photonic efficiencies (5.68%-7.06% at 300 < λ < 400 nm) towards H2 production than bare TiO2 (0.25% at 300 < λ < 400 nm). Varying the B:N ratio in graphene influences the efficiency of H2 generation. A B:N ratio of 0.08 yields the most active composite exhibiting a photonic efficiency of 7.06% towards H2 evolution and a degradation rate of 4.07 × 10-2 min-1 towards 2-chlorophenol (2-CP). Density functional theory (DFT) investigations determine that B-doping (p-type) enhances graphene stability on Cu0 while N-doping (n-type) increases the reduction potential of Cu0 relative to H+ reduction potential. X-ray photoelectron spectroscopy reveals that increasing the B:N ratio increases p-type BC2O while decreasing n-type pyridinic-N in graphene thus altering the interlayer electron density. Isotopic labelling experiments determine water reduction as the main mechanism by which H2 is produced over B/N-graphene-coated Cu/TiO2. The reactive species involved in the degradation of 2-CP are holes (h+), hydroxyl radical (OH•), and O2•-, of which superoxide (O2•-) plays the major role. This work displays B/N -graphene-coated Cu/TiO2 as a potential photocatalyst for large-scale H2 production and 2-CP degradation.
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Affiliation(s)
- Lucy M Ombaka
- Institut für Technische Chemie, Gottfried Wilhelm Leibniz Universität Hannover, Callinstrasse 3, Hannover, 30167, Germany; School of Chemistry and Material Science, Technical University of Kenya, P.O Box 52428-00200, Nairobi, Kenya.
| | - James D McGettrick
- SPECIFIC IKC, Materials Research Centre, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK
| | - Ekemena O Oseghe
- Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Campus, 1709, Johannesburg, South Africa
| | - Osama Al-Madanat
- Institut für Technische Chemie, Gottfried Wilhelm Leibniz Universität Hannover, Callinstrasse 3, Hannover, 30167, Germany
| | - Felix Rieck Genannt Best
- Institute for Physical Chemistry and Electrochemistry, Leibniz University Hannover, 30167, Hannover, Germany
| | - Titus A M Msagati
- Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Campus, 1709, Johannesburg, South Africa
| | - Matthew L Davies
- SPECIFIC IKC, Materials Research Centre, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK; School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban, 4000, South Africa
| | - Thomas Bredow
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, Bonn, Germany
| | - Detlef W Bahnemann
- Institut für Technische Chemie, Gottfried Wilhelm Leibniz Universität Hannover, Callinstrasse 3, Hannover, 30167, Germany; Laboratorium für Nano- und Quantenengineering, Gottfried Wilhelm Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany; Laboratory for Photoactive Nanocomposite Materials, Department of Photonics, Faculty of Physics, Saint-Petersburg State University, Ulianovskaia Str. 3, Peterhof, Saint-Petersburg, 198504, Russia
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Ombaka LM, Ndungu PG, Nyamori VO. Pyrrolic nitrogen-doped carbon nanotubes: physicochemical properties, interactions with Pd and their role in the selective hydrogenation of nitrobenzophenone. RSC Adv 2015. [DOI: 10.1039/c4ra12523a] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The selective synthesis of pyrrolic N-CNTs, which promote the catalytic activity, and selectivity of PdN/CNTs used to hydrogenate nitrobenzophenone.
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Affiliation(s)
- Lucy M. Ombaka
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Westville Campus
- Durban
- South Africa
| | - Patrick G. Ndungu
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Westville Campus
- Durban
- South Africa
| | - Vincent O. Nyamori
- School of Chemistry and Physics
- University of KwaZulu-Natal
- Westville Campus
- Durban
- South Africa
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