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18 pages, 1927 KiB

Open AccessArticle

Optimizing Photoelectrochemical UV Imaging Photodetection: Construction of Anatase/Rutile Heterophase Homojunctions and Oxygen Vacancies Engineering in MOF-Derived TiO₂

by Yueying Ma, Yuewu Huang, Ju Huang, Zewu Xu, Yanbin Yang, Changmiao Xie, Bingke Zhang, Guanghong Ao, Zhendong Fu, Aimin Li, Dongbo Wang and Liancheng Zhao

Molecules 2024, 29(13), 3096; https://doi.org/10.3390/molecules29133096 - 28 Jun 2024

Viewed by 164

Abstract

Self-powered photoelectrochemical (PEC) ultraviolet photodetectors (UVPDs) are promising for next-generation energy-saving and highly integrated optoelectronic systems. Constructing a heterojunction is an effective strategy to increase the photodetection performance of PEC UVPDs because it can promote the separation and transfer of photogenerated carriers. However, both crystal defects and lattice mismatch lead to deteriorated device performance. Here, we introduce a structural regulation strategy to prepare TiO₂ anatase-rutile heterophase homojunctions (A-R HHs) with oxygen vacancies (OVs) photoanodes through an in situ topological transformation of titanium metal–organic framework (Ti-MOF) by pyrolysis treatment. The cooperative interaction between A-R HHs and OVs suppresses carrier recombination and accelerates carrier transport, thereby significantly enhancing the photodetection performance of PEC UVPDs. The obtained device realizes a high on/off ratio of 10,752, a remarkable responsivity of 24.15 mA W⁻¹, an impressive detectivity of 3.28 × 10¹¹ Jones, and excellent cycling stability. More importantly, under 365 nm light illumination, a high-resolution image of “HUST” (the abbreviation of Harbin University of Science and Technology) was obtained perfectly, confirming the excellent optical imaging capability of the device. This research not only presents an advanced methodology for constructing TiO₂-based PEC UVPDs, but also provides strategic guidance for enhancing their performance and practical applications. Full article

(This article belongs to the Special Issue Recent Progress in Nanomaterials in Electrochemistry)

14 pages, 1757 KiB

Open AccessArticle

Promoting the Photoelectrochemical Properties of BiVO₄ Photoanode via Dual Modification with CdS Nanoparticles and NiFe-LDH Nanosheets

by Guofa Dong, Tingting Chen, Fangxia Kou, Fengyan Xie, Caihong Xiao, Jiaqi Liang, Chenfang Lou, Jiandong Zhuang and Shaowu Du

Nanomaterials 2024, 14(13), 1100; https://doi.org/10.3390/nano14131100 - 26 Jun 2024

Viewed by 417

Abstract

Bismuth vanadate (BiVO₄) has long been considered a promising photoanode material for photoelectrochemical (PEC) water splitting. Despite its potential, significant challenges such as slow surface water evolution reaction (OER) kinetics, poor carrier mobility, and rapid charge recombination limit its application. To address these issues, a triadic photoanode has been fabricated by sequentially depositing CdS nanoparticles and NiFe-layered double hydroxide (NiFe-LDH) nanosheets onto BiVO₄, creating a NiFe-LDH/CdS/BiVO₄ composite. This newly engineered photoanode demonstrates a photocurrent density of 3.1 mA cm⁻² at 1.23 V vs. RHE in 0.1 M KOH under AM 1.5 G illumination, outperforming the singular BiVO₄ photoanode by a factor of 5.8 and the binary CdS/BiVO₄ and NiFe-LDH/BiVO₄ photoanodes by factors of 4.9 and 4.3, respectively. Furthermore, it exhibits significantly higher applied bias photon-to-current efficiency (ABPE) and incident photon-to-current efficiency (ICPE) compared to pristine BiVO₄ and its binary counterparts. This enhancement in PEC performance is ascribed to the formation of a CdS/BiVO₄heterojunction and the presence of a NiFe-LDH OER co-catalyst, which synergistically facilitate charge separation and transfer efficiencies. The findings suggest that dual modification of BiVO₄ with CdS and NiFe-LDH is a promising approach to enhance the efficiency of photoanodes for PEC water splitting. Full article

(This article belongs to the Section Energy and Catalysis)

14 pages, 3348 KiB

Open AccessArticle

Enhanced Electricity Generation in Solar-Driven Photo-Bioelectrochemical Cells Equipped with Co₃(PO₄)₂/Mg(OH)₂ Photoanode

by Razieh Rafieenia, Mohamed Mahmoud, Mahmoud S. Abdel-Wahed, Tarek A. Gad-Allah, Anna Salvian, Daniel Farkas, Fatma El-Gohary and Claudio Avignone Rossa

Water 2024, 16(12), 1683; https://doi.org/10.3390/w16121683 - 13 Jun 2024

Viewed by 512

Abstract

We developed a solar-driven photo-bioelectrochemical cell (s-PBEC) employing a novel anode photocatalyst material (Co₃(PO₄)₂/Mg(OH)₂) intimately coupled with electrochemically active bacteria for synergic electricity generation from wastewater. An s-PBEC was inoculated with a natural microbial community and fed with synthetic wastewater to analyze the performance of the system for electricity generation. Linear sweep voltammetry indicated an increase in power output upon light illumination of the s-PBEC after 1 h, rising from 66.0 to 91.5 mW/m². The current density in the illuminated s-PBEC exhibited a rapid increase, reaching 0.32 A/m² within 1 h, which was significantly higher than the current density in dark conditions (0.15 A/m²). Shotgun metagenomic analysis revealed a significant shift in the microbial community composition with a more diverse anodic biofilm upon illumination compared to the microbial communities in dark conditions. Three unclassified genera correlated with the enhanced current generation in illuminated s-PBEC, including Neisseriales (16.31%), Betaproteobacteria (7.37%), and Alphaproteobacteria (5.77%). This study opens avenues for further exploration and optimization of the solar-driven photo-bioelectrochemical cells, paving the way for integrative approaches for sustainable energy generation and wastewater treatment. Full article

(This article belongs to the Special Issue Application of Biotechnology in Water Purification)

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14 pages, 2045 KiB

Open AccessFeature PaperReview

Advances in Functional Ceramics for Water Splitting: A Comprehensive Review

by Julia Exeler and Thomas Jüstel

Photochem 2024, 4(2), 271-284; https://doi.org/10.3390/photochem4020016 - 12 Jun 2024

Viewed by 436

Abstract

The global demand for sustainable energy sources has led to extensive research regarding (green) hydrogen production technologies, with water splitting emerging as a promising avenue. In the near future the calculated hydrogen demand is expected to be 2.3 Gt per year. For green hydrogen production, 1.5 ppm of Earth’s freshwater, or 30 ppb of saltwater, is required each year, which is less than that currently consumed by fossil fuel-based energy. Functional ceramics, known for their stability and tunable properties, have garnered attention in the field of water splitting. This review provides an in-depth analysis of recent advancements in functional ceramics for water splitting, addressing key mechanisms, challenges, and prospects. Theoretical aspects, including electronic structure and crystallography, are explored to understand the catalytic behavior of these materials. Hematite photoanodes, vital for solar-driven water splitting, are discussed alongside strategies to enhance their performance, such as heterojunction structures and cocatalyst integration. Compositionally complex perovskite oxides and high-entropy alloys/ceramics are investigated for their potential for use in solar thermochemical water splitting, highlighting innovative approaches and challenges. Further exploration encompasses inorganic materials like metal oxides, molybdates, and rare earth compounds, revealing their catalytic activity and potential for water-splitting applications. Despite progress, challenges persist, indicating the need for continued research in the fields of material design and synthesis to advance sustainable hydrogen production. Full article

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14 pages, 13846 KiB

Open AccessArticle

Advancing BiVO₄ Photoanode Activity for Ethylene Glycol Oxidation via Strategic pH Control

by Jun-Yuan Cui, Tian-Tian Li, Long Chen and Jian-Jun Wang

Molecules 2024, 29(12), 2783; https://doi.org/10.3390/molecules29122783 - 11 Jun 2024

Viewed by 380

Abstract

The photoelectrochemical (PEC) conversion of organic small molecules offers a dual benefit of synthesizing value-added chemicals and concurrently producing hydrogen (H₂). Ethylene glycol, with its dual hydroxyl groups, stands out as a versatile organic substrate capable of yielding various C1 and C2 chemicals. In this study, we demonstrate that pH modulation markedly enhances the photocurrent of BiVO₄ photoanodes, thus facilitating the efficient oxidation of ethylene glycol while simultaneously generating H₂. Our findings reveal that in a pH = 1 ethylene glycol solution, the photocurrent density at 1.23 V vs. RHE can attain an impressive 7.1 mA cm⁻², significantly surpassing the outputs in neutral and highly alkaline environments. The increase in photocurrent is attributed to the augmented adsorption of ethylene glycol on BiVO₄ under acidic conditions, which in turn elevates the activity of the oxidation reaction, culminating in the maximal production of formic acid. This investigation sheds light on the pivotal role of electrolyte pH in the PEC oxidation process and underscores the potential of the PEC strategy for biomass valorization into value-added products alongside H₂ fuel generation. Full article

(This article belongs to the Special Issue Advanced Materials in Photoelectrochemistry)

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15 pages, 5136 KiB

Open AccessArticle

Structural Refinement and Optoelectrical Properties of Nd₂Ru₂O₇ and Gd₂Ru₂O₇ Pyrochlore Oxides for Photovoltaic Applications

by Assohoun Fulgence Kraidy, Abé Simon Yapi, Mimoun El Marssi, Arbelio Penton Madrigal and Yaovi Gagou

Materials 2024, 17(11), 2571; https://doi.org/10.3390/ma17112571 - 27 May 2024

Viewed by 524

Abstract

High-performance photovoltaic devices require active photoanodes with superior optoelectric properties. In this study, we synthesized neodymium ruthenate, Nd₂Ru₂O₇ (NRO), and gadolinium ruthenate pyrochlore oxides, Gd₂Ru₂O₇ (GRO), via the solid-state reaction technique, showcasing their potential as promising candidates for photoanode absorbers to enhance the efficiency of dye-sensitized solar cells. A structural analysis revealed predominantly cubic symmetry phases for both materials within the Fd-3m space group, along with residual orthorhombic symmetry phases (Nd₃RuO₇ and Gd₃RuO₇, respectively) refined in the Pnma space group. Raman spectroscopy further confirmed these phases, identifying distinct active modes of vibration in the predominant pyrochlore oxides. Additionally, a scanning electron microscopy (SEM) analysis coupled with energy-dispersive X-ray spectroscopy (EDX) elucidated the morphology and chemical composition of the compounds. The average grain size was determined to be approximately 0.5 µm for GRO and 1 µm for NRO. Electrical characterization via I-V measurements revealed that these pyrochlore oxides exhibit n-type semiconductor behavior, with conductivity estimated at 1.5 (Ohm·cm)⁻¹ for GRO and 4.5 (Ohm·cm)⁻¹ for NRO. Collectively, these findings position these metallic oxides as promising absorber materials for solar panels. Full article

(This article belongs to the Special Issue Functionalized Ceramics and Their Composites: Preparation, Properties and Applications)

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15 pages, 4586 KiB

Open AccessArticle

Improving the Conversion Ratio of QDSCs via the Passivation Effects of NiS

by Edson Leroy Meyer and Mojeed Adedoyin Agoro

Nanomaterials 2024, 14(11), 905; https://doi.org/10.3390/nano14110905 - 22 May 2024

Viewed by 519

Abstract

To revolutionize the photochemical efficiency of quantum dots sensitized solar cells (QDSSCs) devices, herein, a passivation of the cells with multilayer material has been developed for heterojunctions TiO₂/NiS/MnS/HI-30/Pt devices. In this study, NiS and MnS were deposited on a photoanode for the first time as passivated photon absorbers at room temperature. The adoption of NiS as a passisvative layer could tailor the active surface area and improve the photochemical properties of the newly modified cells. The vibrational shifts obtained from the Raman spectra imply that the energy change is influenced by the surface effect, giving rise to better electronic conductivity. The electrochemical stability and durability test for the N/M-3 device slows down and remains at 8.88% of its initial current after 3500 s, as compared to the N/M-1 device at 7.20%. The disparity in charge recombination implies that both the outer and inner parts of the nanoporous material are involved in the photogeneration reaction. The hybridized N/M-3 cell device reveals the highest current density with a low potential onset, indicating that power conversion occurs more easily because photons tend to be adsorbed easily on the surface of the MnS. The Nyquist plot for N/M-1 and N/M-3 promotes the faster transport of electrolytic ions across the TiO₂/NiS/MnS, providing a good interaction for the electrolyte. The I-J Value of 9.94% shows that the passivation with the NiS layer promotes electron transport and enhances the performance of the modified cells. The passivation of the TiO₂ layer with NiS attains a better power conversion efficiency among the scant studies so far on the surface passivation of QDSCs. Full article

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10 pages, 4895 KiB

Open AccessArticle

Design and Preparation of Bending-Resistant Flexible All-Solid Dye-Sensitized Solar Cells

by Yan Li, Yu-Xuan Hou, Wei-Wu Dang, Li Liu, Jian-Hua Chen and Xian Gu

Coatings 2024, 14(4), 504; https://doi.org/10.3390/coatings14040504 - 18 Apr 2024

Viewed by 783

Abstract

All-solid-state flexible dye-sensitized solar cells will not only expand the application scenarios of solar cells but also significantly extend the lifetime of solar cells. However, improving their bending-resistant ability is still a great challenge. In this study, a bending-resistant flexible all-solid dye-sensitized solar cell was designed and prepared. Firstly, for the preparation of TiO₂ photoanode, the traditional nano-sized film has been replaced by dual-porous film with both nano and submicron pores, which can not only benefit the filling of the electrolyte but also supply the space for stress release. Secondly, for the filling of the Poly(vinylidene fluoride)/Poly(ethylene oxide)-based electrolyte, the solvent is removed by a vacuum method, and the electrolyte fibers forming in the submicron pores also show the potential for stress release. Lastly, combined with the advantages of the dual-porous TiO₂ film and the fast evaporation of the polymer electrolyte, the conversion efficiency of the solar cells remains constant after the 20,000 bending times. The study supplies a demonstration for the development of all-solid-state flexible dye-sensitized solar cells. Full article

(This article belongs to the Special Issue Advanced Polymer and Thin Film for Sustainable Energy Harvesting)

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14 pages, 5941 KiB

Open AccessArticle

Sustainable and Low-Cost Electrodes for Photocatalytic Fuel Cells

by Naveed ul Hassan Alvi and Mats Sandberg

Nanomaterials 2024, 14(7), 636; https://doi.org/10.3390/nano14070636 - 6 Apr 2024

Cited by 1 | Viewed by 921

Abstract

Water pollutants harm ecosystems and degrade water quality. At the same time, many pollutants carry potentially valuable chemical energy, measured by chemical oxygen demand (COD). This study highlights the potential for energy harvesting during remediation using photocatalytic fuel cells (PCFCs), stressing the importance of economically viable and sustainable materials. To achieve this, this research explores alternatives to platinum cathodes in photocathodes and aims to develop durable, cost-effective photoanode materials. Here, zinc oxide nanorods of high density are fabricated on carbon fiber surfaces using a low-temperature aqueous chemical growth method that is simple, cost-efficient, and readily scalable. Alternatives to the Pt cathodes frequently used in PCFC research are explored in comparison with screen-printed PEDOT:PSS cathodes. The fabricated ZnO/carbon anode (1.5 × 2 cm²) is used to remove the model pollutant used here and salicylic acid from water (30 mL, 70 μM) is placed under simulated sunlight (0.225 Sun). It was observed that salicylic acid was degraded by 23 ±0.46% at open voltage (OV) and 43.2 ± 0.86% at 1 V with Pt as the counter electrode, degradation was 18.5 ± 0.37% at open voltage (OV) and 44.1 ± 0.88% at 1 V, while PEDOT:PSS was used as the counter electrode over 120 min. This shows that the PEDOT:PSS exhibits an excellent performance with the full potential to provide low-environmental-impact electrodes for PCFCs. Full article

(This article belongs to the Section Environmental Nanoscience and Nanotechnology)

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13 pages, 3922 KiB

Open AccessArticle

Modulating Interfacial Charge Transfer Behavior through the Construction of a Hetero-Interface for Efficient Photoelectrochemical Water Splitting

by Li Xu, Jingjing Quan, Li Xu, Meihua Li, Chenglong Li, Saqib Mujtaba, Xingming Ning, Pei Chen, Qiang Weng, Zhongwei An and Xinbing Chen

Separations 2024, 11(4), 109; https://doi.org/10.3390/separations11040109 - 1 Apr 2024

Viewed by 940

Abstract

Surface-coupled transition metal oxyhydroxide (TMOOH) on semiconductor (SC)-based photoanodes are effective strategies for improving photoelectrochemical (PEC) performance. However, there is a substantial difference between the current density and theoretical value due to the inevitable interfacial charge recombination of SC/TMOOH. Here, we employ BiVO₄/FeNiOOH as a model, constructing the BiVO₄/MnO_x/CoO_x/FeNiOOH integrated system by introducing a novel hetero-interface regulation unit, i.e., MnO_x/CoO_x. As expected, the optimized integrated system demonstrates a photocurrent density as high as 5.0 mA/cm² at 1.23 V versus the reversible hydrogen electrode (RHE) under 1 sun AM 1.5G illumination, accompanied by 12-h stability. The detailed electrochemical analysis and intensity modulated photocurrent spectroscopy (IMPS) have confirmed that the high PEC performance mainly originates from the hetero-interface structure, which not only suppresses the interfacial charge recombination by accelerating the photogenerated hole transfer kinetics from BiVO₄ to FeNiOOH but promotes the kinetics of surface oxygen evolution reaction (OER). Notably, these findings can also be extended to other structures (CeO_x/CoO_x), reflecting its universality. This finding has provided a new insight into the highly efficient solar energy conversion in the SC/TMOOH system. Full article

(This article belongs to the Special Issue Adsorption and Solar-Powered Decomposition for Removing Pollutants)

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Abstract

In order to expand the application of bismuth vanadate (BiVO₄) to the field of photoelectrochemistry, researchers have explored the potential of BiVO₄ in catalyzing or degrading organic substances, potentially presenting a green and eco-friendly solution. A study was conducted to investigate the impact of electrolytes on the photocatalysis of benzyl alcohol by BiVO₄. The research discovered that, in an acetonitrile electrolyte (pH 9) with sodium bicarbonate, BiVO₄ catalyzed benzyl alcohol by introducing saturated V⁵⁺. This innovation addressed the issue of benzyl alcohol being susceptible to catalysis in an alkaline setting, as V⁵⁺ was prone to dissolution in pH 9 on BiVO₄. The concern of the photocorrosion of BiVO₄ was mitigated through two approaches. Firstly, the incorporation of a non-aqueous medium inhibited the formation of active material intermediates, reducing the susceptibility of the electrode surface to photocorrosion. Secondly, the presence of saturated V⁵⁺ further deterred the leaching of V⁵⁺. Concurrently, the production of carbonate radicals by bicarbonate played a vital role in catalyzing benzyl alcohol. The results show that, in this system, BiVO₄ has the potential to oxidize benzyl alcohol by photocatalysis. Full article

12 pages, 2321 KiB

Open AccessProceeding Paper

Effect of Titanium Oxide (TiO₂) on Natural Dyes for the Fabrication of Dye-Sensitized Solar Cells

by Isioma M. Ezeh, Omamoke O. E. Enaroseha, Godwin K. Agbajor and Fidelis I. Achuba

Eng. Proc. 2024, 63(1), 25; https://doi.org/10.3390/engproc2024063025 - 8 Mar 2024

Viewed by 488

Abstract

Titanium oxide (TiO₂) is the most widely used white pigment because of its brightness and very high reflective index, traits surpassed by only a few other materials; it has gained adequate ground in the fabrication of solar cells due to its wide band gap of 3.32 eV. Various natural dyes such as laali plant dye, zobo leaf dye and tomato seed dye act as sensitizers. This research intends to explore the effect of this titanium oxide on enhancing sensitivity in light harvesting by using dye-sensitized solar cell fabrication. Indium tin oxide, one of the transparent, conducting optical glasses, was chosen for the photoanode, on which the prepared titanium powder and the extracted dye were coated using the screen printing method. TiO₂ was screen printed over the TCO (ITO) or plain glass slide and annealed at 4000 °C for 3 min; then, the dyes were injected drop by drop and analysis was carried out for XRD and UV–optical. From the XRD results obtained for the laali dye, the XRD showed no prominent peaks and when improved by introducing titanium oxide, it showed the peaks as having a rutile nature which enhances light harvesting. The optical properties showed a transmittance edge at 350 nm which gradually increased as the wavelength increased with no visibility on the absorbance graph. For the tomato dye, a visible peak was observed and this increased with the addition of titanium oxide, while transmittance rose at 380 nm and fell at 550 nm, with no absorbance. The zobo dye showed no evidence of visible peaks and little change in the peak visibility with the addition of TiO₂ was observed, with the transmittance edge at 350 nm, maximum at 390 nm and constant with TiO₂ enhancement, and showing no visible absorbance properties. Laali and zobo are good transmittance materials, unlike the tomato dye which is a good absorbance material. Conclusively, TiO₂ is effective in dye-sensitized solar cell fabrication since there were visible changes within the scientific environment which further enhanced light harvesting. Full article

(This article belongs to the Proceedings of The 7th Mechanical Engineering, Science and Technology International Conference)

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