Carbon-Based Nanomaterials for Visible-Light Photocatalysis and Photoelectrocatalysis

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (31 August 2023) | Viewed by 18115

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Departamento de Quimica and Instituto Universitario de Tecnologia Quimica (CSIC-UPV), Universitat Politecnica de Valencia, Av. De los Naranjos s/n, 46022 Valencia, Spain
Interests: heterogeneous catalysis; photocatalysis
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School of Chemistry, Madurai Kamaraj University, Madurai 625 021, India
Interests: heterogeneous catalysis; metal–organic frameworks; solid catalysts; chitosan; carbocatalysis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, the use of carbonaceous solids in photocatalysis and photoelectrocatalysis has attracted many researchers around the world due to their availability, good stability, reliable preparation, and the wide diversity of possible structures. In addition, different types of heterojunctions have also been developed by combining semiconductors with photoresponsive carbons, introducing co-catalysts, and controlling the interfacial contact. One of the fundamental reasons to employ carbon-based solids for photocatalysis is their fast electron mobility, large surface area, high physicochemical stability, and viable synthetic strategies from different precursors. On the other hand, the photocatalytic activity of the carbonaceous solids is very much influenced by doping, the presence of defects, confinement,  and morphology. Some of the most widely used carbonaceous materials for the development of photocatalysts/photoelectrocatalysts are activated carbons, carbon dots, carbon nanotubes, nanofibers, graphene-based solids, graphitic carbon nitrides, fullerenes, and three-dimensional structured carbons. This Special Issue aims to show the breadth of the field and the potential for various applications of carbon based materialsincluding photocatalysis for organic compound transformation, special cases of organic pollutant photodegradation, photocatalytic hydrogen generation, oxygen evolution and water splitting, photoreduction of CO2, photocatalytic, and related solar fuels production.

Prof. Dr. Hermenegildo García
Prof. Dr. Amarajothi Dhakshinamoorthy
Guest Editors

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Keywords

  • activated carbon
  • carbon dot
  • graphene
  • photocatalysis
  • photoelectrocatalysis
  • reduced graphene oxide
  • solar light conversion
  • visible light

Published Papers (10 papers)

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Research

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18 pages, 8211 KiB  
Article
Nanometric Cu-ZnO Particles Supported on N-Doped Graphitic Carbon as Catalysts for the Selective CO2 Hydrogenation to Methanol
by Lu Peng, Bogdan Jurca, Alberto Garcia-Baldovi, Liang Tian, German Sastre, Ana Primo, Vasile Parvulescu, Amarajothi Dhakshinamoorthy and Hermenegildo Garcia
Nanomaterials 2024, 14(5), 476; https://doi.org/10.3390/nano14050476 - 06 Mar 2024
Viewed by 955
Abstract
The quest for efficient catalysts based on abundant elements that can promote the selective CO2 hydrogenation to green methanol still continues. Most of the reported catalysts are based on Cu/ZnO supported in inorganic oxides, with not much progress with respect to the [...] Read more.
The quest for efficient catalysts based on abundant elements that can promote the selective CO2 hydrogenation to green methanol still continues. Most of the reported catalysts are based on Cu/ZnO supported in inorganic oxides, with not much progress with respect to the benchmark Cu/ZnO/Al2O3 catalyst. The use of carbon supports for Cu/ZnO particles is much less explored in spite of the favorable strong metal support interaction that these doped carbons can establish. This manuscript reports the preparation of a series of Cu-ZnO@(N)C samples consisting of Cu/ZnO particles embedded within a N-doped graphitic carbon with a wide range of Cu/Zn atomic ratio. The preparation procedure relies on the transformation of chitosan, a biomass waste, into N-doped graphitic carbon by pyrolysis, which establishes a strong interaction with Cu nanoparticles (NPs) formed simultaneously by Cu2+ salt reduction during the graphitization. Zn2+ ions are subsequently added to the Cu–graphene material by impregnation. All the Cu/ZnO@(N)C samples promote methanol formation in the CO2 hydrogenation at temperatures from 200 to 300 °C, with the temperature increasing CO2 conversion and decreasing methanol selectivity. The best performing Cu-ZnO@(N)C sample achieves at 300 °C a CO2 conversion of 23% and a methanol selectivity of 21% that is among the highest reported, particularly for a carbon-based support. DFT calculations indicate the role of pyridinic N doping atoms stabilizing the Cu/ZnO NPs and supporting the formate pathway as the most likely reaction mechanism. Full article
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17 pages, 4133 KiB  
Article
Enhanced Visible Light-Driven Photocatalytic Water-Splitting Reaction of Titanate Nanotubes Sensitised with Ru(II) Bipyridyl Complex
by Mauro Malizia, Stuart A. Scott, Laura Torrente-Murciano, Adam M. Boies, Talal A. Aljohani and Herme G. Baldovi
Nanomaterials 2023, 13(22), 2959; https://doi.org/10.3390/nano13222959 - 16 Nov 2023
Viewed by 838
Abstract
The ion exchange of Na+ cations was used to photosensitise titanates nanotubes (Ti-NTs) with tris(2,2’-bipyridine)ruthenium(II) cations (Ru(bpy)32+); this yielded a light-sensitised Ti-NTs composite denoted as (Ru(bpy)3)Ti-NTs, exhibiting the characteristic absorption of Ru(bpy)32+ in visible light. [...] Read more.
The ion exchange of Na+ cations was used to photosensitise titanates nanotubes (Ti-NTs) with tris(2,2’-bipyridine)ruthenium(II) cations (Ru(bpy)32+); this yielded a light-sensitised Ti-NTs composite denoted as (Ru(bpy)3)Ti-NTs, exhibiting the characteristic absorption of Ru(bpy)32+ in visible light. Incident photon-to-current efficiency (IPCE) measurements and the photocatalytic reduction of methyl viologen reaction confirmed that in the photosensitisation of the (Ru(bpy)3)Ti-NTs composite, charge transfer and charge separation occur upon excitation by ultraviolet and visible light irradiation. The photocatalytic potential of titanate nanotubes was tested in the water-splitting reaction and the H2 evolution reaction using a sacrificial agent and showed photocatalytic activity under various light sources, including xenon–mercury lamp, simulated sunlight, and visible light. Notably, in the conditions of the H2 evolution reaction when (Ru(bpy)3)Ti-NTs were submitted to simulated sunlight, they exceeded the photocatalytic activity of pristine Ti-NTs and TiO2 by a factor of 3 and 3.5 times, respectively. Also, (Ru(bpy)3)Ti-NTs achieved the photocatalytic water-splitting reaction under simulated sunlight and visible light, producing, after 4 h, 199 and 282 μmol×Hgcat−1. These results confirm the effective electron transfer of Ru(bpy)3 to titanate nanotubes. The stability of the photocatalyst was evaluated by a reuse test of four cycles of 24 h reactions without considerable loss of catalytic activity and crystallinity. Full article
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14 pages, 5065 KiB  
Article
A Porphyrin-Based Covalent Organic Framework as Metal-Free Visible-LED-Light Photocatalyst for One-Pot Tandem Benzyl Alcohol Oxidation/Knoevenagel Condensation
by Sara Oudi, Ali Reza Oveisi, Saba Daliran, Mostafa Khajeh, Amarajothi Dhakshinamoorthy and Hermenegildo García
Nanomaterials 2023, 13(3), 558; https://doi.org/10.3390/nano13030558 - 30 Jan 2023
Cited by 6 | Viewed by 2200
Abstract
A porphyrin-based covalent organic framework (COF), namely Porph-UOZ-COF (UOZ stands for the University of Zabol), has been designed and prepared via the condensation reaction of 5,10,15,20-tetrakis-(3,4-dihydroxyphenyl)porphyrin (DHPP) with 1,4-benzenediboronic acid (DBBA), under the solvothermal condition. The solid was characterized by spectroscopic, microscopic, and [...] Read more.
A porphyrin-based covalent organic framework (COF), namely Porph-UOZ-COF (UOZ stands for the University of Zabol), has been designed and prepared via the condensation reaction of 5,10,15,20-tetrakis-(3,4-dihydroxyphenyl)porphyrin (DHPP) with 1,4-benzenediboronic acid (DBBA), under the solvothermal condition. The solid was characterized by spectroscopic, microscopic, and powder X-ray diffraction techniques. The resultant multifunctional COF revealed an outstanding performance in catalyzing a one-pot tandem selective benzylic C-H photooxygenation/Knoevenagel condensation reaction in the absence of additives or metals under visible-LED-light irradiation. Notably, the catalytic activity of the COF was superior to individual organic counterparts and the COF was both stable and reusable for four consecutive runs. The present approach illustrates the potential of COFs as promising metal-free (photo) catalysts for the development of tandem reactions. Full article
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10 pages, 3798 KiB  
Article
Enhanced Photocatalytic Degradation Activity Using the V2O5/RGO Composite
by Anuja A. Yadav, Yuvaraj M. Hunge, Seok-Won Kang, Akira Fujishima and Chiaki Terashima
Nanomaterials 2023, 13(2), 338; https://doi.org/10.3390/nano13020338 - 13 Jan 2023
Cited by 39 | Viewed by 3059
Abstract
Semiconductor-based photocatalyst materials played an important role in the degradation of organic compounds in recent years. Photocatalysis is a simple, cost-effective, and environmentally friendly process for degrading organic compounds. In this work, vanadium pentoxide (V2O5) and V2O [...] Read more.
Semiconductor-based photocatalyst materials played an important role in the degradation of organic compounds in recent years. Photocatalysis is a simple, cost-effective, and environmentally friendly process for degrading organic compounds. In this work, vanadium pentoxide (V2O5) and V2O5/RGO (reduced graphene oxide) composite were synthesized by a hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, and UV-Vis spectroscopic analysis, etc. Raman analysis shows the occurrence of RGO characteristic peaks in the composite and different vibrational modes of V2O5. The band gap of flake-shaped V2O5 is reduced and its light absorption capacity is enhanced by making its composite with RGO. The photocatalytic degradation of methylene blue (MB) was studied using both V2O5 and V2O5/RGO composite photocatalyst materials. The V2O5/RGO composite exhibits a superior photocatalytic performance to V2O5. Both catalyst and light play an important role in the degradation process. Full article
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17 pages, 4229 KiB  
Article
Photocatalytic Hydrogen Production from Glycerol Aqueous Solutions as Sustainable Feedstocks Using Zr-Based UiO-66 Materials under Simulated Sunlight Irradiation
by Celia M. Rueda-Navarro, Belén Ferrer, Herme G. Baldoví and Sergio Navalón
Nanomaterials 2022, 12(21), 3808; https://doi.org/10.3390/nano12213808 - 28 Oct 2022
Cited by 9 | Viewed by 2052
Abstract
There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H2 generation from photoreforming of glycerol aqueous solutions under simulated [...] Read more.
There is an increasing interest in developing cost-effective technologies to produce hydrogen from sustainable resources. Herein we show a comprehensive study on the use of metal–organic frameworks (MOFs) as heterogeneous photocatalysts for H2 generation from photoreforming of glycerol aqueous solutions under simulated sunlight irradiation. The list of materials employed in this study include some of the benchmark Zr-MOFs such as UiO-66(Zr)-X (X: H, NO2, NH2) as well as MIL-125(Ti)-NH2 as the reference Ti-MOF. Among these solids, UiO-66(Zr)-NH2 exhibits the highest photocatalytic H2 production, and this observation is attributed to its adequate energy level. The photocatalytic activity of UiO-66(Zr)-NH2 can be increased by deposition of small Pt NPs as the reference noble metal co-catalyst within the MOF network. This photocatalyst is effectively used for H2 generation at least for 70 h without loss of activity. The crystallinity of MOF and Pt particle size were maintained as revealed by powder X-ray diffraction and transmission electron microscopy measurements, respectively. Evidence in support of the occurrence of photoinduced charge separation with Pt@UiO-66(Zr)-NH2 is provided from transient absorption and photoluminescence spectroscopies together with photocurrent measurements. This study exemplifies the possibility of using MOFs as photocatalysts for the solar-driven H2 generation using sustainable feedstocks. Full article
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15 pages, 3169 KiB  
Article
Phosphorus-Rich Ruthenium Phosphide Embedded on a 3D Porous Dual-Doped Graphitic Carbon for Hydrogen Evolution Reaction
by Aicha Anouar, Antonio Doménech-Carbó and Hermenegildo Garcia
Nanomaterials 2022, 12(20), 3597; https://doi.org/10.3390/nano12203597 - 13 Oct 2022
Cited by 1 | Viewed by 1474
Abstract
Metal phosphides have recently emerged as promising electrocatalysts for hydrogen evolution reaction (HER). Herein, we report the synthesis of ruthenium diphosphide embedded on a dual-doped graphitic carbon by pyrolyzing chitosan beads impregnated with ruthenium chloride and phosphorus pentoxide. The as-synthesized RuP2@N-P-C [...] Read more.
Metal phosphides have recently emerged as promising electrocatalysts for hydrogen evolution reaction (HER). Herein, we report the synthesis of ruthenium diphosphide embedded on a dual-doped graphitic carbon by pyrolyzing chitosan beads impregnated with ruthenium chloride and phosphorus pentoxide. The as-synthesized RuP2@N-P-C displays a good electrocatalytic activity in acidic, neutral and alkaline media. We show that the HER activity of the electrocatalyst can be tuned by varying the concentration of Li+ cations. Co-diffusion effects on H+ exerted by Li+ on HER in the porous carbon matrix have been observed. Full article
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13 pages, 2957 KiB  
Article
Promotional Effects on the Catalytic Activity of Co-Fe Alloy Supported on Graphitic Carbon for CO2 Hydrogenation
by Bogdan Jurca, Lu Peng, Ana Primo, Alvaro Gordillo, Amarajothi Dhakshinamoorthy, Vasile I. Parvulescu and Hermenegildo García
Nanomaterials 2022, 12(18), 3220; https://doi.org/10.3390/nano12183220 - 16 Sep 2022
Cited by 4 | Viewed by 1408
Abstract
Starting from the reported activity of Co-Fe nanoparticles wrapped onto graphitic carbon (Co-Fe@C) as CO2 hydrogenation catalysts, the present article studies the influence of a series of metallic (Pd, Ce, Ca, Ca, and Ce) and non-metallic (S in various percentages and S [...] Read more.
Starting from the reported activity of Co-Fe nanoparticles wrapped onto graphitic carbon (Co-Fe@C) as CO2 hydrogenation catalysts, the present article studies the influence of a series of metallic (Pd, Ce, Ca, Ca, and Ce) and non-metallic (S in various percentages and S and alkali metals) elements as Co-Fe@C promoters. Pd at 0.5 wt % somewhat enhances CO2 conversion and CH4 selectivity, probably due to H2 activation and spillover on Co-Fe. At similar concentrations, Ce does not influence CO2 conversion but does diminish CO selectivity. A 25 wt % Fe excess increases the Fe-Co particle size and has a detrimental effect due to this large particle size. The presence of 25 wt % of Ca increases the CO2 conversion and CH4 selectivity remarkably, the effect being attributable to the CO2 adsorption capacity and basicity of Ca. Sulfur at a concentration of 2.1% or higher acts as a strong poison, decreasing CO2 conversion and shifting selectivity to CO. The combination of S and alkali metals as promoters maintain the CO selectivity of S but notably increase the CO2 conversion. Overall, this study shows how promoters and poisons can alter the catalytic activity of Co/Fe@C catalysts, changing from CH4 to CO. It is expected that further modulation of the activity of Co/Fe@C catalysts can serve to drive the activity and selectivity of these materials to any CO2 hydrogenation products that are wanted. Full article
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19 pages, 4904 KiB  
Article
Photocatalytic Water Splitting Promoted by 2D and 3D Porphyrin Covalent Organic Polymers Synthesized by Suzuki-Miyaura Carbon-Carbon Coupling
by Maria Novoa-Cid, Arianna Melillo, Belén Ferrer, Mercedes Alvaro and Herme G. Baldovi
Nanomaterials 2022, 12(18), 3197; https://doi.org/10.3390/nano12183197 - 14 Sep 2022
Cited by 3 | Viewed by 1897
Abstract
This work deals with the synthesis of metal-free and porphyrin-based covalent organic polymers (COPs) by the Suzuki–Miyaura coupling carbon-carbon bond forming reaction to study the photocatalytic overall water splitting performance. Apart from using 5,10,15,20-Tetrakis-(4-bromophenyl)porphyrin, we have chosen different cross-linker monomers to induce 2-dimensional [...] Read more.
This work deals with the synthesis of metal-free and porphyrin-based covalent organic polymers (COPs) by the Suzuki–Miyaura coupling carbon-carbon bond forming reaction to study the photocatalytic overall water splitting performance. Apart from using 5,10,15,20-Tetrakis-(4-bromophenyl)porphyrin, we have chosen different cross-linker monomers to induce 2-dimensional (2D) or 3-dimensional (3D) and different rigidity in their resulting polymeric molecular structure. The synthesised COPs were extensively characterised to reveal that the dimensionality and flexibility of the molecular structure play an intense role in the physical, photochemical, and electronic properties of the polymers. Photoinduced excited state of the COPs was evaluated by nanosecond time-resolved laser transient absorption spectroscopy (TAS) by analysing excited state kinetics and quenching experiments, photocurrent density measurements and photocatalytic deposition of Ru3+ to RuO2, and photocatalysis. In summary, TAS experiments demonstrated that the transient excited state of these polymers has two decay kinetics and exhibit strong interaction with water molecules. Moreover, photocurrent and photocatalytic deposition experiments proved that charges are photoinduced and are found across the COP molecular network, but more important charges can migrate from the surface of the COP to the medium. Among the various COPs tested, COP–3 that has a flexible and 3D molecular structure reached the best photocatalytic performances, achieving a photocatalytic yield of 0.4 mmol H2 × gCOP–3−1 after 3 h irradiation. Full article
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15 pages, 3812 KiB  
Article
Enhanced Visible Light-Driven Photoelectrocatalytic Degradation of Paracetamol at a Ternary z-Scheme Heterojunction of Bi2WO6 with Carbon Nanoparticles and TiO2 Nanotube Arrays Electrode
by Nondumiso Mahhumane, Leskey M. Cele, Charles Muzenda, Oluchi V. Nkwachukwu, Babatunde A. Koiki and Omotayo A. Arotiba
Nanomaterials 2022, 12(14), 2467; https://doi.org/10.3390/nano12142467 - 19 Jul 2022
Cited by 4 | Viewed by 1705
Abstract
In this study, a ternary z-scheme heterojunction of Bi2WO6 with carbon nanoparticles and TiO2 nanotube arrays was used to remove paracetamol from water by photoelectrocatalysis. The materials and z-scheme electrode were characterised using X-ray diffraction (XRD), field emission scanning [...] Read more.
In this study, a ternary z-scheme heterojunction of Bi2WO6 with carbon nanoparticles and TiO2 nanotube arrays was used to remove paracetamol from water by photoelectrocatalysis. The materials and z-scheme electrode were characterised using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), EDS mapping, ultraviolet diffuse reflection spectroscopy (UV-DRS), photocurrent measurement, electrochemical impedance spectroscopy (EIS), uv-vis spectroscopy and total organic carbon measurement (TOC). The effect of parameters such as current density and pH were studied. At optimal conditions, the electrode was applied for photoelectrocatalytic degradation of paracetamol, which gave a degradation efficiency of 84% within 180 min. The total organic carbon removal percentage obtained when using this electrode was 72%. Scavenger studies revealed that the holes played a crucial role during the photoelectrocatalytic degradation of paracetamol. The electrode showed high stability and reusability therefore suggesting that the z-scheme Bi2WO6-CNP-TiO2 nanotube arrays electrode is an efficient photoanode for the degradation of pharmaceuticals in wastewater. Full article
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Review

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15 pages, 6795 KiB  
Review
Graphitic Carbon Nitride as Visible-Light Photocatalyst Boosting Ozonation in Wastewater Treatment
by Amarajothi Dhakshinamoorthy, Antón López-Francés, Sergio Navalon and Hermenegildo Garcia
Nanomaterials 2022, 12(19), 3494; https://doi.org/10.3390/nano12193494 - 06 Oct 2022
Cited by 2 | Viewed by 1496
Abstract
Light can boost ozone efficiency in advanced oxidation processes (AOPs), either by direct ozone photolysis with UV light or by using a photocatalyst that can be excited with UV-Vis or solar light. The present review summarizes literature data on the combination of ozone [...] Read more.
Light can boost ozone efficiency in advanced oxidation processes (AOPs), either by direct ozone photolysis with UV light or by using a photocatalyst that can be excited with UV-Vis or solar light. The present review summarizes literature data on the combination of ozone and the g-C3N4 photocatalyst for the degradation of probe molecules in water, including oxalic, p-hydroxybenzoic and oxamic acids as well as ciprofloxacin and parabens. g-C3N4 is a metal-free visible-light photocatalyst based on abundant elements that establishes a synergistic effect with ozone, the efficiency of the combination of the photocatalysis and ozonation being higher than the sum of the two treatments independently. Available data indicate that this synergy derives from the higher efficiency in the generation of hydroxyl radicals due to the efficient electron quenching by O3 of photogenerated conduction band electrons in the g-C3N4 photocatalyst. Given the wide use of ozonizers in water treatment, it is proposed that their implementation with g-C3N4 photocatalysis could also boost ozone efficiency in the AOPs of real waste waters. Full article
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